How to Learn and Understand the Physiological Function of the Endocrine System in Humans

Step-by-Step Guide

1. 1

   Step 1: The endocrine system of humans is composed of several glands that have communications with a master endocrine gland which is called the pituitary gland.

   This gland is part of the brain and is located at the bottom aspect of the brain below the hypothalamus.
   
   The communication between the master gland and the other endocrine glands that are spread along the body organs is done via special mechanisms that are called feedback mechanisms.
2. 2

   Step 2: These mechanisms are mostly autonomic in nature and are controlled by loops between the pituitary gland and the other endocrine glands.

   The endocrine glands secrete special types of organic molecules that are called hormones.
   
   These molecules are the mediators of communication between the pituitary gland and the other endocrine glands.
   
   The feedback mechanism depends on the concentration of the individual hormone in the blood. , The amount of secreted hormone by the pituitary gland will dictate the amount of hormone that is secreted by the target endocrine gland.
   
   For example, the hormone thyroid stimulating hormone (TSH) is secreted by the pituitary gland and it functions to stimulate the secretion of the thyroid hormone by the thyroid gland. , After the concentration of the thyroid hormone is high enough the feedback loop starts to work.
   
   In this case the excess amount of the TH in the blood exerts a negative feedback signaling the pituitary gland to decrease its secretion of the TSH.
   
   This in turn decreases the amount of the TSH that is secreted by the pituitary gland.
   
   This mechanism ensures that the body maintains a state of equilibrium and homeostasis. , The feedback mechanism that applies to all hormones of the glands in the body has two exceptions to this rule.
   
   One is the hormone aldosterone and the other is the hormone vasopressin.
   
   The secretion of these two hormones to the blood circulation is regulated by different mechanism than the normal feedback mechanism typical of the other endocrine glands in the body. , This is so due to the unique function of these two hormones in the body.
   
   Both of these hormones have an effect on the blood volume and in particular they have direct effect on the amount of water in the body. , The reverse is observed when there is a state of hypovolemia or low blood volume in the arteries.
   
   The hormone aldosterone is usually secreted by the adrenal cortex in response to decreased blood volume or in the case of hyponatremia. , The same effect is observed with the secretion of the hormone vasopressin.
   
   This hormone is usually secreted by the pituitary gland from its posterior part. , The secretion of hormones by the pituitary gland is its self regulated by the hypothalamus. ,
3. 3

   Step 3: The secretion of hormones by the various endocrine glands is controlled by the secretion of regulatory hormones that are secreted by the master gland

4. 4

   Step 4: the pituitary gland.

5. 5

   Step 5: High level of the TSH hormone will initially cause an increase in the secretion of the thyroid hormone (TH).

6. 6

   Step 6: All the endocrine glands that are spread in the body are under the direct control and regulation by hormones of the pituitary gland.

7. 7

   Step 7: Both of these hormones are regulated by the degree of osmolality of the blood plasma and by the status of blood volume in the arteries.

8. 8

   Step 8: Usually high blood volume signals the decrease of secretion of both of these hormones to the blood circulation.

9. 9

   Step 9: The secretion of this hormone usually signals the kidney to conserve water to the blood.

10. 10

    Step 10: This hormone is regulated by the level of water or blood in the arteries and by the degree of osmolality of the blood.

11. 11

    Step 11: This structure of the brain controls the hormonal secretions by the pituitary gland through the release to the blood of releasing hormones that control by a mechanism of positive feedback the secretion of the hormones by the pituitary gland.

Detailed Guide

About the Author