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MCAT bio > excretory and digestive system > Flashcards

excretory and digestive system Flashcards

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1
Q

liver function

A

chemically modifies wastes and releases them into bile, deals with waste that can’t be filtered out by the kidneys,
synthesizes urea

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2
Q

colon function

A

reabsorbs water and ions from feces

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3
Q

kidney function

A

functions as a filtration system that removes unwanted materials from the blood and passes them to the bladder for storage and eventual elimination

  1. excretion of hydrophilic waste
  2. maintenance of constance solute concentration and constant pH
  3. maintenance of constant fluid volume (important for blood pressure and cardiac output)

Accomplished by filtration, selective reabsorption, and secretion, ultimately resulting in urine

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4
Q

renal artery

A

where blood enters the kidney

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5
Q

internal/external sphincter

A

control release of bladder

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6
Q

nephron

A

functional unit of the kidney

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7
Q

urine direction in kidney

A

empties from collecting ducts

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8
Q

direction of blood in filtration

A

renal artery to afferent arteriole to glomerulus to efferent arteriole.

Fluid then passes through filter (glomerular basement membrane) and enters Bowman’s capsule.

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9
Q

selective reabsorption

A

returning of some substances to the blood stream, usually via active transport.

They are then picked up by peritubular capillaries, which drain into venues that lead to the renal vein.

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10
Q

secretion

A

movement of substances into the filtrate, increasing the rate at which they are removed from the plasma

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11
Q

ADH function

A

prevents water loss in urine, increases water reabsorption in distal nephron (primarily the collecting duct), making it permeable to water.

Increases blood pressure

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12
Q

parts of nephron

A

capsule and renal tubule, which empties filtrate into a collecting duct

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13
Q

aldosterone function

A

released by adrenal cortex when blood pressure is low, causes increased reabsorption of Na+ by the distal nephron, causing increased thirst and water retention .

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14
Q

loop of Henle

A

where PCT empties into, has a long loop that dips into renal medulla.

Consists of a thin descending limb, which heads into the medulla, and an (part thin, part thick) ascending limb, which heads back out toward the cortex

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15
Q

different permeabilities of loop of Henle

A

descending limb is permeable to water, ascending limb is only permeable to ions,

This results in the loop of Henle being a countercurrent multiplier that creates a salty medulla facilitating water resorption from the collecting duct

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16
Q

distal/ proximal tubules

A

function in reabsorption

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17
Q

JG cells

A

found in afferent arteriole, monitors systemic blood pressure and secretes renin when a decrease In BP occurs. This catalyzes formation angiotensin II, which functions as a vasoconstrictor and raises blood pressure.

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18
Q

Glomerular filtration rate and pressure

A

correlated

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19
Q

How does kidney maintain constant blood pH

A

when plasma pH is too high, HCO3- is excreted in urine and when plasma pH is too low, H+ is excreted.

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20
Q

erythropoietin

A

made by kidneys, causes increases synthesis of red blood cells in the bone marrow

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21
Q

gastrointestinal tract

A

accomplishes digestion, long muscular tube extending from the mouth to the anus

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22
Q

GI lumen

A

inside of the gut, continuous with the space outside the body, innermost lining is composed of epithelial cells, which are responsible for most of the secretory activity of the GI tract

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23
Q

GI motility

A

rhythmic contraction of GI smooth muscle, serves the purpose of mixing food and moving food down the gut

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24
Q

peristalsis

A

orderly form of contraction responsible for movement of food down the GI tract

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25
Q

enteric nervous system

A

branch of ANS that helps to control digestion via innervation of the gastrointestinal tract, pancreas, and gall bladder

made up of two networks of neurons: myenteric plexus, which primarily helps to regulate gut motility and submucosal plexus, which is found in the submucosa and helps to regulate enzyme secretion, gut blood flow, and ion/water balance in the lumen

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26
Q

GI secretions

A

stimulated by food in the gut and by the parasympathetic nervous system, inhibited by sympathetic stimulation.

two types: exocrine (composed of specialized epithelial cells organized into sacs called acini) and endocrine, which empty into nearby capillaries.

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27
Q

gastric glands

A

found in stomach, secrete acid and pepsinogen.

28
Q

goblet cells

A

found along entire GI tract, secrete mucus.

29
Q

mouth function in digestion

A

fragmentation, lubrication, some enzymatic digestion

30
Q

salivary amylase

A

found in saliva, hydrolyzes starch, breaking it into fragments.

31
Q

pharynx

A

contains opening to trachea, which conveys air to and from the lungs and the esophagus, conveys food and drink to the stomach

32
Q

stomach function

A

partial digestion of food, regulated release of food into small intestine, destruction of microorganisms

33
Q

what causes conversion of pepsinogen to pepsin

A

acidity

34
Q

pepsin

A

secreted by chief cells, catalyzes proteolysis

35
Q

effect of pyloric sphincter contracting

A

inhibition of further stomach emptying, preventing passage of food from stomach into the duodenum

36
Q

gastrin

A

hormone secreted by G cells when food is in the stomach, stimulates acid and pepsin secretion and gastric motility

37
Q

small intestine

A

where food leaving the stomach enters, divided into the duodenum, jejunum, and ileum

38
Q

villus

A

projection of the wall of the gut into the lumen, has three important structures:

  1. capillaries that absorb dietary monosaccharides and amino acids
  2. lacteals, capillaries which absorb dietary fats
  3. Peyer’s patches, which function as part of the immune system
39
Q

two ducts that empty into the duodenum

A

pancreatic duct, which delivers the exocrine secretions of the pancreas, and the common bile duct which delivers bile.

40
Q

function of bile

A

vehicle for disposal of waste products by the liver, essential for the digestion of fats

41
Q

duodenal enzymes

A

enterokinase and brush border enzymes, which hydrolyze the smallest carbohydrates and proteins

42
Q

three main duodenal hormones

A

CCK- secreted in response to fats in the duodenum, stimulating gallbladder contraction (bile release) and decreasing gastric motility
secretin - released in response to acid in the duodenum, causing pancreas to release large amounts of a high-pH aqueous buffer, neutralizing HCl released by the stomach enterogastrone - decreases stomach emptying

43
Q

jejunum and ileum

A

where substances are absorbed if not absorbed in duodenum

44
Q

colon

A

large intestine, role is to absorb water and minerals, and to form and store feces until time of defecation

45
Q

colonic bacteria function

A

presence of large numbers of normal bacteria keeps dangerous bacteria from proliferating and they supply us with vitamin K

46
Q

GI accessory organs

A

pancreas, liver, gallbladder, and salivary gland

47
Q

function of pancreatic enzymes

A

released into duodenum and essential for digestion

48
Q

how does nervous system affect pancreatic secretion

A

parasympathetic nervous system activation increases it, sympathetic reduces it

49
Q

glucagon and insulin

A

hormones secreted by islets of Langherhans in pancreas

glucagon responds to low blood sugar, causing release of glucose and fats into the blood stream, insulin has opposite effect of glucagon, removing glucose from blood for storage as glycogen and fat

50
Q

liver function

A

secretes bile, which emulsifies large fat particles in the duodenum, also processes absorbed nutrients, can release free glucose into blood stream

functions in lipid metabolism

51
Q

hepatocytes and their functions

A

liver cells that extract nutrients from blood

52
Q

ghrelin and leptin

A

ghrelin stimulates appetite while leptin acts as an appetite suppressant

53
Q

vitamins

A

must be include in diet, since they can’t be synthesized in the body, divided into fat soluble and water soluble categories

54
Q

proximal convoluted tubule function

A

where most of the reabsorption occurs in the part of the tubule nearest to Bowman’s capsule

55
Q

renal cortex

A

outer layer of the kidney

56
Q

where does loop of Henle lead to?

A

the distal convoluted tubule, which dumps into a collecting duct.

57
Q

vasa recta function

A

forms a loop that maintains a high concentration of salt in the medulla, they return to the bloodstream any water that is reabsorbed from the filtrate

58
Q

What is GI muscle made of

A

two layers of Smooth muscle, one that is longitudinal and one that is circular

59
Q

What does it mean that GI smooth muscle is a functional syncytium?

A

When one cell has an action potential and contracts, the impulse spreads to neighboring cells

60
Q

sphincter of Oddi

A

the orifice in which the bile duct and the pancreatic duct empty into

61
Q

what is bile made of?

A

bile acids made from cholesterol in the liver

62
Q

What is true about duodenal pH?

A

It must be kept neutral or even slightly basic for pancreatic digestive enzymes to function

63
Q

What hydrolases are in the pancreas?

A

amylase, lipase, nuclease, and proteases

64
Q

hepatic portal system function

A

helps liver process absorbed nutrients

  1. liver receives oxygenated blood from hepatic arteries
  2. Liver receive veinous blood draining the stomach and intestine through the hepatic portal vein
65
Q

chylomicrons

A

molecules in which lipids exit the intestine and enter the lymphatic system, degraded into chylomicron remnants, taken up by hepatocytes, and combined with protein to make lipoproteins

MCAT bio (11 decks)

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