Some renal phys Flashcards

1
Q

How much C.O. do the kidneys receive?

A

20-25%

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2
Q

What is the functional unit of the kidney?

A

nephron

(1 million/kidney)

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3
Q

What are the main parts of a nephron?

A

Glomerulus / bowman’s capsule

Proximal convoluted tubule (PCT)

Loop of Henle - Ascending and descending

Distal convoluted tubule (DCT)

Collecting duct

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4
Q

Which type of nephron has the most control in regulating the concentration of urine?

A

juxtamedullary

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5
Q

After the renal artery, what arteries does the blood flow through?

A

Renal A –> lobar A –> segmental A –> interlobar A –> Arcuate A –> Interlobular A –> Afferent arterioles

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6
Q

What do afferent arterioles lead to?

A

Glomerulus

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7
Q

How does blood leave the glomerulus?

A

Efferent artery –> peritubular capillaries –> vasa recta

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8
Q

Which vessels have the greatest control over glomerular pressure?

A

afferent/efferent arterioles

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9
Q

Do glomerular capillaries have high or low pressure?

A

high

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10
Q

do peritubular capillaries have high or low pressure?

A

low

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11
Q

what happens at the glomerulus?

(options for these questions: filtration, H20 reabsorption, solute reabsorption, secretion)

A

filtration

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12
Q

Is there active or passive transport at the glomerulus?

A

passive

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13
Q

At the glomerulus, can cells and proteins get through?

A

No - too big

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14
Q

How much does the glomerulus filter per day? per minute?

A

180 L/day

1.2 L/min

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15
Q

How is GFR regulated extrinsically? (2 mechanisms)

A
  1. by sympathetic nerves in eff/aff arterioles
    (e. g. baroreceptor reflex - if blood pressure is low, afferent arteriole will constrict to increase renal pressure)
  2. by hormonal control of RAA axis
    (e. g. if blood pressure is low, renin is released to increase pressure)
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16
Q

There are 3 other hormones that regulate GFR. What are they and what do they do? (“the 3 A’s”)

A

ADH: retains h20

Aldosterone: reasborbs Na

ANP: the opposite. inhibits Na/H20 reabsorption but promotes their secretion; inhibits ADH secretion

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17
Q

How if GFR regulated intrinsically? (2 mechanisms)

A
  1. myogenic mechanism
    (e. g. aff/eff arterioles measure passive stretch and adjust BP to maintain their normal stretch)
  2. tubuloglomerular feedback
    (e. g. macula densa senses total solute concentration, and adjusts afferent arteriole constriction/dilation to all more/less filtrate to pass)
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18
Q

Where is renin released from?

A

granular cells

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19
Q

What structure tells granular cells to release renin?

A

macula densa

(tubuloglomerular feedback)

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20
Q

Renin causes vasoconstriction, but what other hormone does it signal?

What does that hormone do?

A

aldosterone

retains Na in the body (to also retain H20)

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21
Q

What other chemical can the macula densa have released?

What do these do?

A

releases PGE2, NO

these tell afferent arteriole to dilate

(would be released with low solute concentration)

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22
Q

If GFR is low, will you have constriction or dilation

1) at the afferent arteriole
2) at the efferent arteriole

A

afferent: constricts
efferent: dilates

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23
Q

If GFR is high, will you have constriction or dilation

1) at the afferent arteriole
2) at the efferent arteriole

A

afferent: dilates
efferent: constricts

24
Q

Lastly, what is the renorenal reflex?

A

stretch receptors in the pelvis lead to an increase in urine flow rate and an increase in Na excretion

25
Q

How can we measure GFR? (2 major substances)

A

inulin and creatinine

26
Q

Which GFR measurement is more accurate, but harder to measure?

A

inulin

27
Q

Which GFR measurement is a byproduct of muscle metabolism, is less accurate but easier to measure?

A

Creatinine

28
Q

What happens during reabsorption?

A

water and solutes get returned to the blood stream

29
Q

can glucose, cells and protein get reabsorbed?

A

yes

30
Q

How much of the filtrate gets reabsorbed?

A

99%

31
Q

Where does the bulk of the reabsorption occur in the nephron?

What structures also reabsorb?

A

PCT and DCT

reabs also occurs at loop of henle, collecting duct

32
Q

By what process is sodium reabsorbed?

A

Primary Active Transport - Na/K pump

33
Q

But what process are glucose and amino acids reabsorbed?

A

seconary active transport - enter/leave with Na

34
Q

By what process is H2O reabsorbed?

A

passive - osmosis - dragged by Na

35
Q

By what process is Cl reabsorbed?

A

passive - electrical drag

36
Q

By what process are some large proteins and molecules reabsorbed?

A

some undergo pinocytosis

37
Q

There are two types of H2O reabsorption - obligatory and facultative (selective). What’s the difference?

A

obligatory is when Na and other electrolytes are reabsorbed, and water follows

Facultative (selective) occurs in the collecting ducts, and water leaves through H2O channels

38
Q

which hormone regulates facultative h2o reabsorption?

A

ADH

not regulated by solutes like the others

39
Q

How are the water channels formed in the collecting ducts?

A

vasopressin binds to receptors, activates cAMP, and creates pores

40
Q

Is H20 reabsorption in the collecting ducts bulk or not?

A

NO.

it’s very much the fine tuning before the filtrate becomes urine

41
Q

What is the descending loop of henle only permeable to?

A

h20 reabsorption

42
Q

what is the ascending loop of henle only permeable to?

A

Na, Cl reabsorption

43
Q

What happens during secretion?

A

materials go from the blood back into the kidney

44
Q

Does secretion involve active or passive transport?

A

active

45
Q

What types of things usually get secreted, especially in the PCT?

A

toxins and foreign things

46
Q

Which two electrolytes may be secreted, especially in the DCT and collecting duct, in exchange for Na+ to be reabsorbed?

A

K+ and H+ ions

47
Q

What happens during excretion?

A

blood filtrates leave the body via urine

48
Q

How is urine concentration autoregulated?

A

“glomerulotubular balance”

always, 65-70% of filtrate is reabsorbed at the PCT despite the GFR.

49
Q

How is urine concentration regulated by the nervous system? (4 ways)

A
  1. renal plexus nerves (regulate pressure at eff/aff arterioles)
  2. Change in GFR (causes contraction/dilation of eff/aff arterioles)
  3. A naturally high reabsorption of Na in PCT (this sounds like autoregulation to me but what do I know)
  4. Increased renin (causes constriction); increased NO and PGE2 (cause dilation)
50
Q

Which hormone is released from the pituitary gland, and determines the permeability of the collecting duct to water?

A

ADH

51
Q

why

A

just why

that’s all

52
Q

So if there’s a LOT of ADH, do you get a LOT of pee or just a wee bit of pee?

A

just a wee

and it’s highly concentrated

53
Q

So when you wee, how does that process happen?

(called the micturition reflex)

A

Stretch receptors in bladder make internal urethral sphincter (sm muscle) relax

Signal from stretch receptors go to pons……..

54
Q

What happens at the pons when there is urine in the bladder?

a) if you want to wee
b) if you don’t want to wee

A

a) if OK - pons relaxes both internal and external sphincters
b) if not OK - pons keeps external sphincter contracted

55
Q

Which system opens your internal urethral spinchter, sympathetic or para?

A

para

56
Q

What 4 kidney changes occur with aging?

A
  1. decreased nephrons
  2. decreased GFR
  3. decreased ADH sensitivity
  4. problems with micturition reflex
57
Q

Why is life extra good today?

A

Because you have control over your external anal sphincter AND your external urethral sphincter!

congratulations you rock