Blood pressure and Kidneys

Hi, can anyone help me - I need to find out how a drop in blood pressure is detected and what mechanisms come into action?? Then I have to explain the role of the kidney in raising the blood pressure...can anyone help??

Thanks

Reply 1

ShinyApple

http://en.wikipedia.org/wiki/Blood_pressure

http://en.wikipedia.org/wiki/Kidney

A bit of reading will go a looooonnnng way.

Reply 2

iceman_jondoe

Form what im aware, a drop in blood pressure causes the activation of the renin-angiotensin system, i strongly recommend you read up on it. Briefly, it invovles the production of an enzyme renin, and hormones angiotensin 1 and 2, aswell as agiotensin converting enzyme (also known as ACE and also related to ACE inhibiting drugs)

Reply 3

digitalis

A fall in blood pressure translates into a lowered kidney glomerular filtration rate due to decreased renal perfusion causing a release of renin, causing angiotensin I to be converted to angiotensin II and the release of aldosterone. Angiotensin II causes vasoconstriction and aldosterone causes sodium and water retention.

I'm also thinking something like activation of the sympathetic nervous system causing arteriole vasoconstriction and stimulation of B1 and A1 receptors on the heart causing an increased cardiac muscle contraction, with consequent increase in stroke volume and cardiac output to maintain blood pressure.

Edit: Just looked up in a textbook, as well as a fall in GFR, baroreceptors (that measure say the "pressure" of arterial blood flow) in the carotid sinus and aortic arch (wiki these) are inhibited, hence "detecting" a fall in BP, activing the vasomotor centre in the brain leading to vasoconstriction and increase in cardiac output.