Question

What is endocrine axis and write a sample for one hormone?

Answer 1

What is endocrine axis and write a sample for one hormone?

ENDOCRINE AXIS

Endocrine glands release hormones into the bloodstream, and the hormones travel to cells in other parts of the body. An endocrine axis is a complex set of direct influences and feedback interactions among three organs crucial to endocrine function: the hypothalamus, the pituitary gland, and the adrenal glands

A SAMPLE ENDOCRINE AXIS FOR ONE HORMONE

            Growth Hormone Axis

Hormonal pathways that control the production of growth hormone (GH). GH is very important for bone, muscle, and organ growth and development.

Hypothalamus

               GHRH

Anterior pituitary

   GH                   Metabolism

         Liver

        IGF 1

      

Bone and muscle growth

The hypothalamus starts off this hormonal pathway by the release of Growth Hormone Releasing Hormone (GHRH). GHRH stimulates somatotroph cells of the anterior pituitary to release Growth Hormone (GH), also known as somatotropin. GH has direct actions on tissues by binding to cells, and has indirect effects whereby it stimulates the liver to produce Insulin-like Growth Factor-1 (IGF-1) to mediate actions.

The direct actions of GH on tissues mainly include:

· More lipolysis

· Decreased glucose oxidation

· Reduced protein oxidation.

The indirect actions of GH mainly include:

· Increases protein synthesis.

· Increases carbohydrate oxidation

WHAT DO INSULIN-LIKE GROWTH FACTORS (IGF-1) DO?

IGF-1 have the following activity:

· Promote linear bone development in individuals who have the growth plates of long bones still open

· Stimulate muscle growth

· Increase insulin resistance

· Feed back inhibition on the GH hormone axis (at the level of the hypothalamus and anterior pituitary).

The overall effects, arising from an interplay between the two substances, are important for the : -

· Skeletal growth

· Muscle strength

· Bone density

· Cardiac function

Regulation

Several factors including stress, exercise, nutrition and sleep modulate the production of growth hormone. GHRH promotes GH release, Somatostatin, produced by the hypothalamus, the intestines and delta cells of the endocrine pancreas, inhibits GH. There is also inhibition of GH production by IGF-1, which prevents somatotroph releasing GH and promotes somatostatin release from the hypothalamus.