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MCAT - biology > excretory system > Flashcards

excretory system Flashcards

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1
Q

each kidney has approximately how many nephrons?

A

1 million

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2
Q

_____________ is the kidneys outermost layer, ____________ is the kidneys innermost layer

A

outermost = cortex
innermost = medulla

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3
Q

____________ consists of two capillary beds in seris through which blood must travel before returning to the heart

A

portal system

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4
Q

the renal artery branches out, passes through the medulla, and enters the cortex as ____________ arterioles

A

afferent

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5
Q

after blood passes through the glomerulus the _____________ arterioles form a second capillary bed

A

efferent

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6
Q

______________ are the capillaries that surround the loop of henle

A

vasa recta

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7
Q

the bladder has a muscular lining known as the _____________

A

detrusor muscle

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8
Q

(parasympathetic / sympathetic) activity causes the detrusor muscle to contact

A

parasympathetic

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9
Q

(internal / external) uretral sphincter consists of smooth muscle and is under involuntary control

A

internal

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10
Q

the external urethral sphincter consists of ___________ muscle and is under _______________ control

A

skeletal muscle
voluntary control

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11
Q

the ___________ filter blood to form urine

A

kidneys

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12
Q

if blood volume is low and blood osmolarity is high, is the body more or less likely to retain water?

A

more likly

*this will result in low volume, highly concentrated urine

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13
Q

what are the three divisions of kidney function?

A

filtration
secretion
reabsorption

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14
Q

_____________ is the collected fluid of the blood that passes through the glomerulus that is filtered as fluid into the bowmans space

A

filtrate

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15
Q

the hydrostatis pressure in the glomerulus is (higher / lower) than that in bowmans space

A

higher

*fluid moves into the nephron

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16
Q

T / F - under most circumstances the fluid will flow from the bowmans space to the glomerulus

A

false, flow from glomerulus to bowmans capsule

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17
Q

the filtrate and blood have similar compositions, what differs between the two?

A

filtrate = does not contain cells or proteins due to the filter’s ability to select based on size

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18
Q

filtrate is (hypotonic / hypertonic / isotonic) to blood

A

isotonic

*neither the capsule nor the capillaries swell

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19
Q

nephrons are able to secrete _______, ___________, ___________, and ___________ into the tubule by either active or passive transport

A

salts
bases
acids
urea

20
Q

what substances are typically always reabsorbed?

A

glucose
amino acids
vitamins

21
Q

hormones such as __________ and ____________ can alter the quantity of water reabsorbed within the kidney in order to maintain blood pressure

A

ADH
aldoesterone

22
Q

in the proximal convuluted tubule, what is reabsorbed?

A

water
salts (NaCl)
water soluable vitamins
amino acids
glucose

23
Q

in the proximal convuluted tubule, what is secreted?

A

waste products:
H+
K+
NH3
urea

24
Q

the descending loop of henle is only permeable to ___________

A

water

25
Q

the medulla has an (increasing / decreasing) osmolarity as the descending limb travels deeper into it

A

increasing

26
Q

the increasing interstitial concentration of the medulla favors the (out / in) flow of water from the descending limb

A

outflow

*reabsorbed by the vasa recta

27
Q

what is the countercurrent multiplier system?

A

the flow of filtrate through the loop of henle is in the opposite direction from the flow of blood in the vasa recta

28
Q

the ascending limb is only permeable to ___________

A

salts

29
Q

the descending limb maximizes (salt / water) reabsorption by taking advantage of the (increasing / decreasing) medulla osmolarity

A

water reabsorption
increasing medulla osmolarity

30
Q

the ascending limb maximizes (salt / water) reabsorption by taking advantage of the (increasing / decreasing) medulla osmolarity

A

salt reabsorption
decreasing medullary osmolarity

31
Q

the distal convuluted tubule responds to aldosterone which promotes ___________ reabsorption

A

sodium

*water follows salt, this concentrates the urine and decreases its volume

32
Q

T / F - the collecting duct is responsive to both ADH and aldosterone

A

true

33
Q

collecting duct permeability increases = water absorption (increases / decreases)

A

increases

*urine = concentrated

34
Q

describe the permeability of the collecting duct when the body is very well hydrated

A

impermeable to salts / water

35
Q

describe the permeability of the collecting duct when the body is in conservation mode

A

ADH and aldosterone will each act to increase reabsorption of waer in the collecting duct

*greater water retention
*concentrated urine output

36
Q

aldosterone is a steroid hormone that is secreted by the ___________ in response to (increased / decreased) blood pressure

A

adrenal cortex
decreased

37
Q

decreased blood pressure sitmulates the release of _____________ from the kidneys

A

renin

*juxtaglomerular cells in the kidneys

38
Q

renine cleaves ____________ to form _____________, which is then metabolized by angiotensin-converting enzyme to form ____________

A

angiotensinogen –>
angiotensin I –>
angiotensin II

39
Q

angiotensin II promotes the release of _____________ from the adrenal cortex

A

aldosterone

40
Q

where is ADH synthesized?

A

hypothalamus

41
Q

ADH is released by the ___________ in response to (high / low) blood osmolarity

A

posterior pituitary gland
high

42
Q

_________ and __________ both inhibit ADH

A

caffeine
alcohol

43
Q

constriction of the afferent ateriole will lead to a (higher / lower) blood pressure reaching the glomeruli

A

lower

44
Q

when blood osmolarity is ________, excess water will be excreted while solutes will be reabsorbed in higher concentration

A

low

45
Q

explan the reabsorption / excretion process when blood osmolarity is high

A

water reabsorption increases
solute excretion increases

46
Q
A

MCAT - biology (35 decks)

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