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Flashcards in renal part 2 Deck (75)
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1
Q

After filtration, __________ is subject to reabsorption and secretion

A

tubular fluid

2
Q

what are the 2 modes of transport for molecules in the tubular fluid?

A

transcellular

paracellular

3
Q

in ________ transport, molecules move through tubular cells

A

transcellular

4
Q

in ________ transport, molecules move between tubular cells

A

paracellular

5
Q

________ diffusion requires a specific membrane protein

A

facilitated

6
Q

what types of transporter proteins are used for facilitated diffusion?

A

uniporter

symporter

antiporter

7
Q

65% of all filtered Na+ will be reabsorbed in the ____________

A

proximal tubule

8
Q

20% of all filtered Na+ will be reabsorbed in the ____________

A

thick ascending limb

9
Q

only ___% of the initial Na+ that was filtered remains once the filtrate reaches the collecting duct

A

3

10
Q

what percentage of the Na+ that is initially filtered ends up being excreted?

A

less than 1%

11
Q

what molecules are reabsorbed with Na+ in the proximal tubule?

A

glucose and amino acids are rebsorbed with Na+

12
Q

what type of transporter is used to reabsorb glucose and amino acids from the proximal tubule?

A

symporters

use Na+ to pull glucose and AAs

13
Q

what keeps intracellular Na+ low in the walls of the proximal tubule?

A

Active transport on basal side of the PT cells

the Na+/K+ antiporter

14
Q

in the PT (proximal tubule), ________ move via paracellular transport

A

Water (and solutes)

15
Q

how are small proteins reabsorbed in the PT? how is this accomplished?

A

Small proteins reabsorbed via endocytosis

requires ATP (active transport)

16
Q

what is reabsorbed in the proximal tubule using a Na+/H+ antiporter?

A

Bicarbonate ions

reabsorption is NOT direct- coupled to the Na+/H+ exchanger

17
Q

what reaction produces H+ and HCO3- in tubule cells?

A

Carbonic Anhydrase (CA) reaction

18
Q

T/F: Organic ions are commonly bound to plasma proteins so they are not filtered at the glomerulus

A

true

19
Q

how does the proximal tubule secrete organic ions?

A

The proximal tubule has organic cation and organic anion transporters to secrete these molecules into the tubular fluid

20
Q

by the end of the proximal tubule, how much of the initial Na+, Cl-, and water are reabsorbed?

A

2/3 of Na+, Cl-, and water reabsorbed

small proteins too

21
Q

in the proximal tubule, K+ and divalent cations are reabsorbed by __________

A

solvent drag

22
Q

In the loop of Henle, __% of filtered NaCl and ___% of water is reabsorbed

A

25% of filtered NaCl and 15% of water is reabsorbed

23
Q

the Descending thin limb is impermeable to ______, but permeable to ______

A

impermeable to salt, but permeable to water

24
Q

the Ascending thin limb is impermeable to _____, but permeable to ______

A

impermeable to water, but permeable to salt

25
Q

reabsorption in the Ascending and Descending thin limbs is a _______ process

A

passive

26
Q

T/F: fluid in the ascending THICK limb is diluted

A

true

27
Q

in the ascending thick limb, Na+ K+ 2Cl- symporter are found in the ______ membrane

A

apical

28
Q

in the ascending thick limb, Na+ K+ ATPase transporters are found in the ________ membrane

A

basolateral

29
Q

T/F: paracellular transport of monovalents and divalents in the ascending thick limb is due to solvent drag

A

FALSE

30
Q

tubular fluid becomes positive when what is reabsorbed?

A

Cl-

31
Q

Fluid leaving loop of henle is _________

A

hyposmotic

32
Q

what establishes an osmotic gradient required for formation of hyperosmotic urine in the loop of henle?

A

the renal countercurrent mechanism

33
Q

where is the “vasa recta” found?

A

at the bottom of the peritubular capillaries

most concentrated solute area

34
Q

where does ADH work in the nephron? what does its absence cause?

A

ADH works on the collecting duct

absence of ADH causes a LARGE amount of DILUTE urine

35
Q

in the DISTAL tubule, there is a Na+ Cl- symporter in the ______ membrane, and a Na+ K+ ATPase in _________ membrane

A

Na+/Cl- symporter on the apical membrane

Na+ K+ ATPase on the basolateral membrane

36
Q

principal cells of the distal tubule have ___________ channels that reabsorb Na+ and secrete K+

A

epithelial sodium channels (ENaC)

37
Q

what drives paracellular Cl- reabsorption in the distal tubule?

A

Na+ reabsorption drives paracellular Cl- reabsorption

38
Q

how is K+ secreted in the distal tubule?

A

K+ secreted due to Na+ K+ ATPase

39
Q

A positive or negative shift in water balance shifts extracellular volume away from _______ (normal)

A

euvolemia

40
Q

___________ is released from the posterior pituitary, and helps control kidney volume regulation

A

Vasopressin or antidiuretic hormone (ADH)

41
Q

at what osmolarity is vasopressin (ADH) released?

A

respond to osmolality above a set point of 275-290 mOsm/kg H2O

42
Q

T/F: vasopressin release can be stimulated by changes in blood volume/pressure

A

true

43
Q

what kind of baroreceptors respond to a decrease in blood pressure?

A

high pressure baroreceptors in aortic arch and carotid sinus

44
Q

what kind of baroreceptors respond to a decrease in blood volume?

A

low pressure baroreceptors in left atrium and large pulmonary vessels

45
Q

what effect does ADH have on the nephron?

A

ADH increases the permeability of the late distal tubule and the collecting duct to water

46
Q

ADH (vasopressin) causes insertion of _______ into the apical membrane of the nephrons

A

aquaporins

47
Q

ADH (vasopressin) increases permeability of medullary collecting duct to ______

A

urea

48
Q

what happens when ADH levels are low?

A

solutes reabsorbed in distal tubule and collecting duct, but no water reabsorption; urine as dilute as 50 mOsm/kg H2O

49
Q

what is the result of high ADH levels?

A

water reabsorbed as fluid passes through collecting duct; urine can be concentrated up to 1200 mOsm/kg H2O

50
Q

_______________ and __________ stimulate events which increase sodium and water reabsorption

A

Angiotensin II and aldosterone

51
Q

when is renin released?

A

renin released in response to:

1) a drop in perfusion pressure
2) decreased NaCl delivery to macula densa
3) sympathetic input to juxtaglomerular cells

52
Q

what converts angiotensinogen into angiotensin 1?

A

Renin

53
Q

what molecule is responsible for the conversion of angiotensin 1 into angiotensin 2?

A

ACE

angiotensin converting enzyme

54
Q

where is ACE produced?

A

Endothelial cells of the lung and kindey

55
Q

angiotensin 2 will stimulate _______ and ___________ secretion

A

aldosterone and ADH

56
Q

how does aldosterone (from the adrenal cortex) Increase NaCl reabsorption?

A

increase NaCl reabsorption in the distal tubule and collecting duct by increasing transport protein synthesis

57
Q

Natriuretic peptides are secreted when what occurs?

A

the heart dilates (during volume expansion)

58
Q

what are the effects of natriuretic peptides? (theres 4 of them)

A

1) vasodilation of AFFERENT arterioles
2) vasoconstriction of EFFERENT arterioles
3) inhibits renin (and aldosterone)
4) inhibits ADH secretion

59
Q

what is the net effect of natriuretic peptide release?

A

increases the excretion of NaCl and water

- does this by REDUCING reabsorption

60
Q

during volume expansion, where in the nephron is the reabsorption of Na+ and Cl- actually increased?

A
  • Thick ascending limb*

- Distal tubule

61
Q

______ is a major determinant of membrane resting potential

A

potassium (K+)

62
Q

____________ will depolarize Vm, while ____________ will hyper-polarize Vm

A

hyperkalemia will depolarize

hypokalemia will hyper-polarize

63
Q

the kidneys typically excrete ________% of ingested K+

A

90-95%

64
Q

In the _________ K+ is freely filtered

A

glomerulus

65
Q

in the ______________ about 67% of filtered K+ is reabsorbed, mostly by paracellular route

A

proximal tubule

66
Q

how is most K+ reabsorbed in the proximal tubule

A

mostly by paracellular route

67
Q

how is K+ reabsorbed in the thick ascending limb of the nephron?

A

reabsorption by Na+K+2Cl- symporter and paracellular transport

68
Q

K+ is secreted by principal cells of what nephron structures?

A

late distal tubule

and

collecting duct

69
Q

what determines K+ secretion or reabsorption in the late distal tubule, and collecting duct?

A
depends on:
- ATPase activity
- K+ gradient
and/or 
- apical K+ permeability
70
Q

what 2 factors affect excretion of potassium?

A

1) plasma concentrations of K+

2) flow rate of tubular fluid

71
Q

how do plasma potassium concentrations affect excretion?

A
  • increased K+ stimulates aldosterone release

- aldosterone increases Na+ K+ ATPases in principal cells

72
Q

how does the flow rate of tubular fluid affect the excretion of potassium?

A

increased flow rate increases K+ secretion

local response to bending cilium

73
Q

increased _____ reabsorption will favor K+ secretion

A

Na+

74
Q

which nephron segments will reabsorb potassium (K+) when plasma concentrations are low?

A

distal tubule

cortical collecting duct

75
Q

if plasma concentrations of potassium are high, which structures will begin increasing secretion of potassium?

A

distal tubule

cortical collecting duct