Blood Pressure And The Kidneys Flashcards
What senses a change in the concentration of sodium in the ECF?
Atrial stretch receptors
Arterial baroreceptors
Afferent arteriole
NaCl delivery to DT
What does decreases in stretch receptors, baroreceptors and sodium chloride delivery to the distal tubule lead to?
Decreases in blood volume and increased sodium absorption
What is RAAS activated by?
Reduced renal perfusion or increased sympathetic activity
What are the two stimuli for aldosterone secretion?
RAAS and increased plasma [K+]
How does reduced renal perfusion lead to renin release?
Macula densa cells signal to the juxtaglomerular apparatus. Juxtaglomerular cells secrete renin
What does renin do?
Angiotensinogen -> angiotensin I
What catalyses angiotensin I-> angiotensin II?
ACE
What are the effects of angiotensin II?
Increased thirst
Aldosterone secretion
Vasoconstriction
Where is most sodium reabsorbed?
Proximal tubule
What mediates sodium absorption?
Aldosterone
What does sodium reabsorption do?
Increases plasma osmolarity
What system controls plasma osmolarity?
ADH by pure water reabsorption
What are the effects of aldosterone acting on the principal collecting duct tubules?
increasing sodium potassium ATPase and increased expression of ENaC channels
What does aldosterone acting on the principal collecting duct cells result in?
Increased sodium reabsorption and increased potassium secretion
What are the effects of aldosterone acting on intercalated cells of the collecting duct?
Increased hydrogen ATPase
What does increased hydrogen ATPase result in?
Increased hydrogen secretion and increased HCO3- reabsorption
What are the two defences against volume depletion?
RAAS and ADH
What are the parameters for hypertension?
Systolic > 140mmHg
Diastolic > 90mmHg
What is secondary hypertension?
When you know the cause
What is essential hypertension?
When you dont know what’s causing it
What is Liddles syndrome?
Rare, genetic gain of function mutation in epithelial sodium channels
What are the symptoms of liddles syndrome?
Increase in:
Renal sodium retention
ECFV
BP
Low aldosterone and renin
What is conns syndrome?
Primary hyperaldosteronism
What is the cause of conns syndrome?
Adenoma of the adrenal cortex
What are the symptoms of conns syndrome?
Increased:
Renal sodium retention
ECFV
BP
Decreased plasma [K+]
Low renin and aldosterone
What is a renal artery stenosis?
Abnormal narrowing of the blood vessel
What changes would you see in the non-stenotic kidney?
Reduced renin and RAAS but overall high renin and aldosterone
What changes will you see in the stenotic kidney?
Increased renin -> increased aldosterone and vasoconstriction -> sodium retention and high blood pressure
Why does renin increase in the stenotic kidney?
Drop in blood volume so more RAAS takes place
What is Addison’s disease?
Progressive failure of the adrenal cortex
What does Addison’s disease cause a lack of?
Cortisol and aldosterone
What happens in an adrenal crisis?
Hypotension, hypovolaemia, hypokalaemia, hyponatraemia
