There is a pair of adrenal glands located on the top of kidneys like a crown/cap. One kidney has one adrenal gland. A section of the gland show that it has 2 parts.
L Adrenal Cortex: The outer portion of the adrenal gland is called adrenal cortex.
It can be divided into three layers:
- Zona glomerulosa: the outermost layer.
- Zona fasciculata: the middle layer.
- Zona recticularis: the inner most layer.
The cortex secrets many hormones which are collectively called corticoids.
(a) The corticoids involved in the carbohydrate metabolsim are called glucocorticoids. The main one in called cortisol.
(b) The corticoids responsible/regulate the electrolytes and water balance in the body are called mineralocorticoids. The main one is aldosterone.
Functions of glucocorticoids:
1. They stimulate - gluconeogenesis, lipolysis and proteolysis and inhibit the cellular uptake and utilization of amino acids.
2. Cortisol the main glucocorticoid is involved in maintaining cardiovascular system, kidney functions, anti - inflammatory reactions, supression of the immune response, stimulation of RBC production (erythropoiesis). Under production/ secretion/hyper condition of the adrenal cortex changes the carbohydrate metabolism resulting in acute weakness and fatigue. This disease/ condition is called Addison’s disease.
Functions of Mineralocorticolds:
1. Aldosterone is the main mineral corticoid that acts on renal tubules of kidneys and stimulates the reabsorption of Na and water and excretion of K and phosphate (PO4 )- ions.
2. Helps in maintenance of electrolytes, blood fluid volume, osmotic pressure and blood pressure. Secretion of small amounts of androgenic steroids are also, secreted by adrenal cortex. They help in growth of axial hair, pubic hair and facial hair during puberty.
2. Adrenal Medulla: It is the centrally located portion of the gland that produces two hormones.
- Adrenaline/epinephrine.
- Noradrenaline/nor epinephrine.
Collectively these hormones are called catecholamines. These hormones are rapidly secreted in response to emergency situation and hence also termed as emergency hormones or hormones of fight or flight. i.e., in such situations either you fight / face the situation and overcome it or ffight/escape from it.
- Increase alterness, pupil dilation, piloerection (raising of hair) and sweating etc.
- Increase in heart beats, strength of heart contraction (for pumping move blood) and rate of respiration.
- Stimulation of breakdown of glycogen: glycolysis, hyperglycemia: high concentration of glucose in blood (for more production of energy), Lipolysis (break - down of lipids), protolysis (break down of proteins).
Disorder and Diseases due to Hypersecretton of Adrenal Glands:
- Addison’s disease
- Hypoglycemia
- Conn’s disease.
Hyposecretion of Adrenal Gland:
- Cushing’s syndrome
- Aldosteronism
- Adrenal Virilism: Female develops male like characters, sterlity in females, sexual imaturity in male.
