They are located at the side of the renal organ,i.e. Kidney. They are also called supra-renal glands.

 Origin

 The adrenal cortex originates from embryonic mesoderm. Adrenal medulla develops from embryonic neural ectoderm.

 Structure

 Right adrenal gland is roughly triangular while the left is semilunar in shape. Each gland has an outer cortex and inner medulla.Each gland is 5 cm long, 3 cm broad and 1 cm thick and weighs 7 to 10 grams. Adrenal cortex consists of three layers:- zona glomerulosa(outermost), zona fasciculata(middle), zona reticularis(innermost).

 Functions

 Adrenal cortex hormones are called adrenocorticoids. They are as follows.

 1)Mineralocorticoids

- They are a group of hormones that help in salt retention. The main hormone is aldosterone. It plays an important role to maintain blood pressure. It causes retention of sodium and water from the renal tubules, intestinal,sweat and tear glands.

 2)Glucocorticoid

 -They are produced by zona fasciculata. The main glucocorticoid is cortisol. It causes  gluconeogenesis.

 3)Gonadocorticoids

 -The main gonadocorticoids are testosterone and oestrogen. They control the development of reproductive organs and secondary sexual characters.

 Adrenal medulla produce epinephrine(adrenaline) and norepinephrine(non-adrenaline). These are called hormones of emergency. They induce flight or fight reaction during emergencies. They cause dilation of pupils, dilation of bronchioles, constriction of peripheral blood vessels, dilation of blood vessels of the heart, increased breathing and heart rate, etc.

Disorders

 1)Addison's disease

 -It is caused due to the deficiency of adrenal cortex hormones. It is characterized by tiredness, hypertension, dehydration, less detention of sodium, increased thirst, hyper 

pigmentation, headache, etc.

  2)Cushing’s disease

-It is caused due to hyposecretion of cortisol. It results in hyperglycemia, obesity, decreased immune response, high blood sodium level, hypertension, etc.

 3)Aldosteronism

 -It is caused by hyposecretion of aldosterone. It is characterized by high blood sodium, low blood potassium, convolutions, hypertension,etc.

 4)Gynecomastia

 -It is seen in males. It is caused due to increased secretion of oestrogen. It is characterized by female-like voice, less body hair, increased breast size,etc.

5)Adrenal virilism

 -It occurs in females. It is caused due to over secretion of testosterone. It is characterized by male-type voice, facial hair, underdeveloped ovaries,etc.