BY Dr APEKSHA PANWAR DEPARTMENT OF KRIYA SHARIR ID: 914507
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HORMONES OF ANTERIOR PITUITARY GLAND
BY Dr. APEKSHA PANWAR DEPARTMENT OF KRIYA SHARIR HAMC
Slide2INTRODUCTIONPituitary gland also called hypophysis is a small gland that lies in
sella turcica, a bony cavity at the base of the brain.It is connected to hypothalamus by the pituitary stalk.It is about 1cm in diameter and its weight is 0.5-1gm in weight.Phsiologically pituitary gland is divisible into two distinct portions:1- The anterior pituitary, also known as the Adenohypophysis.2- The posterior pituitary also known as the Neurohypophysis.Between these is a small, relatively avascular zone called the pars intermedia which is much less developed in the human being.
Slide3Slide4HORMONES OF ANTERIOR PITUITARYEmbroyologically
the two portions of the pituitary originate from different sources- anterior pituitary from Rathke pouch, which is an embryonic invagination of the pharyngeal epithelium.The posterior pituitary originates from a neural tissue outgrowth from the hypothalamus.Six important peptide hormones are secreted by anterior pituitary:-1- Somatotropes- Growth hormone(GH)2- Corticotropes- Adrenocorticotropin(ACTH)3- Thyrotropes- Thyroid stimulating hormones(TSH)4-Gonadotropes- Leutenizing hormones(LH) and Follicle stimulating hormones(FSH).5- Lactotropes- Prolactin(PRL)
Slide5Slide6HYPOTHALAMIC HYPOPHYSIAL PORTAL SYSTEM
Secretion by the anterior pituitary is controlled by hormones called Hypothalamic releasing and Hypothalamic inhibitory hormone. These are secreted within the hypothalamus, and then conducted to the anterior pituitary through minute vessels called Hypothalamic hypophysial portal vessel.In the anterior pituitary , these releasing and inhibitory hormones act on glandular cells to control their secretion.Anterior pituitary is a highly vascular gland with extensive capillary sinuses among the glandular cells.The hypopyseal portal system is a system of blood vessels in the microcirculation at the base of the brain, connecting the hypothalamus with the anterior pituitary.Main function of this system is to quickly transport and exchange hormones between the hypothalamus and the pituitary.Special neurons in the hypothalamus synthesize and secrete hypothalamic releasing and inhibitory hormones that control secretion of anterior pituitary hormones.
Slide7PHYSIOLOGICAL FUNCTIONS OF GROWTH HORMONES
Growth hormone also called Somatotrophic hormones, is a small protein molecule that contains 191 amino acids in a single chain.Unlike other pituitary hormones it does not function through target gland but exert its effect directly on all or almost all tissues of the body.1- Growth hormone promotes protein deposition in tissues.2- It enhances fat utilization for energy.3-It decreases carbohydrate utilization.4- Growth hormones stimulate cartilage and bone growth.5- It causes the liver to form several small proteins called Somatomedins, that have potent effects of increasing all aspects of bone growth.
Slide8REGULATION OF GROWTH HORMONE
Growth hormone is secreted in pulsatile pattern, increasing and decreasing.The precise mechanism that control secretions of growth hormone are not fully understood but several factors related to person state of nutrition or stress are known to stimulate secretion as:-A- Starvation especially with severe protein deficiency.B- Hypoglycemia or low concentration of fatty acids in the blood.C- ExerciseD-ExcitementE- TraumaF-Ghrelin- Hormone secreted by the stomach before meals.
Slide9ABNORMALITIES OF GROWTH HORMONE
1- Panhypopituitarism:- It means decreased secretion of all the pituitary hormones. This decrease in secretion may be congenital or may occur suddenly or slowly, most often resulting from a pituitary tumour that destroys pituitary gland.Dwarfism:-It results from generalized deficiency of anterior pituitary secretion during childhood. In this all the physical parts of the body develop in appropriate proportion to one another, but he rate of development is greatly decreased.Causes of Dwarfism-Tumour of chromophobesDeficiency of growth hormone releasing hormone secreted by hypothalamus.
Deficiency of Somatomedin C
Atrophy or degeneration of acidophilic cells in the anterior pituitary.
Panhypopituitarism
Slide10GIGANTISMOccasionally, the acidophilic growth hormone producing cells of the anterior pituitary gland become excessively active.As a result large quantities of growth hormone is produced.
In this all tissues grow rapidly including the bones.If the condition occurs before adolescence before the epiphysis of the long bones have become fused with the shafts, height increases so that the person becomes a giant upto 8 ft tall.Giant ordinarily has Hyperglycemia and the beta cells of the islet of Langerhans in the pancreas are prone to degenerate because they become overactive.
Slide11ACROMEGALYIf an acidophilic tumour occurs after adolescence person cannot grow taller but the bones can become thicker and the soft tissues can continue to grow.
1- There is a marked enlargement in the bones of hands and feet.2- Enlargement of membranous bones i.e cranium, forehead, protrusion of lower jaw, portions of vertebra increase in size.3- Enlargement of soft tissue organ like tongue become greatly enlarged and there is enlargement of liver and kidneys.