Physiology - Control of Arterial Blood Pressure Part 2 Flashcards
What makes up ECF volume?
Plasma volume and interstitial fluid volume. Slide 3
What are the two main factors that affect extracellular fluid volume?
Water excess/deficit
Na excess/deficit
Slide 5
What are the hormones that help regulate extracellular fluid volume?
RAAS
Natriuretic peptides
ADH. Slide 7
How does the RAAS system work?
Renin stimulates the production of angiotensin I from angiotensinogen. Angiotensin I is converted into Angiotensin II whcih stimulates the release of aldosterone from the adrenal cortex. Slide 8
What does aldosterone do?
Systemic vasoconstriction which increases SVR.
Also stimulates thirst and ADH release.
It increases the Na and H2O retension whcih increases plasma volume. Slide 8
What is the rate limiting step in RAAS?
The renin secretion. Slide 10
Where is renin released from and how can the release be stimulated?
Released from the juxtaglomerular apparatus.
It can be stimulated by:
Renal artery hypotention cause by a drop in blood pressure
Stimulation of renal sympathetic nerves
Decreased Na in renal fluid. Slide 10
What are natriuretic peptides and when are they released?
Peptide hormones synthesised by the heart. They are released in response to cardiac distension or neurohormonal stimuli. Slide 11
What do natriuretic peptides do?
They are the counter-regulatory system for RAAS.
Cause excretion of salt and water, decrease renin release, cause vasodilation.
What are the main 2 types of natriureetic peptides and where are they mainly released?
Released from the heart
Atrial natriuretic peptide (ANP) and brain type natiuretic peptide (BNP). Slide 12
How lon gis ANP and BNP?
ANP - 28 amino acids
BNP - 32 amino acids. Slide 12
How is ADH stimulated?
When there is reduced extracellular fluid volume, increased extracellular fluid osmolarity or increased plasma osmolarity. Slide 14
What does ADH do?
Increases water reabsorption in the kidneys
Causes vasoconstriction. Slide 15
