• List the hormones secreted by the anterior pituitary gland.
• Discuss Physiological actions of growth hormone.
• Outline the role of Somatomedins as mediators of
Growth Hormone actions.
• Describe the mechanisms that regulate GH production & release.
• Describe the sources,actions of somatostatin & relate it to growth hormone control.
• Correlate this knowledge to Clinical conditions related to hypo & hyper of Growth Hormone.

secreted by Anterior Pituitary gland.
• Growth hormone.
• Thyroid Stimulating hormone.
• Aderno Corticotropic hormone.
• Prolactin.
•
•
• Follicle Stimulating Hormone.
• Leuteinizing Hormone.

Structure:
• Polypeptide, unbranched with191AA
• Shows species specificity.
• hGH & monkey’sGH have similar biological activities in humans.

• Genes for human growth hormone, known as growth hormone 1 (somatotropin) and growth hormone 2 , are localized in the q22-24 region of chromosome 17 [4][5] and are closely related to human chorionic somatomammotropin (also known as placental lactogen ) genes. GH, human chorionic somatomammotropin, and prolactin belong to a group of homologous hormones with growth-promoting and lactogenic activity
.

• Somatotrophs of ant.pituitary.
• Released in pulsatile fashion.
• GHRH(of Hypothalamus)binds receptors on somatotroph(of ant.pit)then cAMP & Ca mediate the release of GH.

• About 2-4ng/ml.(0.2 – 1 mg/day).
• Released in pulses- 10 – 20 pulses / day.
• Level varies with age.
B=at birth
C- Childhood
P= puberty
A= Adult life
O= Old age

• Nocturnal sleep burst: 1-2hrs after sleep, accounts for 70% of secretion ( More you sleep more you grow!!).
• Circulating Gh binds with GH binding protein( is a part of receptor ).
• Half life = 20 min.
• Metabolism: Mainly in liver, also by kidneys.

• Present on membrane of target cells.
• Has extracellular, transmembrane and intracellular portion.

GH
Directly By IGF-I
Produced by Liver
IGF types- IGF-I( = Somatomedin C ) &
IGF-II

GH
On Growth & On Metabolism
• Skeletal tissue * Carbohydrate
(cartilage&bones) * Fat
• Extraskeletal * Proteins
(muscles&visceras) * minerals

Skeletal tissue:
1. Cartilage: proliferation of chondrocytes, increased thickness of epiphyseal cartilage.
2. Bones: St. of osteoblasts, convert cartilage to bone till epiphyseal plate fuses with shaft of long bones. In adults: increases girth of bones.

Extraskeletal tissue growth:
*St skeletal muscle growth ( not contractile unit ) = bulk without power.
* Visceral growth increases.

On Carbohydrate:
* Hyperglycemic:-increases gluconeogenesis(hepatic ),decresases peripheral utilization of glucose, inhibits glycolysis.

• Gh Adipose tissue Lipolysis
• Increased FFA in circulation.This acts as energy source during hypoglycemia, fasting and stress.

• ANABOLIC.
• Promotes protein deposition in tissues by increased uptake of AA,protein synthesis.
• Causes + ve nitrogen balance.

• Positive balance of Calcium, phosphates,magnesium.
• Increased renal reabsorption of calcium,phospates,Na.

• On milk production: Gh has lactogenic action.
• On erythropoiesis: stimulates erythropoiesis. Increases EP from kidney
• Stimulates growth of lymphocytes.
• Stimulates growth of genitelia.

1. Hypothalamic control by release of a. GHRH b. GHIH.
2. Negative feedback control by a. Somatomedins b. GH c. GHRH

• GHRH
Factors stimulating GHRH secretion and there by increase secretion of GH:
-Hypoglycemia(through glucoreceptors)
-Emotion,exercise,physical stress(nervous)
-Sleep.
-Increased plasmaAA levels.
-Ghrelin(gh Releasing Peptide)

• GHIH( = Somatostatin)
Blocks GHRH stimulation
Decreased GH
Factors stimulating GHIHsecretion & GH.
-Hyperglycemia
-Plasma FFA

GH: Increased Secretion:1. GIGANTISM
2.ACROMEGALY
GH: Decreased secretion: DWARFISM

• Increased secretion of Gh in children i,.e before closure of epiphysis of long bones.
• Abnormal height(7-8 feet).=gaint.
• Large hands & feets.
• Thick lips.macrogosia.
• Gynaecomastia
• Loss of libido.
• Hyperglycemia- insulin-overactivity of beta cells& degeneration- DM
• If due to tumors- Head ache, visual defects.

Robert Wadlow , the tallest man known to have lived (2.72 metres or 8 feet 11 inches) with his father, Harold
Wadlow (1.82 metres or
6 feet 0 inches)

• Increased Gh secretion in adults(after epiphyseal closure)
• Acromegalic face:Thick lips,macroglosia, thick and broadnose,PROGNATHISM.
• Acral part enlargment- hands,feets.
• Excessive growth of internal organshepato,spleeno,renomegaly.
• Poor gonadal function.

Prognathism

Brow ridge and forehead protrusion normal & acromegalic hands

PITUITARY DWARF:
-Decreased Gh secretion at early age.
-Shortness of strature.
-Normal mental activity.
-Sexual maturity- may not be if associated with deficiency of Gonadotropin.
Otherwise sexual maturity present.

• Short strature due to LACK OF GH
RECEPTORS IN TISSUES.

• CONGENITAL ABNORMALITY OF GH
RECEPTORS.

• When pancreatectomy is done it results in
Diabetes. If hypophysectomy is done diabetes is brought under control. This shows that GH is a diabetogenic hormone.