Question

Using Growth Hormone (GH) as an example, explain a hypothalamic – pituitary – target organ relationship. A drawing may be helpful but be sure to include words to explain the picture.

Answer 1

1)Growth hormone is Produced by Somatotrophs

2)Growth hormone is always release in Pulsatile manner and not continuously

3)Hypotahalmus secrete GHRH ( Growth hormone releasing hormone ) it goes and Stimulate the Somatotrophs to release GH ( Growth hormone in blood ) and then GH exerts its action on Target Tissues .Actions are mediated through IGF -1 ( Insulin like growth factor 1 ) .IGF 1 is Produced from the Liver in response to Growth hormone binding to its receptor in Liver .High levels of IGF -1 in blood cause Hypothalamus to secrete GHIH( Growth hormone inhibiting hormone ) and decrease the release of Growth hormone from Pituitary .

4)GH acts on Target tissues through IGF -1

a)Adipose Tissues --> Lipolysis breakdown of stored fats and help in growth of cells

b)Bones ,Muscles ,Immune system ,Nervous syetem -->Protein Synthesis ,Epiphyseal growth in Bones ,Cellular proliferation and decreased Apoptosis and thus promote growth .

c)Liver --> Promote to break Glycogen to glucose and cause Diabetogenic effects .