Parathyroid Gland and Related Hormones Vitamin D and Calcitonin Prof. K. Sivapalan.
Posterior Pituitary Prof. K. Sivapalan. 08-01-14Hypophysis.2 Structure and Blood Supply. Posterior...
-
Upload
augustine-norris -
Category
Documents
-
view
215 -
download
3
Transcript of Posterior Pituitary Prof. K. Sivapalan. 08-01-14Hypophysis.2 Structure and Blood Supply. Posterior...
Posterior Pituitary
Prof. K. Sivapalan
08-01-14 Hypophysis. 2
Structure and Blood Supply.
• Posterior lobe is supplied by inferior Hypophysial artery.
• Neurons in the hypothalamus, endings in posterior lobe.
08-01-14 Hypophysis. 3
Anti Diuretic Hormone [Vasopresin]
• 9 amino acids, 1000 mw.• Half life- 18 minutes.• Action in physiologic doses:
– Increase water and urea permeability in collecting ducts.
– Anti diuresis.• Action in large doses:
– Contraction of vascular smooth muscles.– Increase blood pressure.
08-01-14 Hypophysis. 4
Control of secretion of ADH.
• Increased osmolality stimulates osmoreceptors in hypothalamus and increases secretion.
• Increased blood volume stimulates volume receptors in IVC and Left atrium, inhibits secretion.
08-01-14 Hypophysis. 5
Other Factors influencing ADH.
Stimulation:• Increase of OP of plasma.• Decreased ECF volume.• Pain, emotion, stress, exercise.• Nausea and vomiting.• Standing• Angeotensin II• Carbamazapine, clofibrate
Inhibition:• Decreased Osmotic pressure.• Increased ECF volume.• Alcohol.
08-01-14 Hypophysis. 6
Abnormal Secretion.
• Excess- water intoxication.– Reduced plasma osmolality.– Dilutional hyponatreamia.
• ? Drinking water after surgery, child birth etc.
• Insufficiency- diabetes Insipidus.– Polyurea and polydepsia.
08-01-14 Hypophysis. 7
Oxytocin.
• 9 Amino acids.• Synthesized in hypothalamus and
released in Post. Pituitary.
08-01-14 Hypophysis. 8
Actions of Oxytocin.
• Contraction of myo-epithelial cells of the breast.
• Contraction of pregnant uterus– Enhanced by estrogen– Inhibited by progesterone.
• ?facilitate sperm trans port and fertilization
• Contraction of Vas deferens during ejaculation.
08-01-14 Hypophysis. 9
Stimulation of Secretion.
• Stimulation of nipple- milk ejection reflex.
• Stretch of cervix of the uterus- parturition
• Sexual stimulation.
08-01-14 Hypophysis. 10
Inhibition of Oxytocin Secretion.
• Alcohol• Stress.• Pain• Discomfort.• Embarrassing conditions.• Fear• Anger.