GROWTH HORMONE

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GROWTH HORMONE
Introduction:
Growth hormone is a hormone of the
anterior pituitary gland and is also known
as somatotropin or somatotropic
hormone.Its basic function is to cause
body cell to grow.

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SITE OF SECRETION
Growth Hormone is secreted by the
acidophils of the anterior pituitary which are also
known as somatotropes.
Nature.
Growth hormone is a small protein (peptide).
Plasma level.
The normal conc. of GH in the plasma of an
adult is b/w 1.5 to 3ng/ml and in children it is
about 6ng/ml.

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HALF-LIFE
The half-life of circulating GH in humans is 5-
20 minutes. The daily GH output has been
found to be 0.2-1.0mg/d in adults.
Functions of GH
I. Effects on protein metabolism.
GH has predominantly anabolic effects on
skeletal and cardiac muscles. It stimulates
the synthesis of protein, RNA and DNA.

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• It promotes amino acid entry into cells.
• It decreases the catabolism of protein b/c GH
mobilizes free fatty acid to supply energy.
• It decreases gluconeogenesis from proteins.
II. Effects on carbohydrate
metabolism.
• GH is a diabetogenic hormone b/c of its anti-
insulin effect, GH has a tendency to cause
hyperglycemia.

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• It increases the deposition of glycogen b/c
glucose cannot to be used for energy.
• It decreases the entry of glucose into cells
due to the saturation of glycogen.
III. Effects on fat metabolism.
• Release of fatty acid from adipose tissues
and therefore increasing the conc. of fatty
acid in the fluids.
• It increases the conversion of free fatty acids
into acetyl-CoA which is utilized for energy.

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IV. Mineral metabolism.
• GH causes greater retention of calcium,
sodium and phosphate in the body.
• Hyperpituitarism is associated with a
raised inorganic phosphate level of
plasma.

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V. Effects on bone, cartilage and soft
tissues.
• GH increases the formation somatomedines
by the liver.
• It acts on cartilage and bone, stimulating
growth.
• Increases the deposition of connective tissue.
• Increases the growth of viscera. (liver,
kidney).

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Regulation of GH
I. Factors that increase GH secretion.
• Hypoglycemia.
• Decreased fatty acids.
• Increased amino acids.
• Hypolpidemia.
• Hypocholesteremia.
• Estrogen.
• Dopamine.

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II. Factors decreasing GH secretion.
• Hyperglycemia.
• Increased fatty acids.
• Decreased amino acids.
• Hyperlipedemia.
• Hypercholesteremia.
• Decreased insulin secretion.
• Increased glucagon secretion.