6: Control of arterial blood pressure (2) Flashcards
(42 cards)
Long-term control of blood volume and MAP is achieved by controlling…
extracellular fluid volume
What two volumes make up the extracellular fluid volume (ECF)?
ECF = Plasma Volume (PV) + Interstitial Fluid Volume (IFV)
Interstitial fluid bathes ___.
cells
If plasma volume falls, compensatory mechanisms shift ___ ___ back to the plasma compartment.
interstitial fluid
Which two factors affect extracellular fluid volume?
- Water excess or deficit
2. Na+ excess or deficit
Extrinsic control of MAP is carried out by…
the nervous system and hormones.
How do hormones regulate the extracellular fluid volume?
They regulate the water and salt balance in our bodies
Which three hormone systems regulate extracellular fluid volume?
- Renin-Angiotensin-Aldosterone System (RASS)
- Atrial Natriuretic Peptide (ANP)
- Antidiuretic Hormone (Vasopressin) or ADH
What two constituents of MAP does the RAAS system regulate?
Plasma volume
Total peripheral resistance
Where is renin released?
The kidneys
What molecule does renin act on to produce angiotensin I?
Angiotensinogen
Where is angiotensinogen produced?
The liver
Renin stimulates the formation of ___ _ from angiotensinogen.
Angiotensin I
Which enzyme converts angiotensin I to angiotensin II?
Angiotensin converting enzyme (ACE)
Where is ACE produced?
Pulmonary vascular endothelium
ACE converts angiotensin I into ____ _.
Angiotensin II
What stimulates the release of aldosterone from the adrenal cortex?
Angiotensin II
What is released from the adrenal cortex when the cortex is stimulated by angiotensin II?
Aldosterone
Where is aldosterone released after stimulation by angiotensin II?
Adrenal cortex
Angiotensin II stimulates the release of aldosterone from the adrenal cortex.
Name another effect it has.
Causes vasoconstriction, increasing TPR and therefore MAP
Increases thirst and ADH release, increasing plasma volume and therefore MAP
Where does aldosterone act?
The kidneys
What is the effect of aldosterone once it has stimulated the kidneys?
Increases Na+ and water retention, increasing plasma volume –> increases MAP
What is the rate limiting step for the RAAS system?
Renin secretion (from the juxtaglomerular apparatus) from the kidney
Name three conditions which stimulate renin secretion from the kidneys.
1) Renal artery hypotension (decreased blood pressure)
2) Stimulation of renal sympathetic nerves
3) Decreased [Na+] in renal tubular fluid
