Final Hormones and their role in human body

hormones and their role

1. Hormone ( Gk horman , ‘ to stir up or excite’) Ernest Henry Starling: In 1905 coined the term HORMONE in his famous lecture ‘The chemical correlation of the functions of the body’ Hormones are produced by Special cells or glands Pancreas & intestinal mucosa Adrenals, ovaries, testes, parathyroid, pituitary, and thyroid gland Endocrine glands: secrete directly into the blood stream Exocrine glands: Tears, sweat, digestive enzymes outwards

2. Hormone: Chemicals Messengers Hormones Carry messages from glands or special cells to target cells Hormones are chemical messengers that coordinate different functions in the body. Several glands, organs and tissues make and release hormones, many of which make up endocrine system. Hormones are extremely potent & produced in very small amounts

3. Target cells refer to cells that contain specific receptors (binding sites) for a particular hormone. Once a hormone binds to receptor on a target cell, a series of cellular events occur

4. Receptor A protein molecule, embedded in either the plasma membrane or the cytoplasm or nucleus of a cell, to which a mobile signaling molecule may attach Intracellular receptors Steroid hormones Derivatives of vitamin D₃, retinoic acid, and thyroid hormones Modulate gene expression Plasma membrane receptors Protein/peptide hormone catecholamine

5. Hormonal signals integrate and coordinate the metabolic activities Every process - regulated by one or more hormones Maintenance of blood pressure Blood volume Electrolyte balance Embryogenesis Sexual differentiation Development & Reproduction Hunger, eating behavior , digestion Fuel metabolism

6. Classification of hormones Hormonal communications are classified according to the distance over which the signal acts Endocrine Paracrine Autocrine Based on their chemical structure Water soluble: Peptides or proteins, Catecholamines Lipophilic: Steroid hormones, Vit D, Retinoic acid, Thyroid hormones, Eicosanoids Based on their modes of action Slow acting & Fast acting

7. ( b ) paracrine signals are directed at nearby cells e.g. Eicosanoid hormone Endocrine signals are directed at distant cells through the intermediacy of the bloodstream C. autocrine signals are directed at the cell that produced them

8. Classes of hormones in mammals, distinguishable by their chemical structure and their modes of action

9. Slow-acting hormones act through Nuclear receptors Hydrophobic molecules readily pass through the plasma membrane of target cells and bind to intracellular receptors. Fast acting Hormones act through cell surface receptors

10. Peptide Hormones 3 -200 or more amino acids All hormones of hypothalamus and pituitary Pancreatic hormones insulin, glucagon, and somatostatin Parathyroid hormone, calcitonin Gastrin , Secritin , Cholecystokinin (CCK), Gastric Inhibitory pepetide (GIP), Chorionic gonadotropin (CG) Prohormones , secretary vesicles, cleaved to form active peptides

11. Wide Variety of physiological Responses to acute stress

12. Eicosanoids, paracrine hormones Prostaglandins, thromboxanes , and leukotrienes Arachidonate is precursor for Eicosanoids not synthesized in advance and stored but produced when needed Enzymes that produce eicosanoids are widely distributed, Most cells can produce them Many tissues respond to them Prostaglandins : Pain & Inflammation, Contraction of smooth muscles( Intestine & Uterus) Anti-inflammatory drugs inhibit synthesis of PGs Thromboxanes : Regulate Platelet function & Blood Clotting Leukotrienes ( LTC4, LTD4): Contraction of smooth muscle in Intestine, Pulmonary airways & Trachea, Mediators of anaphylaxis ( severe ,detrimental response) P hospholipase A2

13. Steroid Hormones Carrier Protein Nuclear receptors Slow acting hormones

14. Koolman , Color Atlas of Biochemistry, 2nd edition © 2005 Thieme Testosterone: Testes

15. Glucocorticoid: CORTISOL Minralocorticoid : Aldosterone

16. Vitamin D Hormone Calcitriol Ca 2+ homeostasis Synthesis of an intestinal Ca 2+ -binding protein essential for uptake of dietary Ca 2+

17. Retinoid Hormones Potent hormone nuclear retinoid receptors Regulate the growth Survival & differentiation of cells cornea, skin, epithelia of lungs & trachea, immune system RA regulates the synthesis of proteins essential for growth or differentiation Liver Many tissues Targets of retinoic acid are All tissues

18. Thyroid Hormones

19. Stable free radical: Molecular oxygen & guanidino nitrogen of arginine NO synthase (NOS), It is present in many tissues and cell types like neurons, macrophages, hepatocytes, myocytes of smooth muscle, endothelial cells of the blood vessels, and epithelial cells of the kidney. It acts near its point of release, cytosolic guanylyl cyclase, cGMP NO synthase ( NOS) Nitric Oxide (NO)

20. https://www.youtube.com/watch?v=TgNwxF3aQpE Mechanism of Hormone Actions at Cell Surface Receptor https://www.youtube.com/watch?v=UhZB6aBJM-w https://www.youtube.com/watch?v=bEtZHeCPsBs https://www.youtube.com/watch?v=PUXkZ-tJSp8 https://www.youtube.com/watch?v=m9jOXiYdMeY Replication https://www.youtube.com/watch?v=TNKWgcFPHqw Transcription https://www.youtube.com/watch?v=gG7uCskUOrA