The Biochemistry Online – Free Online Lectures for Medical, Dental and Allied Health Sciences students by the Biochemistry Club.
Growth Hormone
Growth hormone is a polypeptide with 191 amino acids.
It is also known as Somatotropin.
It is synthesized by the acidophils (somatotropic cells) of the anterior pituitary.
The GH secretion is regulated by the balance between GHRH & GHIH (somatostatin).
Plasma concentration of GH is < 2 ng/ml during day.
The Secretary peak of GH occurs 3 hours after meals.
Maximum level of GH is seen during deep sleep.
Hypoglycemia stimulates Growth Hormone secretion & hyperglycemia suppresses it.
Certain amino acids in blood increase Growth Hormone.
Stress also stimulates GHRH (Growth Hormone Releasing Hormone).
The hypothalamic GHRH stimulates Growth Hormone synthesis & release.
Ghrelin, a peptide derived from stomach induces GHRH, directly stimulates the release of Growth Hormone.
Somatostatin (hypothalamus) inhibits the GH secretion.
The metabolic effect of Growth Hormone is mainly mediated by somatomedin, also known as Insulin-like Growth Factor-1 (IGF-1).
Growth Hormone acts on receptors present in liver/skeletal muscles.
Liver/muscles produces IGF-1 in response.
Receptors act through the JAK – STAT pathway (will be discussed separately in pathways).
Growth Hormone is anabolic.
Increases the uptake of amino acids by cells; enhances protein synthesis (produces positive nitrogen balance) – insulin like effect.
The anti-insulin effect of Growth hormone causes lipolysis – increased FFA – hyperlipidemia (energy production) & hyperglycemia.
Overall effect is to stimulate growth of soft tissues, cartilage and bone (liver – somatomedin).
The metabolic effect of Growth Hormone is mainly mediated by somatomedin(IGF-1).
The growth of long bones is stimulated by …
All these lectures are organized and listed in detail in their proper sections. To view these lessons please visit the Hormones and Signal Transduction Section in Biochemistry II. This can be approached by directly clicking the Biochemistry II button or it can also be approached from the drop down menu in Biochemistry II tab. Once you reach the section click the curriculum tab to view the full list in the section. Any further questions or inquiries are welcome.
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