Page 15 - G43 ASSIGNMENT

Changes in volume largely influence the baroreceptors in the venous system. Decreased frequency in action
potentials in low-pressure scenarios leads to the secretion of antidiuretic hormone, renin, and aldosterone.

These lead to a downstream effect to regulate arterial pressure.

Antidiuretic Hormone

Antidiuretic hormone (ADH), also known as vasopressin, is a hormone synthesized in the magnocellular
neurosecretory cells within the paraventricular nucleus and supraoptic nucleus of the hypothalamus. ADH is
synthesized and released in response to multiple triggers which are:

High serum osmolarity, which acts on osmoreceptors in the hypothalamus

Low blood volume causes a decreased stretch in the low-pressure baroreceptors, leading to the production of
ADH

Decreased blood pressure causes decreased stretch in the high-pressure baroreceptors, also leading to the
production of ADH

Angiotensin II
The antidiuretic hormone produced in the hypothalamus makes its way down the pituitary stalk to the posterior
pituitary where it is kept in reserve for release in response to the above-listed triggers.

ADH mainly functions to increase free water reabsorption in the collecting duct of the nephrons within the
kidney, causing an increase in plasma volume and arterial pressure.

ADH in high concentrations has also been shown to cause moderate vasoconstriction, increasing peripheral
resistance, and arterial pressure.[7][8]

Clinical Significance:

The role of arterial pressure regulation is to maintain a high enough pressure that allows for proper perfusion of
body tissue and organs; but not so high as to cause bodily harm.

When the body enters a state of acute hypotension, the baroreflex function attempts to return arterial pressure to
its stable state to allow continuous perfusion.

[9] The body may enter a state of chronic hypertension, but most often there is not an identifiable cause but
rather a consequence of the interaction between multiple risk factors.

The term for this condition is essential hypertension. It represents approximately 95% of patients with
hypertension.

[10][11] Treating hypertension is critical because it can result in cerebral, cardiac, and renal complications.

First line medications to treat essential hypertension include calcium channel blockers, ACE inhibitors,
angiotensin receptor blockers, and thiazide diuretics.

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