Function of Growth Hormone - PPT/PDF
Download notes (PPT/PDF) detailing the function of growth hormone (GH), also known as somatotropin. These notes cover the various physiological roles of GH, including its effects on growth, metabolism, and cell regeneration. Suitable for B.Pharm and related health science programs.
Keywords: Growth Hormone, GH, Somatotropin, Function, Physiology, Growth, Metabolism, Cell Regeneration, B.Pharm, Human Anatomy and Physiology, PPT, PDF, Download.
Function of Growth Hormone - Detailed Explanation
What is Growth Hormone?
Growth hormone (GH), also called somatotropin, is a peptide hormone produced and secreted by the somatotropic cells of the anterior pituitary gland. It is a crucial hormone for growth and development, particularly during childhood and adolescence, but it also plays important roles throughout life.
Regulation of Growth Hormone Secretion
GH secretion is primarily regulated by two hypothalamic hormones:
- Growth Hormone-Releasing Hormone (GHRH): Stimulates GH release.
- Growth Hormone-Inhibiting Hormone (GHIH, Somatostatin): Inhibits GH release.
GH secretion is also influenced by various factors, including:
- Age: GH levels are highest during childhood and adolescence, declining with age.
- Sleep: GH secretion is pulsatile, with the largest pulses occurring during deep sleep.
- Nutrition: Hypoglycemia (low blood sugar) and amino acids stimulate GH release. Hyperglycemia (high blood sugar) and fatty acids inhibit GH release.
- Stress: Stress can stimulate GH release.
- Exercise: Exercise can stimulate GH release.
Functions of Growth Hormone
Growth hormone has both direct and indirect effects on various tissues and organs in the body. Many of its growth-promoting effects are mediated indirectly through insulin-like growth factor 1 (IGF-1), which is produced primarily by the liver in response to GH stimulation.
1. Growth-Promoting Effects:
- Linear Growth: GH, primarily through IGF-1, stimulates the growth of long bones at the epiphyseal plates (growth plates) during childhood and adolescence. This leads to increased height.
- Increased Cell Number and Size: GH promotes cell division (proliferation) and protein synthesis, leading to an increase in both the number and size of cells in various tissues, including muscle and bone.
2. Metabolic Effects:
- Protein Metabolism:
- Stimulates Protein Synthesis: GH promotes the uptake of amino acids into cells and their incorporation into proteins.
- Inhibits Protein Breakdown: GH reduces the breakdown of proteins, conserving them for growth and repair.
- Fat Metabolism:
- Promotes Lipolysis: GH stimulates the breakdown of stored fats (triglycerides) into fatty acids, which can be used for energy. This leads to a decrease in body fat.
- Carbohydrate Metabolism:
- Increases Blood Glucose Levels: GH has an "anti-insulin" effect. It decreases the uptake of glucose by muscle and fat cells and stimulates the liver to produce glucose (gluconeogenesis). This can lead to increased blood glucose levels. This effect helps ensure that glucose is available for growing tissues.
3. Other Effects:
- Electrolyte Balance: GH can influence the balance of electrolytes, such as sodium, potassium, and calcium.
- Immune Function: GH may play a role in stimulating the immune system.
- Organ Growth: GH can contribute to the growth and maintenance of various organs.
Disorders of Growth Hormone Secretion
- Growth Hormone Deficiency: In children, this can lead to dwarfism (short stature). In adults, it can cause decreased muscle mass, increased body fat, and reduced bone density.
- Growth Hormone Excess:
- Gigantism: Excess GH *before* the closure of the epiphyseal plates (before puberty) leads to excessive linear growth, resulting in very tall stature.
- Acromegaly: Excess GH *after* the closure of the epiphyseal plates (after puberty) leads to enlargement of bones in the hands, feet, and face, as well as thickening of soft tissues.
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