18-Mar-16Male Reproductive System1 PARTURITION

18-Mar-16Male Reproductive System 2 Overview Means birth of the baby Towards the end of pregnancy Increased uterine excitability Leading to strong rhythmical contraction that the baby is expelled Cause ! Progressive hormonal changes Increase excitability of the uterine musculature Progressive mechanical changes

18-Mar-16Male Reproductive System 3 PARTURITION Hormonal factors Increase uterine contractility Increased ratios of estrogen to progesterone Progesterone Inhibits uterine contractility Estrogen Increase uterine contractility From 7 th month onwards estrogen levels increase progesterone levels remains constant/diminishes

18-Mar-16Male Reproductive System 4 PARTURITION Oxytocin Secreted by neurohypophysis increases uterine contractility near term Observations Increased oxytocin receptors towards the end Increased rate f oxytocin secretions at the time of labor Labour prolonged in hypophysectomised animals Uterine-cervix irritation/stretch increase oxytocin production

18-Mar-16Male Reproductive System 5 PARTURITION Fetal hormones i. Oxytocin from pituitary gland ii. Cortisone from adrenal glands iii. PGs from fetal membranes All increase the intensity of uterine contraction

18-Mar-16Male Reproductive System 6 PARTURITION Mechanical factors that increase uterine contractility 1. Stretch of the uterine musculature Increased fetal movements Twins are born on average 19 days earlier than a single child Increase contractility 2. Stretch or irritation of the cervix Elicit uterine contractions  Rupture of membranes; head of baby stretches cervix more forcefully than usual /irritation

18-Mar-16Male Reproductive System 7 PARTURITION Onset of labour A positive feedback mechanism for its initiation Weak and slow rhythmical contractions occurs most of pregnancy period Braxtom Hicks contractions At the end we have stronger contractions that stretch the cervix and later force the baby thru the birth canal thereby causing parturition process called labour

18-Mar-16Male Reproductive System 8 PARTURITION Theory Stretching of cervix by the fetus head finally becomes great enough to elicit a strong reflex increase in contractility of the uterine body This pushes the baby forward which stretches the cervix more and initiates more positive feedback to the uterine body Once the stretch of the uterine contraction becomes greater than a critical value each contraction leads to subsequent contraction that becomes stronger and stronger until maximum effect is achieved

18-Mar-16Male Reproductive System 9  Two types of positive feedback  Stretch of the cervix 1. Uterine contractions even more stretching of the cervix 2. Pituitary gland releases oxytocin  Abdominal muscle contraction during labour  Pain signals- from uterus and birth canal during labour elicit a neurogenic reflexes in the spinal cord to the abdominal muscles causing intense contractions of the muscles  Add greatly to the expulsion of the baby PARTURITION

18-Mar-16Male Reproductive System 10 Labour pains Ist stage Comes with each contraction Caused by hypoxia of uterine musculature Resulting from compression of the blood vessels in the uterus 2 nd stage When the fetus is being expelled thru the birth canal Much,ore severe pain caused by i. Cervical stretching ii. Perineal stretching iii. Tearing of structures in the vaginal canal itself PARTURITION

18-Mar-16Male Reproductive System 11 PARTURITION Pain conducted thru The mothers spinal cord to the brain by somatic nerves instead of by the visceral sensory nerves

18-Mar-16Male Reproductive System 12 Involution of the uterus after the parturition Occurs during the 1 st -5 th weeks Wt becomes less than half parturition wt within 1 week 4 th week in lactating mothers as small as before pregnancy Cause Suppression of pituitary gonadotropin and ovarian secretion due to lactation PARTURITION

18-Mar-16Male Reproductive System 13 Placental site on the endometrial surface autolyses, causing a vaginal discharge (lochia) Is first blood then serous in nature approx 10days Endometrial surface becomes re- epithelialised and ready for normal non gravid sex life PARTURITION

18-Mar-16Male Reproductive System 14 Development of the breast 1. monthly female sexual cycle Begins at puberty Stimulated by the estrogen Stimulates growth of the breast mammary glands Deposition of fats to give the breast mass 2. high eostrogen state of pregnancy Glandular tissue become completely developed for production of milk LACTATION

18-Mar-16Male Reproductive System growth of the ductal system Eostrogen-major role Secreted by placenta all thru pregnancy Growth & branching of ductal system Increased breast stroma quantity Large quantity of fat laid down in stroma Other hormones Growth hormone Prolactin Adrenoglucocorticoids insulin  Each plays some role in protein metabolism LACTATION

18-Mar-16Male Reproductive System 16 LACTATION 2. Development of the lobule-alveolar system Role of progesterone Development of milk secreting organs Progesterone acts synergistically with all above hormones Occurs after development of ductal system 1. Additional growth f the breast lobules 2. Budding of alveoli 3. Development of secretory characteristics in the cells of alveoli

18-Mar-16Male Reproductive System 17 LACTATION Initiation of lactation Function of prolactin From mother anterior pituitary gland Progesterone/oestrogen inhibit actual milk secretion Other hormones with lactogenic effect Placental human chorionic somatomammotropin

18-Mar-16Male Reproductive System 18 LACTATION CLOSTRUM Fluid produced last few days before and after the fisrts few days after parturition Contain protein & lactogen as milk No fat Maximum rate of production is 1/100 that of milk production Soon after birth Sudden loss of progesterone and eostrogen from placenta Prolactin lactogenic effect takes over From days 1-7 breast begins to secrete copious quantities of milk instead of colostrum Background production of growth hormone, insulin, cortisol, parathyroid hormone provide amino acids, fatty acids, glucose and calcium required for milk production

18-Mar-16Male Reproductive System 19 LACTATION Prolactin levels decreases soon after birth Each time the mother nurses the baby, nervous signals from the nipples to hypothalamus cause a fold surge in prolaction secretion that last for about 1 hour

18-Mar-16Male Reproductive System 20 LACTATION Hypothalamic control of prolactin secretion Hypothalamus inhibit prolactin production Damage to the hypothalamus or blockage of the hypothalamic hypophysial portal tract Increase prolactin secretion Decrease secretion of the anterior pituitary hormones Prolactin inhibitory hormone formed in hypothalamus is transported to hypothalamic hypophysial portal system then to anterior pituitry gland

18-Mar-16Male Reproductive System 21 SUPPRESSION of the female ovarian cycles in nursing mothers Nerve signals from the breast to the hypothalamus that cause prolactin secretion inhibit secretion of GnRH by the hypothalamus Decreasing LH/FSH LACTATION

18-Mar-16Male Reproductive System 22 LACTATION Ejection/let down process in milk secretion Function of oxytocin Neurogenic reflex Hormonal reflex When the baby suckles Sensory impulses are transmitted thru somatic nerves from the nipples to mothers spinal cord then to her hypothalamus

18-Mar-16Male Reproductive System 23 LACTATION Increased nerve signals promote oxytocin secretion & cause prolactin secretion Oxytocin Increases contraction of myoepithelial cells surrounding the outer walls of alveoli Milk expressed from alveoli into ducts at a pressure of +10 to 20mmHg seconds after a baby begins to suckle, milk begins to flow Process called milk ejection/milk let down

18-Mar-16Male Reproductive System 24 LACTATION milk production Physical touch/suckling/fondling Psychic – baby cry Inhibition of milk ejection Psychogenic factors Generalized sympathetic nervous system stimulation through out the mothers body Inhibit oxytocin secretion Depress milk production

18-Mar-16Male Reproductive System 25 LACTATION Milk composition Nutrients Antibodies Against E. coli Other anti-infection agents Wbc Neutrophills macrophages Macrophages against E.coli which cause lethal diarrhoea in newborns

18-Mar-16Male Reproductive System 26 LACTATION Metabolic drain on the mother caused by lactation With this degree of lactation great quantities of metabolic substrates are lost from the mother For instance 50 gm of fat per day 100gm of lactose per day 2.3 of ca2pho4 per day Out put of calcium & phosphates by lactating mammals is greater than intake

18-Mar-16Male Reproductive System 27 Unless the mother is drinking large quantities of milk and has adequate intake of vit D to supply the needed calcium & phosphate Parathyroid glands enlarge greatly Bone becomes progressively decalcified LACTATION