Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Urinary System Physiology SA > ECF volume regulation > Flashcards

ECF volume regulation Flashcards

1
Q

What is the main regulatory of ECF volume

A

Regulation of Na+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is causes of hyovoleaemia (decreased ECF volume)

A

Increased salt and H2O loss can be caused by:

Vomiting
diarrhoea
excess sweating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the cardiovascular reflex to a decrease in plasma volume in hypovolaemia

A

Decreases in: Venous pressure—> Venous return—> Artrial pressure –> End diastolic volume—> stroke volume —> blood pressure

This decreases in blood pressure, decreases the high pressure baroreceptors inhibition of sympathetic discharge, therefor sympathetic discharge in increased

Increasing sympathetic vasoconstrictor, increasing total peripheral resistance, and increasing blood pressure back towards normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does the cardiovascular reflex to hypovalemia affect ADH secretion

A

Causes a decrease in atrial pressure and carotid sinus baroreceptors discharge, therefore stimulating increase in secretion of ADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is GFR maintained in hypovalemia

A

Due to autoregulation

The cardiovascular reflex causes sympathetic discharge which causes the renal arteriolar to constrict,

this is then coupled with angiotensin II which mediates the constriction of efferent,

so Vasoconstrictor of afferent and efferent means little effect on GFR until volume depletion sever enough to cause considerable decrease in mean arterial pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the specific function of the kidney in hypovalemia

A

Increase reabsorption of Na+ by peritubular capillaries

Produce renin which stimulates angiotensin II production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does the rate of Na+ uptake in peritubular capillaries change in hypovalemis

A

Due to Readjustments of starling forces in pertibubular capillary: decreased pertiubular capillary hydrostatic pressure and the increased osmotic pressure more than normal due to loss of NaCl and H2O

causing greater reabsorption due to greater reabsorption forces in peritubular capillaries determined by the osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where and how much Na+ is reabsorbed in hypovalemia

A

Can reabsorb up to 75% of the filtrate at the proximal tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What stimulates the release of renin in the kidney

A

Decreased blood pressure means pressure in afferent arteriole at the level of the juxtaglimeualr cell decreases causing decreased distension, resulting in secretion of renin

Increased sympathetic nerve activity, as beta i receptors cause vasoconstriction, increases renin production

Decreased NaCL delivery in specialised distal tube the macula densa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the action of the renin hormone

A

A proteolytic enzyme which acts on angiotensin, to split it of into from angiotensin I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is angiotensin and where is it produces

A

A decapeptide present in the plasma and constantly produced from the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What converts angiotensin I and angiotensin II

A

ACE enzymes found in the vascular epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where is renin hormone secreted in the kidney

A

Juxtaglomerular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What inhibits renin secretion

A

ANP (atrial natriuretic peptide) - lower BP

The macula densa detecting high rate of delivering NaCl,

angiotensin feedsback to inhibit renin

ADH inhibits renin release - for osmolarity control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the juxtaglomerular apparatus

A

Juxtaglomerular cells plus the macula densa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the macula densa

A

The macula densa is a collection of specialized epithelial cells in the distal convoluted tubule that detect sodium concentration of the fluid in the tubule,

so its main function is to regulate blood pressure and the filtration rate of the glomerulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the juxtaglomerular cells

A

Smooth muscle media of the afferent arteriole, just before it enters the glomerulus has become specialised and contains large epithelial cells with plentiful granules that release the hormone renin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the benefit of the juxtaglomerular cells plus the macula densa

A

The close relationship between the juxtaglomeualr cells and macula densa, creates a tubuloglomerular feedback which affects the GFR and controls the rein rate of production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the rate of renin production inversely proportional to

A

The rate of secretion is inversely proportional to the rate of delivery of NaCL at the macula densa

eg decreased delivery of NaCl increases renin production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does tubuloglomerular feedback contribute to GFR constancy

A

As in increased GFR, causes the flow in tubules to increase and therefore increase in the macula densa, this causes paracrine hormone from macula densa go to afferent arteriole, causing it constrict, so the resistance in the afferent arteriole increase, so hydrostatic pressure in glomerulus decreases meaning the GF decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The main function of renin is the production of angiotensin II, where does angiotensin have an effect

A

arterioles

cardiovascular control centre in medulla

hypothalamus

adrenal cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the affect of angiotensin II on the arteriole

A

Cause vasoconstriction, therefore increase blood pressure

23
Q

what is the affect of angiotensin II on the cardiovascular control centre in the medulla

A

Increase cardiovascular reflex to increase blood pressure

24
Q

what is the affect of angiotensin II on the hypothalamus

A

Increase ADH - so increase volume and maintain osmolarity to increase the blood pressure

Stimulate thirst mechanism and salt appetite

25
Q

what is the affect of angiotensin II on the adrenal cortes

A

The angiotensin II produced stimulates the aldosterone secreting cells in the zona glomerulosa of the adrenal cortex to increase aldosterone

26
Q

What is the affect of aldosterone

A

Aldosterone passes in the blood to the kindey where it then stimulates the distal tubular Na+ ion reabsorption

20% reabsorbed, increasing volume and maintains osmoloraity

27
Q

How does the kidney help to restore volume deficits mediated by the CV reflex in hyovalemia

A

Due to the overall the increasesed proximal and distal tubule Na+ reabsorption together with osmotic equivalents of H2O

28
Q

What affect on ADH secreting cells would occurs when you ECF volume decreases but you also have hyposomolarity

eg diarrhoea 3L loss then drinking 2L of pure water

A

Opposing inputs

ECF volume decreases would cause increase of AH secretion via baroreceptor

Hyposmolarity would cause inhibition of ADH secretion via osmoreceptors

29
Q

In the situation of decreased ECF volume with hyposomolarity what takes priority and why

A

Normally osmolarity is main determinant of ADH concentration but if there is sufficient volume changes to compromise brain perfusion then volume becomes primary drive

acts as an emergency mechanism to save perfusion for the brain

30
Q

What then occurs indecreased ECF volume with hyposomolarity when volume becomes primary drive

A

therefore ADH will increase because of the baroreceptors as aim to conserve water and tolerate disturbed osmolarity and once volume is restored, the osmolarity will then be normalised

31
Q

Where does sodium absorption occur and what is the percentage of absorption there

A

65-75% of NaCl and H2O reabsorbed from proximal tubule

15-20% of NaCl and H2O reabsorbed from the loop of henle

5-20% of NaCl reabsorbed from distal tubule and collecting duct

32
Q

What hormone promotes sodium reabsorption and where

A

Aldosterone promotes Na+ reabsorption in the distal tubule

33
Q

What is aldosterone hormone also responsible for inn the distal tubule

A

Potassium secretion

34
Q

Why is weight gain seen due to excess aldosterone

A

as increased Na+ reabsorption causes weight gain due to increased H2O and Na+ retention, increasing the volume

35
Q

Why would spontaneous diereses occur in excess aldosterone

A

As ANP overrides aldosterone effects

because the volume expansion due to NA+ reabsorption weight gain stimulates the release of ANP from atrial cells, causing spontaneous diuresis secondary to aldosterone volume expansion

36
Q

Why are patients with hyperaldoteronsim (excess aldosterone) depleted of K+ but don.t have a high sodium level

A

As when spontaneous diuresis occurs when ANP overrides aldosterone, it cause loss of Na+ and h2O, but aldosterone still continue K+ loss, because still increase K+ secretion

37
Q

What syndromes is associated with excess aldosterone

A

Conns syndrome

38
Q

What hormone promotes Na+ excretion

A

ANP (atira naitriuretic peptide)

39
Q

What causes secretion of ANP and where is it secreted

A

Increased blood/ECFvolume causes increased atrial stretch of myocardial cells, realising ANP

40
Q

What is the overall affect of ANP

A

Natriuresis - loss of H2O and Na+ in urine

Decreases blood pressure

41
Q

Where does the hormone ANP affect

A

hypothalamus

kidney

Adrenal cortex

medulla oblongata

42
Q

What is the affect on ANP on the hypothalamus

A

Inhibits ADH, so increases NaCl and H20 Excretion

43
Q

What is the affect on ANP on the kidneys

A

Increase GFR,

Decreases Renin (as opposes the actions of angiotensin II)

  • Less aldosterone so increases NaCl and H20 Excretion
  • decreased blood pressure
44
Q

What is the affect of ANP on the adrenal cortex

A
  • Less aldosterone so increases NaCl and H20 Excretion
45
Q

What is the affect of ANP on the medulla oblongata

A

decrease blood pressure

46
Q

How does diabetes mellitus abolish interstitial gradient

A

As the high plasma level of glucose Tm

Glucose remains in tubule and extras osmotic affect to retain H2O, decreases osmolarity in tubule

The decreases passive diffusion of sodium due to reduced concentration gradient, therefore further prevents NaCl pumps in the loop of henle

This means the movement of H2O out of tubules into the interstium is reduced as no concentration gradient is created as sodium remains in tubule

this means the medullary insterstial gradient is much less as there is a considerable reduction of NaCl and H20 reabsorbed from the loop of henle

47
Q

How is glucose reabsorption further prevented in diabetes mellitus

A

As when reduces passive diffusion of sodium, further prevents glucose reabsorption as is a symport with sodium

48
Q

Why is there a large volume of NaCl and H2O delivered to the distal tubule

A

As because of the high concentration of glucose in the tubules, it means that water and sodium is retained in the tubule with glucose and is not reabsorbed

49
Q

What affect does the high volume of NaCl and H2O in the distal tube in diabetes mellitus cause

A

The body thinks a large volume of NaCl and H2O delivered to the distal tubule would mean there is excess ECF volume, rather than just a high volume of h20 and Na+ in ECF

So macula densa decreases renin secretion, further decreasing Na+ reabsorption at distal tube

further getting ride of NaCl and H2O

50
Q

What further affect does wrecking the interstial gradient have in diabetes melitus

A

Decreases the ability of ADH to conserve water,

as water cant move out into the interstium from collecting ducts as It is driven by the hypertonic medullary interstitial gradient, created by the countercurrent multiplier of the loop of Henle which no longer exists

51
Q

The mechanism of diabetes mellitus increasing the volume of NaCl and H2O delivered to the distal tubule, wrecking the interstice gradient has what affect on your urine output

A

Excrete 6-8L of isotonic urine/day ( large volume of urine produced)

= polyuria

52
Q

How does diabetes mellitus cause a hyperglycaemia coma

A

The large volume or nealt isotonic urine will be excreted,This can cause severe salt and water depletion in Diabetic patients, which results in hypotension, which can can become severe when it result in inadequate blood flow to the brain which can cause a hyperglycaemia coma

53
Q

What occurs in a hypoglycaemia coma

A

due to inadequate glucose for the brain

54
Q

How is thirst one of the first sign of diabetes mellitus

A

This can cause severe salt and water depletion in Diabetic patients and if ingestion is not enough will trigger thirst mechanism

= polydipsia

Urinary System Physiology SA (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions