Tuesday, August 11, 2020

Chemical Coordination and Integration - Notes | Class 11 | Part 4: Testis, Ovary, Hormones of Heart, Kidney & Gastrointestinal Tract

22. CHEMICAL CO-ORDINATION AND INTEGRATION

9. TESTIS (MALE GONAD)

It is the male primary sex organ and an endocrine gland.

A pair of testis is present in the scrotal sac.

It is formed of seminiferous tubules and interstitial (stromal) tissues.

Leydig (interstitial) cells in the inter-tubular spaces produce hormones called androgens (mainly testosterone).

Functions of androgens:
  • Regulate development, maturation and functions of the accessory sex organs.
  • Spermatogenesis (sperm production).
  • Stimulate sexual behavior (libido), growth of muscles, hairs, aggressiveness, low pitch voice etc.
  • Help in anabolism of protein and carbohydrate.

10. OVARY (FEMALE GONAD)


It is the female primary sex organ.

A pair of ovaries is located in the abdomen.

It produces one ovum during each menstrual cycle.

Ovary is formed of ovarian follicles and stromal tissues.

Ovarian follicles produce Estrogen (a steroid hormone).

After ovulation, ruptured follicle forms a structure called Corpus luteum. It secretes progesterone (a steroid hormone).

Functions of Estrogen:
  • Growth and activities of female secondary sex organs.
  • Development of ovarian follicles & mammary glands.
  • Female secondary sex characters (e.g. high pitch voice) and sexual behavior.
Functions of Progesterone:
  • It supports pregnancy.
  • It acts on mammary glands to stimulate formation of alveoli (sacs to store milk) and milk secretion.

HORMONES OF HEART, KIDNEY & GASTROINTESTINAL TRACT


1. Atrial wall of heart: 
  • Produce a peptide hormone called Atrial natriuretic factor (ANF). 
  • When BP increases, ANF causes dilation of blood vessels to reduce the BP. 
2. JGA of kidney: 
  • Produces Erythropoietin (peptide hormone). 
  • Erythropoietin stimulates erythropoiesis (formation of RBC).
3. Gastro-intestinal tract: 

Produce peptide hormones. E.g.
  • Gastrin: Stimulates gastric glands to secrete HCl and pepsinogen.
  • Secretin: Stimulates exocrine pancreas to secrete water and bicarbonate ions.
  • Cholecystokinin (CCK): Stimulates secretion of bile from gall bladder and pancreatic enzymes from pancreas.
  • Gastric inhibitory peptide (GIP): Inhibits gastric secretion.
Several other non-endocrine tissues secrete hormones called growth factors. These help for the normal growth of tissues and their repairing or regeneration.

Based on the chemical nature, hormones are various types:
  1. Peptide, polypeptide, protein hormones: Insulin, glucagon, pituitary hormones, hypothalamic hormones etc.
  2. Steroids: Cortisol, testosterone, estradiol & progesterone.
  3. Iodothyronines (thyroid hormones).
  4. Amino-acid derivatives: Adrenaline, nor-adrenaline etc.

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