Androgens are hormones produced by the leydig cells or institial cells of testis. The androgens perform the following function :
1. It regulates the developement , maturationand functions of the male accessory sex organs like epidydimis, vas deferens etc.
2. It regulates muscular growth, growth of facial hair.
3. It plays an important role in the stimulation of the process of spematogenesis.
Endocrine glands : These are ductless glands which produce hormones. The hormones secreted by them are transported by the blood to the different parts of the body.
Hormones : The hormones are chemical informational regulatory molecules secreted by endocrine glands. They non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.
i. Placenta : secretes a human chorionic gonadotrophin hormone (hCG). It stimulates the corpus luteum to secrete progesterone.
ii. Enteric epithelium of stomach : It secretes gastrin hormone when bolus comes into stomach. The gastrin hormone stimulates gastric glands to secrete the gastric juice.
Abnormalities of parathyroid gland :
1. Due to hyposecretion : Secretion of the PTH in lesser amount that the normal results in :
(a) Decrease of calcium of blood which causes cramps and convulsions.
(b) It also causes parathyroid tetani which is characterised by sustained contraction of muscles of face, larynx, limbs etc.
2. Due to hypersecretion : Secretion of the hormone in excess amount results in abnormal increase in the amount of calcium in blood. The increased calcium levels may results in easy fractures of bones.
Endocrine system : It consists of endocrine glands that secrete hormones directly into the circulatory system to be carried towards distant target organs.
Types of endocrine glands :
1. Pure endocrine glands : These glands only secrete hormones e.g. thyroid gland, pituitary gland etc.
2. Heterocrine glands : These glands secrete both enzymes and hormones. Thus, they act as endocrine and exocrine e.g. pancreas.