Terms you need to know about central control of blood pressure

 

Renin-angiotensin-aldosterone pathway or RAA pathway

The pathway outlined below, which begins with the kidneys detecting low blood flow and ends with aldosterone’s causing the kidneys to reabsorb Na+ and water into the blood and bring blood volume back up to normal.

Renin

The compound secreted by the kidneys when they don’t get enough blood

Angiotensinogen

Means ‘angiotensin maker’ – a compound already in the bloodstream, which reacts with renin to form angiotensin I

Angiotensin I

Means ‘blood vessel tightener’. A weak vasoconstrictor.

Angiotensin converting enzyme or ACE

An enzyme found in the lungs. Converts angiotensin I to angiotensin II. This enzyme is targeted by some anti-hypertensive drugs, the ACE inhibitors

Angiotensin II

A stronger vasoconstrictor. It also stimulates the production of Aldosterone

Adrenal cortex

The outer layer of the adrenal gland

Aldosterone

A hormone produced by the adrenal cortex when it detects angiotensin II in the blood. This hormone causes the kidneys to turn on their Na+/K+ ATPase, and they then pump 3 Na+ from the urine into the blood and 2K+ from the blood into the urine. Water follows the majority of ions, so water also enters the blood, raising the blood volume.

 

 

Vasomotor center

A group of neurons in the medulla oblongata that causes blood vessels to constrict or dilate in order to keep blood pressure stable

Antidiuretic hormone or ADH

Means ‘against urination.’ A hormone secreted when blood pressure is low. It causes the kidneys to reabsorb water into the blood, increasing blood volume. This reduces the production of urine.

baroreceptors

Cells in  the carotids and aorta which measure stretch in the vessel walls to tell how high the blood pressure is.

Atrial natriuretic hormone (or factor or peptide)

Secreted by the atria when they are over-stretched. It causes the person to lose Na+ and water in the urine, reducing blood volume

B-type natriuretic hormone (or factor or peptide)

Secreted by the ventricles when they are over-stretched. It causes the person to lose Na+ and water in the urine, reducing blood volume