ECF Volume Regulation Flashcards
What are the major osmoles in ECF?
Na and Cl
What are the major ICF osmoles?
Potassium
The regulation of ECF volume is linked to the regulation of what?
Body sodium levels
What effect does more sodium in a compartment have on the amount of water in the compartment?
The more sodium, the more water which is retained
RECAP FROM FOM- lol x
How many litres of water in TBW?
42L
->TBW makes up approx. 60% of body
RECAP FROM FOM- lol x
How many litres of water in ECF?
14L
RECAP FROM FOM- lol x
How many litres of water in ICF?
28L
RECAP- what are the components of ECF?
Plasma and interstitial fluid
->11L for interstitial fluid and 3L for plasma
Hypovolaemia?
A condition that occurs when your body loses fluid, like water or blood
Give some times in which hypovolaemia occurs.
Vomiting, diarrhoea, excess sweating
What happens to salt and water levels in hypovolaemia?
Decrease
What is the renal response to hypovolaemia?
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
RECAP- what effect does more ADH have on urine quantity and concentration?
Less urine but higher concentration
What effect does increased sympathetic discharge have?
Increased vasoconstriction, total peripheral resistance and blood pressure increases towards normal too
What effect does the increased sympathetic vasoconstriction, TPR and BP have on the kidneys?
Increased renal arterial constriction
Release of renin
What is renin?
Regulatory hormone of the kidney
What does renin stimulate the release of?
Angiotensin II
What does angiotensin II increase the reabsorption of in the proximal tubule?
NaCl and water
What does angiotensin II stimulate the release of?
Aldosterone
What effect does aldosterone have?
Increases NaCl and water reabsorption in the distal tubule
Okay to summarise this wee bit-
Which hormone increases reabsorption of NaCl and water in:
a. the proximal tubule
b. the distal tubule
a. Angiotensin II
b. Aldosterone
What are the changes seen in the kidney as a result of the increased sympathetic discharge?
-Increased renal nerve activity -> increased renal arteriolar constriction
-Increased renin
If there is increased renin, what will there also be an increase in?
Angiotensin II
-> and then in turn, increased angiotensin II increases the release of aldosterone
Is angiotensin II a vasodilator or vasoconstrictor?
Strong vasoconstrictor
RECAP- what type of hormone is aldosterone?
Steroid hormone
Smooth muscle of the afferent arteriole is specialised. It contains many cells with plentiful granules. What are these cells called?
Juxtaglomerular cells
What two components make up the Juxtaglomerular apparatus?
Juxtaglomerular cells
Macula densa
->macula densa is a specialised loop of the distal tubule
What hormone do Juxtaglomerular cells produce?
Renin
->remember, renin is a renal hormone, these cells are to do w renal system whilst others are more linked to brain etc.
What do the Juxtaglomerular cell detect?
Changes in blood pressure as they don’t stretch as much in low BP
What is produced by Juxtaglomerular cells when there is low BP?
Renin
Renin is used to convert angiotensinogen into what?
Angiotensin I
Which enzyme converts angiotensin I into angiotensin II?
ACE- angiotensin converting enzyme
What is really the only function of angiotensin I?
To be converted into angiotensin II
What effect does angiotensin II have on arterioles?
Constricts them
->remember, angiotensin II is a strong vasoconstrictor
What effect does angiotensin II have on the hypothalamus?
Increased vasopressin/ADH release
Increased thirst
What effect does angiotensin II have on the adrenal cortex?
Increase aldosterone release
So, the amount of angiotensin II depends on what?
The amount of renin in the plasma
Angiotensin II stimulates the aldosterone-secreting cells. Where are these cells found?
Zona glomerulosa of the adrenal cortex
What are some of the things which can control release of renin?
- Decreased pressure of afferent arteriole at level of JG cells
- Increased sympathetic nerve activity
Via which type of receptors can increased sympathetic nerve activity cause release of renin?
Via beta-1 receptors
How does angiotensin II increase water reabsorption from the collecting duct?
Acts on the hypothalamus to stimulate ADH secretion which increases water reabsorption
In hypovolaemia, what does the body prioritise- osmolarity or volume?
Replenishes volume first before fixing osmolality
Simple rule- if salt and water is lost…
Salt and water has to be replaced
Which hormones promotes the excretion of sodium, therefore counteracting the sodium reabsorption?
ANP- atrial natriuretic peptide
What would happen if aldosterone was given to an individual with adequate sodium from diet?
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
What is the effects of aldosterone at the distal tubule?
Increases sodium reabsorption
Increases potassium secretion
Does aldosterone override ANP or does NAP override aldosterone?
ANP overrides aldosterone
RECAP- hyperaldosteronism is a cause of which condition?
Conn’s syndrome
RECAP- what causes hyperaldosteronism?
Tumour of the adrenal cortex
Which cells secrete ANP and when do they do this?
Atrial cells in response to expansion of ECF volume
What effect does ANP have on the hypothalamus?
Less ADH
What effect does ANP have on the kidney?
Increased GFR
Decreased renin
What effect does ANP have on the adrenal cortex?
Less aldosterone
What effect does ANP have on the medulla oblongata?
Decreased blood pressure
In uncontrolled diabetes mellitus, what is the rate of reabsorption in the renal tubule like?
Reduced compared to normal
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
Sorry x
In the ascending loop of Henle, there is a transporter which co-transports three ions- which three?
Sodium, chloride and potassium
Is the co-transportation of sodium, chloride and potassium active or passive?
Passive
-> energy is provided by the sodium-potassium pump
