Anatomy And Physiology

Anatomy Physiology

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In this article, I will discuss briefly the effect of human growth hormone on the metabolism of biomolecules inside the body, namely, proteins, carbohydrates and lipids.  I mentioned the word human because each creature has different growth hormone in structure and function.   In humans, deficiency of this hormone cannot be compensated by growth hormone obtained from animals.

Growth hormone is one of several hormones that are secreted by the pituitary gland in its anterior part.  The feature that distinguishes growth hormone from other hormones is its being universal in its function.  Namely, the other pituitary hormones usually have a specific target organ that they function at.

For example, thyroid stimulating hormone which is also secreted by the anterior pituitary gland targets the thyroid gland specifically.  On the other hand, the growth hormone has no specific organ to act upon.  Its function is universal that is directed at all tissues and cells of the body. 

The other hormone in the body and which has similar effects to this hormone is the hormone which is secreted by the thyroid gland, called thyroid hormone.  This hormone has similar universal function on body tissues similar to that of growth hormone. 

Growth hormone is a polypeptide hormone that is secreted by the pituitary gland in response to a stimulation by a releasing hormone and which is secreted by the hypothalamus.  This hormone is called: growth hormone releasing hormone.  Growth hormone is unique in some respect  as it is also under the negative feedback from an inhibitory hormone which is called somatostatin and which is secreted by the hypothalamus.

Next, I will discuss the effect of growth hormone on proteins and carbohydrates and fatty acids metabolism.  In addition to its general effect on increasing cellular metabolism, it also increases the rate of proteins formation.  In addition, there is an increase in energy production using fatty acids.

Its effect on carbohydrates is that it decreases uptake of glucose by cells.  All these effects will be discussed sequentially.  Growth hormone has a function that is related to stimulation of the uptake of amino acids by cells.  This process facilitates the increase in number of amino acids in the cell, which will ultimately synthesize proteins by translation of these amino acids on the ribosome. 

The effect of growth hormone on transporting amino acids into the cells for protein synthesis has similarity to the process in which insulin transports glucose to the cells.  In addition to this function, growth hormone stimulates the protein synthesis by increasing the rate of translation of amino acids.   Also there is a decrease in protein degradation which is stimulated by the growth hormone.

As far as fats are concerned so growth hormone increases the mobilization of fatty acids from adipose tissue and increases the energy production rate from fatty acids.  It stimulates the conversion of fatty acids to acetyl-coA.  Due to the effect of fats conversion to acetyl-coA by growth hormone excessive amount of ketoacids are produced in the body such as acetoacetic acid with subsequent development of ketoacidosis.

In addition, this process of fat mobilization from adipose tissue can often cause fatty liver.  Growth hormone effect on glucose is that of retention of glucose in the blood increasing its concentration with subsequent hyperglycemia.  As a result of this hyperglycemia insulin secretion is stimulated.  Excessive secretion and stimulation of insulin can trigger diabetes mellitus in affected individuals.

More about this author: Tarek Musslimani

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