Endocrine Control of Fluid and Salt Balance Flashcards

1
Q

what is the total body water content

A

0.6 x body weight = 42L

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2
Q

what is the intracellular fluid content

A

0.4 x body weight = 28L

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3
Q

what is the extracellular fluid content

A

0.2 x body weight = 14L

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4
Q

what does the extracellular fluid subdivides into?

A

plasma - 1/4 of ECF = 3.5L

interstitial fluid - 3/4 of ECF = 10.5L

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5
Q

what does ECF contains

A

Na+ 145 moles/L
K+ 4
Cl- 105
HCO3- 25

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6
Q

approximate value of osmolarity

A

[Na+ + K+] x2 or 290-295 milliosmoles/L

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7
Q

how much fluid do we take in as drinks

A

1200 ml/day

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8
Q

how much fluid do we take in as food

A

1000ml/day

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9
Q

how much water do we get form the catabolism of food

A

300ml/day

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10
Q

how much water do we lose from lungs and skin

A

700ml/day

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11
Q

how much water do we lose from sweat

A

100ml/day

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12
Q

how much water do we loose from faecal loss

A

200ml/day

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13
Q

how much water do we lose form urine

A

1500ml/day

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14
Q

what is hypovolaemia

A

a decreased volume of circulating blood in the body.

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15
Q

which receptors receive the decrease in the volume of circulating blood

A

baro-receptors, angiotensin II on subfornical area

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16
Q

which receptors receive hypertonicity

A

osmoreceptors

17
Q

where do the signals from the baroreceptors and osmorecpetors go to?

A

hypothalamus

18
Q

what are the responses produced by the hypothalamus in response to hypertonicity and hypovalaemia

A

hypertonicity - thirst

hypokalaemia - vasopressin (ADH) release rom posterior pituitary

19
Q

what is the function of retention of sodium ion

A

to maintain extracellular volume

20
Q

how does an increase in extracellular volume influence renal loss

A

it enhances renal loss of sodium ion and hence a fall in volume after diuresis

21
Q

how does a decrease in extracellular volume influence the renal uptake of sodium ion

A

it enhances renal uptake of sodium ion and hence an increase in volume after antidiuresis

22
Q

fall in venous blood volume

A

1) general sympathetic discharge
2) constriction of the afferent arteriole
3) reduction in renal blood flow
4) reduction in glomerular filtration rate
5) reduction in sodium chloride presented to
distal convoluted tubule
6) conservation of sodium chloride

23
Q

fall in blood pressure in circulation

A

1) renal sympathetic nerve discharge - direct effect on renin releasing cells in afferent arteriole
2) reduced renal blood flow and glomerular filtration
3) reduced sodium chloride delivery detected by macula dense cells of the distal convoluted tubule
4) increased renin release
5) eventual increase sodium chloride reabsorption as well as reduced loss

24
Q

what converts angiotensinogen from liver secreted into circulation

A

plasma renin

25
Q

what does Angiotensin I in lungs and kidneys do

A

converts enzyme ACE in lung and renal endothelium

26
Q

functions of AT1 receptors

A

1) pressor effect on smooth muscle of arteries
2) acts on subfornical area to stimulate ADH production and thirst
3) actions on zona glomerulosa cells of adrenal cortex to produce aldosterone

27
Q

functions of aldosterone

A

increase Na+/K+ ATPase activity in distal tubule

increase sodium ion reabsorption

28
Q

what did de Wardener’s experiment confirmed?

A

existence of ANP

29
Q

what was done in the gardener’s experiment

A

1) an inflatable catheter inserted into the renal artery to stimulate reduced blood pressure
2) injection of maximal stimulatory dose of aldosterone

30
Q

what was the aim of de gardener’s experiment

A

intention to maximise sodium resorption in the distal convoluted tubuleq

31
Q

the site of atrial natriuretic peptide action

A

1) reduces arterial smooth muscle tone - reduces blood pressure
2) inhibits ADH release
3) inhibits renin release
4) reduces sodium ion absorption in distal convoluted tubule leads to natriuresis