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Urology > Regulation of Osmolarity > Flashcards

Regulation of Osmolarity Flashcards

1
Q

where is AHD synthesised?

A

supraoptic and paraventricular nuclei in the hypothalamus

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2
Q

what is the primary control of ADH secretion?

A

plasma osmolarity

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3
Q

true or false:

an increase in the effective oncotic pressure of the plasma causes an increased rate of discharge of ADH

A

true

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4
Q

what endocrine organ releases ADH?

A

the posterior pituitary

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5
Q

what mediates changes in the neural discharge of ADH secreting hormones?

A

osmoreceptors in the anterior hypothalamus

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6
Q

what is the effective of an increase in osmolarity on the osmoreceptors?

A

they activates as the cell shrinks due to H20 moving out of the cell

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7
Q

True or false:

an increase in osmolarity causes a decrease in neural discharge and ADH secretion

A

false:
this causes ad increase in ADH secretion and neural discharge and the stretch sensitive ion channels (in the osmoreceptors) are activated

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8
Q

how does a decrease in osmolarity cause a decrease in ADH secretion?

A

> H20 enters the cell (osmoreceptors) causing it to swell

> osmoreceptors do not fire and so there is an increase in ADH secretion

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9
Q

what is normal plasma osmolarity?

A

280-290 mOsm/kg H20

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10
Q

what is tonicity?

A

The effective osmotic pressure gradient

penetrating solutes that move with the water and do not create an osmotic drag

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11
Q

Name that missing word:

An increase in osmolarity that does not cause and increase in ??? is ineffective in causing an increase in ADH

A

tonicity

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12
Q

how does aquaporin 2 increase the permeability of the collecting duct to H20?

A

it incorporates channels into the luminal membrane

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13
Q

how does ADH increase water reabsorption in the collecting duct?

A

by binding to cell surface receptors it creates the release of aquaporin 2 which increases the permeability of the cell to water

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14
Q

why does the contents of the collecting duct become highly concentrated at the tip if the medulla?

A

> ADH is present so it equilibrates with the medullary interstitium through H20 osmotic effect
the medullary interstitium has become hypertonic due to the loop of henle counter current multiplier

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15
Q

is ADH is absent is the medullary interstitial gradient still ineffective at inducing H20 movement out of the collecting duct?

A

yes as the collecting duct would be impermeable to H20

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16
Q

what is the effect of ADH on the permeability of the collecting ducts to urea?

A

it increases the permeability

17
Q

Tue or Flase:

urea reinforces the interstitial gradient in the region of the thin ascending loops of henle

A

True

18
Q

why must urea be reabsorbed?

A

it would exert an osmotic effect and hold H20 in the tubule reducing potential for rehydration

19
Q

would and increase or an decrease in ECF volume cause an increase in ADH?

A

a decrease

20
Q

there is an inverse relationship with the rate of ADH secretion and what?

A

the rate of discharge of the stretch receptor afferent in low and high pressure areas of circulation

21
Q

where are the low pressure receptors?

A

> left and right atria

> great veins

22
Q

where are the high pressure receptors?

A

> carotid baroreceptors

> aortic arch baroreceptors

23
Q

what is the normal effect of atrial receptors on ADH secreting neurons?

A

inhibition of discharge

24
Q

what is the effect of a decrease in ECF volume on atrial receptor discharge?

A

there is a decrease in discharge

25
Q

in haemorrhage which receptors will contribute to changes in ADH secretion?

A

carotid and aortic receptors

26
Q

what stimuli would cause in increase in ADH?

A 
> morphine
> nicotine
> exercise
> emotion
> pain
> stress
> traumatic surgery
27
Q

what is the effect of alcohol on ADH secretion?

A

it decreases it

28
Q

what us the effect on ADH secretion of:
> high osmolarity
> decreased atrial stretch
> decreased BP

A

an increase in ADH secretion

29
Q

what will a deficiency in ADH cause?

A

diabetes insipidus

30
Q

what could cause central diabetes insipidus?

A

damage to the hypothalamic areas synthesising ADH:
> Tumour
> meningitis
> surgery

31
Q

what could cause peripheral diabetes insipidus?

A

collecting duct insensitivity to ADH

32
Q

what is diabetes insipidus usually secondary to?

A

> hypercalcaemia

> hypokalaemia

Urology (9 decks)

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