Growth Hormone physiology by Dr nooria ppt

Physiology growth hormones

1. Dr. Nooria Naeem Assistant professor physiology

2. Relative importance of hormones in human growth Ref: Ganong’s Physiology Fig: 18-9, P:330

3. Regulation of Growth Hormone

4. Regulation of Growth hormone secretion Stimulation factors Starvation/ fasting Increase amino acids in blood Hypoglycemia or low fatty acids in the blood Exercise Excitement, trauma, stress Deep Sleep ( stage II and IV) Ghrelin, testosterone, estrogen

5. Inhibit Growth Hormone Secretion Increased blood glucose Increased blood free fatty acids REM Sleep Aging Obesity Growth hormone inhibitory hormone (Somatostatin) Growth hormone (exogenous) Somatomedins or IGF-I

6. Growth Hormone Exerts Much of Its Effect Through Intermediate Substances Called " Somatomedins " Also called " Insulin-Like Growth Factors ’’( IGF-I) Short Duration of Action of Growth Hormone but prolonged Action of Somatomedin C

7. Growth Hormone Actions on Protein Metabolism Growth hormone enhances almost all facets of amino acid uptake and protein synthesis by cells Reducing the breakdown of proteins Increased RNA translation and nuclear transcription of DNA to form RNA

8. GH has Diabetogenic effect Growth hormone induced “ Insulin resistance ” reduces insulin’s actions : Decreased uptake & utilization of glucose in skeletal muscle and fat Increase in glucose synthesis by the liver Increase of glucose concentration in the blood Compensatory increase of insulin Excess in GH may cause metabolic disturbance similar to those found in patients with DM II .

9. It increases the plasma glucose concentration by decreasing carbohydrate utilization Decreases glucose uptake in tissues Increases gluconeogenesis by the liver I ncreases Insulin secretion Glucose sparing ( Diabetogenic, Type II )

10. Direct & Indirect effects of Growth Hormone

11. Disorders of Growth Hormone Hyposecretion Adults : As part of Panhypopituitarism Childhood: Dwarfism Hypersecretion Childhood: Gigantism Adults: Acromegaly

12. DWARFISM Mostly panhypopituitarism in childhood Parts of body are develop in appropriate proportion to one another Defect in rate of development No Puberty due to deficient Gonadotropic hormones in case of panhypopituitarism Only one third have just GH deficient so sexually normal. Levi-Lorain Dwarfs (Somatomedin C deficient)

13. GIGANTISM: Acidophilic tumor of Ant. Pituitary Rapid growth of all tissues and bones Excess of growth hormone before puberty…..increase in height Hyperglycemia Kyphosis may develop

14. ACROMEGALY Excess of Growth hormone after adolescence Bones thicken, soft tissue grows Bones of hands, feet, skull, vertebra enlarge

15. Gigantism Identical twins, 22 years old, excess GH secretion

16. MCQs Which one of the following is the function of growth hormone Protein catabolism Fat synthesis Gluconeogenesis Glycolysis Fat deposition

17. 2. Which of the following is true for growth hormone? It is synthesized in the hypothalamus It stimulates the production of somatomedins by the liver Its release is stimulated by somatostatin It is deficient in acromegaly It increases in old age

18. Key Points Growth Hormone is a peptide hormone produced from Pituitary under the influence of GHRH Responsible for the growth of bones & cartilage through IGF-I Increases the rate of protein synthesis Increases the mobilization of fatty acids in the blood and used it for energy Decreases the rate of glucose utilization throughout the body- Diabetogenic Abnormalities Dwarfism Acromegaly Gigantism