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Flashcards in renal 2 Deck (79)
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1
Q

what can happen to tubular fluid after filtration

A

Reabsorption and secretion

2
Q

what are the modes of transport in secretion and reabsorption

A

Transcellular (through tubular cells)

Paracellular (between tubular cells

3
Q

what is the diffusion of water

A

Osmosis

4
Q

what regulates the rate of osmosis in membrane transport

A

Aquaporins

5
Q

what type of trasnport proteins are found in faciliated diffusion

A
Ion channels
Transport proteins
 - uni
 - symp
 - anti
6
Q

what are the types of vesicular transport

A

Endocytosis

Exocytosis

7
Q

where can Sodium be reabsorbed in the nephron

A

All but one segment

  • ocurs in:
    • the proximal tubule(most)
    • ascending limbs of loop of henle
    • distal tubule
    • collecting duct
8
Q

how does Glucose and amino acids get reabsorbed in the proximal tubule

A

Glucose and amino acids reabsored using Na symporters

9
Q

what keeps intracellular Na low in the proximal tubule

A

active transport on the basal side

10
Q

how does water and solutes move in the proximal tubule

A

paracellular transport to keep the osmolarity of the tubular fluid constant

11
Q

what does Na reabsorption occur with

A

With bicarbonate reabsorption using an Na/H antiporter

12
Q

how is Bicarbonate reabsorbed

A

Not direct since H seceretion leads to HCO3 reabsorption

13
Q

how is H secretion related to HCO non direct reabsorption

A
  • Ca reaction produces H and HCO3 in tubule cell
  • HCO3 transported into blood
  • H transported into tubular fluid where it recombines with filtered HCO3
14
Q

why is it important that the proximal tubular has transporters for organic cations and anions

A

to secrete drugs that are often organic ionic compounds, often bound to plasma proteins(not filtered)
- need to be secreted

15
Q

what is the pro/con of transporters in the proximal tubule for drugs

A

low specificity so do lots of drugs, but are easily saturated

16
Q

what all is resorbed in the proximal tubule

A

2/3 Na, Cl, water, and small proteins by endocytosis
K and divalent cation reabsored by solvent drag
All amino acids and glucose reabsored
Bicarbonate reabsored due to Na/H transporter

17
Q

what all is secreted in the proximal tubule

A

Organic ions (Drugs)

18
Q

what is reabsorbed in the loop of henle

A

25% of filtered Nacl

15% of water reabsorbed

19
Q

what can and cannot pass through the descending thin limb

A

impermeable to slat

Permeable to water

20
Q

what can and cannot pass through the ascending thin limb

A

impermeable to water

permeable to salt

21
Q

how does reabsorption occurin the thin desending and ascending limb

A

passive

22
Q

what happens to the fluid in the ascending thick limb

A

Fluid is diluted

23
Q

what transport protein is found in the apical membrane in the ascending thick limb

A

Na, K, 2Cl symporter (goes into the cells)

24
Q

what transport protein is found in the basolateral membrane in the thick ascending limb

A

Na K ATPase (Na out of cell, K into cell)

25
Q

does solvent drag pull monovalents and divalents in the tick ascending limb

A

No, paracellular transport

26
Q

how does paracellular transport occur in the thick ascending limb

A

tubular fluid becomes positive when Cl reabsored

- cations diffuse along electrical gradient

27
Q

what is the concentration of solutes in the loop

A

Hyopsmotic

28
Q

how does fluid leveling the loop become hyperosmotic urine

A

Countercurrent mechanisms to create an osmotic gradient

29
Q

what hormone leads to concentration of tubular fluid

A

acting of ADH/Vasopressin in the collecting duct

30
Q

what are peritubular capillaries pereable to

A

NaCl and water

31
Q

what happens to plasma osmolarity as the capillaries follow the loop

A

changes, but eventually leaves in a vein as a normal osmolarity

32
Q

what does the inital segment of the distal tubule reabsorb

A

about 8% of filtered NaCL

33
Q

how does the inital segment of the distal tubule reabsorb NaCl

A

NaCl symporter in apical membrane

Na K ATPase in basolateral membrane

34
Q

how does sodium reabsorb in the latter half of idstal tubule and collecting duct occur

A

Similar to the inital segments

35
Q

what are the types of cells in the collecting duct and late distal tubule

A

primcipal cells

intercalated cells

36
Q

what is found on principle cells of the late distal tubule and collecting duct

A

Epithelial sodium channels

37
Q

what do epiethlial sodium channels do

A

Reabsorb Na and secrete K

38
Q

what is the importance of principle cells of the late distal tubule and collecting duct

A

Na reabsorption driving paracellular Cl reabsorbtion

K secreted due due to NaK APTase activity in the basal membrane

39
Q

what is the roll of intercalated cell in the late distal tubule and collecting duct

A

Acid-base balance

reabsorb K

40
Q

what hormones aid in regulate blood volume

A

ADH/Vasopressin

Natuiuretic pepetides

41
Q

what releases Vasopressin/ADH

A

posterior pituitary

42
Q

what causes a release of ADH

A
  • by change in osmolality of body fluid at set point 275-290 mOsm/kgH2O
  • change in blood volume/pressure
43
Q

what responds to a change in low blood pressure to lead to a release of Vaopressin/ADH

A

baroreceptors in left atrium and large pulmonary vessels

44
Q

what responds to a change in high blood pressure to lead to less Vasopressin/ADH

A

baroreceptors in aortic arch and carotid sinus

45
Q

what is the action of ADH/vasopresin

A
  • Increase permeability of the late distal tubule and collecting duct by increasing aquaporins in the apical membrane (basolateral is freely permeable to water)
  • increase permeability of medullary collecting duct to urea
46
Q

what is diuresis

A

Low ADH

47
Q

what happens in Diuresis

A

Solutes reabsorbed in distal tubule and collecting duct, but no water reabsorption
- urine dilute as 50 mOsm/Kg H2O

48
Q

what is Antidiuresis

A

ADH high

49
Q

what happens in ANtidiuresis

A

Water reabsored as fluid passes through collecting duct

- urine concentrated up to 1200 mOsm/kg H2O

50
Q

what does the renin-angiotensin-aldosterone system stimulate

A

Events that increase reabsorption of sodium and water (combat volume contraction)

51
Q

what is renin release

A

responding to a drop in perfusion pressure
decrease in NaCL delivery to macula densa
Sympa input to juxtaglomerular cells

52
Q

what does renin do

A

Converts angiotensinogen to angiotensin I

53
Q

what converts Angiotensin I to Angiotensin II

A

angiotensin converting enzyme

54
Q

what is the effect of angiotensin II

A

Vasoconstriction
Stimulates release of ADH
increase sympa activity
Stimulate aldosterone secretion

55
Q

what does aldosterone from the adrenal cortex do

A

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

56
Q

when are natriuretic peptides secreted

A

when the heart dilates (during volume expansion)

57
Q

where does atrial natriuretic pepetide come from

A

the atria

58
Q

where does brain natriuretic peptide come from

A

Ventricles

59
Q

what are the effects of natriuretic peptides

A

vasodilation of afferent arterioles
Vasoconstriction of efferent arterioles
inhibit renin and aldosterone
inhibit ADH secretion

60
Q

what is the net efffect of natriuretic peptides

A

increase excretion of NaCl and water

61
Q

why is it important to regulate potassium

A

major determinant of membrane resting potential

- affect electrically excitable cells

62
Q

what does hyperkalemaia lead to

A

depolarize V

63
Q

what does hypokalema

A

hyperpolarize V

64
Q

what does a change in K do to the heart

A

causes cardiac arrhythmias

65
Q

what happens to ingesting K

A

fast shifted into cells mediated by insulin, epinephrine, and aldosterone

66
Q

how much ingested K is excreted by the kidney

A

90-95%

67
Q

is K freely filtered in the Glomerulus

A

yes

68
Q

where is K reabsorbed

A

67% in the proximal tubule

Thick ascending limb

69
Q

how is K reabsorbed in the proximal tubule

A

paracellular transport/solvent drag like Na

70
Q

how K reabsorbed in the thick ascending limb

A

Na, K, 2Cl symporter and paracellular transport (non solvent drag)

71
Q

how is K secreted in the late distal tubule and collecting duct

A
  • K secreted by principal cells depending on ATPase activity, K gradient, apical K permeability
  • intercalated cells reabsorb K when Potassium is depleted
72
Q

what are the factors that affect excretion of Potassium

A

Plasma K

Flow rate of tubular fluid

73
Q

how does plasma K change the excretion of Potassium

A

increased K simulates Aldosterone release

aldoserone increase Na/K ATPases in principle cells

74
Q

what does an increase in flow rate do to K secreteion

A

Increases K secertion

75
Q

why does in creased flow lead to an increase in K secretion

A

local response to bending of cilia

76
Q

how does increased flow increase K secretion

A

increased flow
increased Na in collected
Na reabsorption
favors increased K secretion

77
Q

does reabsorption of K in proximal tubule and thick ascending limb change a lot dpending on poassium presence

A

No

78
Q

wha does secretion increase if plasma K is high

A

increases in distal tubule and cortical collection

79
Q

where does reabsorption of K occure when plasma concetrations are low`

A

distal tubule

cortical collecting duct