Renin Angiotensin System

The renin-angiotensin system (RAS) is a collection of hormones that work together to manage inflammation and regulate blood pressure. It’s called a system because each component has an impact on the others, and all are required for the whole to function properly.

The renin-angiotensin system, which works in conjunction with the kidneys to control blood pressure, is a critical component of the body’s blood pressure management system. The conventional renin-angiotensin-aldosterone system (RAAS) pathway is used to do this.

Renin Angiotensin System

Inappropriate activation of the classical route can also have negative consequences, such as hypertension (high blood pressure for an extended period) and the development of vascular disease. However, the renin-angiotensin system’s alternative renin-angiotensin pathway supports protective, anti-inflammatory responses.

The classical and alternative RAS pathways work together to create reactions that are antagonistic to one another yet balance out their effects.

Working on Classical RAS Pathway

• Renin
• Angiotensin I
• Angiotensin II
• Angiotensin-converting enzyme 1
• Aldosterone

Renin

When blood pressure falls for any reason, specific kidney cells sense the change and release renin into the bloodstream. Renin does not affect blood pressure on its own.

It floats around instead, converting angiotensinogen to angiotensin I. Angiotensinogen is a substance produced mostly by the liver that circulates throughout the body. As a precursor molecule, it is unable to change blood pressure. It must be converted into angiotensin’s active form.

Angiotensin I

Angiotensin I has a negligible effect on blood pressure. Instead, the majority of angiotensin I am converted to angiotensin II, a far more powerful hormone that can cause significant blood pressure increases.

Angiotensin-converting enzyme 1

This second conversion, which results in angiotensin II, occurs primarily in the lungs and is mediated by an angiotensin-converting enzyme. Angiotensin-converting enzyme 1 is the full name of this enzyme (ACE1). Drugs known as ACE Inhibitors, a common type of high blood pressure medication, can prevent this change.

Angiotensin II

Angiotensin II is a potent hormone that can operate directly on blood arteries, narrowing or constricting them and raising blood pressure. It also stimulates the release of aldosterone, which is an important function.

Aldosterone

Aldosterone is a hormone that causes the kidneys to retain both salt and water, causing the body to retain more fluid over time. Blood pressure rises as a result of this rise.

Other Effects of the RAA Pathway

Angiotensin II can connect to receptors in several parts of the body in addition to blood vessels. It helps to elevate blood pressure by sending information to the brain and kidneys.

Neural Effects

Angiotensin II helps to raise blood pressure by stimulating the “thirst centre” in the brain. This thirst centre is found in the hypothalamus, a portion of the brain. When the thirst centre receives a signal from angiotensin II that the blood pressure is too low, it produces a thirst sensation. Drinking water elevates blood pressure by increasing the fluid content in the body.

Angiotensin II also helps to raise blood pressure by stimulating the body’s “fight-or-flight response”. This response stimulates the heart to beat faster and more forcefully to increase the circulating volume and blood pressure. It is generally triggered under stressful conditions.

Renal Effect

The brain does not simply send thirst signals in reaction to low blood pressure. Angiotensin II also instructs the hypothalamus to boost the synthesis of an antidiuretic hormone-related protein. The kidneys are told to reabsorb water from the urine by this hormone, which travels from the brain to the kidneys.

Angiotensin II also works directly on the kidneys to assist raise blood pressure and blood flow by instructing them to:

• To assist raise blood pressure, it constricts its small blood arteries.
• Increase sodium retention and hydration.
• Control the rate at which the kidneys filter fluid.

Conclusion

In cardiovascular illnesses such as hypertension, heart failure, and renal disease, the RAA System is well-known. Several drugs that block the classical RAA pathway have been created, and they have proven to be useful in slowing the progression of vascular disorders.

The RAA inhibitors also have an indirect effect on the COVID-19 infectious illness process and the alternative RAA pathway. It’s crucial to discuss the dangers and advantages of RAA inhibitor medication with your doctor.