long term control of blood pressure

Question 1

What does blood pressure depend on and by which organ is it controlled?

Answer 1

depends on plasma volume
controlled by the kidneys
High Plasma volume = high BP
low plasma volume = low BP

Question 2

control of what in the kidneys affects the plasma volume?

Answer 2

concentration of sodium
permeability of collecting duct- the more permeable- the more water adds to the plasma volume and less is lost in urine- this increases M.A.P.

Question 3

Renin-angiotensin-aldosterone system

Answer 3

Renin is released by the juxtaglomerular cells in response to a low M.A.P.
Response:
-converts angiotensin- precursor found in the blood- into angiotensin 1
-angiotensin 1 into angiotensin 2 by angiotensin converting enzyme

Question 4

what does angiotensin do?

Answer 4

• vasocontriction- increases TPR
• stimulates release of ADH: increases permeability of collecting tube which decreases diuresis, increases plasma volume
• releases aldosterone: stimulates reabsorption of Na+ into loop of Henley

Question 5

ADH system

Answer 5

released from pituitary. synthesised by hypothalamus in response to low MAP.
triggered by:
-angiotensin 2
-increased osmolarity of interstitial fluid detected by osmoreceptors in the hypothalamus
-decreased blood volume detected by cardiopulmonary baroreceptors
response:
-increases permeability of collecting duct to h20
-vasoconstriction

Question 6

atrial natriuretic peptide

Answer 6

produced by myocardial cells of atria in response to high MAP
triggers:
-distension of the atria
Response:
-increases excretion of Na +
-inhibits release of renin
-acts on cardiovascular centres

Question 7

When is renin produced

Answer 7

• decreased delivery of Na+ and Cl-
• distension of the afferent arterioles
• sympathetic nerves activated