adh & oksitosin
TRANSCRIPT
ADH DAN OKSITOSIN
ST. RAHMAWATI (P 1502208005)ALIA ANDRIANY (P 1502208002)
PROGRAM STUDI BIOMEDIK JUR. FISIOLOGIPROGRAM STUDI BIOMEDIK JUR. FISIOLOGIPASCASARJANA UNHASPASCASARJANA UNHAS
Posterior Pituitary (neurohypophysis)
• Cell bodies in SON (ADH) & PVN (Oxytocin) of hypothalamus
•Consists of neural endings withassociated blood vessels
•Acts as storage area, secretory granules travel down axon
•Connects to hypothalamus via hypothalamic-hypophyseal
tract
• Processes extend through infundibulum and end in Post. Pit
Amino acid sequence in oxytocin Amino acid sequence in oxytocin & vasopressin& vasopressin
http://www.neurosci.pharm.utoledo.edu/MBC3320/vasopressin.htm
The posterior pituitary gland hormones
Posterior pituitary gland releases 2 hormones:
1. Antidiuretic hormone (ADH), or arginine vasopressin (AVP). 2. Oxytocin
Both hormones are produced in hypothalamic nuclei: - Supraoptic nucleus (ADH + 1/6 oxytocin) - Paraventricular nucleus (Oxytocin + 1/6 ADH)
1. Oxytocin:
Action of oxytocin
1. Contraction of smooth muscles of the uterus
enhance labor.2. Contraction of mammary gland myoepithelial cells of the alveoli & the ducts Ejection of milk as a reflex in lactating women.
3. In men ejaculation.
Remember: Oxytocin is concerned with releasing or ejection of milk, while prolactin is
concerned with synthesis & production of milk.
Control of oxytocin release
1. Stimulation of nipple (suckling reflex) oxytocin.
2. Visual or auditory stimuli from the baby oxytocin secretion.
3. Distension of uterus & stretching of cervix during delivery oxytocin release.
4. During coitus oxytocin secretion.
5. Psychological & emotional factors, e.g. Fear, anxiety & pain
oxytocin.6. Alcohol oxytocin secretion.
7. Hormones: a. progesterone uterine sensitivity to oxytocin.
b. estrogen uterine sensitivity to oxytocin.
Neuroendocrine Reflex Arc of Milk Let-Down
Takes only milliseconds from suckling to hypothalamus
OT reaches its target a few seconds later
OT binds receptors on myoepithelial cells of mammary
gland
NeuroendocrineReflex
Neuroendocrine Reflex
The posterior pituitary hormones – 2. ADH (vasopressin):
Antidiuretic hormone (ADH), or arginine vasopressin
(AVP), is produced mainly in SON of hypothalamus.
ADH activates (2) second messenger systems: 1. cAMP 2. IP3
Action of ADH
ADH has 2 main effects:
1. water re-absorption (retention) by distal tubules & collecting ducts of the kidneys decrease osmotic pressure of the blood.
* This effect is regulated by V2 receptors, through the
action of cAMP.2. Contraction of vascular smooth muscles generalized vasoconstriction.
* This effect is regulated by V1 receptors, through the action
of IP3/Ca2+.
Control of ADH release1. in osmotic pressure of the ECF ( in plasma
osmolality), as in dehydration which will stimulate osmoreceptors in the hypothalamus ADH. Hyperosmolarity of
ECF
Receptors in hypothalam
us
More ADH release
Thirst
Collecting ducts of kidneys
Reabsorption of water
Water intake
Dilution of ECF
-ve feedback
Control of ADH release … cont.
Loss of ECF volume
Less pressure in Rt. atrium & great
vessels
Less nerve impulse to the
hypothalamus
Thirst
More ADH release
More water reabsorption by kidneys
Water intake
Maintains ECF volume
2. blood volume ( 10%) stimulate mechanoreceptors in the great arteries (aorta & carotids) & right atrium ADH.
Control of ADH release …cont.
3. arterial blood pressure, due to blood volume ADH.
4. Age: ADH secretion water retention & hyponatremia.
5. Pain, emotional stress & physical trauma ADH secretion.
6. Drugs, e.g. morphine, barbiturates, & nicotine ADH
secretion.7. Alcohol ADH secretion.
Abnormalities of ADH release – Hyposecretion:
Lack of ADH Diabetes insipidus.
2 types of DI: a. Neurogenic (central, or cranial) … Problem in Hypothalamus or Post
pituitary gland
b. Nephrogenic … in collecting ducts of the kidneys.
Symptoms: Polyurea 20 L/day (N 1.5 L/d), Polydepsia,
specific gravity of urine (diluted urine),
plasma osmolality.
Abnormalities of ADH release – Hypersecretion:
ADH, ‘Schwartz-Bartter Syndrome’: - occurs after surgery. - adenoma, ectopic kidney. - Bronchial carcinoma.
Signs & Symptoms:
- Hyponatremia, i.e. [Na+] extracellularly to 110 mM.
(N = 140 mM); resulting in: - Mental confusion. - Coma. - Death, due to ventricular fibrillation.
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