Angiotensin II

Definition

Angiotensin II is a potent peptide hormone that plays a critical role in regulating blood pressure and fluid balance in the body. It is produced from angiotensin I through the action of angiotensin-converting enzyme (ACE) and is known for its ability to constrict blood vessels, increase sodium reabsorption in the kidneys, and stimulate the release of aldosterone from the adrenal glands. This hormone is central to the mechanisms of hypertension and atherosclerosis, as it contributes to vascular remodeling and increased vascular resistance.

5 Must Know Facts For Your Next Test

1. Angiotensin II is considered one of the most potent vasoconstrictors in the human body, leading to increased peripheral resistance.
2. The hormone not only raises blood pressure but also stimulates thirst, prompting increased fluid intake to further raise blood volume.
3. Angiotensin II can contribute to structural changes in blood vessels and the heart, leading to hypertrophy and increased stiffness.
4. Medications that inhibit ACE or block angiotensin II receptors are commonly used to treat hypertension and reduce cardiovascular risks.
5. In addition to its cardiovascular effects, angiotensin II also has roles in inflammation and can influence the development of atherosclerotic plaques.

Review Questions

• How does angiotensin II contribute to the regulation of blood pressure and fluid balance in the body?
  • Angiotensin II regulates blood pressure by causing vasoconstriction, which narrows blood vessels and increases vascular resistance. Additionally, it promotes sodium reabsorption in the kidneys, leading to higher blood volume. By stimulating aldosterone secretion, it further enhances water retention, creating a feedback loop that elevates overall blood pressure.
• Discuss the role of angiotensin II in the pathophysiology of hypertension and atherosclerosis.
  • Angiotensin II plays a pivotal role in hypertension by increasing systemic vascular resistance through vasoconstriction. In atherosclerosis, it contributes to endothelial dysfunction and promotes inflammation, which accelerates plaque formation within arteries. This combination leads to both high blood pressure and the progression of atherosclerotic disease, increasing cardiovascular risks.
• Evaluate how therapeutic interventions targeting angiotensin II can impact cardiovascular health outcomes.
  • Therapeutic interventions that target angiotensin II, such as ACE inhibitors and angiotensin receptor blockers (ARBs), significantly improve cardiovascular health outcomes by effectively lowering blood pressure. These medications reduce the harmful effects of angiotensin II on vascular remodeling and organ damage associated with chronic hypertension. By alleviating these effects, they decrease the incidence of heart attacks, strokes, and heart failure, contributing to better long-term health.

Related terms

Renin:

An enzyme secreted by the kidneys that initiates the renin-angiotensin-aldosterone system (RAAS) by converting angiotensinogen into angiotensin I.

Aldosterone: A steroid hormone produced by the adrenal glands that promotes sodium and water retention in the kidneys, thus increasing blood volume and blood pressure.

Vasoconstriction: The narrowing of blood vessels, which increases blood pressure and decreases blood flow to various tissues, often stimulated by hormones like angiotensin II.