ADRENAL GLANDS

INTRODUCTION: The two adrenal glands are located one on top of each kidney, which gives them their other name of suprarenal glands. Each adrenal gland consists of two parts: an inner adrenal medulla and an outer adrenal cortex. The hormones produced by each part have very different functions.

ADRENAL MEDULLA: The cells of the adrenal medulla secrete epinephrine and norepinephrine, which collectively are called catecholamines and are sympathomimetic. The section of both hormones is stimulated by sympathetic impulses from the hypothalamus, and their functions duplicate and prolong those of the sympathetic division of the autonomic nervous system.

EPINEPHRINE AND NOREPINEPHRINE: Epinephrine also known as Adrenalin and norepinephrine also known as noradrenalin, are both secreted in stress situations and help prepare the body for the so called fight or flight response. Norepinephrine is secreted in small amounts, and its most significant function is to cause vasoconstriction in the skin, viscera, and skeletal muscles throughout the body, which raises blood pressure.

The other counterpart epinephrine, secreted in larger amounts, increases the heart rate and force of contraction and stimulates vasoconstriction in skin and viscera and vasodilation in skeletal muscles. It also dilates the bronchioles, decreases peristalsis, stimulates the liver to change glycogen to glucose, increases the use of fats for energy, and increases the rate of cell respiration. Epinephrine in this sense, is more effective than sympathetic stimulation, however, because the hormone increases energy production and cardiac output to a greater extent.

ADRENAL CORTEX: The adrenal cortex secretes three types of steroid hormones;

1. Mineralocorticoids,

2. Glucocorticoids, and

3. Sex hormones.

The sex hormones which for females are the estrogens and for the males are the androgens baring some similarity to testosterone, are produced in very small amounts contribute to rapid body growth during early puberty. They may also be important in supplying estrogen to women after menopause and to men throughout life and are discussed in our previous discussions as in the links below.

RELATED;

1.  EPINEPHRINE

2.  THE NEUROTRANSMITTER SYSTEMS

3.  DOPAMINE

4.  THE ENDOCRINE PANCREAS

5.  ADRENERGIC BLOCKING DRUGS

REFERENCES