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57 Cards in this Set
- Front
- Back
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Digestive tract
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1. mouth
2. esophagus 3. stomach 4. small intestines (duodenum, ileum, jejunum) 5. large intestines (ascending colon, transverse colon, descending colon, sigmoid colon) 6. rectum 7. anus |
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Mouth
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Digestion begins in the mouth with alpha-amylase contained in saliva
breakdown of starch chewed food forms clump called bolus |
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alpha-amylase
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contained in saliva
begins breakdown of starch (carbohydrates) into polysaccharides |
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esophagus
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bolus is pushed into esophagus from mouth by swallowing
bolus is moved down esophagus by peristaltic action saliva acts to lubricate esophagus to help food move down no digestion occurs |
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peristaltic action
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wave motion, similar to squeezing a tube of toothpaste at bottom and sliding fingers toward top to expel toothpaste
movement is performed by smooth muscles |
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stomach
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bolus moves into stomach through lower esophageal sphincter (cardiac sphincter)
very flexible pouch that mixes and stores food reduces bolus to semifluid mass called chyme contains exocrine glands begins protein digestion with enzyme pepsin low pH assists by denaturing proteins (pH 2) and kills bacteria no absorption occurs |
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chyme
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semifluid mass of food in stomach
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4 major cell types of stomach
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1. mucous cell
2. chief (peptic) cell 3. parietal (oxyntic cells) 4. G cell |
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G cell
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secrets gastrin into interstitium, which stimulates parietal cells to secrete HCl
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Mucous cell
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contains rough ER and golgi to make mucus, composed of glycoprotein and electrolytes
secretes mucus to lubricate stomach and protect epithelial lining different types line stomach wall and necks of exocrine glands some secrete small amounts of pepsinogen |
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parietal (oxyntic) cell
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many mitochondria to produce sufficient energy to establish proton gradient
found in exocrine glands of stomach secrete HCl, which diffuses to lumen used to lower pH of stomach and raise pH of blood also secrete intrinsic factor, helps ileum absorb B12 |
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Chief (peptic) cell
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synthesizes pepsinogen on rough ER, which is later cleaved to active pepsin
deep in exocrine glands secret pepsinogen, zymogen precursor of pepsin |
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epithelial lining
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protected by mucus from acidic environment of stomach
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pepsinogen
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zymogen precursor to pepsin
activated to pepsin by low pH in stomach once activated, pepsin beings protein digestion |
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gastrin
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secreted by G cells into interstitium
large peptide hormone absorbed into blood stimulates parietal cells to secrete HCl |
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Major hormones affects secretion of stomach juices
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1. acetylcholine: increases secretion of all cell types
2. gastrin: increase secretion of HCl 3. histamine: increase secretion of HCl |
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Small intestines
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90% of digestion and absorption occurs in small intestines
3m in length divided into 3 parts (smallest to largest): 1. duodenum (digestion) 2. jejunum (absorption) 3. ileum (absorption) |
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villi
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finger-like projections that covers outermost layer of small intestines
increases surface area, allowing for greater digestion and absorption each contain capillary network and lymph vessel (lacteal) through which absorbed nutrients pass |
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microvilli
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on apical (lumen side) surface of cells of each villus (enterocytes)
smaller finger-like projections increase surface area appear as fuzzy covering |
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brush border
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fuzzy covering of microvilli on villus
contains membrane bound digestive enzymes for carbohydrates, proteins, nucleotides |
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goblet cells
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small intestine lining
epithelial cells secrete mucus to lubricate intestines and help protect brush border from mechanical and chemical damage |
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Pancreas
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secretes bicarbonate ion into duodenum to make pH 6
exocrine glands also secretes enzymes: trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease and deoxyribonuclease all enzymes are released as zymogens activated trypsin, activates other enzymes |
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trypsin and chymotrypsin
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degrade proteins into small polypeptides
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pancreatic amylase
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like salivary alpha-amylase, but more powerful
digests starch, carbohydrates hydrolyzes polysaccharides to disaccharides and trisaccharides degrades carbohydrates of chyme to small glucose polymers |
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lipase
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degrades fats, specifically triglycerides
since intestinal fluid is aqueous solution, fat clumps together, reducing surface area, which makes degradation difficult, problem fixed by addition of bile |
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bile
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produced by liver and stored in gall bladder
gall bladder releases bile into small intestines needed to increase surface area of fat physically separates fat molecules, but does not chemically break down fat emulsifies fat, doesn't digest fat reabsorbed by small intestine and transported back to liver |
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emulsification
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what bile does to fat
breaking up of fat into small particles without changing it chemically increases surface area of fat, allowing lipase to degrade it into fatty acids and monoglycerides |
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peristalsis
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moves chyme through intestines
wave-motion |
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large intestines
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site of water and electrolyte reabsorption
profuse water loss, diarrhea, results when there is a problem with large intestines mutualistic symbiosis between humans and bacteria (E. coli) in large intestines, bacteria get our leftovers and we get vitamins (K, B12, thiamin and riboflavin) made up of: 1. ascending colon 2. transverse colon 3. descending colon 4. sigmoid colon |
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glycogenesis
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formation of glycogen from glucose
glycogen is stored occurs when blood glucose levels increase occurs in liver and muscle cells all cells are capable of storing glycogen, liver and muscle cells store most glycogen |
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glycogenolysis
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occurs when blood glucose levels decrease
glycogen in converted to glucose takes place in the liver and glucose is returned to blood |
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urea
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ammonia is converted to urea by liver and then excreted in urine by kidney
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albumin
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fatty acids combine with albumin in the blood
single molecule of albumin carried 3 fatty acid molecules, but is capable of carrying up to 30 |
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vena cava
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location where all blood that has passed through liver is deposited
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functions of liver
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1. blood storage
2. blood filtration 3. carbohydrate metabolism (gluconeogenesis, glycogenesis, storage of glycogen) 4. fat metabolism 5. protein metabolism (urea) 6. detoxification 7. erythrocyte destruction 8. vitamin storage when liver mobilizes fat or protein for energy, blood acidity increases (acidosis) |
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Kidney function
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1. excrete waste products (urea, uric acid, ammonia and phosphate)
2. maintain homeostasis of body fluid volume and solute composition 3. help control plasma pH |
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Kidney
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2 fist-size organs
made up of: 1. outer cortex 2. inner medulla creates urine, which empties into renal pelvis |
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cortex
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outer part of kidney
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medulla
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inner part of kidney
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renal pelvis
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where urine is emptied to
emptied by ureter |
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ureter
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carries urine to bladder
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bladder
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drained by urethra
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nephron
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functional unit of kidney
Made up of: 1. glomerulus 2. bowman's capsule 3. renal corpuscle 4. proximal tubule 5. loop of henle 6. distal tubule 7. collecting duct 8. juxtaglomerular apparatus |
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glomerulus
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blood flows into the 1st capillary bed of nephron
contains fenestrations hydrostatic pressure of glomerulus controls amount of filtrate |
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renal corpuscle
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made up by bowman's capsule and glomerulus
where filtration occurs |
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hydrostatic pressure
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forces plasma through fenestrations of glumerular endothelium and into bowman's capsule
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fenestration
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like a sieve
screens out blood cells and large proteins from entering bowman's capsule |
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bowman's capsule
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fluid is called filtrate or primary urine
fluid from bowman's capsule to proximal tubule |
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proximal tubule
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most reabsorption and secretion takes place
secondary active transport proteins in apical membranes of proximal tubule cells are responsible for reabsorption of: glucose, proteins and other solutes water is reabsorbed across relatively permeable tight junctions due to favorable osmotic gradient net result: reduce amount of filtrate in nephron, while changing solute composition without changing osmolarity |
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secreted
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drugs, toxins and other solutes are secreted into filtrate by cells of proximal tubule
also secreted into proximal tubule: uric acid, bile pigments, antibiotics and other drugs |
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antiport system
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secretes H ions with Na+
driven by Na+ concentration gradient similar to transport system of glucose with Na+, except H+ crosses membrane in opposite direction to Na+ |
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loop of henle
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filtrate flows to here from proximal tubule
dips into medulla functions to increase solute concentration, thus osmotic pressure, of medulla concentrates solute in medulla water passively diffuses out and into medulla 2 parts: 1. descending loop of henle 2. ascending loop of henle |
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descending loop of henle
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low permeability to salt
filtrate osmolarity goes up permeable to water |
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ascending loop of henle
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filtrate rises out of medulla into cortex
salt diffuses out, passively at first and then actively impermeable to water actively transports Na+ into kidney |
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distal tubule
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reabsorbs Na+ and Ca +2
secretes K+, H+ and HCO3- ADH acts on distal tubule cells to increase Na+ & K+ membrane transport proteins net effect: lower filtrate osmolarity ADH acts to increase permeability of cells to water presence of ADH, water flow from tubule, concentrating filtrate |
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collecting duct
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where distal tubules empties
carries filtrate into highly osmotic medulla impermeable to water and sensitive to ADH presence of ADH, collecting duct becomes permeable to water allowing it to passively diffuse in medulla, concentrating urine lead to renal pelvis |
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juxtaglomerular apparatus
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monitors filtrate pressure in distal tubule
cells secrete renin enzyme, to initiate regulatory cascade which ultimately stimulates adrenal cortex to secrete aldosterone aldosterone acts on distal tubule, stimulating formation of membrane proteins that absorb Na+ and secrete K+ |
