BSC 216 Exam 3 Study Guide
BSC 216 Exam 3 Study Guide BSC 216
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This 28 page Study Guide was uploaded by Caroline Laird on Friday October 9, 2015. The Study Guide belongs to BSC 216 at University of Alabama - Tuscaloosa taught by Dr. Pienaar in Winter2015. Since its upload, it has received 113 views. For similar materials see Anatomy & Physiology II in Art at University of Alabama - Tuscaloosa.
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AampP Exam 3 Study Guide 4715 1021 PM Ascendingdescending loopRemember which part gains and loses what as far as salt water and the rest goes Name and locate the 6 organs of the urinary system 0 2 kidneys 2 ureters 1 bladder 1 urethra List functions of the kidneys in addition to urine formation 1 regulate blood volume amp pressure by eliminating or conserving water 2 regulate body fluid osmolarity by controlling watersolute elimination ratio 3 secrete renin an enzyme that activates hormonal control of blood pressure secrete erythropoietin that stimulates red blood cell synthesis Collaborate with lungs to regulate pH of body fluids add hydroxyl group to calcitriol gt calcium homeostasis initiate gluconeogenesis from amino acids during extreme starvation NP P P Name the major nitrogenous wastes and identify their sources 0 Ammonia 0 Removed from amino acids so it comes from the amino group removed from amino acids 0 Converted to urea by the liver 0 Urea 0 Broken down form of ammonia by the liver 0 Uric acid 0 Product of nucleic acid metabolism 0 Creatinine 0 Product of creatinine phosphate metabolism Define excretion and identify the systems that excrete wastes Excretion separation of wastes from body fluids and elimination of the wastes from the body 0 4 Body Systems Excrete Wastes 0 Respiratory system 0 Integumentary system 0 Digestive system 0 Urinary system Describe the location and general appearance of the kidney 0 Location retroperitoneal at the level of T12 to L3 0 Bean shaped 0 Protected by lower rib cage fat and a fibrous capsule o Layers Deep Superficial Fibrous capsule hard layer that protects against infection Fat capsule attached kidneys to body wall cushions Fascia dense connective tissue that anchors kidneys in place Understand the external and internal features of the kidney as it relates to blood and fluid flow Nephron 0 Each is an identical functional unit 0 Renal corpusclefilters blood plasma 0 Renal tubuleconverts filtrate into urine 0 Cortical nephronsshort nephron loops efferent arterioles branch into peritubular capillaries surrounding distal and PCT o Juxtamedullary nephronslong nephron loops efferent arterioles branch into vasa recta around each nephron loop 0 Renal tubule o PCTlong tubule simple cuboidal epithelium with prominent microvilli lots of absorption 0 Nephron loop Simple cuboidal thick segments a lots of mitochondria n involved in active transport of salts Simple squamous thin segments permeable to water 0 DCTshorter less coiled than PCT simple cuboidal epithelium devoid of microvilli end of the nephron 0 Collecting duct Receives fluid from the DCTs of several nephrons Numerous collecting ducts converge near the tip of the medullary pyramids to form papillary ducts Papillary ducts end in pores where urine passes into the minor calyx El Trace the flow of blood through the kidney Figure 235 PPFP P PPP 10 11 12 13 14 15 Aorta Renal artery Segmental artery Interlobar artery Arcuate artery Cortical radiate artery Afferent arteriole Glomerulus Efferent arteriole Peritubular capillaries cortical nephron OR vasa recta juxtamedullary nephron Cortical radiate vein Arcuate vein Interlobar vein Renal vein Inferior vena cava Trace the flow of fluid through the renal tubules First paragraph of page 904 quot Glomerular filtrate gt Urine N The flow of fluid from the point where the glomerular filtrate is formed to the point where urine leaves the body Glomerular capsule PCT Nephron loop h DCT Collecting duct 0 Fluid is called urine once it enters the collecting duct Papillary duct Minor calyx Major calyx Renal pelvis 10 Ureter 11 Urinary bladder 12 Urethra U1 399 Describe the process by which the kidney filters the blood plasma including the relevant cellular structure of the glomerulus Glomerular Filtration 0 Process where water and some solutes in the blood plasma pass from capillaries of the glomerulus into the capsular space of the nephron through the filtration membrane 0 Fluid passes through 3 barriers of the filtration membrane 0 Fenestrated endothelium of the capillary Highly permeable although their pores are small enough to exclude blood cells from the filtrate 0 Basement membrane Proteoglycan gel negative charge excludes molecules greater than 8 nm Albumin repelled by negative charge Blood plasma is 7 protein the filtrate is only 003 protein 0 Filtration Slits Podocyte cell extensions pedicels wrap around the capillaries to form a barrier layer with 30 nm filtration slits Negatively charged which is an additional obstacle for large anions Explain the forces that promote and oppose filtration and calculate the filtration pressure if given the magnitude of these forces 0 Blood hydrostatic pressure BHP pressure exerted by blood at rest 0 Much higher in glomerular capillaries 60 mmHg compared to 1015 in most other capillaries Because afferent arteriole is larger than efferent arteriole larger inlet and smaller outlet 0 Primary means of pushing solutes and water out of blood across filtration membrane 0 Hydrostatic pressure in capsular space pressure exerted by fluid at rest in capsular space 0 18 mmHg clue to high filtration rate and continual accumulation of fluid in the capsule 0 Pressure within capsule tends to push water back in to glomerulus Colloid osmotic pressure COP of blood due to proteins in blood osmotic pressure exerted by proteins albumin in vessel s blood plasma that usually tends to pull water into the circulatory system 0 About the same as others 32 mmHg 0 Glomerular filtrate is almost proteinfree and has no significant COP 0 Proteins in glomerular blood tend to pull water back into glomerulus Higher outward pressure of 60 mmHg opposed by two inward pressures of 18 mmHg and 32 mmHg gives a net filtration pressure NFP of o 60 out 18 in 32 in 10 mmHg out o BHP COP CP NFP Glomerulus is a more efficient filter than other capillaries because 0 it is a filtration membrane with a large surface area 0 high blood pressure within it which results in a high NFP Describe how the nervous system hormones and the nephron itself regulate filtration GFR control is achieved by 3 homeostatic mechanisms 1 Renal Autoregulation The ability of the nephrons to adjust their own blood flow and GFR without external nervous or hormonal control Enables the nephrons to maintain a stable GFR in spite of changes in systemic arterial blood pressure Two methods Myogenic mechanism El El Based on the tendency of smooth muscle to contract when stretched Increased arterial blood pressure stretches the afferent arteriole 9 arteriole constricts and prevents blood flow into the glomerulus from changing much When blood pressure falls 9 afferent arteriole relaxes and allows blood flow more easily into the glomerulus Result filtration remains stable Tubuloglomerular feedback El Mechanism by which glomerulus receives feedback on the status of the downstream tubular fluid and adjusts filtration to regulate the composition of the fluid stabilize its own performance and compensate for fluctuation in systemic blood pressure Juxtaglomerular apparatus complex structure found at the very end of the nephron loop where it has just reentered the renal cortex Three special kinds of cells occur in the juxtaglomerular apparatus 0 1 Macula densa Senses variations in flow or fluid composition and secretes a paracrine that stimulates JG cells 0 2 Juxtaglomerular JG cells When stimulated by the macula they dilate or constrict the arterioles 3 Mesangial cells Connected to macula densa and JG cells by gap junctions and communicate by means of paracrines o Constrict or relax capillaries to regulate flow 2 Sympathetic Control 0 Sympathetic nerve fibers richly innervate the renal blood vessels 0 Sympathetic nervous system and adrenal epinephrine constrict the afferent arterioles in strenuous exercise or acute conditions like circulatory shock Reduces GFR and urine output Redirects blood from the kidneys to the heart brain and skeletal muscles GFR may be as low as a few milliliters per minute 3 Hormonal Control 0 Renin Angiotensin Aldosterone Mechanism Renin is secreted by juxtaglomerular cells if BP drops dramatically Renin converts angiotensinogen a blood protein into angiotensin I In the lungs and kidneys angiotensinconverting enzyme ACE converts angiotensin I to angiotensin II the active hormone n Works in several ways to restore fluid volume and BP Describe how the renal tubules reabsorb useful solutes from the glomerular filtrate and return them to the blood 0 Tubular reabsorption process of reclaiming water and solutes from the tubular fluid and returning them to the blood 0 PCT reabsorbs 65 of glomerular filtrate 0 Two routes of reabsorption in the PCT o Transcellular route Substances pass through the cytoplasm of the PCT epithelial cells and out of their base 0 Paracellular route Substances pass between PCT cells Junctions between epithelial cells are quite leaky and allow significant amounts of water to pass through Solvent drag water carries with it a variety of dissolved solutes 0 Taken up by peritubular capillaries Sodium reabsorption is the key to everything else 0 Creates an osmotic and electrical gradient that drives the reabsorption of water and other solutes 0 Most abundant cation in filtrate o Creates steep concentration gradient that favors its diffusion into the epithelial cells Two types of transport proteins in the apical cell surface are responsible for sodium uptake 1 Symports that simultaneously bind Na and another solute such as glucose amino acids or lactate 2 NaH antiport that pulls Na into the cell while pumping out H into tubular fluid SodiumPotassium pumps in the basal surface of the epithelium prevent sodium from accumulating in the epithelial cells 0 Pumps Na out into the extracellular fluid 0 Picked up by peritubular capillaries 0 ATP consuming active transport pumps Negative chloride ions follow the positive sodium ions by electrical attraction 0 Various antiports in the apical cell membrane that absorb CI in exchange for other anions they eject into the tubular fluid 0 K Cl symport drives chloride and potassium OUT of epithelial cells Potassium magnesium and phosphate ions diffuse through the paracellular route with water Some calcium is reabsorbed through the paracellular route in the PCT but most Ca2 reabsorption occurs later in the nephron 4060 of urea is reabsorbed through paracellular route with water Nearly all uric acid is reabsorbed but secreted back later All of these paracellular movements are driven by solvent drag Reabsorption of all the salt and organic solutes makes the tubule cells and tissue fluid hypertonic 0 Water follows solutes by osmosis through both paracellular and transcellular routes through water channels called aquapo ns o In PCT water is reabsorbed at constant rate called obligatory water reabsorption Describe how the tubules secrete solute from the blood into the tubular fluid 0 Tubular secretion process in which renal tubule extracts chemicals from capillary blood and secretes them into tubular fluid 0 Two purposes in PCT and Nephron loop 0 Waste removal Urea uric acid bile acids ammonia catecholamines prostaglandins and a little creatinine are secreted into the tubule Secretion of uric acid compensates for its reabsorption earlier in PCT Clears blood of pollutants morphine penicillin aspirin and other drugs Explains need to take prescriptions three to four timesday to keep pace with the rate of clearance o Acid base balance Secretion of hydrogen and bicarbonate ions help regulate pH of body fluids Describe how the nephron regulates water excretion Primary function of nephron loop is to generate salinity gradient that enables collecting duct to concentrate the urine and conserve water 0 Electrolyte reabsorption from filtrate 0 Thick segment reabsorbs 25 of Na K and Cl Ions leave cells by active transport and diffusion n NaCl remains in the tissue fluid of renal medulla a Water cannot follow since thick segment is impermeable o Tubular fluid very dilute as it enters distal convoluted tubule Explain how the collecting duct and antidiuretic hormone regulate the volume and concentration of urine 0 The collecting duct is regulated by several hormones in terms of the volume and concentration of urine 0 Aldosterone salt retaining hormonequot Acts on cortical portion of collecting duct n Stimulates reabsorption of more Na and secretion of K a Water and Cl follow the Na a Net effect is that the body retains NaCl and water which helps maintain blood volume and pressure a Urine volume is reduced In Urine has an elevated K concentration 0 Atrial natriuretic peptide ANP secreted by atrial myocardium of the heart in response to high blood pressure Four actions result in the excretion of more salt and water in the urine thus reducing blood volume and pressure a Dilates afferent arteriole constricts efferent arteriole T GFR n Inhibits renin and aldosterone secretion n Inhibits secretion of ADH n Inhibits NaCl reabsorption by collecting duct Antidiuretic hormone ADH secreted by posterior lobe of pituitary in response to dehydration and rising blood osmolarity o Action make collecting duct more permeable to water Water in the tubular fluid reenters the tissue fluid and bloodstream rather than being lost in urine Explain how the kidney maintains an osmotic gradient in the renal medulla that enables the collecting duct to function What are the main organs associated with the urinary system Can you identify the flow of blood from the heart through the kidney and back to the heart Kidneys Ureters Urinary bladder Urethra Aorta Renal artery Segmental artery Interlobar artery Arcuate artery Cortical radiate artery Afferent arteriole Glomerulus Efferent arteriole 10 Peritubular capillaries 11 Cortical radiate vein 12 Arcuate vein 13 Interlobar vein 14 Renal vein 15 Inferior vena cava 16 Heart PPFP P PPP Can you trace the flow of fluid from the glomerulus to the urethra If given a place in the nephron could you tell me if the fluid is glomerular filtrate tubular fluid or urine What is the main function of the kidney what are other functions of the kidney 0 The kidneys are the primary functional organ of the urinary system 0 Main function filter blood plasma and separate waste from useful chemicals What gives the medullary renal pyramids their characteristic stringy appearance 0 Renal cortex What are the minor calyx and the major calyx Minor calyx is cup that houses papilla of each renal pyramid and it collects urine 0 2 or 3 minor calyx converge to form a major calyx 2 or 3 major calyx converge in the sinus to form the funnellike renal pelvis What is the structural and functional unit of the kidney Nephron loop Do you know the nephron structure glomerulus Bowman s capsule renal corpuscle proximal convoluted tubule loop of Henle ascending and descending distal convoluted tubule collecting duct Glomerulus ball of capillaries enclosed in a glomerular capsule Bowman39s capsule AKA glomerular capsule encloses glomerulus 2 layered Renal corpuscle glomerulus Bowman s capsule Proximal convoluted tubule longest tubule and highly coiled simple cuboidal epithelium with prominent microvilli brush border that aids in a great deal of absorption 0 Loop of Henle AKA nephron loop 0 Descending looponly in medulla o Ascending loopextends to cortex 0 Simple cuboidal thick segments Lots of mitochondria Involved in active transport of salts 0 Simple squamous thin segments Permeable to water Thinwater reabsorption Distal convoluted tubule shorter tubule and less coiled than PCT cuboidal epithelium devoid of microvilli the end of the nephron loop 0 Collecting duct received fluid from the DCT s of several nephrons 0 Numerous collecting ducts converge near the tip of the medullary pyramids to form papillary ducts o Papillary ducts end in pores where urine passes into the minor calyx What is a podocyte 0 Cells of the visceral layer of the renal corpuscle that are wrapped around the capillaries of the glomerulus Can you describe at least 2 differences between cortical nephrons and juxtamedullary nephrons Hint hint know peritubular capillaries and vasa recta Cortical nephrons 0 Make up 85 of all nephrons 0 Short nephron loops 0 Efferent arterioles branch into peritubular capillaries surrounding distal AND proximal convoluted tubules Juxtamedullary nephrons 0 Make of 15 of nephrons Long nephron loops maintain salinity gradients Efferent arterioles branch into vasa recta around each nephron loop Why is blood pressure very high in the glomerulus compared to other capillaries 0 Because the afferent arteriole is larger than the efferent arteriole larger inlet and smaller outlet Where is the juxtaglomerular apparatus located and what are the 3 special kinds of cells that it is made of 0 Located at the very end of the nephron loop where it has just reentered the renal cortex 0 Made of 3 kinds of cells 0 Macula densa o Juxtaglomerular JG cells 0 Mesangial cells What are the functions of the 3 cell types of the juxtaglomerular apparatus 0 Macula densa Senses variations in flow or fluid composition and secretes a paracrine that stimulates JG cells 0 Juxtaglomerular JG cells When stimulated by the macula they dilate or constrict the arterioles Mesangial cells Connected to macula densa and JG cells by gap junctions and communicate by means of paracrines o Constrict or relax capillaries to regulate flow What 3 structures is the filtration membrane composed of o Fenestrated endothelium of glomerular capillaries o 70 to 90 nm filtration pores exclude blood cells 0 Highly permeable 0 Basement membrane 0 Proteoglycan gel negative charge excludes molecules greater than 8 nm 0 Albumin repelled by negative charge 0 Blood plasma is 7 protein the filtrate is only 003 protein Filtration slits o Podocyte cell extensions pedicels wrap around the capillaries to form a barrier layer with 30 nm filtration slits o Negatively charged which is an additional obstacle for large anions How does the filtration membrane facilitate the transfer of fluidssolutes from the glomerulus to Bowman s capsule and the kidney tubules What substances will easily pass through the filtration membrane What substances will NOT 0 Easily pass Water electrolytes glucose fatty acids amino acids nitrogenous wastes and vitamins Will not pass Calcium iron and thyroid hormone substances of low molecular weight have to bind to plasma proteins disabling them from passing through membrane What39s the difference between filtrate and urine Filtrate fluid in the capsular space similar to blood plasma except that it has almost no protein 0 Urine fluid that enters the collecting duct undergoes little alteration beyond this point except for changes in water content How does glomerular filtration occur and why is the glomerulus more efficient at filtration than other capillaries in the body 0 Water are some solutes in the blood plasma pass from the capillaries of the glomerulus into the capsular space of the nephron Glomerulus is more efficient at filtration than other capillaries because 0 Filtration membrane with large surface area 0 High BP within glomerulus 60 mmHg vs 15 mmHg 0 Result high net filtration pressure What are the three forces that generate a glomerular net filtration pressure of 10 mmHg Can you describe these 3 forces Can you describe the 3 mechanisms that can alter glomerular filtration rates Why is tubular reabsorption necessary 0 To reabsorb essential substances 0 Especially sodium reabsorption How are sodium ions transported from kidney tubule to the peritubular capillary SodiumPotassium pumps How does the movement of sodium ion facilitate the movement of anions negative ions and water from lumen to capillaries A symporter simultaneously binds Na and another solute like glucose amino acids or lactate How is Aldosterone Natriuretic peptides ADH and PTH involved in Tubular Secretion Aldosterone salt retaining hormonequot o Acts on cortical portion of collecting duct Stimulates reabsorption of more Na and secretion of K Water and Cl follow the Na Net effect is that the body retains NaCl and water which helps maintain blood volume and pressure Urine volume is reduced Urine has an elevated K concentration Atrial natriuretic peptide ANP secreted by atrial myocardium of the heart in response to high blood pressure 0 Four actions result in the excretion of more salt and water in the urine thus reducing blood volume and pressure Dilates afferent arteriole constricts efferent arteriole T GFR Inhibits renin and aldosterone secretion Inhibits secretion of ADH Inhibits NaCl reabsorption by collecting duct Antidiuretic hormone ADH secreted by posterior lobe of pituitary in response to dehydration and rising blood osmolarity o Action make collecting duct more permeable to water Water in the tubular fluid reenters the tissue fluid and bloodstream rather than being lost in urine 0 Parathyroid hormone PTH secreted from parathyroid glands in response to calcium deficiency hypocalcemia o Increases phosphate content and lowers calcium content in urine 0 Because phosphate is not retained the calcium ions stay in circulation rather than precipitating into the bone tissue as calcium phosphate How does the countercurrent Multiplier work in Water Conservation 0 Nephron loop acts as countercurrent multiplier o Multiplier continually recaptures salt and returns it to extracellular fluid of medulla which multiplies the salinity in adrenal medulla o Countercurrent because of fluid flowing in opposite directions in adjacent tubules of nephron loop 0 Fluid flowing downward in descending limb Passes through environment of increasing osmolarity Most of descending limb very permeable to water but not to NaCl Water passes from tubule into the ECF leaving salt behind Concentrates tubular fluid to 1200 mOsmL at lower end of loop 0 Fluid flowing up ward in ascending limb Impermeable to water a Reabsorbs Na K and Cl by active transport pumps into ECF n Maintains high osmolarity of renal medulla n Tubular fluid becomes hypotonic 100 mOsmL at top of loop What is the countercurrent exchange system and how does this work to keep salts and urea in the medulla o The large volume of water reabsorbed by the collecting duct must be returned to the bloodstream The water picked up and carried away by the vasa recta but the vasa recta does not also carry away the urea and salt neede to maintain the high osmolarity of the medulla because the vasa recta forms a countercurrent exchange system that prevents it from happening 0 Countercurrent exchange system prevents the vasa recta from carrying away urea and salt needed to maintain the high osmolarity of the medulla Vasa recta are capillaries branching off efferent arterioles in the medulla o It provides blood supply to medulla and does not remove NaCl and urea from medullary ECF The countercurrent system is formed by blood flowing in opposite directions in adjacent parallel capillaries Descending capillaries as blood flows downward into the medulla o Vessels exchange water for salt 0 Water diffuses out of capillaries and salt diffuses in 0 As blood flows back up to the cortex the opposite occurs Ascending capillaries o Exchanges salt for water 0 Water diffuses into blood and NaCl diffuses out of blood 0 Vasa recta gives the salt back and does not subtract from the osmolarity of the medulla Vasa recta absorb more water on the way out than the way in and thus they carry away water reabsorbed from the urine by collecting duct and nephron loop Can you describe the neural control of urination both involuntary and voluntary see Fig 2324 Copyright ID The McGraw Hill Companies Inc Permission mired for reproduction Ordisolay39 Involuntary micturition re ex To pom r r From eons 0 Stretch receptors detect filling O of bladder transmit afferent signals to spinal cord Signals return to bladder from spinal cord segments 52 and 83 via parasympathetic fibers in pelvic nerve Pelvic nerve i Efferent signals excite 39Sensory Motor detmsor muscle In Efferent signals relax internal urethral sphincter Urine is gazggfggznu involuntarily voided if not inhibited by brain 32 Voluntary control 39 39 39 39 For voluntary control micturition 33 center in pons receives signals from stretch receptors 8 If it is timely to urinate pons returns signals to Sympathwc spinal intemeurons that Ganglion 390 excite detrusor and relax quotmoquot W3 internal urethral sphincter Stretch receptors 1 Urine is voided If it is untimer to urinate signals from pons excite spinal intemeurons that keep external urethral Motor fibers to detrusor muscle lntemal urethral xx momquotquot1 sphincter contracted Urine sphincter involuw lt J is retained in bladder somauc quot390 quot mm If it is time to urinate si nals Erh gngxggm am 0f Wdondal mm from ponsZease and extegmal urethral sphincter relaxes Urine is voided Define buffer and write chemical equations for the bicarbonate buffer systems 0 A buffer is any mechanism that resists changes in pH 0 Chemical equations for bicarbonate buffer systems 0 Carbonic acid and bicarbonate ions C02 H20lt gtH2CO3 lt gtHCO3 H o Reversible reaction important in ECF C02 H20 gtH2CO3 gtHCO3 H n Lowers pH by releasing H C02 H20lt H2CO3 lt HCO3 H n Raises pH by binding H Discuss the relationship between pulmonary ventilation pH of the extracellular fluids and the bicarbonate buffer system 0 Increased C02 and decreased pH stimulate pulmonary ventilation Increased pH inhibits pulmonary ventilation Explain how the kidneys secrete hydrogen ions and how these ions are buffered in the tubular fluid 0 Kidneys can neutralize more acid or base than either the respiratory system or chemical buffers Renal tubules secrete H into the tubular fluid 0 Most bind to bicarbonate ammonia and phosphate buffers Bound and free H are excreted in the urine actually expelling H from the body 0 Other buffer systems only reduce its concentration by binding it to other chemicals What is the normal pH range of human blood and tissue fluid 0 735745 What determines the pH of a solution 0 The concentration of a solutions hydrogen ions H 0 So the more H in the solution the lower the pH and vice versa How does a chemical buffer work Binds H and removes it from solution as its concentration begins to Releases H into solution as its concentration How does the bicarbonate buffer system act to lower pH And increase pH 0 Lower pH 0 Releases H Increase pH 0 Binds H In general how do the kidneys lower pH 0 To lower pH kidneys excrete HCO3 In general how do the kidneys and lungs work together to raise pH 0 To raise pH kidneys excrete H and lungs excrete C02 If we remove C02 from a solution does it become more acidic or alkaline 0 Alkaline Why can the kidneys neutralize more acids and bases than other buffer systems Describe the enteric nervous system 0 A nervous network in the esophagus stomach and intestines that regulate digestive tract motility secretion blood flow and emotions Thought to have over 100 million neurons massive number of dendrtes 0 Even more than the spinal cord 0 Functions completely independently of the central nervous system 0 CNS exerts a significant influence on its action sympathetic and parasympathetic pathways 0 Contains sensory neurons that monitor tension in gut wall and conditions in lumen o It maintains muscle tone for a given action like peristalsis Describe the process of mastication and swallowing Mastication chewing breaks food into smaller pieces to be swallowed and exposes more surface to the action of digestive enzymes 0 First step in mechanical digestion 0 Mostly performed by skeletal muscles 0 Food stimulates oral receptors that trigger an involuntary chewing reflex Describe the composition and functions of saliva 0 Composition of Saliva o Hypotonic solution of 970 to 995 water and the following solutes Salivary amylase enzyme that begins starch digestion in the mouth Lingual lipase enzyme that is activated by stomach acid and digests fat after the food is swallowed Mucus binds and lubricates the mass of food and aids in swallowing Lysozyme enzyme that kills bacteria Immunoglobulin A IgA an antibody that inhibits bacterial growth Electrolytes Na K Cl phosphate and bicarbonate 0 pH 6870 raises pH from what it is in blood plasma becomes more acidic bc of stomach acid etc 0 Functions of Saliva Moisten mouth Begin starch and fat digestion by lowering activation energy Cleanse teeth Inhibit bacterial growth Dissolve molecules so they can stimulate the taste buds Moisten food and bind it together into bolus to aid in swallowing 0 00000 Describe the neural control of salivation and swallowing Neural Control of Salivation o Salivary nuclei in the medulla oblongata and 1 respond to signals generated by presence of food Tactile pressure and taste receptors Receive input from higher brain centers as well n Odor sight thought of food stimulates salivation Send signals by way of autonomic fibers in the facial and glossopharyngeal nerves to the glands n Parasympathetics stimulate the glands to produce an abundance of thin enzymerich saliva n Sympathetic stimulation stimulates the glands to produce less and thicker saliva with more mucus 0 Dry or sticky under stress or dehydration Neural Control of Swallowing o Swallowing center pair of nuclei in medulla oblonqata that coordinates swallowing Communicates with muscles of the pharynx and esophagus by way of trigeminal facial glossopharyngeal and hypoglossal nerves What is the primary function of the alimentary canal gastrointestinal tractwhich organs are associated with this canal Mouth 0 Pharynx Esophagus Stomach 0 Small intestine Large intestine What types of accessory organs participate in the digestive process 0 Teeth tongue salivary glands liver gallbladder and pancreas Can you walk me through the 5 stages of the digestive process 0 1 Ingestion selective intake of food 0 2 Digestion mechanical and chemical breakdown of food into a form usable by the body 0 Mechanical digestion the physical breakdown of food into smaller particles Cutting and grinding action of the teeth Churning action of stomach and small intestines Exposes more food surface to the action of digestive enzymes 0 Chemical digestion a series of hydrolysis reactions that breaks dietary macromolecules into their monomers residues Carried out by digestive enzymes produced by salivary glands stomach pancreas and small intestine Results n Polysaccharides into monosaccharides n Proteins into amino acids n Fats into monoglycerides and fatty acids In Nucleic acids into nucleotides 3 Absorption uptake of nutrient molecules into the epithelial cells of the digestive tract and then into the blood and lymph 4 Compaction absorbing water and consolidating the indigestible residue into feces 5 Defecation elimination of feces Define peristalsis How does it work Peristalsis wave of muscular contraction that pushes the bolus ahead of it Entirely involuntary reflex When standing or sitting upright the food and liquid drops through the esophagus by gravity faster than peristalsis can keep up with it Peristalsis ensures you can swallow regardless of body position Liquid reaches the stomach in 1 to 2 seconds Food bolus in 4 to 8 seconds When it reaches lower end of the esophagus the lower esophageal sphincter relaxes to let food pass into the stomach Define segmentation How does it work What39s the difference between a short and a long reflex 0 Short myenteric reflexes 0 Stretch or chemical stimulation acts through myenteric plexus o Stimulates parestaltic contractions of swallowing Long vagovagal reflexes parasympathetic stimulation of digestive motility and secretion Which body cavity do all of the digestive organs sit in 0 Oral thoracic and pelvic Alimentary canal What is a serous membrane and which kind of serous membrane is associated with digestive organs Mesentery of small intestines holds many blood vessels 0 Mesocolon anchors colon to posterior body wall 0 Greater and lesser omentum 0 Greater encloses most of the stomach and intestines o Lesser is behind the greater What is the difference between the visceral and parietal peritoneums What is mesentery Can you name at least 3 functions of the mesentery Mesenteries are connective tissue sheets that loosely suspend the stomach and intestines from the abdominal wall 0 Functions 0 Allow stomach and intestines to undergo strenuous contractions 0 Allow freedom of movement in the abdominal cavity 0 Hold abdominal viscera in proper relationship to each other 0 Prevent the intestines from becoming twisted and tangled by changes in body position and by its own contractions 0 Provide passage of blood vessels and nerves that supply digestive tract 0 Contain many lymph nodes and lymphatic vessels What are the 4 layers that you will find in organs of the alimentary canal Mucosa Submucosa Muscularis externa Serosa What is the function of the myenteric nerve plexus The submucosal nerve plexus Myenteric Auerbach plexus parasympathetic ganglia and nerve fibers between the two layers of the muscularis interna 0 Controls peristalsis and other contractions of muscularis externa Submucosal Meissner plexus in submucosa 0 Controls glandular secretion of mucosa 0 Controls movements of muscularis mucosae What does the epiglottis do 0 Block food from entering airway What is the tongue39s main function in the digestive process 0 Compresses food against palate to form a bolus Provides bigger surface area for enzymes Which of the salivary glands is most susceptible to myxovirus mumps Extrinsic salivary glands Can you distinguish the salivary glands based on their method of excretion duct no duct Intrinsic no duct 0 Lingual o Labial o Buccal Extrinsic ducts o Parotid o Submandibular o Sublingual Where do the parotid submandibular and sublingual glands empty their products 0 mouth What are the functions of the upper and lower esophageal sphincters 0 Upper esophageal sphincter o Prevents bolus from coming out again by constricting as the bolus passes downward 0 Lower esophageal sphincter o Prevents stomach contents from regurgitating into the esophagus o Protects esophageal mucosa from erosive effect of the stomach acid Can you describe the 5 steps of swallowing 1 Tongue compresses food against palate to form a bolus 2 Bolus passes into pharynx Misdirection of bolus is prevented by tongue blocking oral cavity soft palate blocking nasal cavity and epiglottis blocking larynx 3 Upper esophageal sphincter constricts and bolus passes downward 4 Peristalsis drives bolus down esophagus Esophagus constricts above bolus and dilates and shortens below it 5 Lower esophageal sphincter relaxes to admit bolus to stomach Describe the buccal and pharyngealesophageal phases of deglutition swallowing 1 Buccal phase 0 Under voluntary control 0 Tongue collects food presses it against the palate forming a bolus and pushes it posteriorly Food accumulates in oropharynx in front of blade of the epiglottis Epiglottis tips posteriorly and food bolus slides around it through the laryngeal opening Bolus enters laryngopharynx and stimulates tactile receptors and activates next phase 2 Pharyngoesophageal phase 0 O Involuntary Three actions prevent food and drink from reentering the mouth or entering the nasal cavity or larynx Root of the tongue blocks the oral cavity Soft palate rises and blocks the nasopharynx Infrahyoid muscles pull the larynx up to meet the epiglottis while laryngeal folds close the airway Food bolus is driven downward by constriction of the upper then middle and finally the lower pharyngeal constrictors Bolus enters esophagus stretches it and stimulates peristalsis What is the importance of oblique smooth muscle located only in the stomach Within the gastric glands what is the function of the mucous neck cells parietal cells 0 Mucous neck cells secrete mucus and are concentrated at the neck of the glands Parietal cells secrete HCI intrinsic factor and ghrelin hunger hormone What are 3 mechanisms that the stomach uses to prevent corrosion of itself due to the very acidic environment Which nerve stimulates stomach activity Where in the brain does this nerve originate
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