BSC 216 Final Exam Study Guide
BSC 216 Final Exam Study Guide BSC 216
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AampP II Final Exam Study Guide 10915 1024 AM Identify the secretions of the stomach and state their functions 0 Five main secretions by gastric glands 1 Hydrochloric Acid HCI o Activates pepsin and lingual lipase o Breaks up connective tissues and plant cell walls Helps liquefy food to form chyme o Converts ingested ferric ions Fe3 to ferrous ions Fe2 Fe2 absorbed and used for hemoglobin synthesis 0 Contributes to nonspecific disease resistance by destroying most ingested pathogens 2 Pepsin o Digests dietary proteins into shorter peptide chains Protein digestion is completed in the small intestine 3 Gastric Lipase 0 Along with lingual lipase it plays a minor role in digesting dietary fats Digests 1015 of dietary fats in the stomach The rest is digested in the small intestine 4 Intrinsic Factor 0 Essential to absorption of vitamin 312 by the small intestine Binds 812 and then intestinal cells absorb this complex by receptormediated endocytosis 0 Vitamin 812 is needed to synthesize hemoglobin Prevents pernicious anemia o Secretion of intrinsic factor is the only indispensible function of the stomach Digestion can continue if stomach is removed but 812 supplements will be needed 5 Chemical Messengers 0 Most are hormones that enter blood and stimulate distant cells 0 Others are paracrine secretions that stimulate neighboring cells 0 Several are peptides produced in both the digestive tract and the CNS gut brain peptides Secretincholecystokinin Explain how the stomach produces hydrochloric acid and pepsin Hydrochloric Acid HCI Production 0 Parietal cells produce HCI and contain carbonic anhydrase CAH CAH 0 C02 H20 gtH2C03 gtHC03 H o H is pumped into gastric gland lumen by H K ATPase Pump Antiporter uses ATP to pump H out and K in o HC03 exchanged for CI chloride shift from blood 0 Plasma Cl chloride ion pumped into the lumen of gastric gland to join H forming HCI Elevated HCO3 bicarbonate ion in blood causes alkaline tide increasing blood pH I39U I39WUIUUI I IUIT WITHIN quot139 I I39fm39 Fm Iv IvyWilm v39 wu VUF IIUIIS w I Blood Parietal cell Lumen of gastric gland l l Alkaline tide Cl39 Stomach acid H HK ATPaso Pepsin Production 0 Zymogens digestive enzymes secreted as inactive proteins Converted to active enzymes by removing some of their amino acids 0 Pepsinogen zymogen secreted by the chief cells Hydrochloric acid removes some of its amino acids and forms pepsin active form that digests proteins Autocatalytic effect as some pepsin is formed it converts more pepsinogen into more pepsin o Acidic environment needed to change pepsinogen to pepsin Acidic environment needed to change pepsinogen to pepsin r e V i Pa39iota39 quot Removed Dietary l peptide proteins we 30 J 39 viii Pepsin gt L active enzyme J u 3 J a Chief cell Popsinogon a 1 94quot 0 zymogen 3 6 3 a Partially digested protein Copyright if lhe MoGrewHill Companies Inc Permnssion required lior reproduction or display Gastric gland Describe the contractile responses of the stomach to food Swallowing center of medulla oblongata signals stomach to relax to get the stomach ready to accept food 0 Food stretches the stomach activating a receptiverelaxation response 0 It resists stretching briefly but relaxes to hold more food 0 Soon after receptiverelaxation response the stomach shows a rhythm of peristaltic contractions controlled by pacemaker cells in the longitudinal layer of the muscularis externa o Gentle ripple of contraction every 20 seconds churns and mixes food with gastric juice gastric juicemainly HCI o Contraction becomes stronger at the pyloric region 0 After 30 minutes or so these contractions become quite strong They churn the food mix it with gastric juice and promote its physical breakup and chemical digestion Churning is important to break up lipidsfat bolus o Antrum holds about 30 mL of chime 0 As a peristaltic wave passes down the antrum it squirts only about 3 mL of chyme into the duodenum at a time Allowing only a small amount into the duodenum enables the duodenum to n Neutralize the stomach acid a Digest nutrients little by little 0 If duodenum is overfilled it inhibits gastric motility because the duodenum needs time to digest and absorb the entering chyme 0 Typical meal emptied from stomach in 4 hours Less time if the meal is more liquid As long as 6 hours for a highfat meal Describe the three phases of gastric function 1 Cephalic phase stomach being controlled by the brain 0 CNS responds to sight smell taste or thought of food 0 Sensory and mental inputs converge on the hypothalamus Relays signals to medulla oblongata o fibers from medulla oblongata stimulate the enteric nervous system of stomach In turn 2 Gastric phase stomach controlling itself enteric nervous system 0 Period in which swallowed food and semidigested protein activate gastric activity Twothirds of gastric secretion occurs in this phase 0 Ingested food stimulates gastric activity in two ways By stretching the stomach I Activates short refex mediated through myenteric nerve plexus n Activates long refex mediated through the vagus nerves and the brainstem By increasing the pH of its contents 0 Gastric secretion is stimulated by 3 chemicals Acetylcholine ACh secreted by of both reflexes Histamine a paracrine secretion from enteroendocrine cells in the gastric glands n Up regulates HCI secretion Gastrin a hormone produced by the enteroendocrine G cells in pyloric glands n Up regulates HCI secretion 3 Intestinal phase stomach being controlled by small intestine 0 Stage in which the duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous re exes o Duodenum initially enhances gastric secretion but soon inhibits it Enhancing mechanisms n Stretching of the duodenum accentuates vagovagal reflex that stimulates the stomach I Peptides and amino acids in chyme stimulate G cells of the duodenum to secrete more gastrin which further stimulates the stomach Inhibitory mechanisms n Enterogastric reflex duodenum sends inhibitory signals to the stomach by way of the enteric nervous system and signals to the medulla oblongata triggered by acid and semidigested fats in the duodenum Inhibits vagal nuclei reducing vagal stimulation of the stomach Stimulate sympathetic neurons send inhibitory signals to the stomach n Chyme also stimulates duodenal enteroendocrine G cells to release secretin and cholecystokinin They stimulate the pancreas and gallbladder important in digestion in the small intestine 0 Also suppress gastric secretion Phases overlap and can occur simultaneously Copyright The MoGrawHill Companies Inc Permission required for reproduction or display Sensory and mental Input Long vagovagal re ex Sensory fibers Motor fibers Sympathetic nerve Intestinal gastri Secretln and CCK Histamine Gastrin Enterogastrlc myenterlc re ex re ex Ce hallc hase Gastric phase Intestinal hase s mulates Food stretches the stomach and briefl stimulates the gastric secretion even activates and stomach but then and the before food is swallowed These inhibit gastric secretion reflexes stimulate gastric and motility while the duodenum processes Key secretion Histamine and gastrin the chyme already in it Sympathetic nerve o sumu39auon also stimulate acid and enzyme fibers suppress gastric activity while vagal e 39 mm secretion parasympathetic stimulation of the n on vagovagal gastnc secretion stomach is now nmbmd Reduced 0quot no effect bu erbicarbonate ion Figure 2517 How is gastric activity activated and inhibited o Swallowing center of medulla oblongata signals stomach to relax to get the stomach ready to accept food 0 Food stretches the stomach activating a receptive relaxation response It resists stretching briefly but relaxes to hold more food 0 Soon after receptiverelaxation response the stomach shows a rhythm of peristaltic contractions controlled by pacemaker cells in the longitudinal layer of the muscularis externa Gentle ripple of contraction every 20 seconds churns and mixes food with gastric juice a gastric juicemainly HCI o If duodenum is overfilled it inhibits gastric motility because the duodenum needs time to digest and absorb the entering chyme Describe the digestive secretions and functions of the liver gallbladder and pancreas SECRETIONS FROM THE LIVER AND PANCREASE ARE VITAL TO THE DIGESTIVE PROCESS OF THE SMALL INTESTINE Liver gt secretes which contributes to digestion Gallbladder gt store and concentrate bile by absorbing water and electrolytes o DOES NOT PRODUCE BILE THE LIVER DOES THAT Bile yellow bc bilirubin bilirubin to urobilinogen brown in feces lecithin aid in fat digestion and absorption Gallstones may form if bile becomes too concentrated Pancreas Endocrine portion pancreatic isletssecrete insulin and qlucaqon Exocrine portion 99 of pancreassecrete 1200 to 1500 mL of pancreatic juice per day 0 Secretary acini release their secretion pancreatic juice into small ducts that converge on the main pancreatic duct 0 Pancreatic juice alkaline mixture of water enzymes zymogens sodium bicarbonate buffers HCI and other electrolytes o Acini secrete the enzymes and zymogens o Ducts secrete bicarbonate which buffers HCL arriving from the stomach Pancreatic duct runs lengthwise through the middle of the gland o Joins the bile duct at the hepatopancreatic ampulla o Hepatopancreatic sphincter controls release of both bile and pancreatic juice into the duodenum Accessory pancreatic duct is a smaller duct that branches from the main pancreatic duct opening independently into the duodenum bypassing the sphincter to allow pancreatic juice to be released into the duodenum even when bile is not 0 Pancreatic zymogens o Trypsinoqen Secreted into intestinal lumen Converted to trypsin by enterokinase an enzyme secreted by the mucosa of the small intestine Trypsin is autocatalytic so it converts trypsinogen into still more trypsin n Trypsin digests proteins 0 Chymotrypsinoqen Converted to chymotrypsin by trypsin n Chymotrypsin also digests proteins 0 Procarboxypeptidase Converted to carboxypeptidase by trypsin n Carboxypeptidase also helps with protein digestion o Other pancreatic enzymes nonzymogens o Pancreatic amylase digests starch o Pancreatic lipase digests fat 0 Ribonuclease and deoxyribonuclease digest RNA and DNA respectively Explain how hormones regulate secretion by the liver and pancreas Liver producessecretes bile Pancreas secretes pancreatic juice 0 3 stimuli are responsible for the release of pancreatic juice and bile 1 Acetylcholine ACh to secrete their enzymes during the cephalic phase of gastric control even before food is swallowed a While waiting for food to be swallowed the enzymes remain in acini and ducts until chyme enters the duodenum 2 Cholecystokinin CCK in response to arrival of fats in small intestine Stimulates pancreatic acini to secrete enzymes Strongly stimulates gallbladder Induces contractions of the gallbladder and relaxation of the hepatopancreatic sphincter causing discharge of bile into the duodenum 3 Secretin in response to acidic chyme arriving from the stomach Stimulates ducts of both liver and pancreas to secrete more sodium bicarbonate buffering action Raising pH to level pancreatic and intestinal digestive enzymes require to protect against HCI State how the mucosa of the small intestine differs from that of the stomach and explain the functional significance of the differences 0 The mucosae of the small intestine involves the submucosa and form the circular folds plicae circulares that effectively increase the surface area of the intestines The mucosa of the small intestine is the primary source for contact digestion due to 3 tissue layers 0 Circular folds cause chyme to flow in spiral path causing more contact with mucosa to promote more thorough mixing and nutrient absorption 0 Villi fingerlike projections that make mucosa look fuzzy o Microvilli fuzzy border on apical surface of each absorptive cell the brush border increases absorptive surface area Define contact digestion and describe where it occurs 0 Contact digestion chyme must contact the brush border for digestion to occur 0 The process of contact digestion is one reason that it is so important that intestinal contractions churn the chyme and ensure that it all contacts the mucosa Occurs in the microvilli on the apical surface of each absorptive cell in the small intestine Describe the types of movement that occur in the small intestine Segmentation movement in which stationary ringlike constrictions appear in several places along the intestine o It squeezes the chyme together to break it up to get it in contact with the sides of the intestine 0 Most common kind of intestinal contraction Peristalsis Gradual wavelike movement of contents toward colon o Peristaltic wave begins in duodenum and travels 1070 cm and dies out only to be followed by another wave starting further down the tract These successive overlapping waves of contraction are called a migrating motor complex a They milk the chyme toward the colon over a period of 2 hours Describe the locations of carbohydrate protein fat and nucleic acid digestion Name the enzymes involved in the digestion process see powerpoint flow chart AND Describe how each is absorbed by the small intestine see powerpoint flow chart 0 Carbohydrates and proteins are similarly absorbed by the small intestine Carbohydrate digestion o Locationsite of action mouth small intestine o Enzymes salivary amylase from salivary glands to mouth pancreatic amylase from pancreas to small intestine brush border enzymes from small intestine to small intestine o How absorbed by small intestine Monosaccharides glucose and galactose absorbed via cotransport with sodium ions Fructose passes via facilitated diffusion All monosaccharides enter the capillary blood in the villi and are transported to the liver via the hepatic portal vein 0 Protein digestion 0 Location stomach small intestine o Enzymes Pepsin from stomach glands in the presence of HCI to stomach Pancreatic enzymes from pancreas trypsin chymotrypsin carboxypeptidaseto small intestine Brush border enzymes from small intestine aminopeptidase carboxypeptidase and dipeptidase to small intestine o How absorbed by small intestine Amino acids are absorbed via cotransport with sodium ions They enter the capillary blood in the villi and are transported to the liver via the hepatic portal vein Starchhow plants store their glucose Text Foodstu We and source Site 0 action Path at absorption Carbohydrate keep adding amylase to continue digestion amylase break starch down into oligosac and disac brush border enzymes break down disac into monosac Protein digestion breaks bio proteins into smaller amino acids duodenum arnino acids go to blood stream oome m zymogens Everything you need to know about chemical digestion and absorption is here Soctlon 256 I embedded in cell membrane break small oolvoeptidesfoeotides into amino acids 0 Fat digestion 0 Location small intestine o Enzymes Pancreatic lipase from pancreas to small intestine o How absorbed by small intestine Fatty acids and monoglycerides enter the intestinal cells via diffusion They are combined with proteins withibn the cells and the resulting chylomicrons are extruded They enter the lacteals of the villi and are transported to the systemic circulation via the lymph in the thoracic duct Glycerol and shortchain fatty acids are absorbed into the capillary blood in the villi and transported to the liver via the hepatic portal vein 0 Nucleic acid digestion 0 Location small intestine o Enzymes Pancreatic ribonuclease deoxyribonuclease and brush border enzymes from pancreas nucleosidases and phosphatases to small intestine o How absorbed by small intestine Active transport via membrane carriers Absorbed into capillary blood in the villi and transported to the liver via the hepatic portal vei 39know where the enzymes come from Foodattm Enzyme and aouroo Site of action Path ol abaorptlon aided by bile salts to keep fat droplets small most fats are made up of triglycerides most fat dinestion in small intestine Nucleic acid digoation break down nucleotides into Everything You ne39ed to suboomnonentslohosphate etc know about chemlcal digestion and absorption is here Soctlon 256 I State the physiological significance of intestinal bacteria 0 Bacterial flora o Populate large intestine About 800 species of bacteria 0 They provide us with nutrients from our food that we are not equipped to extract on our own So they digest for example cellulose and other undigested carbohydrates that the body has no digestive enzymes for and we absorb the resulting sugars 0 Help in synthesis of vitamins B and K which are absorbed by the colon o A product of this bacteria is intestinal gas are formally known as flatus 0 Most is swallowed air but hydrogen sulfide indole and skatole produce odor Discuss the types of contractions that occur in the colon Haustral contractions o Occur every 30 minutes 0 A form of segmentation o Involuntary o Distension of a haustrum stimulates it to contract 0 Mass movements 0 Occur 13 times a day 0 Triggered by gastrocolic and duodenocolic reflexes Filling of the stomach and duodenum stimulates motility of the colon Moves residue for several centimeters with each contraction Explain the neurological control of defecation The process of defecation involves 2 involuntary reflexes The intrinsic defecation reflex mediated by myenteric plexus stretch signals travel through the plexus to the muscularis of the descendingsigmoid colon and rectum this activates a peristaltic wave that drives feces downward and relaxes the internal anal sphincter is a relatively weak reflex The parasympathetic defecation reflex a spinal reflex in which stretch signals are transmitted to spinal cord and motor signals return by way of the pelvic nerves to intensify peristalsis in the descendingsigmoid colon and rectum and to relax the internal anal sphincter However the external anal sphincter is controlled voluntarily by inhibitory signals sent from the brainstem 1 Filling of the rectum 2 Reflex contraction of rectum and relaxation of internal anal sphincter 3 Voluntary relaxation of external sphincter Abdominal contractions Valsalva maneuver increase abdominal pressure 0 Feces will fall away Senaoly there Internal anal aphlncter External anal aphlncter Feceaalretchlherachnmandalinulatealnlch reeeplon which Itanamll alpnala to the aplnal cord Aaplnal re ex mam contraction o he rectum The aplnal re ex alao relaxea the Internal anal aphlncler lmpulaee tom the Ireln ptevenl untimely Mecallon by keeping the external anal aphlncler contracted Delecallon ocwn only It tnla aphan alao telaxea What is the primary function of the alimentary canal gastrointestinal tractwhich organs are associated with this canal Define peristalsis How does it work 0 Peristalsis wave of muscular contraction that pushes the bolus ahead of it o Gradual wavelike movement of contents toward colon esophageal phase is a wave of involuntary contractions controlled jointly by the brainstem swallowing center and the myenteric plexus in the esophageal wall which moves food downward in the tract 0 Entirely involuntary reflex o Peristaltic wave begins in duodenum travels 10 to 70 cm and dies out o Followed by another wave starting further down the tract 0 Migrating motor complex successive overlapping waves of contraction 0 Milk chyme toward colon over a period of 2 hours Define segmentation How does it work 0 Segmentation movement in which stationary ringlike constrictions appear in several places along the intestine o Pacemaker cells in muscularis externa set rhythm of segmentation When most nutrients have been absorbed and little remains but undigested residue segmentation declines and peristalsis begins What39s the difference between a short and a long reflex Short reflex is mediated through myenteric nerve plexus Long reflex is mediated through the vaqus nerves and the brainstem What are the 5 main secretions of the stomach HCI Pepsin Gastric lipase Intrinsic factor Chemical messengers WPWP39 Within the gastric glands what is the function of the mucous neck cells parietal cells chief cells and enteroendocrine G cells 0 Mucous neck cells 0 Secrete mucus o Predominate in cardiac and pyloric glands o Concentrated at the neck of the gland Parietal cells 0 Found mostly in the upper half of the gland o Secrete HCI intrinsic factor and ghrelin hunger hormone 0 Chief cells 0 Most numerous o Secrete gastric lipase and pepsinogen o Dominate lower half of gastric glands 0 Absent in pyloric and cardiac glands Enteroendocrine G cells 0 Concentrated in lower end of gland o Secrete hormones and paracrine messengers that regulate digestion How is HCI made what are its functions 0 HCI is produced by parietal cells containing carbonic anhydrase CAH CAH 0 C02 H20 gtH2C03 gtHC03 H o H is pumped into gastric gland lumen by H K ATPase Pump Antiporter uses ATP to pump H out and K in o HC03 exchanged for CI chloride shift from blood 0 plasma Cl chloride ion pumped into the lumen of gastric gland to join H forming HCI Elevated HCO3 bicarbonate ion in blood causes alkaline tide increasing blood pH 0 Functions of HCI o Activates pepsin and lingual lipase o Breaks up connective tissues and plant cell walls Helps liquefy food to form chyme o Converts ingested ferric ions Fe3 to ferroud ions Fe2 Fe2 absorbed and used for hemoglobin synthesis 0 Contributes to nonspecific disease resistance by destroying most ingested pathogens How is pepsin made Functions 0 Pepsinogen a zymogen secreted by the chief cells 0 HCI removed som of its amino acids and forms pepsin active form that digests proteins 0 Autocatalytic effect as some pepsin is formed it converts more pepsinogen into more pepsin 0 Functions of pepsin o Digests dietary proteins into shorter peptide chains Completes protein digestion in the small intestine What is a zymogen Zymogens are digestive enzymes secreted as inactive proteins 0 Converted to active enzymes by removing some of their amino acids Understand the general function of gastric lipase intrinsic factor and chemical messengers Gastric lipase 0 Minor role in digesting dietary fats Intrinsic factor 0 Essential for vitamin 312 absorption by the small intestine Binds vitamin 812 and then intestinal cells absorb this complex by receptormediated endocytosis o 312 is needed to synthesize hemoglobin Prevents pernicious anemia o Secretion of intrinsic factor is the only indispensable function of the stomach Digestion can continue if stomach is removed gastrectomy but 812 supplements will be needed 0 Chemical messengers o Produced by enteroendocrine G cells 0 Most are hormones that enter blood and stimulate distant cells 0 Others are paracrine secretions that stimulate neighboring cells 0 Several are peptides produced in both the digestive tract and the central nervous system gutbrain peptides Secretincholecystokinin What are 3 mechanisms that the stomach uses to prevent corrosion of itself due to the very acidic environment 1 Mucous coat 0 Thick highly alkaline mucus resists action of acid and enzymes 2 Tight junctions 0 Between epithelial cells 0 Prevent gastric juice from seeping between them and digesting the connective tissue of the lamina propria and beyond 3 Epithelial cell replacement 0 Stomach epithelial cells live only 3 to 6 days 0 Sloughed off into the chyme and digested with the food 0 Replaced rapidly by cell division in the gastric pits Which nerve stimulates stomach activity Where in the brain does this nerve originate Vagus nerve originates from medulla oblongata Does the sympathetic nervous system inhibit or stimulate gastric secretion 0 The sympathetic system inhibits gastric secretion while the duodenum processes chyme already in it Which hormone produced by enteroendocrine cells stimulates enzyme and HCI secretion 0 Gastrin Can you distinguish between the cephalic gastric and intestinal phases of the digestive process 1 Cephalic phase 0 Stomach controlled by brain 0 CNS responds to sight smell taste or thought of food 0 Sensory and mental inputs converge on the hypothalamus Relays signals to medulla oblongata o Vagus nerve fibers from medulla oblongata stimulate the enteric nervous system of stomach 2 Gastric phase 0 Stomach controlling itself 0 Period in which swallowed food and semidigested protein activate gastric activity 0 23 of gastric secretion occurs 0 Ingested food stimulates gastric activity in two ways By stretching the stomach I Activates short reflex mediated through myenteric nerve plexus n Activates long reflex mediated through the vagus nerves and the brainstem By increasing the pH of its contents Gastric secretion is stimulated by 2 chemicals acetylcholine ACh histamine gastrin 3 Intestinal phase 0 Stomach being controlled by small intestine 0 Stage in which the duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous re exes o Duodenum initially enhances gasdtric secretion but soon inhibits it o Inhibits it by Enterogastric reflex sending inhibitory signals What are the 3 divisions of the small intestine Duodenum 0 First division to receive stomach contents pancreatic juice and bile from pyloric valve 0 Site Of Stomach acid neutralization Emulsification of fats by bile acids Inactivation of pepsin by increased pH Chemical digestion taken over by pancreatic enzymes Duodenal glands in submucosa that secrete an abundance of bicarbonaterich mucus to neutralize stomach acid and shield the mucosa from its erosive effects 0 Jejunum 0 Rich blood supply gives it a red color a lot of absorption 0 Region where most digestion and nutrient absorption occurs Ileum 0 Less vascular less muscular paler pink color less absorption 0 Peyer patches immune surveillance of pathogens in the small intestine Which sphincter controls the flow of bile and pancreatic juice into the duodenum Hepatopancreatic sphincter What are adaptations of the small intestine for purposes of enhancing absorption of nutrients Large internal surface area 0 Brush border enzymes Intestinal crypts The tissue layers circular folds villi microvilli What is the primary function of the large intestine 0 Reception reduction and elimination of feces Eliminate feces by defecation Absorbs water and salts from indigestible residue What is the role of commensal bacteria in our large intestine They provide us with nutrients from our food that we are not equipped to extract on our own 0 So they digest for example cellulose and other undigested carbohydrates that the body has no digestive enzymes for and we absorb the resulting sugars Help in synthesis of vitamins B and K which are absorbed by the colon How does the defecation reflex work 0 The intrinsic defecation reflex mediated by myenteric plexus stretch signals travel through the plexus to the muscularis of the descendingsigmoid colon and rectum this activates a peristaltic wave that drives feces downward and relaxes the internal anal sphincter is a relatively weak reflex The parasympathetic defecation reflex a spinal reflex in which stretch signals are transmitted to spinal cord and motor signals return by way of the pelvic nerves to intensify peristalsis in the descendingsigmoid colon and rectum and to relax the internal anal sphincter 1 Filling of the rectum 2 Reflex contraction of rectum and relaxation of internal anal sphincter 3 Voluntary relaxation of external sphincter Identify the most fundamental biological distinction between male and female 0 Males produce sperm 0 Females produce eggs Define primary sex organs secondary sex organs and secondary sex characteristics 0 Primary sex organs organs that produce gametes o Gonads testes or ovaries 0 Secondary sex organs Organs other than the gonads that are necessary for reproduction o Male system of ducts glands penis delivers sperm cells 0 Female uterine tubes uterus and vagina receive sperm and harbor developing fetus 0 Secondary sex characteristics 0 Features that further distinguish the sexes and play a role in mate attraction 0 Develop at puberty to attract a mate 0 Both sexes pubic and axillary hair and their associated scent glands and the pitch of the voice 0 Male facial hair coarse and visible hair on the torso and limbs relatively muscular physique o Female distribution of body fat breast enlargement and relatively hairless appearance of the skin Explain the role of the sex chromosomes in determining sex 0 Sex of child is determined by the type of sperm that fertilizes the mother s egg 0 Xcarrying sperm fertilizes the eggfemale o Ycarrying sperm fertilizes the eggmale Explain how the Y chromosome determines the response of the fetal gonad to prenatal hormones In the first 7 weeks following fertilization a fetus is sexually undifferentiated as to which sex it will become Its gonads begin to develop at 5 to 6 weeks as gonadal ridges The gonads produced will be according to which sex chromosome X or Y that was present in the sperm Adjacent to the ridges are two ducts the mesonephric wolffian duct and the paramesonephric mullerian duct In males the mesonephric ducts develop into the reproductive tract and the paramesonephric ducts degenerate In females the opposite occurs 0 SRY genesexdetermining region of Y chromosome 0 In males codes for a protein testesdetermining factor TDF that initiates development of testes 0 Begin to secrete testosterone at 8 to 9 weeks 0 Stimulates mesonephric ducts to develop into the male anatomy 0 At same time the testes secrete miillerianinhibiting factor MIF causing degeneration of the paramesonephric ducts Androgens eg testosterone 0 Development of male reproductive organs 0 Development of secondary sexual characteristics 0 More prevalent in males 0 Estrogens estradiol amp Progestins progesterone o Pubertal development of female reproductive traits o Estrogens involved in masculinization too NOTE Estrogen levels are always high in pregnancy 0 If estrogen was the hormone that directed female development then all fetuses would be feminized 0 Female development occurs in absence of androgen hormones 0 Male development is based on estrogen AND testosterone Identify which of the male and female external genitalia are homologous to each other 0 Male and female organs that develop from the same embryonic structure are homologous o Penis is homologous to the clitoris o Scrotum is homologous to the labia majora Describe the descent of the gonads and explain why it is important 0 Both male and female gonads initially develop high in the abdominal cavity near the kidneys and migratedescend into the pelvic cavity ovaries or scrotum testes Gubernaculum a connective tissue cord extends from the gonad to the floor of the pelvic cavity in the embryo o Shortens over time as it guides migrationdescent in males and females 0 Descent of testes covers a substantial distance 0 As the m gubernaculum continues to grow it passes between the internal and external abdominal oblique muscles and into the scrotal swelling Independently of the migration of the testes the peritoneum also develops a fold that extends into the scrotum called the vaginal process The gubernaculum and vaginal process create a path of low resistance through the groin anterior to the pubic symphysis called the inguinal canal o Ie TESTIS Pass through inguinal canal around 7 months Position of testes becomes important later in spermatogenesis Testes accompanied by elongating testicular arteries and veins lymphatic vessels nerves spermatic ducts and extensions of internal abdominal oblique muscle 3month fetus 8month fetus 1monthold infant Parietal peritoneum Muscular wall Epididymis of abdomen Testis lnguinal canal Closed proximal portion of vaginal process Spermatic cord Tunica vaginalis Vaginal process Vaginal process Scrotum Gubemaculum A l o In females the gubernaculum extends from the inferior pole of the ovary to the labiosacral fold The ovaries eventually lodge just inferior to the brim of the lesser pelvis o Ie OVARIES Scrotal swelling penis Gubemaculum o Descend to lesser extent 0 Lodge on inferior brim of the lesser pelvis o Gubernaculum becomes a pair of ligaments that supports the ovary and the uterus Describe temperature regulation in the scrotum Testes cannot produce sperm at core body temperature of 37 degrees Celsius 0 Temperature must be held at about 35 degrees Celsius Scrotum has three mechanisms to regulate temperature of the testes 1 Cremaster muscle Strips of the internal abdominal oblique muscle a Cold temperaturesgtcontracts and draws testes upward toward body a Warm temperaturesgt relaxes suspending testes further from the body cre because it regulates temperature of testes at both cold AND warm temperatures 2 Dartos muscle Subcutaneous layer of smooth muscle a Cold temperaturesgtcontracts wrinkling the scrotum holding testes against warm body a Reduces heat loss 3 Pampiniform plexus An extensive network of veins from the testes that surrounds the testicular artery and spermatic cord n Countercurrent heat exchanger without the pampiniform plexus warm arterial blood would heat the testis and inhibit sperm production a Removes heat from the descending arterial blood a By the time it reaches the testis the blood is 15 25 degrees Celsius cooler ger a s Heat t the a man nding a s the Arterial blood cools as it descends Testis Venous blood rries Heat away as it ascends Section 27 Describe the pathway taken by a sperm cell from its formation to its ejaculation naming all the passages it travels Seminiferous tubule o Sperm development Rete testis 0 Where sperm partially mature Efferent ductules o Ciliated to move sperm Headbody of epididymis 0 Where sperm my mature 20 clays Tail of epididymis o Sperm storage for 4060 clays o Reabsorbed if not used Ductus vas deferens o Vasectomy sever the vas deferensbirth control Ampulla 0 End that unites with seminal vesicle Ejaculatory duct 0 Last of spermatic ducts Urethra 0 Where sperm actively swim mmommmrmm Wmmvmo39m 5 Tall of l 39 columnIs M Figure 279b CowIt C Tm MLCIM HH Gamams lfnL PunMl maul tn rmcmwau om Unto E 7 Ampulla Scum gquot mid 39 8 Ejaculatory duct Proust gland 39 0 mm 339 d Bulbourethral g 1 S I I e 2 r l l I I 9 Urethra r State the names locations and basic functions of the male accessory reproductive glands 1 Seminal vesicles 0 Secretes to ejaculatory duct 0 Forms 60 of semen 2 Prostate gland o Secretes to prostatic urethra 0 Thin milky secretion forms 30 of semen 3 Bulbourethral glands secretes to urethra 0 During sexual arousal they produce a clear slippery fluid that lubricates the head of the penis in preparation for intercourse 0 Most importantly the clear slippery fluid it produces protects the sperm by neutralizing the acidity of residual urine in the urethra 0 About 10 of semen Understand meiosis and the outcome of this cell division 0 Meiosis is a type of cell division that yields haploid 1N cells gametes like sperm and egg 0 Occurs in 2 stages Meiosis I amp Meiosis II o Meiosis I Chromosomes replicate in preparation for division Synapses formed between homologous chromosomes 9 tetrads Crossingover recombination occurs maternal and paternal chromosomes swap genetic material Homologous chromosomes drawn to opposite ends of cell during anaphase Haploid chromosome number results reduction division of meiosis bc diploid9haploid o Meiosis II Same as basic cell division mitosis except chromosomes are NOT replicated at the start 0 HAPLOID DAUGHTER CELLS RESULT o In nearly all living organisms except bacteria there are two forms of the cell division meiosis and mitosis Mitosis is the basis for division of the single celled fertilized egg growth of the embryo and all postnatal growth and tissue repair Meiosis is for division of gametes o Meiosis is split into four stages Prophase Metaphase Anaphase and Telophase But with two cycles 0 Properties of Meiosis 2 cell divisions in succession n reduces the of chromosomes by half the parent cell will be diploid 2n with 46 chromosomes and the daughter cell will be haploid n with 23 chromosomes n in the early stages of meiosis chromosomes of each homologous pair join and exchange portions of their DNA This creates new combinations of genes so the chromosomes we pass onto our offspring are not the same ones that we inherited from our parents a In meiosis each parent ce produces four daughter cells from a single diploid cell Spermatogenesis 1 4 Oogenesis 1 1 two poar bodies are shed o Meiosis reduces chromosomal number by half from diploid haploid 0 Through crossing over meiosis yields genetic variability No 2 gametes are alike Describe the sequence of cell types in spermatogenesis and relate these to the stages of meiosis At puberty the rise of testosterone secretion reactivates spermatogenic ces spermatogonia in epithelial walls of seminiferous tubules to begin spermatogenesis by dividing through mitosis Spermatogonia diploid undergo mitosis to yield two daughter cells 0 One daughter cell from each division remains nearis stored in the walls of seminiferous tubules which is the Type A daughter cellspermatogonium 2n Type A serve as a lifetime supply of spermatogonia n Ie They maintain a germ line of spermatogonia 0 Type B daughter cellspermatogonium is the daughter ce destined to become sperm so it migrates sighty away from the wall on its way to producing sperm 0 Type B undergoes growth by enlarging and becoming a primary spermatocyte which then undergoes meiosis I to give rise to 2 equalsize HAPLOID amp genetically unique secondary spermatocytes The two secondary spermatocytes undergo meiosis II dividing into 2 nonmotile Spermatids a total of 4 for each spermatogonium Spermatogonia 2n 1 Mitosis Type A daughter cells 2n maintain germ line spermatogonia Type 3 daughter cells 2n destined to become sperm Growth Primary spermatocyte 2n Meiosis Secondary spermatocyte 1 n Meiosis II Spermatids nonmotile Tight junction between auatentacular calla Cyloplaam ol adjaoanl Sualanlacular aualanlacular calla cal nuclaua Sparmalogonlum atom call Baaal lamina IU quot v Q Daughter call type A Spormalogonlu em aquot aparmalogonlum romaina r 39 I l at baaal lamina aa a Miloaia precursor call 39 V Daughlar call lypo 3 v 4 lt i atomquot oparmalogonlum EMquot Mom lo adlumlnal 39 moloola I V compartment quot 0 Primary aparmalocyla Maloala l complalod l aala Moioala ll Meiosis early W l Spermiogenesis late apermalogeneaia I aaaal comporlmanl I Adlumlnal comparlmanl What happens during spermiogenesis Spermiogenesis is production of tailed sperm from spermatids Ie Production of motile sperm Acrosomal enzymes packaged by Golgi apparatus Acrosome is formed at anterior end of nucleus Microtubules arrange to begin forming the agellum Mitochondria multiply rapidly and position themselves along agellum WHY 6 Excess cytoplasm is removed streamlining Mature sperm is born About 70 days from being a type B spermatocyte wwswwe Mitochondria Golgi apparatus Acrosomal 4 WHY because vesncle Acrosome Nucleus getting rid of cytoplasm makes it lighter g gt so it is more motile t V J Spermatid Centrioles V Microtubules nucleus L Mid iece Head Fla ellum p a 9 Kquot LExcessJ a cytoplasm l Section 274 Why pack enzymes into the acrosome The enzymes are used to penetrate the egg to fertilize if the sperm is successful Why are mitochondria very abundant around the flagellum 0 They produce the ATP energy needed for the beating of the tail when the sperm migrates up the female reproductive tract 0 Ie For motility Describe the composition of semen and functions of its components 0 Semen seminal fluid is fluid expelled during male orgasm 0 Composition of Semen o 25 mL of fluid expelled during ejaculation o 60 seminal vesicle fluid 0 30 prostatic fluid 0 10 sperm and spermatic duct secretions normal sperm count50 to 120 millionmL lower than 2025 millionmL infertility 0 Function of Semen Components 0 Seminal vesicle fluid Assists in providing an energy source for sperm motility by being secreted to provide fructose and other sugars to the mitochondria of the sperm 0 Prostatic fluid Acts as a buffer to vaginal acidity to elevate pH from 3575 for sperm motility Contributes to stickiness to promote fertilization because after ejaculation serine protease from the prostatic fluid breaks down seminogelin and liquefies the semen o Sperm and spermatic duct secretions Bulbourethral gland secretions n Lubricate head of penis for intercourse n Neutralize acidic residual urine so sperm will survive through urethra Describe the blood and nerve supply to the penis AND explain how these govern erection and ejaculation 0 Internal pudendal penile artery enters root of the penis and divides in two Dorsal artery travels under skin on dorsal surface a Supplies blood to skin fascia and corpus spongiosum Deep artery travels through the core of the corpus cavernosa n Gives off smaller helicine arteries that penetrate the trabeculae and enter lacunae a When the deep artery dilates the lacunae fill with blood and the penis becomes ERECT9 ERECTION a When penis is flaccid most blood comes from the dorsal artery n Many anastomoses unite deep and dorsal arteries THERE ARE MANY ANASTOSOMES UNITING THE DEEP AND DORSAL ARTERIES SO NEITHER OF THEM IS THE EXCLUSIVE SOURCE OF BLOOD TO ANY ONCE ERECTILE TISSUE Deep dorsal vein drains blood from penis o The penis is richly innervated by sensory and motor nerve fibers 0 The glans has an abundance of tactile pressure and temperature receptors 0 Dorsal nerve of penis and internal pudendal nerves lead the receptors to integrating center in sacral spinal cord 0 Both autonomic and somatic motor fibers carry impulses from integrating center to penis Sympathetic fibers pass through the hypogastric and pelvic plexuses and innervate the penile arteries trabecular muscle spermatic ducts and accessory glands a They dilate the penile arteries and can induce an erection even when the sacral region is damaged a They also initiate erection in response to input from the special senses and to sexual thoughts Parasympathetic fibers extend from sacral region of spinal cord through the pudendal nerves to the arteries of the penis I They are involved in an autonomic reflex arc that causes an erection in response to direct stimulation of the penis stimuli Pelvic nerve gt gt Effemnt ras thetic Spinal comd sacral pa gyms Q EM Emm md hutIlla sympathetic Spinal cord L1 L2 signals 39 Figure 271 Afferent signals Mullsummation sympathetic Signa39s 39 m mm mm muon m MWMMM mumum Spinal cord 1 54 E39lerent mm mm mm and 59mm mm m mmrootot sugnals m m I upono mm m gt gt Efferent sympathetic Spinal cord L1L2 signals Can you describe the neural control of male stages of excitement orgasm and resolution see fig 2718 Excitement o Sacral spinal cord 0 Efferent parasympathetic nerves pelvic nerve o Characterized by vasocongestion swelling of the genitals with blood myotonia muscle tension and increases in heart rate blood pressure and pulmonary ventilation Bulbourethral glands secrete their fluid Initiated by a broad spectrum of erotic stimuli O O Causes dilation of deep arteries and filling of lacunae with blood 0 Vasocongestion can also cause the testicles to become 50 larger during excitement Plateau o The variables such as respiratory rate heart rate and blood pressure stay increased 0 Marked increased vasocongestion and myotonia o Lasts for a few seconds or a few minutes before orgasm Orgasm or climax o Spinal cord LlL2 o Efferent parasympathetic nerves 0 A short but intense reaction that is usually marked by the discharge of semen o Lasts 315 seconds 0 Heart rate BP and breathing greatly elevate Ejaculation 2 stages 0 Afferent signals 9 spinal cord LlS4 9 Efferent somatic signals 9 Efferent sympathetic signals 0 Emission sympathetic nervous system stimulates peristalsis which propels sperm through ducts as glandular secretions are added 0 Expulsion semen in urethra activates somatic and sympathetic reflexes that stimulate muscular contractions that lead to expulsion Sympathetic reflex constricts internal urethral sphincter so urine cannot enter the urethra and semen cannot enter the bladder 0 Resolution 0 Spinal cord LlL2 Efferent sympathetic signals Body variables return to preexcitement state Sympathetic signals constrict internal pudendal artery and reduce blood flow to penis Penis becomes soft and flaccid detumescence 0 Cardiovascular and respiratory responses return to normal 000 0 What is the genotype of a female Male 0 Female XX Male XY On which chromosome does the SRY gene exist 0 The SRY gene is on the Y chromosome Which substance does the SRY gene code for o In males the SRY gene codes for a protein called testes determining factor TDF that initiates development of testes How does SRY testesdetermining factor and testosterone contribute to sexual differentiation In other words what do these substances do to a sexually undifferentiated individual 0 SRY codes for TDF TDF initiates development of testes Testosterone stimulates mesonephric ducts to develop into the male anatomy 0 SO THEY INITIATE DEVELOPMENT OF TESTES IN A SEXUALLY UNDIFFERENTIATED INDIVIDUAL Which kinds of neurons associated with the penis or clitoris are activated when you think or engage erotically To which regions of the central nervous system do these neurons send signals about arousal Thinking erotically 0 Visual mental and other stimuli is sent to sacral spinal cord to stimulate pelvic nerve with efferent parasympathetic signals 0 Engaging erotically o Stimulation of genital region especially glans sent through internal pudendal nerve to sacral spinal cord to communicate with the pelvic nerve by sending efferent parasympathetic signals Does the parasympathetic or sympathetic nervous system control arousal eg engorgement erection lubrication of penisclitoris Predominantly the parasympathetic nervous system 0 Parasympathetic nervous system controls arousal in response to m stimulation of the penis Sympathetic nervous system controls arousal in response to input from the special senses and to sexual thouqhts Which kinds of neurotransmitters are involved in relaxing arterial smooth muscle in the penisclitoris to stimulate arousal Nitric oxide NO Efferent parasympathetic signals Which kinds of neurons associated with the penisclitoris will trigger orgasmejaculation Pudendal neurons 0 Sympathetic nervous system 0 Sympathetic and somatic reflexes What 3 things act to regulate temperature in the scrotum What do each of these things do 1 Cremaster muscle 0 Strips of the internal abdominal oblique muscle 0 Cold temperaturesgtcontracts and draws testes upward toward body 0 Warm temperaturesgt relaxes suspending testes further from the body 2 Dartos muscle 0 Subcutaneous layer of smooth muscle 0 Cold temperaturesgtcontracts wrinkling the scrotum holding testes against warm body 0 Reduces heat loss 3 Pampiniform plexus 0 An extensive network of veins from the testes that surrounds the testicular artery and spermatic cord 0 Countercurrent heat exchanger without the pampiniform plexus warm arterial blood would heat the testis and inhibit sperm production 0 Removes heat from the descending arterial blood 0 By the time it reaches the testis the blood is 15 25 degrees Celsius cooler Although estrogen is involved in development of female reproductive traits during puberty why is estrogen not directly responsible for female fetal development 0 Because estrogen is not specific to females Male development is based on testosterone AND estrogen Female development is based on ABSENCE of testosteroneandrogen hormones 0 So if estrogen was the hormone that directed the female development all fetuses would be feminized What are the 3 main events during spermatogenesis 0 Remodeling 0 Reduction Shuffling of genes Can you describe the steps of spermatogenesis in detail see notes 0 Spermatogenesis is the process of sperm production in seminiferous tubules Involves 3 principle events 0 1 Remodeling of large germ cells into small mobile sperm cells with flagella o 2 Reduction of chromosome number by onehalf in sperm cells unites with egg to return to 46 o 3 Shuffling of genes so new combinations exist in the sperm that are different from the parents Ensures genetic variation in the offspring Four sperm cells produced from one germ cell by meiosis Begins at puberty and continues throughout life 0 Meiosis I amp II ce division that yields haploid 1n cells Spermatogonia 2n 1 Mitosis Type A daughter cells 2n maintain germ line spermatogonia Type 3 daughter cells 2n destined to become sperm Growth Primary spermatocyte 2n Meiosis I Secondary spennatocyte 1 n Meiosis II Spermatids nonmotile How does semen promote fertilization Stickiness of semen promotes fertilization o Arises when the clotting enzyme from the prostate activates proseminogelin converting it to a sticky fibrinlike protein seminogelin o Seminogelin entangles the sperm sticks to the inner wall of the vagina and cervix and ensures that semen does not drain back into vagina o 20 to 30 minutes after ejaculation serine protease from prostatic fluid breaks down seminogelin and liquefies the semen o Sperm become active through elevated pH and an energy source 0 Prostaglandins of the semen thin the mucus of the cervix and may stimulate peristaltic waves in uterus and uterine tubes that help to spread semen through the female reproductive tract What are the male and female gonads Gametes 0 Male gonadstestes gametessperm 0 Female gonadsovaries gameteseggovum What is the primary goal of the reproductive systems 0 Produce viable offspring What is the external sac in which the testes can be found 0 Scrotum Can you track the flow of sperm from the seminiferous tubule to the epidiymis Seminiferous tubule Rete testis Efferent ductules Epididymis Can you track the movement of sperm from the epidiymis to the outside of the body ie through which ducts does it pass 0 Epididymis9Ductus vas deferens Ampulla Ejaculatory duct9Urethra Why house the testes outside of the body 0 Because they have to be at a temperature of 35 degrees celsius in order to produce sperm and the body is at 37 degrees celsius o For temperature regulation to enable sperm production What is the function of the seminiferous tubules 0 Site of spermatogenesis sperm production Are mature or immature sperm exported from the seminiferous tubule to the epididymis Immature sperm are exported from the seminiferous tubule to the epididymis Sperm maturation occurs in the epididymis What causes the movement of sperm from the epididymis to the ductus vas deferens and urethra Movement of sperm from the epididymis to the ductus vas deferens and urethra is due to the 2 stages of ejaculation 0 Emission Sympathetic nervous system stimulates peristalsis in the smooth muscle of the ductus deferens which propels sperm from the tail of the epididymis along the ductus and into the ampulla Contractions of the ampulla propel the sperm into the prostatic urethra and contractions of smooth muscle in the prostate gland force prostatic fluid into the urethra Secretions of the seminal vesicles join the semen soon after the prostatic secretion 0 Expulsion Semen in urethra activates somatic and sympathetic reflexes that stimulate muscular contractions that lead to expulsion Sensory signals travel to the spinal cord via the internal pudendal nerve and reach an integrating center in the upper lumbar region Sympathetic nerve fibers carry motor signals from here out to the prostate gland and seminal vesicles causing the smooth muscle in their walls to express more fluid into the urethra Sympathetic reflex also constricts internal urethral sphincter so urine cannot enter the urethra and semen cannot enter the bladder Somatic motor signals travel to the bulbospongiosus which envelops the root of the penis and undergoes 5 or 6 strong spasmodic contractions that compress the urethra and forcibly expel the semen What happens to unused sperm Where are sperm stored and how long 0 Unused sperm is reabsorbed Sperm are stored in the tail of the epididymis for 4060 days What are the 3 accessory glands associated with the male reproductive system Can you explain the functions of at least 3 substances secreted by these glands with respect to sperm survival or motility through the female reproductive tract 1 Seminal vesicles secretes to ejaculatory duct 0 Forms 60 of semen Seminal vesicle fluid acts as an energy source for sperm by providing fructose and other sugars to the mitochondria of the sperm 2 Prostate gland secretes to prostatic urethra 0 Thin milky secretion forms 30 of semen Prostatic fluid buffers vaginal acidity from pH 35 to 75 for sperm motility 3 Bulbourethral glands secretes to urethra 0 During sexual arousal they produce a clear slippery fluid that lubricates the head of the penis in preparation for intercourse 0 Clear slippery fluid protects the sperm by neutralizing the acidity of residual urine in the urethra so they will survive 0 About 10 of semen What does it mean to be diploid How many chromosomes do we have Diploid 2N2 sets of 23 homologous chromosomes one maternal and one paternal46 chromosomes 0 We have 46 chromosomes bc we have 23 pairs of chromosomes Which process reduces the diploid cell to haploid gametes like sperm and egg Meiosis During Meiosis I which process creates new genetic combinations Prophase I o Crossing over Why is Meiosis I called reduction division 0 Because cells go from being diploid to haploid 0 Reduced number of chromosomes Ie Cuts number of chromosomes in half What happens in Meiosis II How many cells result from Meiosis II Equational division 0 4 haploid cells result Describe the structures of the ovary uterine tubes uterus and vagina Ovaries 0 Female gonads that produce egg cells ova and sex hormones Almondshaped and nestled in the ovarian fossa Like testes they are lined with a tunica albuginea capsule They have an outer cortex where germ cells develop They have an inner medulla which is occupied by major arteries and veins 0 Ovaries lack ducts so they are endocrine glands so instead each egg develops in its own fluid filled follicle o Ovulation bursting of the follicle releasing the egg 0 Uterine Tubes 0 AKA oviduct or fallopian tube 0 Canal about 10 cm long from ovary to uterus OOOO 0 It is a muscular tube lined with ciliated cells highly folded into longitudinal ridges Uterus 0 Thick muscular chamber that opens into the roof of the vagina Usually tilts forward over the urinary bladder Harbors the fetus provides a source of nutrition and then expels the fetus at the end of its development Pearshaped and made up of the fundus body and cervix 3 muscle layers outermost inner perimetrium myometrium endometrium Vagina O O 0 Birth canal 8 to 10 cm distensible muscular tube allows for discharge of menstrual fluid receipt of penis and semen and birth of baby Has no glands Transudation lubricates vagina vaginal sweatingquot n Serous fluid through its walls and by mucus from the cervical gland above it Transverse friction ridges vaginal rugae at lower end Mucosal folds form hymen across vaginal opening Identify the ligaments that support the female reproductive organs 0 Ovarian ligament Suspensory ligament Round ligament 0 Cardinal ligament Uterosacral ligament Name the hormones that regulate female reproductive function and state their roles Gonadotropinreleasing hormone GnRH triggers puberty FSH stimulates ovarian follicles and they begin to secrete estrogen progesterone inhibin and a small amount of androgen Estrogens are feminizing hormones O Estradiol estriol estrone Describe the principal signs of puberty Thelarche O Onset of breast developmenteariest noticeable sign of puberty Estrogen progesterone and prolactin induce formation of ducts and Iobules in the breast Completion of duct and Iobule formation by glucocorticoids and growth hormone Adipose and fibrous tissue complete breast enlargement by age 20 Pubarche O 0 Appearance of pubic and axillary hair sebaceous glands and axillary glands Androgens from ovaries and adrenal cortex stimulates pubarche and libido Menarche O 0 First menstrual period Requires at least 17 of body fat in teenagers and 22 in aduks Improved nutrition has lowered age of onset to age 12 from about age 16 in 1860 Leptin stimulates gonadotropin secretion If body fat and leptin levels drop too low gonadotropin secretion declines and a female s menstrual cycle might cease First few menstrual cycles are anovulatory no eggs ovulated Girls begin ovulating regularly about a year after they begin menstruating Describe the hormonal changes of female climacteric and their effects 0 Begins when only 10002 million follicles are left Remaining follicles are less responsive to gonadotropins so they secrete less estrogen and progesterone 0 Without these steroids the uterus vagina and breasts atrophy o Intercourse may become uncomfortable and vaginal infections more common as the vagina becomes thinner less distensible and drier 0 Skin becomes thinner cholesterol levels rise and bone mass decHnes 0 Blood vessels constrict and dilate in response to shifting hormone balances and the sudden dilation of cutaneous arteries may cause hot flashes Define and describe menopause and distinguish menopause from climacteric Menopause is cessation of menstruationmenstrual cycles 0 Considered to have occurred when a year or more has gone by without menstruation Climacteric is a midlife change in hormone secretion and begins when only 10002 million follicles are left and it is accompanied by menopause Describe the process of egg production oogenesis and relate it to stages of meiosis Produces haploid gametes by means of meiosis Distinctly cyclic event that normally releases one egg each month 0 Accompanied by cyclic changes in hormone secretion 0 Oogenesis begins during embryonic development of ovary 0 Female germ cells arise from yolk sac 0 They colonize gonadal ridges the first 56 weeks of development 0 They differentiate into oogonia and multiply by mitosis until the 5th month 0 They than transform into primary oocytes early meiosis I 0 Most degenerate atresia by the time the girl is born 0 It is an egg or ovum at any stage from the primary oocyte to the time of fertilization where it then becomes a zygote Egg development resumes in adolescence O FSH stimulates monthly cohorts of oocytes to complete meiosis I Each oocyt divides into 2 haploid daughter cells of unequal size and different destinies Important to produce an egg with as much cytoplasm as possible If fertilized it must divide repeatedly and produce numerous daughter cells Secondary oocyte large daughter cell that is the product of meiosis I First polar body smaller one that sometimes undergoes meiosis II but ultimately disintegrates Merely a means of discarding the extra set of haploid chromosomes Secondary oocyte proceeds as far as metaphase II Arrests until after ovulation If not fertilized it dies and never finishes meiosis If fertilized it completes meiosis II and casts off a second polar body Chromosomes of the large remaining egg unite with those of the sperm Copyright c The McGrawHII Companies In Permission mound let reproduction at minim F Development of egg oogenesls Development of follicle folliculogenesl Before birth Multiplication W i 39 quot quotMbC mi Noelin um 39 I Follicular 39 oolh 39 Primoryoocyto o T g 39 Nochongo JVquot Adolescence to men o cause First polar 6 body 63900 quot5 Second polar body Ill8 ii i 9 1mm 39 mob Embryo What are the female gonads called ovaries Which ligaments anchor the floating ovaries in place To where do these ligaments anchor the ovaries Ovarian ligament anchors ovaries to uterus amp Suspensory ligament anchors ovaries to the pelvic wall What is the functional difference between the cortex and medulla of the ovary In other words what does each of them function to do 0 Cortex is where germ cells develop 0 Medulla house major arteries and veins Where are ovarian follicles located Ovaries What is the antrum What are the functions of the fallopian tube AKA uterine tube 0 Ciliated muscular tube moves egg cell down to uterus What are the main functions of the uterus Harbors fetus 0 Provides a source of nutrition 0 Expels fetus at the end of its development What is the cervix Where is it located Cylindrical inferior end of uterus What is the function of mucus secretions from the cervical canal What are the 3 layers of the uterine wall Which kinds of tissue are they composed of Perimetrium external serosa layer Myometrium middle muscular layer 0 Constitutes most of uterine wall 0 Composed mainly of smooth muscle Produces labor contractions to expel fetus Endometrium inner mucosa 0 Simple columnar epithelium compound tubular glands and a stroma populated with leukocytes macrophages and other cells 0 Consists of 2 layers stratum functionalis and stratum basalis 0 Site of attachment of the embryo during pregnancy and forms the maternal part of the placenta from which the fetus is nou shed What are the 2 main layers of the endometrium What are their functions 0 Stratum functionalis superficial half that begins nourishing a zygote layer that is shed each menstrual period 0 Stratum basalis deep layer stays behind and regenerates a new stratum functionalis with each menstrual cycle What are the main functions of the vagina Allows for discharge of menstrual fluid receipt of penis and semen and birth of baby Where is the urethra located relative to the vaginal orifice anterior Antigenpresenting dendritic cells are the route by which HIV from infected semen invades the female body What is the mons pubis The labia majora and are homologous to which male reproductive characteristics Labia majora is homologous to the scrotum Labia minora is homologous to To which male characteristic is the clitoris homologous Penis What is the vestibule Which two openings does it contain 0 Area enclosed by labia majora and labia minora that contains the two openings urinary and vaginal orifices Which characteristics does the clitoris share with the penis at least 3 Structurally o it has a head called the glans that protrudes slightly from the prepuce 0 at its internal end the corpora cavernosa diverge like a Y as a pair of crura which like those of the penis attach the clitoris to each side of the pubic arch Ie The clitoris shares the characteristic of attachment to each side of the pubic arch by a pair of crura Circulation and innvervation Functionally it is entirely sensory so it serves as the primary center of sexual stimulation With respect to oogenesis what are 2 novel characteristics about female meiosis Oogenesis is a cyclic event that normally releases only one egg per month 0 Whereas spermatogenesis is continuous in males 0 Primary oocyte gives rise to only one mature egg and the other 23 unequal sized daughter cells secondary oocyte and polar bodies polar bodies die 0 Whereas in spermatogenesis a primary spermatocyte gives rise to four equalsized sperm Can you describe the process of meiosis and female oocyteovum development Approximately when does ovulation occur 0 Ovulation begins about a year after first menstruating GONAD DEVELOPMENT Where Initially both male and female gonads develop high in the abdominal cavity near the kidneys and migratedescend into the pelvic cavity ovaries or scrotum testes When Gonads begin to develop at 5 or 6 weeks as gonadal ridges that lie outside of the primitive kidney How There are 2 sets of ducts adjacent to each gonadal ridge 0 The mesonephric wolffian ducts develop into the male reproductive system and the paramesonephric ducts female degenerate o The paramesonephric mullerian ducts develop in the female reproductive tract and the mesonephric ducts male degenerate INGUINAL CANAL Path of low resistance through the groin and anterior to the pubic symphysis created by the gubernaculum and vaginal process ACTIVATION OF PANCREATIC ENZYMES IN THE SMALL INTESTINE The pancreas secretes the zymogen trypsinogen into the intestinal lumen of the duodenum Enterokinase is secreted by mucosa of the duodenumsmall intestine and converts trypsinogen inactive into trypsin active Trypsin not only digests dietary proteins but also catalyzes the production of more trypsin and activatesconverts 2 other pancreatic zymogens chymotrypsinogen and procarboxypeptidase into their active forms chymotrypsin and carboxypeptidase ZYMOGEN VS ENZYME Zymogens are inactive proteins Most enzymes like the pancreatic enzymes are not altered after secretion whereas zymogens are converted to their active form after being secreted CCK vs ACh secretion regulation of pancreas and liver 0 Difference CCK is producedsecreted by the cells of the duodenum whereas ACh is producedsecreted by vagus and enteric nerves Similarity They are similar in that they stimulate pancreatic acini to secrete enzymes SMALL INTESTINE Where nearly all chemical digestion and nutrient absorption occurs CHEMICAL DIGESTION amp ABSORPTION Site of Action 0 Carbohydrate o Mouth small intestine small intestine 0 Protein 0 Stomach small intestine small intestine Fat 0 Small intestine small intestine Nucleic acid 0 Small intestine small intestine Enzymes Carbohydrate o Mouth9small intestine small intestine o Salivary amylase pancreatic amylase brush border enzymes in small intestine 0 Protein 0 Stomach small intestine small intestine o Pepsin Pancreatic enzymes9brush border enzymes 0 Fat 0 Small intestine small intestine o Emulsification by bile salts from liver9Pancreatic lipase Nucleic acid 0 Small intestine small intestine o Pancreatic ribonuclease brush border enzymes and deoxyribonuclease Path of Absorption Carbohydrate GASTRIN Gastrin is a hormone produced by enteroendocrine G cells and it stimulates gastric secretion by stimulating enzyme and HCI secretion PRENATAL HORMONES AND SEXUAL DIFFERENTIAION The SRY gene is the sexdetermining gene of the Y chromosome The SRY gene codes for a protein called testesdetermining factor TDF TDF initiates development of testes By 89 weeks the male gonadal ridge has become a testis that begins to secrete testosterone Testosterone stimulates mesonephric ducts to develop into the male reproductive tract and at the same time the testes secrete mullerianinhibiting factor MIF causing degeneration of the paramesonephric ducts ESTROGEN Estrogen levels are always high in pregnancy If estrogen was the hormone that directed female development then all fetuses would be feminized Female development occurs in absence of androgen hormones testosterone Male development is based on estrogen AND testosteroneandrogen hormones DEVELOPMENT OF EXTERNAL GENITALIA Genitalia is undifferentiated until week 9 So at week 9 the fetus begins to form male or female structures By week 12 either male or female genitalia are distinctly formed BLOOD SUPPLY TO PENIS THERE ARE MANY ANASTOSOMES UNITING THE DEEP AND DORSAL ARTERIES SO NEITHER OF THEM IS THE EXCLUSIVE SOURCE OF BLOOD TO ANY ONCE ERECTILE TISSUE NEURAL CONTROL OF MALE SEXUAL RESPONSE STAGES Excitement o Erection due to parasympathetic triggering of nitric oxide NO secretion 0 Orgasm o Parasympathetic Ejaculation o Afferent signals 9 spinal cord LlS4 9 Efferent somatic signals 9 Efferent sympathetic signals 0 Resolution 0 Sympathetic LIGAMENTS THAT SUPPORT FEMALE REPRODUCTIVE ORGANS 0 Cardinal Ovarian Round 0 Suspensory Uterosacral SEVEN HORMONES THAT REGULATE FEMALE REPRODUCTION 1 GnRH 2 FSH 3 LH IEstrogen 6 Inhibin 7 Androgen small amount HCI PRODUCTION 0 C02 H20 gtH2C03 gtHC03 H Parietal cell pumps H from the above reaction into gastric gland lumen by HK ATPase pump HCO3 is exchanged for CI from the blood plasma by the chloride shift which is a process of getting Cl from the blood into the stomach Cl is pumped into lumen to join H to form HCI 4 FUNCTIONS OF HYDROCHLORIC ACID Activates enzymes pepsin and lingual lipase o The enzymes lingual lipase and pepsin are activated by HCI Breaks up connective tissues and plant cell walls helps liquefy food to form chyme Converts ingested ferric ions ferrous ions which are absorbed and used for hemoglobin synthesis Kills ingested pathogens to contribute to nonspecific disease resistance PEPSIN PRODUCTION The zymogen inactive protein pepsinogen released by chief cell is transformed into pepsin when acted on by HCI To convert a zymogen into an active enzyme some of their amino acids are removed 0 Since an acidic environment is needed to convert pepsinogen to pepsin HCI is used because of its high acidity So HCI is released from the parietal cell and removes some of pepsinogens amino acids and forms the active enzyme pepsin which proceeds to digest dietary proteins It is an autocatalytic effect so as some pepsin is formed it converts more pepsinogen into more pepsin FUNCTIONS OF PEPSIN The main function of pepsin is to digest dietary proteins into shorter peptide chains so the small intestine can break them down easily 0 Protein digestion is completed in the small intestine GASTRIC PHASE Ingested food stimulates gastric activity in 2 ways 0 By stretching the stomach Activates short reflex mediated by myenteric nerve plexus and activates the long reflex mediated through the vagus nerves and the brain stem 0 By increasing the pH of its contents 0 Gastric secretion is stimulated by 3 chemicals 0 Ach is secreted by parasympathetic nerve fibers 0 Histamine is a paractine secretion from G cells in the gastric glands o Gastrin is a hormone produced by G cells in pyloric glands that stimulates enzyme and HCI secretion GASTRIC ACTIVITY Activated by 0 Vagus nerve stimulates gastric secretion before food is swallowed Inhibited by 0 Sympathetic nerve fibers
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