Growth hormone is secreted by the anterior pituitary gland and promotes body cell growth. It has a half-life of 5-20 minutes in humans. Growth hormone increases protein synthesis and amino acid uptake while decreasing protein breakdown. It also increases fat mobilization from adipose tissue while promoting fat breakdown for energy. Growth hormone stimulates bone and cartilage growth by increasing the production of somatomedins in the liver. Hypoglycemia, decreased fatty acids, and increased amino acids stimulate growth hormone secretion, while hyperglycemia, increased fatty acids, and decreased amino acids decrease its secretion.

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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.