Human Growth Hormone

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Secondary Endocrine Function Of The Heart

An informative article on: Secondary Endocrine Function Of The Heart.

The heart is a vital organ of the human body. If the heart malfunctions, blood will stop circulating and the person will not be able to breathe. This is general knowledge, but what they fail to realize is that the heart is actually a secondary endocrine gland, just like the kidney and the liver. It releases natriuretic peptides (NPs), which work by lowering blood pressure in the body. This article will provide information regarding the secondary endocrine function of the heart, its mechanism of action, and its uses as treatment options.

Secondary Endocrine Function of the Heart

As mentioned, the hormones released by the heart are natriuretic peptides. There are two types: A-type and B-type. The A-type, also called ANP (atrial natriuretic peptide), is a peptide with 28 amino acids released from the heartís atria. The B-type, also called BNP (brain natriuretic peptide), is a peptide with 32 amino acids released from the ventricles. The ANP and the BNP work by relaxing the arterioles, preventing the reabsorption of sodium, and preventing the secretion of aldosterone and renin. In addition, these hormones have also been found to play a role in growth regulation, with beneficial effects on cardiovascular growth. With increased levels of ANP and BNP, there is reduced risk of heart failure.

Mechanism of Action

To understand the secondary endocrine function of the heart, it is necessary to find out about the physiological effects of these natriuretic peptides. The ANP binds to ANP receptors, which in turn, causes a decrease in blood volume level. When blood volume is low, systemic blood pressure also goes down. On the other hand, the BNP binds to the ANP receptors, NPRA and NPRB, causing a reduction of systemic vascular resistance and blood pressure. When both of these hormones function normally, the overall effect would be a decrease in cardiac output and lowered blood volume.

Cardiovascular and Renal Functions

The secondary endocrine function of the heart has a great deal of significance to the cardiovascular and renal systems. Because these natriuretic peptides help in the regulation of sodium, blood volume, water balance, and arterial pressure, they are largely responsible for the vasodilator and renal effects. For the cardiovascular aspect, these hormones or peptides dilate the veins and arteries. For the renal aspect, these peptides promote natriuresis and diuresis. They increase glomerular filtration rate causing natriuresis, a condition wherein there is increased excretion of sodium; and they also cause diuresis, a condition wherein there is increased excretion of fluids.

Natriuretic Peptides Used as Treatment

Medical scienceís understanding of the value of the secondary endocrine function of the heart has paved the way for the creation of recombinant human natriuretic peptides in an effort to help treat various problems associated with the renin-angiotensin-aldosterone system. An example of such treatment is the nesiritide, which could help treat congestive heart failure (CHF). There are also drugs created primarily to inhibit neutral endopeptidase, which is responsible for ANP degradation. With these peptides inhibited, plasma levels of ANP and BNP can go back to normal again, thereby preventing heart failure.