1. A group of specialized endocrine cells present in gastro intestinal tract secretes hormones such as gastrin, cholecystokinin, secretin and gastric inhibitory peptides.
2. Gastrin acts on the gastric glands and stimulates the secrete of HCI and pepsinogen.
3. Cholecystokinin [CCK] is secreted by duodenum in response to the presence of fat and acid in the diet.
4. Secretin acts on acini cells of pancreas to secrete bicarbonate ions and water to neutralize the acidity.
5. Gastric inhibitory peptide [GIP] inhibits gastric secretion and motility.

(i) Pancreas is a dual hormone which performs both the function of exocrine and endocrine glands.
(ii) It is a leaf like structure composed of two major tissues such as acini and islets of Langerhans.
(iii) Insulin is a peptide hormone and play an important role in glucose homeostasis.
(iv) When entire pancreas is removed, the body is left without the cells that produce insulin and hormones that help maintain safe blood sugar level. This leads to diabetes.

(i) Adrenalin hormones secreted by adrenal medulla
(ii) Adrenal medulla secretes the hormones adrenalin and noradrenalin and are referred as 3F Hormones ie [fight, flight and fright hormones]
(iii) During emergency it increases heartbeat rate and blood pressure.
(iv) Adrenalin increases liver glycogen breakdown into glucose and increases the release of fatty acids from fat cells.
(v) It stimulates the smooth muscles of cutaneous and visceral arteries to decrease blood flow.
(vi) It increase blood flow to the skeletal muscles thereby increases the metabolic rate of skeletal muscles, cardiac muscles and nervous tissue.

Cretinism is due lower secretion of growth hormone in infants; [ie] hypothyroidism.
Symptoms of Cretinism:
In infants, hypothyroidism causes cretinism .A cretin shows
1. Retarded skeletal growth
2. Absence of sexual maturity.
3. Retarded mental ability.
4. Thick wrinkled skin.
5. Protruded enlarged tongue.
6. Bloated face.
7. Thick and short limbs occurs

In kidney, endocrine gland secretes the hormones such as Renin, Erythropoietin and calcitriol.
(i) Renin secreted by Juxta glomerular cells [JGA], which increases blood pressure when angiotensin is formed in blood.
(ii) Erythropoietin is also secreted by the JGA cells of the kidney and stimulates erythropoiesis in bone marrow
(iii) Calcitriol is secreted by proximal tubules of nephron. It is an active form of vitamin 'D₃' which promotes calcium and phosphorus absorption from intestine and accelerates bone formation.