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MCAT Biology > Excretory System > Flashcards

Excretory System Flashcards

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1
Q

role of liver, what it deals with, what it makes

A

deals with hydrophobic large products kidney cant filter and makes bile. also makes urea with excess nitrogen

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2
Q

3 main roles of kidney

A

excretion of hydrophilic waste, maintain solute concentration and pH, maintain fluid volume

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3
Q

vaopressin, where released from, what it is, what it does

A

peptide hormone, released from posterior pituitary, makes collecting ducts permeable to water via aquaporins

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4
Q

renal vein, renal artery, ureter

A

renal vein has purified blood from kidney, renal artery is how blood enters kidney, ureter is urine’s path to bladder

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5
Q

internal and external sphincter

A

internal is involuntary smooth muscle, external is voluntary skeletal muscle

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6
Q

filtration, where it occurs

A

cells and protein remain in blood, water and small molecules move to renal tubule
occurs via golumerulus capillaries and bowman’s capsule

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7
Q

secretion and absorption, where occurs, what we take back and excrete

A

takes back useful things via active transport from peritubular capillaries (which drain into renal vein, vena cava)
secretes drugs if in urine

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8
Q

urine concentration, where it happens

A

happens at DCT distal convoluted tubule(regulated by hormones) and collecting duct

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9
Q

how ADH and aldosterone work, which is inhibited by alcohol

A

when dehydrated, ADH from posterior pituitary prevents diuresis, increases water reabsorption by making distal nephron permeable to water
ADH inhibited by alcohol
when blood pressure is low, aldosterone released from adrenal cortex to increase absorption of Na+ by distal nephron leading to thirst

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10
Q

pathway of blood into kidney before loop of henle, what happens when efferent arteriole constricts

A

renal artery - afferent arteriole - glomerulus cappilaries - efferent arteriole
when constricts fluid, leaks past glomerular basement membrane into Bowman’s Capsule

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11
Q

after glomerulus? goes to

A

proximal convoluted tubule: reabsorbs water, ions, glucose and amino acids by secondary transport
loop of henle: dips into medulla from cortex
descending loop water exits filtrate
ascending loop active transport of Na+, K+, Cl- out of tiltrate
(vasa recta reclaims all these substances)
distal convoluted tubule: reabsorbs water and urea in response to ADH, reabsorbs Na+ in response to aldosterone

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12
Q

glomerular filtration rate depends on

A

pressure at JG cells (baroreceptors) at juxtoglomerular apparatus (structure formed by distal convoluted tubes and afferent arteriole

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13
Q

macula densa is, how it controls filtrate osmolarity

A

at junction of ascending loop and distal tubules that has chemoreceptors that monitor filtrate osmolarity, when low, stimulate JG cells
dilate afferent arteriole increases flow through glomerulus and increases glomerular filtration rate

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14
Q

what low bp stimulates - renin pathway

A

release renin enzyme used on angiotensinogen to make angiotensin I converted to angiotensin II with ACE leads to vasoconstriction and stimulates aldosterone

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15
Q

how kidney radiates pH

A

low pH, release HCO3-

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16
Q

role of calcitonin, where it releases from, its opposite hormone

A

released from C cells in thyroid gland
when Ca2+ too high, removes from blood by deposition in bone, reduces absorption in gut, excrete in urine
parathyroid hormone does the opposite

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17
Q

lumen of intestine layers from inside to outside

A

basolateral surface, tight junctions (separate body fluids from cellular environment), microvilli at apical surface

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18
Q

2 major nerve supplies of gut

A

myenteric plexus: control gut motility

submucosal plexus: regulate enzyme secretion, gut blood flow, ion/water balance

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19
Q

4 components of autonomic GI motility

A

automacity, functional synctium (like heart), has own enteric nervous system (branch of autonomic nervous system to help blood flow, gut movements, fluid exchange), controlled by hormones

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20
Q

endocrine vs exocrine hormones that are released to gut, where released from

A

endocrine, empty into nearby capillaries, released from islets of langerhans
exocrine, release into gut lumen and made by pancreatic acinar cells

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21
Q

pathway of food from mouth

A

mouth, pharynx, stomach, small intestine

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22
Q

digestion that happens at mouth level

A

fragmentation, lubrication, enzymatic digestion

saliva has salivary enzymes like amylase that breaks down starch, lingual lipase for fat, lysozyme for bacterial walls

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23
Q

components of pharynx

A

trachea and esophagus, with epiglottis in between so you don’t inhale food

24
Q

digestion at stomach level

A
  1. gastric pH of 2
  2. pepsinogen secreted by chief cells in stomach wall go through acidic proteolysis and become pepsin, which breaks down protein
25
Q

what does ulcer drug block

A

parietal cell receptors to decrease acid release

26
Q

zymogen

A

inactive form of an enzyme (usually proteolysis is activated)

27
Q

gastrin and HCl released from?

A

gastrin from G cells in stomach in response to food and parasympathetic
HCl from parietal cells when histamine binds to them (binds when stomach is stretch or gastrin present)

28
Q

sphincter between stomach and small intestine, controlled by what hormone

A

pyloric sphincter, controlled by cholecystokinin

29
Q

3 parts of small intestine

A

duodenum, jejunum, ileum

30
Q

2 ducts that feed into duodenum, sphincter that controls it

A

pancreatic duct: delivers exocrine secretions (digestive enzymes + bicarbonate)
common bile duct: from gallbladder bile made of cholesterol, vehicle for disposal of waste by liver through micelles
stones produced when wrong proportions
sphincter of Oddi

31
Q

blood in capillaries of villi flow to

A

hepatic portal vein to liver

32
Q

what absorbs fat from villi

A

lacteals in villi lead to thoracic duct

33
Q

peyer’s patches

A

collections of lymphocytes in ileum that monitor intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines

34
Q

duodenal secretions: enzymes and hormones

A

enzymes:
enterokinase: activate pancreatic trypsinogen to trypsin
brush border eyzmes: on surface of epithelial cells, break down carbs and proteins
hormones:
CCK (secreted in response to fat), pancrease secretes enzymes, gallbladders increases function, gastric motility decreases
secretin: responds to acid, makes pancreas release HCO3- buffer
enterogastrone: decreases stomach emptying

35
Q

role of jejunum and ileum

A

absorbs what duodenum doesn’t

36
Q

special function of ileum

A

vitamin B and intrinsic factors absorbed here, (glycoproteins from parietal cells of stomach)

37
Q

valve between small intestine and colon

A

ileocecal valve

38
Q

role of colon 3 parts

A

absorbs water and minerals, stores and forms feces

cecum (with appendix), rectum, anus

39
Q

2 parts of anal sphincter

A

smooth muscle autonomic, skeletal muscle voluntary

40
Q

how colonic bacteria work

A

compete out dangerous bacteria and supply vitamin K

41
Q

exocrine pancreas enzymes

A

pancreatic amylase, lipase, nuclease, protease

42
Q

3 zymogens that trypsin activates

A

chymotrypsinogen to chymotrypsin
procarboxypeptidase to carboxypeptidase
procollagenase to collagenase

43
Q

endocrine pancreas: islets of langerhans cells, what they release

A

alpha cells release glucagon
beta cells release insulin
gamma cells release somastati

44
Q

3 hormones to raise blood glucose

A

glucagon, epinephrine, cortisol

45
Q

what does gallbladder secrete

A

nothing

46
Q

blood vessels leading to liver

A

hepatic artery for oxygenated blood

hepatic vein from stomach and intestines

47
Q

roles of liver

A
  1. make plasma proteins, clotting
  2. drug detox (smooth ER in liver)
  3. only liver able to release free glucose w glucose 6 phosphatase
  4. amino acid breakdown
  5. lipid breakdown - breaks down triglycerides, lipoprotein production to transfer fat to other locations
48
Q

hepatic portal system

A

important in that it captures substances from the digestive system and sends them to the liver to be metabolized

49
Q

empty stomach triggers what cells to release what

A

gastric cells to release ghrelin

50
Q

ways that appetite is reduced 2 places that send out 2 different enzymes

A
  1. when colon is full, jejunum releases peptide YY to reduce appetite
  2. adipose tissue releases leptin which reduces appetite
51
Q

what mechanism is used to absorb carbs

A

secondary transport w Na+

52
Q

what mechanism is used to absorb protein

A

secondary transport w Na+

53
Q

water soluble vitamins

A

B1: enzymatic decarboxylation
B2: FAD
B3: NAD+
B6: coenzye in protein metabolism
B12: coenzyme in nucleotide to deoxynucleotide process
C: collagen formation
biotin: prosthetic group to transport CO2

54
Q

fat soluble vitamins

A

A: changes conformation in light
D: ups Ca2+ absorption
E: prevents unsaturated fat oxidation
K: forms blood clot factors

55
Q

folate

A

enzyme cofactor that transports methylene groups and synthesizes purines/thymines

MCAT Biology (10 decks)

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