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Berkeley MCAT Biology > Chapter 3 - Gastrointestinal Tract & Kidney > Flashcards

Chapter 3 - Gastrointestinal Tract & Kidney Flashcards

1
Q

Gastroesophageal sphincter

A

contracts and prevents regurgitation of food back into esophagus

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2
Q

Surface cells

A

secrete mucus to protect lining of stomach and lubricate food

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3
Q

Gastrin

A

in endocrine cells of lower stomach, secreted in response to proteins, stimulates secretion of HCl and pepsinogen

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4
Q

Parietal cells

A

secrete HCl and intrinsic factor

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5
Q

Chief cells

A

secrete pepsinogen

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6
Q

Histamine

A

powerful stimulant that causes HCl to be released into the lumen of the stomach

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7
Q

Cimetidine

A

inhibits binding of histamine to its receptor on parietal cells

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8
Q

Cholecystokinin (CCK)

A

diffuses by way of the bloodstream to the pancreas, causing it to release digestive enzymes

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9
Q

Secretin

A

released from small intestine when chyme enters from stomach, also absorbed by blood

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10
Q

Pancreas

A

endocrine cells that secrete insulin and glucagon

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11
Q

Acini

A

in the pancreas, secretes a fluid into small intestine with high bicarb content (very alkaline) to combine w/ protons from HCl to make carbonic acid —> CO2 + H2O, CO2 is then expired

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12
Q

Where is bile produced and concentrated?

A

the liver

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13
Q

Where is bile stored?

A

the gallbladder

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14
Q

What is the importance of bile salts?

A

help digest and absorb fats

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15
Q

What happens after bile is released from the gallbladder?

A

passes down a duct that connects w/ pancreatic duct, through a constriction that empties to the small intestine

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16
Q

What is the sphincter of Oddi?

A

a constriction that allows bile to empty into the small intestine

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17
Q

Where does majority of fluid and nutrient absorption occur in the body?

A

the small intestine

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18
Q

What does lipase do?

A

breaks fat into fatty acids and glycerol so they can diffuse into the intestinal epithelial cells and become triglycerides

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19
Q

What are chylomicrons?

A

Aggregates of triglycerides released at the basolateral membrane and into the extracellular space

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20
Q

How much of an average weight (154 lbs) man’s body is water weight?

A

roughly 60% (a little < 2/3)

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21
Q

What is a nephron composed of?

A

a glomerulus, Bowman’s capsule, and a tubular system

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22
Q

How does Bowman’s capsule receive blood flow?

A

hydrostatic pressure of the heart pushes blood into the glomerulus, further into capillary walls, and then Bowman’s capsule

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23
Q

Where does reabsorption take place?

A

from filtrate in Bowman’s capsule (organic and inorganic compounds)

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24
Q

What do the epithelial cells lining the tubular lumen of the nephron excrete?

A

protons, potassium, urea, uric acid, and ammonia

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25
Q

What is excreted from the kidneys?

A

waste, salts, and excess water

26
Q

Where does blood leave the kidney?

A

renal vein and eventually empties into inferior vena cava

27
Q

How many nephrons are in a kidney?

A

over 1 million

28
Q

What do collecting ducts do?

A

they collect urine and empty into the renal pelvis of the kidney, then the ureter

29
Q

Where does the afferent arteriole originate and run to?

A

renal artery branches into the kidney to become afferent arteriole, then enters Bowman’s capsule to form capillary bed (glomerulus)

30
Q

Where does the efferent arteriole exit?

A

it leaves the glomerulus to form a capillary network surrounds the renal tubules, goes on to the renal vein via a venule to exit kidney

31
Q

What is the function of the proximal convoluted tubule (PCT)?

A

65% of ALL reabsorption and secretion occurs here, its epithelial cells are active af for a variety of active transport processes

32
Q

What types of molecules are 100% reabsorbed in the proximal convoluted tubule (PCT)?

A

glucose, small MW proteins, amino acids, and vitamins (Na+, Cl-, and H2O are also reabsorbed about 80%)

33
Q

What are the features of the descending thin loop of Henle?

A

very permeable to H2O, only relatively permeable to Na+ and urea

34
Q

What are the features of the ascending thin loop of Henle?

A

much more permeable to urea, but much less to H2O

35
Q

What are features of the ascending thick loop of Henle?

A

actively transport Na+ and K+ from lumen of loop into the interstitial fluid, impermeable to H2O and urea (fluid becomes more dilute)

36
Q

Where does filtrate from the thick portion of the loop of Henle go?

A

distal convoluted tubule

37
Q

What are features of the distal convoluted tubule?

A

impermeable to urea and water, permeable to Na+, Na+ flows out, fluid becomes more dilute

38
Q

What is key about the epithelial cells of the segment of the DCT closest to the collecting duct and that portion of the collecting duct itself?

A

impermeable to urea still, but sensitive to aldosterone

39
Q

What does aldosterone do?

A

it regulates sodium absorption and is secreted by adrenal glands, Na+ gets reabsorbed and K+ is pumped out

40
Q

What does antidiuretic hormone (ADH) do?

A

made by hypothalamus, released by pituitary gland, regulates water absorption, water reabsorption creates more concentrated urine

41
Q

How does the adrenal gland monitor sodium levels?

A

cells in the cortex of adrenal glands are sensitive to Na+ levels in the blood, when Na+ levels drop, aldosterone is released

42
Q

Alcohol inhibits the release of ADH. What would be expected as a result?

A

dehydration, the body will not reabsorb water since ADH is inhibited

43
Q

What are the body’s two primary metabolic sources of nitrogenous wastes?

A

proteins and nucleic acids

44
Q

What are the three forms of getting rid of nitrogen?

A

ammonia (NH3), urea, and uric acid

45
Q

What is the Henderson-Hasselbalch equation?

A

pH = pKa + log ([HCO3]/[CO2])

46
Q

What is the bicarbonate buffer system?

A

hydrogen ions are reversibly bound to a buffer like bicarbonate ion (HCO3-), hemoglobin molecule, or specific plasma proteins

47
Q

What is Cholera toxin (CT)?

A

six-subunit oligomeric protein secreted by the gram-neg Vibrio cholerae—the toxin binds to specific gangliosides on surface of target intestinal cells, metabolic acidosis results from more H+, hyperventilation results

48
Q

Which is LEAST likely to act as a buffer during formation of urine in the nephron?

A

hemoglobin

49
Q

Macula densa cells in the distal convoluted tubule of the juxtaglomerular apparatus regulate:

A

glomerular filtration rate

50
Q

What increases urinary K+ excretion?

A

hyperkalemia, an increase in the GFR, a chronic elevation in plasma aldosterone levels

51
Q

What happens when the glomerular efferent arteriole is constricted?

A

Decreased RPF and an initial increased GFR across glomerular capillaries

52
Q

Glomerular Filtration Barrier

A

Made up of podocytes, fenestrated endothelium, glomerular basement membrane

53
Q

What happens when the glomerular afferent arteriole is constricted?

A

GFR, RPF, and PGC (hydrostatic pressure in glomerular capillary) all decrease

54
Q

How would you distinguish single-unit and multi-unit smooth muscle based on their electrical activity?

A

Single-unit fibers are coupled, with many individual cells containing gap junctions

55
Q

What would severely reduce reabsorption of Na+ across epithelial cells of the proximal convoluted tubule and into the peritubular capillary?

A

Reduced plasma glucose because Na+ crosses the apical membrane via symports (cotransporter protein) symports allow passage of both Na+ and Glucose together into the cell

56
Q

Hypokalemia

A

low plasma K+ levels

57
Q

Excessive aldosterone secretion will result in:

A

hyperpolarization of nerve and muscle membranes, an excessive loss of K+ ions from extracellular fluid, hypokalemia

58
Q

Secondary Active Transport

A

transporter protein couples the movement of an ion (typically Na+) down its electrochemical gradient to the uphill movement of another molecule or ion against a concentration/electrochemical gradient (H+)

59
Q

What hormone increases plasma FFA concentration most?

A

epinephrine

60
Q

A reduction in the tubular reabsorption of phosphate is most likely caused by:

A

a decrease in calcium—the body wants to excrete phosphate in urine by reducing tubular reabsorption, so that calcium can be more readily absorbed rather than binding with phosphate ions and redepositing on bone

61
Q

What is the equation for glomerular filtration rate (GFR)?

A

GFR = ([ ]u x Fu) / ([substance]p)

62
Q

What does cholecystokinin (CCK) do?

A

Stimulate contraction of the antrum and promote constriction of pyloric sphincter to decrease rate of gastric emptying and contribute to mixing of stomach contents

Berkeley MCAT Biology (9 decks)

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