ECF Volume Regulation

Question 1

What are the major osmoles in ECF?

Answer 1

Na and Cl

Question 2

What are the major ICF osmoles?

Answer 2

Potassium

Question 3

The regulation of ECF volume is linked to the regulation of what?

Answer 3

Body sodium levels

Question 4

What effect does more sodium in a compartment have on the amount of water in the compartment?

Answer 4

The more sodium, the more water which is retained

Question 5

RECAP FROM FOM- lol x

How many litres of water in TBW?

Answer 5

42L

->TBW makes up approx. 60% of body

Question 6

RECAP FROM FOM- lol x

How many litres of water in ECF?

Answer 6

14L

Question 7

RECAP FROM FOM- lol x

How many litres of water in ICF?

Answer 7

28L

Question 8

RECAP- what are the components of ECF?

Answer 8

Plasma and interstitial fluid

->11L for interstitial fluid and 3L for plasma

Question 9

Hypovolaemia?

Answer 9

A condition that occurs when your body loses fluid, like water or blood

Question 10

Give some times in which hypovolaemia occurs.

Answer 10

Vomiting, diarrhoea, excess sweating

Question 11

What happens to salt and water levels in hypovolaemia?

Answer 11

Decrease

Question 12

What is the renal response to hypovolaemia?

Answer 12

Reduced plasma volume which reduces venous pressure -> decrease in venous return, atrial pressure, end diastolic volumes which then impacts stroke volume, cardiac output and blood pressure

This stimulates the carotid sinus baroreceptors and reduces their inhibitory sympathetic discharge

All of this increases ADH

->woahhh okay, read through and just understand the pattern ig

Question 13

RECAP- what effect does more ADH have on urine quantity and concentration?

Answer 13

Less urine but higher concentration

Question 14

What effect does increased sympathetic discharge have?

Answer 14

Increased vasoconstriction, total peripheral resistance and blood pressure increases towards normal too

Question 15

What effect does the increased sympathetic vasoconstriction, TPR and BP have on the kidneys?

Answer 15

Increased renal arterial constriction
Release of renin

Question 16

What is renin?

Answer 16

Regulatory hormone of the kidney

Question 17

What does renin stimulate the release of?

Answer 17

Angiotensin II

Question 18

What does angiotensin II increase the reabsorption of in the proximal tubule?

Answer 18

NaCl and water

Question 19

What does angiotensin II stimulate the release of?

Answer 19

Aldosterone

Question 20

What effect does aldosterone have?

Answer 20

Increases NaCl and water reabsorption in the distal tubule

Question 21

Okay to summarise this wee bit-
Which hormone increases reabsorption of NaCl and water in:
a. the proximal tubule
b. the distal tubule

Answer 21

a. Angiotensin II
b. Aldosterone

Question 22

What are the changes seen in the kidney as a result of the increased sympathetic discharge?

Answer 22

-Increased renal nerve activity -> increased renal arteriolar constriction
-Increased renin

Question 23

If there is increased renin, what will there also be an increase in?

Answer 23

Angiotensin II

-> and then in turn, increased angiotensin II increases the release of aldosterone

Question 24

Is angiotensin II a vasodilator or vasoconstrictor?

Answer 24

Strong vasoconstrictor

Question 25

RECAP- what type of hormone is aldosterone?

Answer 25

Steroid hormone

Question 26

Smooth muscle of the afferent arteriole is specialised. It contains many cells with plentiful granules. What are these cells called?

Answer 26

Juxtaglomerular cells

Question 27

What two components make up the Juxtaglomerular apparatus?

Answer 27

Juxtaglomerular cells Macula densa ->macula densa is a specialised loop of the distal tubule

Question 28

What hormone do Juxtaglomerular cells produce?

Answer 28

Renin ->remember, renin is a renal hormone, these cells are to do w renal system whilst others are more linked to brain etc.

Question 29

What do the Juxtaglomerular cell detect?

Answer 29

Changes in blood pressure as they don't stretch as much in low BP

Question 30

What is produced by Juxtaglomerular cells when there is low BP?

Answer 30

Renin

Question 31

Renin is used to convert angiotensinogen into what?

Answer 31

Angiotensin I

Question 32

Which enzyme converts angiotensin I into angiotensin II?

Answer 32

ACE- angiotensin converting enzyme

Question 33

What is really the only function of angiotensin I?

Answer 33

To be converted into angiotensin II

Question 34

What effect does angiotensin II have on arterioles?

Answer 34

Constricts them ->remember, angiotensin II is a strong vasoconstrictor

Question 35

What effect does angiotensin II have on the hypothalamus?

Answer 35

Increased vasopressin/ADH release Increased thirst

Question 36

What effect does angiotensin II have on the adrenal cortex?

Answer 36

Increase aldosterone release

Question 37

So, the amount of angiotensin II depends on what?

Answer 37

The amount of renin in the plasma

Question 38

Angiotensin II stimulates the aldosterone-secreting cells. Where are these cells found?

Answer 38

Zona glomerulosa of the adrenal cortex

Question 39

What are some of the things which can control release of renin?

Answer 39

1. Decreased pressure of afferent arteriole at level of JG cells 2. Increased sympathetic nerve activity

Question 40

Via which type of receptors can increased sympathetic nerve activity cause release of renin?

Answer 40

Via beta-1 receptors

Question 41

How does angiotensin II increase water reabsorption from the collecting duct?

Answer 41

Acts on the hypothalamus to stimulate ADH secretion which increases water reabsorption

Question 42

In hypovolaemia, what does the body prioritise- osmolarity or volume?

Answer 42

Replenishes volume first before fixing osmolality

Question 43

Simple rule- if salt and water is lost...

Answer 43

Salt and water has to be replaced

Question 44

Which hormones promotes the excretion of sodium, therefore counteracting the sodium reabsorption?

Answer 44

ANP- atrial natriuretic peptide

Question 45

What would happen if aldosterone was given to an individual with adequate sodium from diet?

Answer 45

There would be sodium retention and loss of potassium -> this would lead to weight gain due to retention of sodium and subsequent retention of water

Question 46

What is the effects of aldosterone at the distal tubule?

Answer 46

Increases sodium reabsorption Increases potassium secretion

Question 47

Does aldosterone override ANP or does NAP override aldosterone?

Answer 47

ANP overrides aldosterone

Question 48

RECAP- hyperaldosteronism is a cause of which condition?

Answer 48

Conn's syndrome

Question 49

RECAP- what causes hyperaldosteronism?

Answer 49

Tumour of the adrenal cortex

Question 50

Which cells secrete ANP and when do they do this?

Answer 50

Atrial cells in response to expansion of ECF volume

Question 51

What effect does ANP have on the hypothalamus?

Answer 51

Less ADH

Question 52

What effect does ANP have on the kidney?

Answer 52

Increased GFR Decreased renin

Question 53

What effect does ANP have on the adrenal cortex?

Answer 53

Less aldosterone

Question 54

What effect does ANP have on the medulla oblongata?

Answer 54

Decreased blood pressure

Question 55

In uncontrolled diabetes mellitus, what is the rate of reabsorption in the renal tubule like?

Answer 55

Reduced compared to normal

Question 56

Ngl for the last two lectures in this part I have been struggling to make flashcards so may be worth a watch over if you can be bothered

Answer 56

Sorry x

Question 57

In the ascending loop of Henle, there is a transporter which co-transports three ions- which three?

Answer 57

Sodium, chloride and potassium

Question 58

Is the co-transportation of sodium, chloride and potassium active or passive?

Answer 58

Passive -> energy is provided by the sodium-potassium pump