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FBS1 > Kidney function III > Flashcards

Kidney function III Flashcards

1
Q

what is oliguria

A

Low vol of urine produced - below 0.428L/day

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2
Q

What is osmolar clearance

A

volume of plasma cleared of osmotically active particles per unit time

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3
Q

How do you calculate osmolar clearance

A 
C = UV/P where U = osmolarity of urine mosm/ml
V = urine flow rate ml/min
P = plasma osmolarity mosm/ml
C = osmolar clearance ml/min
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4
Q

What is typical fasting osmolar clearance

A

2-3 ml/min

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5
Q

How do you calculate free water clearance

A

Renal clearance - osmolar clearance = free water clearance

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6
Q

What is the free water clearance of a patient producing hypotonic urine

A

> 0

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7
Q

What is the free water clearance of a patient producing hypertonic urine

A

<0

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8
Q

What is the free water clearance of a patient producing isotonic urine

A

0

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9
Q

Where are the osmoreceptors that are involved in the release of ADH

A

Organum vasculosum lamina terminalis
Medican preoptic nucleus
subformical organ

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10
Q

What do the osmoreceptors involved in the release of ADH signal to?

A

Magnocellular neurosecretory cells in paraventricular supraoptic nuclei in hypothalamus

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11
Q

Why is ADH effective in its role

A

It has a short life span = 20-30 mins allowing for fine control

It is released rapidly

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12
Q

What effect does angiotensin II have on ADH secretion

A

It increases it

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13
Q

What effect does natriuretic peptides have on ADH secretion

A

It decreases it

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14
Q

What effect does nicotine have on ADH

A

+

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15
Q

What effect does nausea have on ADH

A

+

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16
Q

What effect does pain have on ADH

A

+

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17
Q

What effect does stress have on ADH

A

+

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18
Q

What effect does alcohol have on ADH

A

-

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19
Q

What can promote/inhibit ADH other than osmoreceptor action?

A 
Alcohol
Stress
Nausea
Pain
Nicotine
20
Q

What are the two types of diabetes insipidus

A

Neurogenic; congenital or from brain injury, trauma, tumour

Nephrogenic; inherited (mutated V2, AQP2 gene), acquired from infection, drug

21
Q

What mutations can cause nephrogenic diabetes insipidus

A

Mutated V2 or AQP2 gene

22
Q

What are the characteristics of diabetes polyuria

A

Polyuria
Polydipsia
nocturia

23
Q

Describe the physiology of the reabsorption of K+ in the PCT of the nephron

A

There is a K+ ion in the apical membrane which is used to move K+ from inside the cell into the lumen.
Then there is transcellular movt of K+ from lumen into the interstitial space.
The Na+:K+ ATPase in the basolateral membrane moves K+ into the cell and then another K+ channel allows K+ to flow into interstitial fluid from inside the cell.
Then a K+:CL- co-transporter also pumps K+ into interstitial fluid
There is paracellular movt of K+ too

24
Q

Describe the physiology of the reabsorption of K+ in the thick ascending limb of the LOH of the nephron

A

In the apical membrane there is a Na+:K+:Cl- cotransporter moving ions inside the cell (NKCC2 transporter). There is also a K+ channel moving K+ ions back into the lumen.
There is a Na:K ATPase pump moving K+ in to the cell. There is a K+ channel in the basolateral membrane moving K+ from the cell into the interstitial space.
There is a K+:CL- cotransporter moving K+ out of the cell with Cl-
There is paracellular movt of K+

25
Q

Describe the physiology of the reabsorption K+ in the collecting ducts

A

Occurs in the intercalated cells of the collecting duct.
There is a H+:K+ exchanger that moves K+ into the cells in favour of H+ from the lumen of the nephron.
Then there is a K+ channel in the basolateral membrane which removes K+ from the cell and allows it to travel into the interstitial space.

26
Q

Describe the physiology of the secretion of K+ in the collecting ducts

A

Occurs in the principle cells of the collecting duct.
There is a Na:K ATPase pump in the basolateral membrane that moves K+ into the cells.
K+ channels in the apical membrane called ROMK = renal outer medullary K+ channels; and Ca2+ activated big conductance K+ channels that allow the flow of K from within the cell into the lumen of the nephron.
There is a Na channel in the apical membrane that allows Na to enter the cell from the lumen.
There is also a K:Cl cotransporter in the apical membrane which removes ions from the cell and places them in the lumen.
There is a K+ channel in the basolateral membrane which moves ions from inside the cell out.

27
Q

What are the K+ channels found in the apical membrane of the principle cells of the collecting ducts of the nephron.

A

Renal outer medullary K+ channels (ROMK)

Ca2+ activated big conductance K+ channels

28
Q

What effect does aldosterone have on K+ channels in the nephron?

A

It activates them

29
Q

What effect does tubular flow rate have on K+ secretion and why?

A

It increases it as positive charges are washed away when tubular flow is higher meaning that an electrochemical gradient is maintained.

30
Q

What effect does acidosis have on K+ secretion?

A

It inhibits it

31
Q

What effect does alkalosis have on K+ secretion?

A

It stimulates it

32
Q

What is hypokalaemia?

A

Plasma [K+] < 3.5 mM

33
Q

What causes hypokalaemia?

A

Increased tubular flow rate (increased K+ secretion)
Hyperaldosteronism
Alkalosis

34
Q

How would you treat a patient with hypokalaemia?

A

KCl administered via IV or orally
Feed w/ foods rich in K+
Treat alkalosis

35
Q

What is hyperkalaemia?

A

Plasma [K+] > 5.5mM

36
Q

How would you treat a patient with hyperkalaemia?

A

Short term -> give Ca2+ to antagonise effect of K+ on heart muscle
Intermediate term -> Give insulin to move K+ into cells, give glucose to prevent hypoglycaemia
Long term -> remove K+ from body giving diuretics

37
Q

Possible C(H2O) range

A

-1.3 to 14.5 ml/min

38
Q

How do osmoreceptors work

A

The OVLT, MPN and SFO signal to magnocellular neurosecretory cells in the paraventricular and supraoptic nuclei in the hypothalamus which then causes the release of ADH from the posterior pituitary gland

39
Q

Normal range of plasma osmolality

A

285-295 mosm/kg

40
Q

What are the characteristics of diabetes insipidus

A

nocturia
polyuria
polydipsia

41
Q

Describe osmotic diuresis

A 
Increased blood glucose
more glomerular filtration of glucose,
increased osmolarity of filtrate
decreased water reabsorption
polyuria
42
Q

Where is the largest amount of potassium reabsorbed in the kidney

A

%65 absorbed passively in the proximal tubule

43
Q

What type of co transporter is used to absorbed K in the asc LOH

A

NKCC2

44
Q

What type of exchanger is used to absorbed K in the distal tubule

A

K+:H+ exchanger

45
Q

What is the normal K plasma range

A

3.5-5 mM

FBS1 (74 decks)

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