Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCAT-BIOLOGY > The Excretory System > Flashcards

The Excretory System Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards AP® Biology flashcards Biology 101 flashcards
1
Q

excretion

A

the disposal of waste products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

liver

A

responsible for excreting many wastes by chemically modifying them and releasing them into bile, deals with hydrophobic or large waste products that can’t be filtered out by the kidney, synthesizes urea and releases it into the bloodstream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

heme is broken down into ______ in the _______

A

bilirubin; liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

urea

A

carrier of excess nitrogen resulting from protein breakdown, excreted in the urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

large intestine (colon)

A

reabsorbs water and ions from feces, processes wastes already destined for excretion, capable of excreting excess ions into the feces using active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

skin

A

produces sweat , which contains water, ions, and urea, controlled by temperature and level of sympathetic nervous system activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

excretory and homeostatic roles of the kidneys

A

1) responsible for excretion of hydrophilic wastes (urea, sodium, bicarbonate, water)
2) maintains homeostasis by constant solute concentration and constant pH
3) maintains homeostasis by constant fluid volume (important for blood pressure and cardiac output)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

homeostasis

A

constancy of physiological variables

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the 3 processes the kidneys perform?

A

1) filtration (passage of pressurized blood over a filter where cells and proteins remain in the blood but water and small molecules are squeezed into the renal tubule which then becomes the filtrate (will eventually be made into urine)
2) selective reabsorption (take back useful items - glucose, water, amino acids, while leaving wastes and some water in the tubule)
3) secretion (addition of substances to the filtrate, increasing the rate at which substances are eliminated from the blood)
4) urine concentration and dilution (involves/determined by the selective reabsorption of water)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

renal artery

A

carries blood to the kidney, a direct branch of the lower portion of the abdominal aorta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

renal vein

A

leaves the kidney and carries purified blood back to the circulatory system, empties into the inferior vena cava

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

ureter

A

carries urine from the kidney to the urinary bladder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

urinary bladder

A

muscular organ that stretches as it fills with urine, sends signal to the brain when full

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the two sphincters that control release of urine from the bladder?

A

internal sphincter (smooth/involuntary muscle) and external sphincter (skeletal/voluntary muscle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

cortex

A

outer region of the kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

medulla

A

inner region of the kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

medullary pyramids

A

pyramid-shaped striations within the medulla, striations due to the presence of many collecting ducts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

collectin ducts

A

where urine empties and leaves the medulla at the tip of the pyramid (papilla)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

calyx

A

space in which each papilla, tip of pyramid, empties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

renal pelvis

A

where calyces eventually converge, a large space where urine collects and ultimately empties into the ureter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

nephron

A

the functional unit of the nephron, consists of:

1) capsule (rounded region surrounding the capillaries where filtration takes place)
2) renal tubule (coiled tube that receives filtrate from the capillaries in the capsule at one end and empties into a collecting duct at the other end and dumps urine into the renal pelvis.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

afferent arteriole carries blood towards the kidneys and forms a ball of capillaries known as the:

A

glomerulus, from there the blood flows into the efferent arteriole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

the efferent arteriole constricts and causes…

A

high pressure in the glomerulus, which causes fluid to leak out of the glomerular capillaries and pass through a filter (glomerular basement membrane) and enter Bowman’s capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what structures does the filtration steps involve?

A

afferent arteriole, glomerulus (and glomerular basement membrane), efferent arteriole, Bowman’s capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

some substances are extracted from the tubule via active transport and picked up by:

A

peritubular capillaries which train into venules that lead to the renal vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

most selective reabsorption occurs at:

A

the proximal convoluted tubule (PCT), some also occurs at the distal convoluted tubule (DCT) but is more regulated in this area (usually by hormones)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

all solute movement in the proximal convoluted tubule is accompanied by:

A

water movement, i.e. a lot of water reabsorption

28
Q

what structures are involved in selective reabsorption?

A

renal tubule (proximal convoluted tubule, distal convoluted tubule), peritubular capillaries

29
Q

secretion occurs mostly:

A

in the distal convoluted tubule and the collecting duct (but also occurs all along the tubule) *impermeable to water

30
Q

concentration and dilution adjusts urine volume and osmolarity and occurs in:

A

the distal nephron, the most distant part of the renal tubule which includes the distal convoluted tubule and the collecting duct, it is controlled by ADH and aldosterone

31
Q

antidiuretic hormone, ADH, vasopressin

A

released by posterior pituitary when blood volume low and blood osmolarity high, increases water reabsorption in the distal nephron by making the distal nephron (especially the collecting duct) permeable to water so that water flows out of the filtrate into the tissue of the kidney (due to high osmolarity of kidney medulla) where it is picked up by peritubular capillaries

32
Q

if there is a lot of water and plasma volume is high, will ADH by released?

A

no, because a large volume of dilute urine is necessary so that collecting duct remains impermeable to water and water in filtrate remains in the tubule and is lost in the urine (diuresed)

33
Q

aldosterone

A

released by the adrenal cortex when the blood pressure is low, causes increased reabsorption of sodium by the distal nephron resulting in increased plasma osmolarity which leads to increased thirst and water retention which raises the blood pressure

34
Q

if blood pressure is high, will aldosterone be released?

A

no, as a result, sodium will be lost, plasma osmolarity and eventually blood pressure will fall

35
Q

aside from blood pressure, what else can trigger release of aldosterone?

A

low blood osmolarity, low blood volume, and angiotensin II

36
Q

where is Bowman’s capsule and proximal convoluted tubule located?

A

in the renal cortex (the outer layer of the kidney)

37
Q

the proximal convoluted tubule empties into:

A

the loop of Henle (the next part of the nephron) which dips down into the renal medulla

38
Q

descending limb of the loop of Henle

A

thin walled, where water exits the tubule causing the filtrate to become more concentrated)

39
Q

ascending limb of the loop of Henle

A

thin (composed of squamous/flat epithelial cells) and thick (cuboidal epithelial cells, perform active transport) ascneding limb

40
Q

the loop of Henle eventually becomes:

A

the distal convoluted tubule which dumps into collecting duct which merges into renal calyces

41
Q

proximal convoluted tubule roles

A

reabsorption of most filtered water and ions, reabsorption of glucose and amino acids by secondary active transport-sodium cotransporters, secretion of drugs, toxins and some ions

42
Q

distal convoluted tubule roles

A

reabsorption of water and urea in response to ADH, sodium reabsorption in response to aldosterone, secretion of drugs, toxin and some ions

43
Q

thick ascending limb of loop of Henle roles

A

active transport of sodium, potassium, and chlorine ions out of filtrate with subsequent passive return of potassium to filtrate, causing:

1) dilution of tubular fluid
2) increased osmolarity of medulla

44
Q

collecting duct secretes:

A

potassium and hydrogen ions

45
Q

the loop of Henle is a:

A

countercurrent multiplier: the ascending and descending limbs have different permeabilities that makes the medullar very salty and facilitates water reabsorption from the collecting duct (whenever the collecting duct is permeable to water; in the presence of ADH)

46
Q

vasa recta

A

branches of efferent arterioles that surround the descending portion of the loop of Henle, forms a loop that helps to maintain the high concentration of salt in the medulla

47
Q

role of vasa recta

A

carries off water that leaves the descending limb of the loop of Henle and returns it to the bloodstream, blood in the vasa recta moves in the opposite direction of the filtrate in the nephron, thus performs countercurrent exchange

48
Q

glomerular filtration rate (GFR) depends on:

A

pressure

49
Q

systemic and local (glomerular) blood pressure is regulated by:

A

built in mechanisms in the kidney

50
Q

juxtaglomerular apparatus (JGA)

A

specialized contact point between the afferent arteriole and the distal tubule

51
Q

juxtaglomerular (JG) cells

A

cells in the afferent arteriole at the juxtaglomerular apparatus, baroreceptors that monitor systemic blood pressure

52
Q

macula densa

A

cells in the distal tubule at the juxtaglomerular apparatus, chemoreceptors that monitor filtrate osmolarity in the distal tubule)

53
Q

what do JG cells secrete when there is a decrease in blood pressure?

A

renin (an enzyme) which catalyzes the conversion of angiotensinogen into angiotensin I, which is further converted to angiotensin II by angiotensin-converting enzyme, angiotensin II is a vasoconstrictor that immediately raises the blood pressure and stimulates the release of aldosterone which helps raise the blood pressure by increasing sodium and water retention

54
Q

angiotensinogen

A

a plasma protein made by the liver, that is converted into angiotensin I by renin

55
Q

angiotensin-converting enzyme

A

in the lungs, converts angiotensin I to angiotensin II (vasoconstrictor and stimulates release of aldosterone)

56
Q

what do macula densa cells do when filtrate osmolarity decreases (decreased filtration rate)?

A

macula densa stimulates JG cells to release renin and also causes a direct dilation of the afferent arteriole to increase blood flow to (and thus blood pressure and filtration rate) in the glomerulus

57
Q

high filtration rate is associated with:

A

high filtrate osmolarity, high blood pressure in the glomerulus

58
Q

how does the kidney regulate pH

A

if the plasma pH is too high, bicarbonate is excreted in the urine; when the plasma pH is too low, hydrogen ions are excreted

59
Q

carbonic anhydrase

A

catalyzes the conversion of carbon dioxide into carbonic acid, which can then dissociate into bicarbonate plus a proton (this reaction needs to occur before the kidney as reabsorb or secrete bicarbonate or protons as needed)

60
Q

generally, how are the amounts of bicarbonate and protons adjusted to maintain pH?

A

generally, protons are secreted and bicarbonate is reabsorbed, amounts are adjusted to adjust pH

61
Q

renal pH adjustments are slow, what other system allows for more rapid maintenance of pH?

A

regulation by the lung

62
Q

what hormone does the kidney make?

A

erythropoietin (EPO), which causes increased synthesis of red blood cells in the bone marrow, it is released when blood oxygen content falls

63
Q

aldosterone

A

released by adrenal cortex, causes sodium reabsorption and potassium secretion by increasing the synthesis of basolateral Na/K ATPases in the distal nephron, results in increased serum sodium, increased blood volume (through the action of ADH), and thus increased blood pressure

64
Q

aldosterone raises blood osmolarity which release of:

A

ADH which helps to raise blood pressure (increased water reabsorption and thus increased plasma volume)

65
Q

ADH

A

released by posterior pituitary when plasma volume/blood pressure is low or plasma osmolarity is too high, causes water reabsorption by causing epithelial cells of the distal nephron to become permeable to water, which allows water to flow out of the filtrate into the medullary interstitium. vasa recta returns water to the bloodstream which results in more concentrated urine and more diluted blood.

66
Q

calcitonin

A

released by C cells located in the thyroid gland when serum calcium is too high. causes calcium to be removed from the blood by deposition in bone, reduced absorption by the gut, and excretion in urine

67
Q

parathyroid hormone

A

released by the parathyroid glands embedded in the thyroid gland, functions opposite to calcitonin to raise serum calcium levels

MCAT-BIOLOGY (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions