Introductory Physiology PSL 250
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This 18 page Class Notes was uploaded by Merle Waelchi MD on Saturday September 19, 2015. The Class Notes belongs to PSL 250 at Michigan State University taught by Adele Denison in Fall. Since its upload, it has received 48 views. For similar materials see /class/207338/psl-250-michigan-state-university in Physiology at Michigan State University.
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Date Created: 09/19/15
Extra Study Questions for Renal Physiology Since stualents seem to learn the material better ifthere is a Stua Questionfor an Objective statement these extra stua questions are an attempt to more completely cover the Learning Objectives and to give more practice with difficult material to help students learn more The hint with the questi0ns gives the pages in the Course Pack which will help QW PNH W a D Ib ID Il W WND O39 4 D ID D Ib I DO mun D N O N N N N N 6 VI 43 W N N 1 Na reabsorption is physiologically controlled by Answer the following True False questions and if the question is False replace the underlined word to make it a correct statement The nephron is the functional unit of the kidney Hint pg 217 of the Course Pack Each kidney contains about one hundred nephrons Hint pg 217 of the Course Pack The afferent arteriole leads to the glomerulus Hint pg 218 of the Course Pack The efferent arteriole leads to the peritubular capillaries Hint pg 218 of the Course Pack The renal cortex is the inner part of the kidney Hint pg 218 of the Course Pack The podocyte layer of the Bowman s capsule is located next to the wall of glomerular capillaries Hint pg 219 of the Course Pack Between the foot processes of the podocyte layer of the Bowman s capsule are ltration slits Hint pg 219 ofthe Course Pack Tubular uid in the Bowman s capsule will next move into the loop of Henle Hint pg 219 of the Course Pack The uid that drips from the collecting duct is urine Hint pg 219 of the Course Pack The kidneys just garbage disposers Hint pg 220 of the Course Pack The kidneys activate vitamin Q Hint pg 220 of the Course Pack The kidneys secrete renin Hint pg 220 of the Course Pack In tubular secretion substances move from the tubular uid into the peritubular capillaries Hint pg 220 ofthe Course Pack The glomerular ltrate has the same concentration of solutes as plasma except for proteins Hint pg 221 of the Course Pack Glomerular capillaries are permeable than typical capillaries Hint pg 222 of the Course Pack Glomerular capillary pressure is lower than the pressure of typical capillaries Hint pg 222 of the Course Pack Glomerular ltration rate is about 125 mlday Hint pg 222 of the Course Pack When the afferent arteriole constricts it causes an increase in GFR Hint pg 223 of the Course Pack Constriction of the afferent arteriole causes an increase in glomerular hydrostatic pressure Hint pg 223 of the Course Pack Decreased sympathetic impulses cause decreased GFR Hint pg 223 of the Course Pack Normally most of the amino acids ltered at the glomerulus are reabsorbed Hint pg 224 of the Course Pack When reabsorption of an ion is physiologically controlled the rate it is reabsorbed and not reabsorbed is always the same Hint pg 224 of the Course Pack In the cortical collecting duct Na from the lumen enters the tubule cell through a channel Hint pg 225 of the Course Pack in the cortical collecting duct Hint pg 225 of the Course Pack In secondary active transport of glucose Na moves down its concentration gradient into the cell and glucose moves against its concentration gradient into the cell Hint pg 226 of the Course Pack Water reabsorption is under physiological control in the proximal tubule Hint pg 227 of the Course Pack When the body is dehydrated ADH levels in the blood would be relatively high and urine volume would be relatively low Hint pg 227 of the Course Pack Exam 5 Study Guide Digestive Physiology 1 2 The function of the digestive system is to transfer nutrients water salts ions and vitamins to the internal environment The lumen of the GI tract opens to the external environment on both ends so the contents of the GI tract are not considered to be within the body proper internal environment 0 This is a good thing b c the conditions of the GI tract can be extreme or too harsh for the rest of the body Digestion is necessary because substances have to be absorbed across intestinal wall from lumen to get into the body proper o Digestion break down of food moleculesunits into small molecules which canbe absor e o Digestion of food molecules break down food molecules into small molecules or absorbable units which can then be absorbed from the lumen into blood or lymph GI system organs of long tube tract and accessory digestive organs 0 Accessory digestive organs I Salivary glands secrete saliva I Liver makes 39 I Gallbladder stores and concentrates bile I Pancreas has an exocrine 8 an endocrine part I Exocrine enzymes and bicarbonate solution from the pancreas are secreted into ducts that dumps into the small intestine I Endocrine secretes hormones into the blood 0 Tract organs I Mouth I Pharynx throat I Esophagus I Stomach I Small intestine I Duodenum I Iejunum I Ileum I Large intestine contains colon I First ascending going up I Then transverse across I Then descending going down I Sigmoid s shaped I The last part of the large intestine is the rectum Digestionbreaks large food molecules into small molecules that can be absorbed The digestive system consists of the organs of the digestive tract and accessory organs that secrete substances into the tract Digestion of the 3 main categories of food 0 Carbohydrates broken down to monosaccharides which is their absorbable unitmostly glucose but also galactose and fructose 0 Proteins broken down to amino acids their absorbable unit 0 Fats triglycerides broken down to 1 monoglyceride and 2 fatty acids Hydrolysis water split apart caused by enzymes that catalyze the reactions breaking the bond of the food molecules by adding water by combining water w the speci c digestive enzyme you can break the food molecule into it39s absorbable unit 0 Digestive enzymes are very speci c for example sucrase lactase maltase breakdown sucrose lactose and maltose respectively tsammbamds and Corfatsusmbnbgjyczndzsand my ands p3 Layzrs mm a ran a Szmsa AKA v Eralpznmnzum Dutzrlayzr mzmbranz smmsnm whmh prmms a E 3 E 5 q a Musdz layzr munch musclzakzrchz part mm Esbphagus mm m byzrswhmh smmg andprbpzumg mbvzmzms mm 5 mm n n m s m EwEularlayEr cantnmamand Emsmttmbz a Submumsa Ennnzmvznssuzswnzrvz Eligblbbdandlymph vzsszlsand glands u sa usmzmbranzwmnh mzansthzmzmbranz sznztzs Eltram slbtalnzrvwssystzmEmzntnzrvwssynzm a W m mm m z nzrvz plzxuszs nztwmcks whmh makz upthz gymquot bmucbus Submucbsal My n Entplzxu a Tmsystzmgbzsmruchzwhnlz llratt a a mum awn lbtalnzrvws gymquot whmh m mm Drgan systzm has a can haw nzuralrz xzswuhwt ENS nvnlvzd bEchz whnlz rz zxu m m mmmm 5 Wu mm 121125 magnum Dr shnnrznzx gm gt me m gt gum Lumiw a mum lung rz zxzsarz d fzrzm myquotmm wk 79quot Eztausz m 5 mm has nulan plzxuszs m um um rz zxzs nan Dmur wuhwt m E Eznlral uzrvbus gymquot bzmg nvnlvzd m chzmmm msamhandznfyw waulbng Enbugh m shppzry and shmy be crzatz 5 mm Ehzwmg and rmxmg ma wsalwa Swa nwmg mm mmphtatzd rz zx Ennrdmatzd by m swa bwmg Ezntzr m m mzdulla s pushmg an m pharynx whmh snmulatzs przssurz rztzpmrs m ms mm 2 phaszs a Drbpharyngzal phasz mm m mum and pharynx mum 1 szcmd m larynxu Envzrzd by m Emma part m m larynx that an m a m m vmzl mas mm mm an mgbw chzmrzspwanmsarzmmbnzd11252 Evzmskzzp 3 239 5 ms1135szbbluspasszschzuppzrzsbphagzalsphmctzt a pm mgsmbvzschzbblusmmchz nnmathakEsJ sztbndsfbrbn Pznsmsu nrmlarmusclzlayzrlbfchzmunch musclzlayzrufchzEltramwhth Dnlramsand 231253 mmmm rm prbgrzsswz Wm DfEDmrammn pushzs mmzmsfarward ahead mm Emsmmvz rmg Can swallow while standing on your head b c it39s mostly peristaltic waves not gravity that gets the food or liquid to the stomach Secondary peristaltic wave distension of the esophagus triggers this wave when something like a sticky bolus of peanut butter doesn39t get to the stomach during the primary wave Heartburn occurs when gastric contents acidic splash into the esophagus and irritates it o NORMALLY Except during swallowing the lower esophageal sphincter LE S is closed and it relaxes during swallowing so the bolus can move into the stomach then closes again 0 Heartburn occurs if LES allows it eg after a large meal or people w weak LES Carbohydrate digestion begins in the mouth with salivary amylase Swallowing is orchestrated by the swallowing center in the medulla there is a precisely programmed sequence of events that occur during swallowing 5 Regions of the stomach Fundus above esophagus opening Body middle part Antrum lower part thickest muscle Pyloric sphincter located at the junction of the stomach and the first part of the small intestine duodenum there39s a small amnt of chime 515ml going thru sphincter at a time I Chime sludge partly digested food in solution contains enzymes salivary amylase 8 pepsin from stomach I The stomach has a storage function 0 Emptied at a rate that is optimum for digestion and absorption of food 0 Can hold about 15L maybe 2L I The swallowing center causes receptive relaxation of the stomach smooth muscle so it can increase volume without much change in pressure b c the muscle is relaxed until the extreme 2L or more then you get an increase in pressure and discomfort I Gastric secretions o HCl hydrochloric acid secreted by parietal cells in the stomach functions are Kills most microorganisms along wlysozyme in saliva that enter w food but some manage to make it to the large intestine and multiply and have function I Dissolves food particles not into single molecules but from large to smaller pieces helps breakdown connective tissue uncoils proteins I Changes pepsinogen to pepsin an inactive form of a protein digesting enzyme I Creates acid environment for pepsin o Pepsinogen secreted by chief cells I Pepsin comes from pepsinogen is a protein digesting enzyme starts protein digestion but doesn39t finish it I Pepsin is secreted in an inactive form which is pepsinogen which protects secreting cells from self digestion lots of cell structure is protein and don39t want it digested by the enzyme on the enzymes way out of the cell I HCl changes pepsinogen to pepsin then pepsin itself can act on pepsinogen I This means it acts autocatalytically enzyme activates inactive molecules of the same enzymeactivates itself see g page 258 o Mucus secreted by the stomach as well as the whole GI tractlining I Forms a protective coating forms a coat with protein in it makes a layer over inner surface I Is alkaline helps neutralize acid next to stomach lining so it protects the stomach from self digestion keeps acid and enzymes from digesting stomach wall 0 Intrinsic factor secreted by parietal cells I The only absolutely essential substance produced by the stomach wout it you can39t absorb vitamin B12 I Secreted by parietal cells for vitamin B12 absorption occurs in terminal ileum OOOO 6 7 o Gastrin is a hormone so doesn39t act in the stomach lumen hormones go into blood to have an ef ect I Different kind of secretion Secreted by cells in antrum which secrete gastrin but not HCl of the stomach then it travels in the blood to other areas including the body of the stomach which secretes HCl but not gastrin then it stimulates acid secretion by parietal cells in the body of the stomach The stomach secretes a protein digesting enzyme in an inactive form HCl mucus as does the whole GI tract lining and gastrin a hormone Peristaltic waves are weak in the body weaker or no wave in the fundus and strongest in the antrum b c the antrum has thicker musc e The peristaltic waves mix the contents and closes the pyloric sphincter A small amount 515mls of chyme sludge in the stomach solution of partially digested food moves into the duodenum w each wave Most of the chyme is forced backward 8 it hits the closed sphincter and is tossed backward and that causes most of the mixing Therefore most of the mixing of chyme is in the antrum where peristaltic contractions are the strongest Distension of the stomach increases stomach emptyingbecause the stomach wants to unload its contents it39s full and needs to get rid of stuff There are 2 important factors in the intestine that will decrease gastric stomach emptying The duodenum of the small intestine can slow down emptying by talking backquotit can tell the stomach the contents are coming too fast and to slow down stop stomach emptying visa nerves shortintratract re exes or long typical re exes and hormones enterogastrones r example if there39s distension of the duodenum b c there39s too much there and fats take longer to digest so it slows the process down Enterogastrones 2 kinds to know 0 Cholecystokinin CCK o Secretin 0 Both released by the small intestine duodenum and inhibit the stomachs activity by inhibiting motility stomach emptying and inhibiting secretions In the stomach contractions are strongest in the antrum Antral contractions force some chyme thru the pyloric sphincter and also close the sphincter so most of the chyme is tossed back which mixes the chyme in the stomach Factors in the stomach distension and intestine distension and fats affect stomach emptying The stomach is emptied at a rate optimum for digestion and absorption of food in the small intestine Along w gastric contents chyme the pancrease and the liver release their secretions into the small intestine The pancreas has an exocrine and an endocrine part 0 Exocrine part secretes enzymes and bicarb solution 0 Endocrine part secretes hormones Pancreatic exocrine enzymes and bicard solution secretions o Pancreatic amylase enzyme I Starch digestionbegins in the mouth by salivary amylase and continues working in the stomach until it39s mixed with HCl 8 is inactivated Pancreatic amylase secreted into the small intestine continues starch digestion and breaks it down to disaccharides 2 sugar units This means you39re still not done w starch digestion b c you39re at disaccharides not monosaccharides 0 Protein digestion enzymes I Secreted in an inactive form like pepsinogen from the stomach it needs to be activated to protect the secreting cells from self digestion I Pancreas secretes trypsinogen which is an inactive form of a protein digesting enzyme quot or quot r r 39J is an the cell fmucosa cells of the duodenum which splits peptide off trypsinogen and forms trypsin I Trypsin then activates other inactive enzymes including trypsinogen which means trypsin acts autocatalytically and does its job of digesting proteins with the other now active enzymes see g page 262 Each of the protein digesting enzymes splits bonds of proteins peptide bonds in different places I Chymotypsinogen 9 chymotrypsin I Procarboxypeptidase 9 carboxypeptidase I Still not done w protein digestion not single amino acids yet 0 Pancreatic lipase enzyme I An enzymes that breaks 1 fat molecule into absorbable units which is 1 monoglyceride and 2 fatty acids I Need bile bile salts for lipase to work well I Fat digestion is not yet completed 0 Bicarbonate ion alkaline solution I Neutralizes chyme from stomach which helps protect the duodenum from acid I Creates a favorable pH for the pancreatic enzyme to work They need slightly alkaline right now I The pancreas and liver release their secretions into the small intestine which are mixed with chyme from the stomach Carbohydrate digestion was halted in the stomach when salivary amylase met HCl The pancreas secretes enzymes for carbohydrate fat and protein digestion Protein digesting enzymes are secreted in inactive forms Pancreatic enzymes work best in an alkaline environment the pancreas secretes an alkaline bicarbonate solution into the duodenum 8 Bile is also secreted into the duodenum It is made by the liver and stored and concentrated in the gall bladder o Bile contains bile pigments from hemoglobin wastes we get rid of cholesterol bile salts derivatives of cholesterol and phospholipids Bile salts assist in fat digestion by acting like a detergent meaning keeps fats broken up Need this because fats are not water soluble so they want to clump together 0 Emulsify fats break large fat drops globs into smaller droplets 0 They make a lipid emulsion w mixing in the GI tract which means many small droplets suspended in a watery solution This greatly increases the surface area for pancreatic lipase to act 0 Bile salts maintain the lipid emulsion meaning they keep the droplets small which increases surface area I W out bile salts the droplets make a big glob which decreases surface area for lipase to act and prolonged fat digestion How bile salts help maintain a lipid emulsion o The nonpolar part dissolves in the fat droplet bile salts attach to the outside of the fat glob w positive charge in and negative charge facing out water polar polar part has negative charges so they repel each other b c like charges repel so we maintain lipid emulsion Bile salts also help in fat absorption by forming micelles o Micelles have an inner core which is hydrophobic and an outer core which is hydrophilic 0 Products of fat digestion can dissolve in hydrophobic core of the micelles o Micelles are like tiny boats that transport the products of fat digestion thru the water in the lumen of the small intestine to the lining of the small intestine where they are absorbed by diffusion If you didn39t have these little boats the products of fat digestion would huddle together since they are hydrophobic meaning they39d make a big glob and absorption wouldbe prolonged I The digestion and absorption of fats is different than other food molecules because fats are not water soluble Bile salts are very important in maintaining an emulsion which helps with fat digestion and in forming micelles which helps with absorption of the products of fat digestion 9 I Secretion of bile by the liver is continuous meals bile is moved to the gall bladder where it39s stored and concentrated 0 During a meal the gall bladder contracts fatty acids in the duodenum means fats are there and need bile to help w their digestion causes release of the hormone CCK which causes the gall bladder contraction and relaxation of the sphincter which allows bile to get into the duodenum I After bile helps w fat digestion and absorption bile salts are reabsorbed returned to the liver and are re secrete o This means bile salts are recycled done by enterohepatic circulation which is the recycling path b w intestine and liver via hepatic portal vein 0 The recycling of bile salts is important b c there39s not enough bile salts in the body for a ical mean if not recycled I Cholecystokinin CCK causes contraction of the gall bladder Bile salts are absorbed and returned to the liver to be secreted again 10 I Pancreatic enzymes and bicarbonate are secreted into the lumen of the small intestine I There are small intestine enzymes on the brush border microvilli o Enterokinase enteropeptidase o Dissaccharidases includes maltase sucrase lactase which all complete carbohydrate digestion 0 Protein digesting enzymes produces amino acids which is the absorbable unit 0 Because of the 3 enzymes above all food is not in a form that can be absorbed I The small intestine has folds villi fingerlike projections and microvilli cell membrane projections which all act to increase the surface area which helps absorption In the villi there are capillaries and lacteals Absorption is into the capillary everything but fats or the lacteal just fats I After food molecules are absorbed into the blood capillaries we get haptic portal circulation 0 Blood from the intestines doe not go directly into the vena cava It goes rst to the liver for processing of nutrients nutrients picked up from the small intestine are not dumped into general circulation they go to the liver first via the hepatic portal vein for processing 0 The only exception to this is fats Fats go into the lymph system I Almost all digestion of nutrients and absorption of nutrients occurs in the small intestine A large volume of water is absorbed from the small intestine Once absorbed the products of fat digestion are resynthesized into fat molecule in the cells lining the small intestine and packaged into chylomicrons which enter the lymph 11 I A very large amount of absorption takes place in the small intestine absorbing food nutrients ions vitamins 8 water 0 Almost all of absorption is in the small intestine If you put 8L in about 7L is absorbed in the small intestine 0 Most of the digestion also occurs here I Start carbohydrate in the mouth and start protein in the stomach but all of the rest is in the small intestine I Absorption in the small intestine into mucosal cells 0 Many of the nutrients rely on active transport of Na I Na is absorbed want water follows I Simple sugars 8 amino acids use secondary active transport meaning they get a free ride wNa I Fructose is an exception uses facilitated diffusion o Monoglycerides 8 fatty acids have simple diffusion into mucosal cells I Fat absorption is in the small intestine but goes into the lymph instead of blood capillaries absorption is different because fat is not soluble in water so it must undergo a series of transformations in order to be digested and absorbed steps g page 269 o Lipid emulsion o Lipase hydrolyzes fats triglycerides into fatty acids and monoglycerides 0 They are water insoluble so carried by micelles which are formed by bile salts and phospholipids to the luminal mucosal surface of the small intestine Passive diffusion from micelles thru intestinal cell membrane since lipid soluble Once inside intestinal cell triglycerides are resynthesized Packaged or enclosed called chylomicron then exocytosis Chylomicrons are unable to center the capillary because the basement membrane won39t let them in Instead they enter the lymphatic vessels lacteal b c they don39t have a basement membrane I Absorption of vitamins in the small intestine 0 Fat soluble vitamins are carried in micelles I They39re absorbed w products of fat digestion 0 Water soluble usually are absorbed by diffusion or carrier mediated transport into mucosal cell then into bloo I The exception is B12 it needs to be bound to intrinsic factor from the stomach and absorbed by endocytosis in the lower ileum 0000 I The chyme needs to be mixed w secretions andbe exposed to the absorptive surface mucosa and after absorption need to move what39s left to the large intestine I Segmentation in the small intestine mixes chyme and propels chyme slowly contraction lasts a few secon s o Divides into segments like sausages and the previous sausage becomes constriction when chops up chyme This mixes the chyme and exposes the chyme to the absorptive mucosa o It propels chyme slowly b c the frequency is higher in the duodenum 12xmin than further down in the ileum 9xmin this means that more chyme is pushed forward or down tract toward ileum more activity higher up means more chyme pushed down I Factors affecting segmentation o Gastrin from the stomach increases segmentation in ileum which is gastroileal re ex o Gastric emptying causes distention of the duodenum which increase segmentation o Extrinsic ANS nerves PS increases 39 8 J I 39 decreases Remember PS is rest 8 digestquot I Migrating motility complex MMC o This occurs after segmentation 8 absorption are over 0 It is weak peristaltic waves which die out after a couple of feet I The site where waves begin moves down the intestine it migrates down the intestine from near the duodenum Once the wave reaches the ileum 2hrs a new wave begins near the duodenum 0 Function is to move undigested remnants 8 bacteria into the large intestine I Good intestinal housekeep it sweeps outquot the small intestine I Segmentation is a mixing movement that occurs in the small intestine segmentation also moves chyme slowly toward the large intestine The migrating motility complex occurs after the absorption of nutrients and sweep the contents of the small intestine into the large intestine 3 I The function of the large intestine is NOT digestion no enzymes are secreted o Mucus is secreted as does the rest of the tract 0 Functions are absorption of water and electrolytes ions from chyme and storage of fecal material indigested stuff remnants of food that never entered the body and bile pigments waste I Bacterial ora in the large intestine 0 Produce vitamins normally not important except vitamin K 0 Break down substances we can39t like carbs in beans 8 produce gas I Mixing movements in the large intestine o Haustral contractions similar to segmentation but must less frequent Produces sacs or haustra like pouches I Mixes contents prev sac becomes contracted part I Exposes contents to the absorptive mucosa 0 Mass movements I Typically follow a meal I Occurs wgastroileal re ex get gastrocolic re ex I Large portions of the colon contract drives contents a substantial length I Causes distention of rectum with mass movement stimulates stretch receptors in the rectum stimulus for defecation re ex I Defecation re ex an autonomic re ex o 2 anal sphincters I Internal anal sphincter smooth muscle involuntary re ex causes to relax I External anal sphincter skeletal muscle voluntary can contract that sphincter and delay defecation this is what you39re teaching to control with potty training I Water is absorbed from the large intestine Bacteria in the large intestine produce vitamins and gas Haustral contractions mix the contents of the large intestine mass movements propel the contents into the rectum Metabolism I Metabolism the total collection of chemical reactions that occur in a living organism Catabolism some of the chemical reactions break down molecules like cell respiration Anabolism some of the chemical reactions make bigger molecules out of smaller cells synthesis reactions make cell structures storage compounds remember anabolic steroids build muscle 0 Metabolism anabolism catabolism I 2 states after a meal you absorb nutrients but b w meals you don39t 0 Absorptive state more anabolism GI tract filled with nutrients and the nutrients are entering blood takes 4hrs to absorb a typical meal 0 Postabsorptive state more catabolism the GI tract is empty of nutrients so energy must come form the body39s energy stores I Carbs in the absorptive state 0 Carbs entering the blood as monosaccharide39s are mostly glucose and they go to the liver via the hepatic portal vein 0 Much of the absorbed glucose is taken up by the liver the glucose that isn39t taken up by the liver can be used for energy to make ATP 0 The main energy source for cells during the absorptive state is glucose I Besides beingused for energy glucose canbe stores as glycogen the liver takes up lucose and stores glycogen o Glucose levels in the blood are VERY important to maintain They must be maintained high enough b c the nervous system nerve cells including the brain generally won39t use other molecules for energy I For survival of the brain and the rest of the neurons you need glucose concentration of blood to be maintained can39t be too low or too high I Carbs in the postabsorptive state 0 When glucose is not entering blood from the GI tract glucose levels are maintained by glycogenolysis I Glycogenolysis is the liver releasing glucose from glycogen this is the 1St line of defense against a drop is blood glucose which lasts for hours 00 2 I Muscles also contain glycogen so they can contribute to blood glucose indirectly by releasing products that the liver makes into glucose I If fast is longer than hours need 2ml line of defense which is gluconeogenesis or new glucose formation I The liver can make new glucose from noncarb39s for example from amino acids and from glycero Also cells other than nervous tissue can switch to utilization of fats for energy This line of defense can only supply 700cals day which is lthalf of what we nee Glucose sparing most organs reduce glucose catabolism and increase fat catabolism which spares glucose made by the liver for the use by the nervous system Fats in absorptivepostabsorptive state 0 In postabsorptive can be used as energy fats are brown down in adipose tissue and fatty acids are released and used for energy in most cells 0 In the absorptive state nutrients are abundant so excess food is stored as fat once all glycogen stores are full and you have your 1St line of defense all excess food is stored as fat Amino acids proteins in absorptivepostabsorptive state In the absorptive state aa are used to replace those proteins that we used during the postabsorptive state in gluconeogenesis and new proteins can be used for energy 0 In the postabsorptive state removal of the nitrogencontaining group is glucogenogenesis becomes part of the urea excreted by the kidneys The rest of the aa is converted to glucose so protein becomes a major source of blood glucose after a few hours in the postabsorptive state Absorptive state vs postabsorptive state 0 Net anabolism vs net catabolism o Glucose use vs fat use 0 Glucose uptake vs glucose release by the liver from gluconeogenesis also glycogenolysis which is glycogen breakdown During the absorptive state anabolism of fat and protein occurs glycogen is stored and glucose is used for energy During the postabsorptive state glycogen is broken down fat and protein catabolism occurs and glucose is spared for use by nervous tissue 2 hormones control the changes occurring when we go from feasting absorptive state to fasting postabsorptive state 0 Insulin most important 0 Glucagon Insulin39s effect 0 When insulin secretion increases the effect is the events in the absorptive state responses to increase insulin are generally anabolism making of protein fat and glycogen sysnthesis also glucose uptake and use increased insulin causes responses in the muscle fat cells and liver as well I Musc e I Increased glucose uptake and utilization I Net glycogen synthesis I Net amino acid uptake I Net protein synthesis I Fat ce 5 I Increase glucose uptake and utilization I Net triglyceride synthesis I Liver I Increased glucose uptake I Net glycogen synthesis I Net triglyceride synthesis I No ketone synthesis 5 0 When insulin decreases the effect is the events in the postabsorptive state decreased insulin also causes responses in the muscle fat cells and liver I Muscle Decreased glucose uptake and utilization I Net glycogen catabolism I Net protein catabolism I Net amino acid release I Fatty acid uptake and utilization e s I Decreased glucose uptake and utilization I Net triglyceride catabolism and release of glycerol and fatty acids I Increased glucose release due to net glycogen catabolism and gluconeogenesis I Increased ketone synthesis and release The effect of blood glucose levels on insulin secretion 0 Increased blood glucose causes increase insulin secretion 0 Decreased blood glucose causes decreased insulin secretion 0 There are other controls of insulin secretionbut plasma glucose is the most important Increased decreased insulin is the primary cause for events of the absorptivepostabsorptive states Glucagon acts to increase blood glucose maintain glucose levels Major effect of glucagon are on the liver effects are opposite to insulin meaning increased glucagon causes 0 Increased glycogen breakdown o Increasedgluconeogenesis 0 Increased synthesis of ketones w prolonged fast they become elevated in the blood glucagon promotes the conversion of fatty acids to ketones in the liver The major stimulus for glucagon release is decreased blood plasma glucose which occurs in the postasborptive state e overall result of glucagon is to increase plasma concentration of glucose 8 ketones 8 this occurs during the postabsorptive state to keep glucose up 0 In the postabsorptive state plasma insulin is low and plasma glucagon is high Push pull system for regulating plasma glucose 0 Increased insulin pushes glucose down in the absorptive state in this state glucose is entering the blood from the GI tract 0 Increased glucagon pulls glucose up in the postabsorptive state the GI tract is empty of nutrients and nerve cells need glucose 0 This shows that the 2 hormones effects are opposite glucagon has an antiinsulin effect Other hormones that have anti insulin effects 0 Cortisol epinephrine and grth hormone all increase blood glucose which increases blood fatty acids and increases fat catabolism I Cortisol also increases protein catabolism I For owth hormone increases protein synthesis is needed for grth 0 All have antiinsulin effects except for growth hormone Glucagon epinephrine cortisol and growth hormone all increase blood glucose levels Diabetes mellitus type 1 due to lack of insulinno or almost no insulin 0 There39s decreased movement of glucose into cells b w there39s no carriers in the membrane for glucose to get in and the liver released glucose w decreased insulin 0 Hyperglycemia above normal glucose levels in the blood o Glucosuria glucose in the urine when blood glucose levels are so high that it exceeds the transport maximum of the kidneys to reabsorb all for the ltered glucose some spills over into the urine 0 Osmotic diuresis loss of water in the urine due to osmotic effects of solute in urine I There39s more solutes in urine b c there39s glucose and ketones in urine which increases the osmotic pressure of urine so it keeps water with it and less water is reabsorbed 0 Over time you39d see decreased protein synthesis and fat synthesis Increased catabolism of fats fats used for energy T e iver produces ketones that cause acidosis acidosis and dehydration due to osmotic pressure and reduced arterial blood pressure affect the brain 0 Untreated diabetes mellitus can cause death SEE FIGURE PAGE 283 Lack of insulin causes increased blood glucose loss of glucose and water in the urine and increased ketone bodies which causes acidosis O Endocrine System 1 2 3 Endocrine glands duct less glands that secrete hormone into the blood which affect the target cell function Nervous system is also a control system generally the nervous system is faster acting but its effects are shorter lasting a typical motor neuron ends at a speci c muscle or gland and sends messages to a speci c place effector o H rmones effects are generally slower acting and longer lasting than typical neurons effects since hormones travel in the blood they can reach all cells but cells only respond to the hormone is they have receptors for the hormone Receptor is specific for the hormone t lock and keyquot 0 If a cell doesn39t have a receptor for a hormone then the cell is unaffected by it E ndocrine glands secrete hormones into blood hormones affect only their target cells Responses caused by hormones binding to receptors affects cell proteins ange channel permeability in the cell mem rane 0 Change activity of proteins present in the cell like enzymes 0 Cause synthesis of new proteins by activating genes or the reversecause inhibition of genes and decreased protein synthesis Hormones that cannot get thru the cell membrane have receptors on the cell membrane 0 These hormones are lipid insoluble I Peptides protein hormones I Catecholamines epinephrine and norepinephrine o The receptors on the cell membrane activate a 2m1 messenger which is a messenger inside the cell which causes the response dictated by the 1St messenger the hormone I Cyclic AMP is an important 2ml messenger but there are others Hormones that can get thru the cell membrane have receptors on the inside of the cell in the cytoplasm or nucleus 0 T ese hormones are lipid soluble I Steroid hormones I Th roid hormones 0 Generally activate turn on genes which cause protein synthesis which causes the response Lipid soluble hormones can pass through the cell membrane to bind with receptors inside the cell Lipid insoluble hormones bind to receptors on the cell membrane Hypothalamus of the brain is an important link b w the 2 control systems nervous and endocrines b c it control the pituitary gland Pituitary gland 2 parts 4 o Anterior pituitary AKA adenohypophysis the part grows as an upward projection of the pharynx contained glandular epithelial cells 0 Posterior pituitary AKA neurohypophysis the part that develops as a downward growth of the hypothalamus tissue is nervous tissue The neurohypophysis is connected by a stalk infundibulum to the hypothalamus this is a direct neural link 0 Neurons in the hypothalamus send axons down the stalk and they terminate in the posterior pituitary the posterior pituitary is an extension of the hypothalamus Hormones secreted from the posterior pituitary are produces in the hypothalamus the hormones are made in the cell bodies in the hypothalamus then they39re transported in vesicles to the axons stored in terminal in posterior pituitary and on the appropriate signal they39re secreted Hormone released is triggered by action potentials from the hypothalamus 2 hormones secreted ADH vasopressin o Oxytocin I Stimulates uterine contractions in delivery of a baby synthetic oxytocin is often given to induce labor I Hormone for milk letdown milk letdown re ex I Causes milk to be ejected into the ducts of the mammary glands of the breasts so that the baby can remove it by nursing W out this re ex the baby cannot remove the milk Milk letdown re ex shows how the nervous and endocrine systems are interrelated it is a neuroendocrine re ex o Suckling causes impulses to the brain 9 hypothalamus 9 posterior pituitary which causes oxytocin release oxytocin travels in the blood to the breast which causes contraction of the myoepithelial cells this causes milk letdown or ejection of milk into the ducts of the breast so that baby can remove it by sucklin 0 However psychological stress can affect this re ex worrying about not being able to nurse can prevent the hormone release Anterior pituitary gland39s relationship with the hypothalamus o The hypothalamus secretes hormones which control the anterior pituitary hormone secretion these hormones are called hypophysiotropic hormones or releasing and inhibiting hormones The way hypophysiotropic hormones get to the anterior pituitary Capillaries in the hypothalamus lead to hypothalamopituitary portal vessels which pass down the pituitary stale and lead to capillaries in the anterior pituitary o A portal vessel connects the 2 capillary beds 0 Hormones from the hypothalamus control anterior pituitary thru a vascular link The anterior pituitary is glandular tissue and is controlled by hormones from the hypothalamus The posterior pituitary is neural tissue It releases hormones that are made in the hypothalamus The releasing and inhibiting hormones from the hypothalamus hypophysiotropic hormones are named for the anterior pituitary hormone they contro Anterior pituitary hormones o FSH amp LH GnRH controls both of these hormones 0 Growth Hormone has dual control both releasing and inhibiting hormones control this hormone o H o Prolactin has dual control both releasing and inhibiting hormones control this hormone 0 Growth hormone39s effect increased growth hormone has the following effects 0 Effects on metabolismanti insulin 6 7 0 Increased protein synthesis which causes increased movement of amino acids into cells and synthesis of proteins 0 Increased growth increased cell number wGH it increased cell division which is needed for growt I GH39s effects on cell number are indirect thru insulinlike growth factorI IGFl GH stimulates the release of insulinlike IGF 1 from the liver and also other cells which causes cell division Prolactin39s effect 0 Promotes lactation milk productionsecretion o Promotes breast gland development 0 Release increases wsucklingnursinghelps keep the mother producing milk need oxytocin w sucking to get the milk into the ducts For nursing you need 2 hormonesoxytocin and prolactin Prolactin is from the anterior pituitary and is for milk secretion 0 Oxytocin is from the posterior pituitary and is for milk letdown Growth hormone39s effect on cell number is thru another hormone grth hormone has effects on metabolism and protein synthesis When rest of the anterior pituitary hormones stimulates the secretion of another hormone those hormones are called tropic hormones 0 Growth hormone acts as a tropic hormone when it stimulates IGF 1 release from the liver 0 0f the anterior pituitary hormones only prolactin is not at all tropic the rest secrete another hormone in the third endocrine gland There39s a chain of 3 hormones o Hypothalamus o Anterior pituitary 0 Third endocrine gland Anterior pituitary tropic hormones and their effects controls the secretion of cortisol from the adrenal cortex 0 TSH thyroid stimulating hormone stimulates the secretion of thyroid hormones from the thyroid gland and stimulates the thyroid gland to grow increased TSH can cause a goiter o FSH follicle stimulating hormone 8 LH leutinizing hormone cause seX hormone secretion and gamete development Negative feedback typically controls hormone secretion which maintains the concentration of hormones in the blood keeps it stable 0 Due to negative feedback control the concentrations of hormones will not be too high or too low like the thermostat when it39s warm enough it turns off the heat means enough hormone which is more neg feedbackor when it39s not warm enough the turns on more hormone b c hormoneheat and there39s less neg feedback 0 Can be variations on the negative feedbacktheme I Short feedback loop is when the anterior pituitary hormones inhibit the hypothalamus I Long feedback loop is when the third endocrine gland effects the anterior pituitary and or the hypothalamus Negative feedback turns off hormone secretion and keeps hormone levels stable Thyroid gland 2 lobes connected by an isthmus composed of follicles and each follicle is a ball of cells lled with a colloid in the middle 0 Follicle cells secreted colloid mostly thyroglobulin TG as well as some enzyme I Thyroglobulin is a large protein that contains thyroid hormonesit stores thyroid hormones when thyroglobulin is split up by enzymes thyroid hormones are released Thyroid hormones are thrpoine T4 and triiodothyronine T4 0 When measuring thyroid hormones the numbers are really the number of iodine atoms attached iodine must be supplied in the diet to make thyroid hormones Follicle cells cotransport of iodide with Na then iodine is attached to TG so it makes T3 8 T4 a part of TG I Almost all of the steps of synthesis and release of thyroid hormones is controlled by TSH I There39s much more T4 than T3 but T3 is a lot more potentactive 0 Most T4 is converted to T3 in the tissues T4 is peripherally stripped of iodineenzymes of the target cell take off an iodine o 3 months worth of thyroid hormones is stored in the colloid therefore if w out iodine it would take 3 months for a de ciency to show up I Effects of thyroid hormone 0 Increased TH causes increase in basal metabolic rate BMR BMR is the metabolic cost of living or idling speed of the body cells are using energy are awake but at rest I This causes increased 02 and energy use food is burned quicker and the by product is heat I Which leads to an increase in heat production I Hyperactive thyroid above normal thyroid hormones results in increased BMR and decreased weight I Hypoactive thyroid below normal thyroid hormones results in decreased BMR and weight gain 0 Increased TH causes an increase in responsiveness to catecholamine39s epi and NE you get an increase in heart rate increased contractility and increased cardiac output happens in hyperthyroid person 0 Effects on growt I TH is needed for normal overall growth I TH promotes the effects of growth hormone on protein synthesis and growth need TH to synthesize GH I TH is also needed for nervous system development and growth de ciency of TH in infancy causes mental retardation known and cretinism I Thyroid hormones are stored as part of thyroglobulin molecules in the colloid of the thyroid gland Thyroid hormones increase metabolic rate 0 9 I Calcitonin 0 From cells b w the follicles cells of the thyroid gland o Calcitonin is not controlled by the anterior pituitary it39s controlled by Ca secretion 0 It decreases blood Ca I Increased blood Ca caused increased calcitonin release which decreases blood Ca bc it decreases Ca release from bone this is negative feedbac 0 Normally not an important controlled of blood Ca I Parathyroid hormone PTH is essential for lifeVERY important in controlling blood Ca 0 From parathyroid glands usually 3 on back side of thyroid gland 0 It39s effect on blood Ca is opposite of calcitonin39sPTH increases blood Ca o Stimulus for release is low blood Ca or decreased blood Ca I Blood Ca m levels are important Low blood Ca causes hypocalcemic tetany which causes spontaneous muscle contractions and they39re tetanic 0 Low Ca causes the membrane to be leaky to Na which in effect opens Na channels and you get more of an effect you get spontaneous depolarization39s and AP39s in excitable membrane It affects respiratory muscles you can die b c you need to stop contractions to breath Removal of parathyroid glands can cause death b c you need PTH to keep blood Ca levels from dropping I PTH39s effect on 3 organs 0 Bone cases release of calcium from bone 00 I PTH stimulates the cells that tear down bone which are osteoclasts causes calcium and hosphate ion release 0 Kidney increased reabsorption of Ca and increased phosphate ion excretion decreases the possibility of precipitation of 2 ions together if both ions increase together in the blood it will redeposit in bone or other tissues and we don39t want thatwant increased Ca w out increased phosphate ion so we can get rid of phosphate in the kidney 0 Intestine I The effect of PTH on the intestine is indirect thru vitamin D I A step in activation of vitamin D in the kidneys is stimulated by PTH PTH stimulates a kidney enzyme that activates vitamin D I Active vitamin D then increases Ca absorption from what in the gut I Parathyroid hormone increases blood calcium ion by an action on 3 organs its effect on the intestine id indirect thru vitamin D 10 11 8 12 I Hormones from the adrenal cortex 0 Glucocorticoids cortisol is the most important one I It acts as an anti insulin hormone I It increases gluconeogenesis so increase blood glucose which increases fat catabolism or increased fatty acids in the blood which increases protein catabolism increased amino acids in the blood I Secretion increases w stress amp also helps reduce stress but unclear how I Causes metabolic changes that are thought to be helpful I Cortisol allows the vasoconstriction caused by catecholamine39s and if stress required vasoconstriction then cortisol would be required for life I Pharmacological effects of cortisol used as an antiin ammatory and to suppress immune response 0 Mineralocorticoids osterone very important mineralocorticoid which affects electrolyte balance 0 Sex hormones I There39s small amounts of both kinds in males and females but the only one of physiological significance is androgen in female which is responsible for pubic and axillary hair and sex drive I Hypersecretion of adrenal androgens results in bearded ladyquot or masculinization of a young child Usually an enzyme defect which instead of producing cortiso produces androgen so the enzyme cannot make cortisol Treatment is cortisol I The adrenal cortex secretes glucocorticoids mineralocorticoids and sex hormones Reproductive 1 I Puberty the time when reproductive organs are functional 0 Reproduction is possible 0 Sperm is produced in the mage and eggs oocytes are produced in the female I The causes of the development of reproductive organs There39s an increase in gonadotropin releasing hormone GnRH from the hypothalamus which causes release of anterior pituitary FSH follicle stimulating hormone and LH luteinizing hormone This causes the release of the sex hormones from the gonads FSH LH and sex hormones testosterone in males and estrogen in females will cause the gamete production and development I Secondary sex characteristics external characteristics that are not involved in reproduction but distinguish males from females 0 Estrogen in females and testosterone in males causes the development of secondary sex characteristics 0 In males it39s a beard growth of the larynx causes deep voice male muscle pattern big arm and leg muscles broad shoulders Overall male shape is like an inverted triangle 2 3 o In females there39s body contours fat in hips breasts and thighs Males secrete testosterone before these secondary seX characteristics changes associated with birth They secrete T before birth in utero and this function causes male reproductive organs to develop If a boy fetus does not secrete testosterone he would look female b c female development is automatic unless testosterone and another hormone MIS are secreted Functions of FSH and LH in the male 0 FSH stimulates spermatogenesis which is sperm production development by stimulating Sertoli cells nurse cellsquot which nourish and protect the cells that become sperm happens in seminiferous tubules nutrients get to developing sperm via Sertoli cells 0 LH also called interstitial cell stimulating hormoneICSH stimulates interstitial cells or Leydig cells to secrete testosterone Spermatogenesis FSH works thru the sertoli cells they release local chemicals paracrines which stimulate the developing gametes to divide and become sperm develop 0 LH causes T secretion but there39s negative feedback control T inhibits GnRH release and causes less LH release to a given amount of GnRH o Inhibin protein hormone from Sertoli cells causes a negative feedbackeffect on anterior pituitary decreases FSH only 0 Testosterone FSH and LH are all needed for spermatogenesis The effects of FSH and LH in the female 0 FSH stimulates follicle development follicles are rings of cells that contain developing eggs also need LH and estrogen which is actually secreted by the follicle for the follicle to develop so follicle secretes a hormone needed for its own development 0 LH causes ovulation and formation of the corpus luteum formed in the ovary from follicle cells left behind after ovulation corpus luteum is a temporary endocrine gland like the follicle I Low levels of LH are need to maintain the corpus luteum and the corpus luteum secretes estrogen and progesterone Gonadotropin releasing hormone FSH and LH secretin increase during puberty In the male and sperm r relatively constant day to day The female has cyclical monthly swings in hormones FSH LH E 8 P are not constant day to day they have a monthly pattern and a cycle which normally produces 1 egg female gamete per month Changes in the levels of FSH and LH each month cause changes in sex hormone secretion and therefore changes in the uterine lining in the female J 39 39 ustant T F SH 8 LH levels are I Menstrual cycle cyclical changes in the uterus that accompany caused by ovarian cycle hormonal changes the menstrual cycle is made up of two uterine and ovarian events phases 0 Uterine events phases cyclical monthly changes in hormone contractions which cause cyclical changes in the uterine lining o Ovarian events phases uterine events phases are causedby cyclical changes that occur in the ovary each mont Ovarian phase of the menstrual cycle 0 15 12 is the ovarian follicular phase I Follicles develop and secrete estrogen I Normally get 1 mature follicle Graafian follicle which is like a blister ready to pop 0 2m1 J72 is the ovarian luteal phase I Corpus luteum are formed from rupture follicle and it secretes estrogen and progesterone after 2 weeks the corpus luteum degenerates selfdestructs and become corpus albicans The uterine phase of the menstrual cycle has 3 phases win it menstrual proliferative and secretory o Averages 28 day which is variable 3a 3b 3c 0 Starts w menstrual phase on day 1 which is the 1St day of bleeding Menstrual phase day 1 of cycle 1st day of bleeding menstruation of menses 0 During this phase the endometrium sloughs off b c blood vessels constrict due to low E and P which causes a decrease in 02 and nutrients Lasts 5 days A drop in E and P allows FSH and LH release to increase remove negative feedback on the hypothalamus and the anterior pituitary E39s effects on hypothalamus and anterior pituitary I Low to moderate level E results in negative feedback on hypothalamus and anterior pituita High level E results in positivefeedback on hypothalamus and anterior pituitary High E w high P results in negative feedback on hypothalamus and anterior pituitary Increased FSH and increase LH cause follicles to grow and secrete E and then E promotes follicle development too 00 Proliferative phase 0 Length is variable but generally from the end of menses to the 14 h da of 28 day cycle or to ovulation 0 Phase in which the endometrium proliferates it becomes thicker as a result of estrogen secretion from the follicle o The endometrium repairs and grows gland and blood vessels grow in thickened endometrium 0 Back at the ovary the ovarian cycle was plodding along to get to the stage of a mature follicle o Estrogen levels have been increasing high levels of E have a positive feedback effect on the hypothalamus and anterior pituitary rising E in follicular phase becomes high enough w the E peak to cause LH surge E peak means the follicle is mature enough which then signals the LH surge Secretory phase 0 Occurs at the same time as the Ovarian Luteal phase 0 The corpus luteum is formed when the follicle ruptures formation maintenance secretion of hormones of corpus luteum all require LH relatively small amounts the corpus luteum secretes E andP so E and P increase 0 P with E released from the corpus luteum inhibits the hypothalamus and pituitary negative feedback effect which prevents a new cycle from occurring b4 this one is over FSH and LH release are inhibited o P acts on the endometrium that has been primed by E E primes the endometrium by E causing synthesis of P receptors in the endometrium P causes glands to grow and start secreting glycogen the endometrium also becomes more vascularized 0 Now ready to receive embryo P also decreases uterine contractions which quiets the uterus and allows implantation of the embryo and the embryo to stay there 0 If the egg is not fertilized than the corpus luteum degenerates E and P levels fall and get menses since E and P levels are low you remove the negative feedbackinhibition FSH and LH release increases and a new cycle begins at day 1 The uterine menstrual phase and proliferative phase occur during the ovarian follicular phase the uterine secretory phase occurs during the ovarian luteal phase With feitilization the developing embryo needs to implant in the endometrium and stay there you need to keep the endometrium intact o This is done by the developing embryo secreting human chorionic gonadotropin hC G hCG keeps the corpus luteum from degenerating and keeps the corpus luteum secreting E and P and the endometrium does not slough I The high E and P during pregnancy causes the menstrual ovarian cycles to stop