Growth hormone

physiology of Growth hormone

1. 1 Surah: 33   Al Ahzab Aya : 21 Growth Hormone Prof. Dr. Rashid Mahmood (Courtesy: Prof. Dr. M. Yousaf)

2. Outline Introduction Growth functions Metabolic Effects Requirements for Growth Hormone to cause growth Variations & Control (Regulation) of Growth Hormone Secretion ABNORMALITIES OF GROWTH HORMONE SECRETION 2

3. Introduction to Growth Hormone Other names: Somatotropic Hormone or Somatotropin Secreted by: Acidophils of Anterior Pituitary Gland 3

4. 4 Functions of Growth Hormone Growth functions Metabolic Effects

5. Outline Growth functions 5

6. Growth functions of Growth Hormone Growth of all tissue capable of growing Proliferation of cells Increase size of the cells Differentiation of the cells Bone and cartilage growth

7. 7 Growth hormone affects growth

8. 8 Bone and cartilage growth GH→ ↑deposition of proteins by chondrocytes and osteogenic cells GH→ ↑ reproduction of bone forming cells GH→ ↑ conversion of chondrocytic cells into osteogenic cells GH → ↑deposition of chondroitin-SO4 and collagen GH→ ↑deposition of cartilage and then calcification at the epiphyseal cartilage→ elongation of the bone

9. Bone and cartilage growth Epiphyseal cartilage is used up and disappears then no more elongation of bone is possible GH→ ↑ osteoblastic activity → ↑ bone deposition Thickness of the bone continues to increase even after disappearance of epiphyseal cartilage 9

10. Assessment Q. 1 What is the effect of Growth Hormone on Cartilages?

11. Outline Metabolic Effects 11

12. 12 Metabolic Functions(Effects ) of Growth Hormone Effects on Protein Metabolism Fats Metabolism Carbohydrates Metabolism

13. 13 Effects of Growth Hormone on Protein Metabolism ↑ of almost all facets of Amino Acids uptake and Protein Synthesis ↓ Catabolism of Protein and Amino Acids

14. Effects of Growth Hormone on Protein Metabolism ↑ Transport of Amino Acids through Cell Membrane ↑ RNA Translation to cause protein synthesis by Ribosomes ↑ RNA Translation to cause protein synthesis by Ribosomes

15. Effects of Growth Hormone on Fats Metabolism ↑ Fats Utilization for energy Adipose tissue Acetyl-CoA ↑ Acetoacetic acid Ketosis ↑ FA ↑ mobilization Energy

16. Effects of Growth Hormone on Carbohydrates Metabolism 1. ↑ glucose production 2. ↑ insulin secretion ↑ blood glucose level Insulin resistance GH is diabetogenic ↓uptake by tissues, like muscles & fats

17. Assessment Q. 2 How does excess Growth Hormone cause Diabetes Mellitus?

18. Outline Requirements for Growth Hormone to cause growth 18

19. Requirements for Growth Hormone to cause growth (Subtopic of “GROWTH PHYSIOLOGY”) Insulin Somatomedins Thyroid Hormone Dietary factors: Carbohydrates Proteins Androgens, Estrogens

20. 20 Insulin and growth Insulin (transport some of the Amino Acids across the Cell Membrane) Growth hormone

21. Somatomedins ( IGF-I= Somatomedin C ) Growth Promoting Actions Direct Action

22. 22 Somatomedins Pygmies of Africa lack Somatomedin C Levi-Lorain dwarfs also have the same problem Somatomedin C may be produced by local tissues for local growth

23. GH deficiency with or without thyroid hormone

24. Kwashiorkor Protein Deficiency

25. Marasmus severe malnutrition characterized by energy deficiency

26. Relative importance of hormones at different ages

27. Assessment Q. 3 Why Growth Hormone cannot cause proper growth if there is deficiency of Insulin?

28. Outline Variations & Control (Regulation) of Growth Hormone Secretion 28

29. Summary of Direct & Indirect functions of Growth Hormone

30. 30 Variations in the secretion of GH GH secretion varies throughout the day

31. Feedback Control of Growth Hormone It secretion is increased by starvation , protein deficiency, hypoglycemia, low concentration of fatty acids, exercise , excitement , trauma and Ghrelin

32. Control (Regulation) of Growth Hormone Secretion

33. Outline ABNORMALITIES OF GROWTH HORMONE SECRETION 33

34. ABNORMALITIES OF GROWTH HORMONE SECRETION

35. Centre: Gigantism Right: dwarfism Left: normal

36. Dwarfs

37. Pygmies of Africa

38. Pygmies of Africa

39. Gigantism A 12 years old giant boy with his mother

40. Typical findings in acromegaly

41. Acromegaly

42. Acromegaly

43. Acromegaly

44. Acromegaly

45. Acromegaly

46. Progressive D evelopment of Acromegaly

47. Assessment Q. 4 Name the diseases caused by growth hormone excess in adults, and children.

48. Take Home points (1/3) Growth Hormone, also called Somatotropic Hormone or Somatotropin , is secreted by Acidophils of A nterior Pituitary Gland It causes Growth of all tissues capable of growing, including bones and cartilages It increases the protein content of the body It causes hyperglycemia and its excess may lead to Diabetes Mellitus It increases the utilization of fats for energy Insulin is an essential requirement for growth hormone to exert its growth related functions

49. Take Home points (2/3) Growth effects of growth hormone are caused by intermediate substances called Somatomedins (also called Insulin-like growth factors ; IGFs) that are synthesized by liver Most important Somatomedin is Somatomedin-C (IGF-I) Growth hormone is secreted in Pulsatile pattern. Its secretion is highest during first two hours of deep sleep It secretion is increased by starvation, protein deficiency, hypoglycemia, low concentration of fatty acids, exercise, excitement, trauma and Ghrelin

50. Take Home points (3/3) Its secretion is controlled by releasing hormones produced by hypothalamus in a negative feedback control mechanism. GHRH (growth hormone-releasing hormone) increases its secretion, and growth hormone inhibitory hormone (also called Somatostatin ) decreases its secretion Panhypopituitarism causes multiple general deficiency effects in adults , while in children it may lead to Dwarfism . Dwarfism may also be caused in cases where there is hereditary inability to form Somatomedin-C Excessive secretion of growth hormone in adults causes Acromegaly , while in children it leads to Gigantism

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