Page 18 - G43 ASSIGNMENT

Catecholamine’s hormone:

Catecholamine’s (CAs) play a central role in the regulation of blood pressure. Sympathetic adrenal effects are
ultimately elicited by the neurotransmitter norepinephrine and the hormone epinephrine. Their release is under

the control of higher centers and is finely modulated by several factors such as presynaptic receptors. Recent
evidences suggest that also the peripheral dopaminergic system can participate in blood pressure regulation

intervening in the blood flow regulation of some regions, and in sodium-water balance. The measurement of CAs

in biological fluids has greatly enhanced our knowledge on the mechanisms regulating blood pressure and is
widely applied in cardiovascular research. Clinical applications of CA measurement are still limited to the

diagnosis of pheochromocytoma and to the differential diagnosis of hypotensive syndromes. [3]

Renin-angiotensin system:

Renin comes from specialized cells that surround the arterioles at the entrance to the glomeruli of the kidneys.
Changes in blood flow and blood pressure are sensitive to the renin-secreting cells.

A decrease in blood flow to the kidneys may be the cause of increased renin secretion. A decapeptide called
angiotensin I is created when Renin converts the angiotensinogen into a decapeptide. Angiotensin I is converted
into angiotensin II by the ACE in the serum. Angiotensin II stimulates the production of aldosterone, which
stimulates salt and water reabsorption by the kidneys, and the constriction of small arteries, which causes an
increase in blood pressure. Angiotensin II works by blocking the reuptake into nerve terminals of the hormone
norepinephrine.

excessive constriction of the small arteries is the cause of high blood pressure. Drugs that block the binding of
angiotensin II can be used. [4]
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