(i) The hormones are chemical messengers released into the blood and circulated as chemical signals.
(ii) They influence the metabolic activities of the body by means of hormones.
(iii) Deficiency or excess secretion of hormones will lead to disorders.
(iv) Thus hormones act as chemical messenger and coordinate different physical, physiological mental activities and maintain homeostasis.

(i) CCK is known as Cholecystokinin.
(ii) CCK is secreted by a group of specialized endocrine cells in duodenum in response to the presence of fat and acid in the diet.
(iii) CCK acts on the gall bladder to release bile into duodenum and stimulates the secretion of pancreatic enzymes and its discharges.

(i) Hormones coordinate different physical, physiological, mental activities and maintain homeostasis.
(ii) Maintenance of constant internal environment of the body by the different coordinating system.

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) 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

(i) A pair of adrenal glands are located at the anterior end of the kidneys. The outer region is the cortex and the inner region is the medulla.
(ii) The adrenal cortex has three distinct zones, they are 1. Zona glomerulosa 2. Zona fasciculata and 3. Zona reticularis.
(iii) Zona glomerulosa an outer thin layer constitutes about 15% of adrenal cortex and its secretes mineralocorticoids.
(iv) Zona fasiculata, the middle layer constitutes about 75% of adrenal cortex and secretes glucocorticoids such as cortisol, corticosterone and trace amounts of adrenal androgen and oestrogen.
(v) Zona Reticularis, an inner zone of adrenal cortex constitute about 10% of adrenal cortex and secretes the adrenal cortex androgen, trace amount of oestrogen and glycocorticoids.