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Regulation of Blood Pressure and Pulse

To regulate systemic blood pressure, two mechanisms are needed: intrinsic mechanisms and nervous mechanisms.
Regulation of blood pressure
To regulate systemic blood pressure, two mechanisms are needed: intrinsic mechanisms and nervous mechanisms. In the nervous mechanisms, the nervous system is involved, while in the intrinsic mechanisms, nerve impulses are not required.

Intrinsic mechanism
"Intrinsic," as the term implies, is what happens within certain organs. As the first of these organs, the heart plays a vital role in our bodies. Increased venous return stretches cardiac muscle fibers, resulting in increased pumping force (Starling's law). The heart's output and blood pressure rise. This is what happens when exercising when high blood pressure is necessary. When you stop exercising, venous return reduces, which makes the heart pump less forcefully, helping to lower blood pressure back to normal.

An intrinsic mechanism involving the kidneys is the second. The kidneys' blood flow decreases, thus decreasing filtration and resulting in less urine being formed. As a result of this decrease in urine production, blood volume does not decline further. When a person suffers a severe hemorrhage or other forms of dehydration, rehydration is vital to maintaining blood pressure. Renin-angiotensin affects kidney function as well. The kidneys produce renin when the blood pressure falls, which triggers a series of reactions that lead to the production of angiotensin II. It also causes the adrenal glands to produce aldosterone through blood vessel constriction.

Nervous mechanism
As well as its role in optimizing blood pressure, the autonomic nervous system and medulla are also crucial. A nervous system that deals with the heart are the first. Another mechanism of nervous control involves peripheral resistance, i.e., the tightened vessels, arterioles, and veins. There are two vessels in the medulla, one of them a vasoconstrictor, the other a vasodilator. The vasodilator area may cause vasodilation by lowering the vasoconstrictor area, thereby lowering blood pressure. The Vasoconstrictor area of the autonomic nervous system may cause more vasoconstrictions through sympathetic division.

Several impulses per second travel along sympathetic vasoconstrictor fibers to maintain normal vasoconstriction in the smooth muscle of all arteries and veins. There is a correlation between higher impulse rates and greater vasoconstriction, as well as a correlation between lower impulse rates and greater vasodilation. Various press receptors in the carotid sinuses and aortic sinuses provide the medulla with the information it needs to make the changes. Blood pressure cannot be maintained normally in cases of circulatory shock.

Regulation of pulse rate
Pulse rate is also known as heart rate. Despite generating and maintaining its beat, the heart's rate of contraction can be changed in response to its surroundings. Changes in heart rate and contraction force can and do occur due to the nervous system. Two cardiac centers are located in the medulla, the accelerator center, and the inhibitory center. These centers are responsible for sending heart impulses along autonomic nerves. Parasympathetic and sympathetic nerves are grouped. During exercise and stressful situations, sympathetic nerves along the accelerator center stimulate the heart and increase contraction force.

The heart rate is reduced by parasympathetic nerve impulses from the inhibitory center. As a result, during a period of rest, the SA node depolarizes slowly, and finally, they also slow the heart after it has finished exercising. Since the heart pumps blood, maintaining normal blood pressure is crucial. Throughout the body, oxygen is continuously delivered to all tissues via the blood. Hence, changes in blood pressure and oxygen levels are factors that affect heart rate. Aortic arch and carotid artery receptors, respectively, respond to pressure and chemoreceptors.

Blood pressure changes in the carotid sinuses and aortic sinuses can cause their symptoms. The aortic and carotid bodies have chemoreceptors capable of sensing changes in blood oxygen levels. It is the glossopharyngeal nerve (9th cranial) that has carotid receptors; for the arch of the aorta, it is the vagus nerve (10th cranial). Getting up from lying down suddenly can cause someone to feel dizzy or light-headed for a few moments, as the blood flow to the brain has been lowered abruptly. Press receptors in the carotid sinuses detect a drop in blood pressure; note that they are headed to the brain, which is a very strategic location.

Press receptors produce fewer impulses when blood pressure drops. The frequency of these impulses decreases when they travel to the medulla, stimulating the accelerator center as they travel along the glossopharyngeal nerve. Through sympathetic nerves, impulses generated at the accelerator center travel to the SA node, the AV node, and the ventricular myocardium. With increasing heart rate and force, blood pressure is elevated to normal levels, and the light-headed feeling subsides. In addition to receiving parasympathetic impulses from the inhibitory center, the SA node and the AV node also receive signals through the vagus nerves when blood pressure is restored to the brain.

As a result of these parasympathetic impulses, the heart rate slows to a resting rate. In addition, the heart also acts as a reflex effector in response to a drop in oxygen in the blood. These receptors are strategically positioned at the aortic end of the heart so that they can detect a change in the blood flow as soon as it leaves. A reflex arc would look like either Aortic chemoreceptors or Vagus nerves (sensory). It could also look like an accelerator centre in the medulla, sympathetic nerves, and

Circulate more oxygen, the heart muscles will contract more forcefully.

When stressful circumstances arise, the adrenal medulla secretes the hormone epinephrine. Epinephrine can increase contraction force and heart rate among its many functions. Increasing the supply of blood will help oxygenate tissues more effectively.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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