PARTURITION 16 Sep20 Male Reproductive System 1 Overview

PARTURITION 16 -Sep-20 Male Reproductive System 1

Overview n n Means birth of the baby n Towards the end of pregnancy n Increased uterine excitability n Leading to strong rhythmical contraction that the baby is expelled Cause ! n Progressive hormonal changes n n 16 -Sep-20 Increase excitability of the uterine musculature Progressive mechanical changes Male Reproductive System 2

PARTURITION n Hormonal factors n n Increase uterine contractility Increased ratios of estrogen to progesterone n Progesterone n n Estrogen n n Inhibits uterine contractility Increase uterine contractility From 7 th month onwards n n 16 -Sep-20 estrogen levels increase progesterone levels remains constant/diminishes Male Reproductive System 3

PARTURITION n Oxytocin n Secreted by neurohypophysis n n increases uterine contractility near term Observations n Increased oxytocin receptors towards the end n Increased rate f oxytocin secretions at the time of labor n Labour prolonged in hypophysectomised animals n Uterine-cervix irritation/stretch increase oxytocin production 16 -Sep-20 Male Reproductive System 4

PARTURITION n Fetal hormones i. iii. n Oxytocin from pituitary gland Cortisone from adrenal glands PGs from fetal membranes All increase the intensity of uterine contraction 16 -Sep-20 Male Reproductive System 5

PARTURITION n Mechanical factors that increase uterine contractility 1. 2. 16 -Sep-20 Stretch of the uterine musculature n Increased fetal movements n Twins are born on average 19 days earlier than a single child n Increase contractility Stretch or irritation of the cervix n Elicit uterine contractions Ø Rupture of membranes; head of baby stretches cervix more forcefully than usual /irritation Male Reproductive System 6

PARTURITION n Onset of labour A positive feedback mechanism for its initiation Weak and slow rhythmical contractions occurs most of pregnancy period n n 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 16 -Sep-20 Male Reproductive System 7

PARTURITION n Theory n n n 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 n each contraction leads to subsequent contraction n n 16 -Sep-20 that becomes stronger and stronger until maximum effect is achieved Male Reproductive System 8

PARTURITION Ø Ø Two types of positive feedback Stretch of the cervix 1. Uterine contractions n even more stretching of the cervix Pituitary gland releases oxytocin Abdominal muscle contraction during labour 2. Ø Ø Ø 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 16 -Sep-20 Male Reproductive System 9

PARTURITION n n Labour pains Ist stage n n Comes with each contraction Caused by hypoxia of uterine musculature Resulting from compression of the blood vessels in the uterus 2 nd stage n n 16 -Sep-20 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 Male Reproductive System 10

PARTURITION n Pain conducted thru n The mothers spinal cord n to n 16 -Sep-20 the brain by somatic nerves instead of by the visceral sensory nerves Male Reproductive System 11

PARTURITION n Involution of the uterus after the parturition Occurs during the 1 st-5 th weeks n Wt becomes less than half parturition wt within 1 week n 4 th week in lactating mothers as small as before pregnancy Cause n n n 16 -Sep-20 Suppression of pituitary gonadotropin and ovarian secretion due to lactation Male Reproductive System 12

PARTURITION n n n Placental site on the endometrial surface autolyses, causing a vaginal discharge (lochia) Is first blood then serous in nature approx 10 days Endometrial surface becomes reepithelialised and ready for normal non gravid sex life 16 -Sep-20 Male Reproductive System 13

LACTATION n n Development of the breast 1. monthly female sexual cycle n Begins at puberty n n 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 n 16 -Sep-20 Glandular tissue become completely developed for production of milk Male Reproductive System 14

LACTATION n 1. growth of the ductal system n Eostrogen-major role n Secreted by placenta all thru pregnancy n n Ø Growth & branching of ductal system Increased breast stroma quantity Large quantity of fat laid down in stroma Other hormones n Growth hormone n Prolactin n Adrenoglucocorticoids n insulin Each plays some role in protein metabolism 16 -Sep-20 Male Reproductive System 15

LACTATION n Initiation of lactation n Function of prolactin n From mother anterior pituitary gland Progesterone/oestrogen inhibit actual milk secretion Other hormones with lactogenic effect n 16 -Sep-20 Placental human chorionic somatomammotropin Male Reproductive System 17

LACTATION n CLOSTRUM n n n 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 n n 16 -Sep-20 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 Male Reproductive System 18

LACTATION n n Prolactin levels decreases soon after birth Each time the mother nurses the baby, nervous signals from the nipples to hypothalamus cause a 10 -20 fold surge in prolaction secretion that last for about 1 hour 16 -Sep-20 Male Reproductive System 19

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

LACTATION n SUPPRESSION of the female ovarian cycles in nursing mothers n Nerve signals from the breast to the hypothalamus that cause prolactin secretion n inhibit secretion of Gn. RH by the hypothalamus n Decreasing LH/FSH 16 -Sep-20 Male Reproductive System 21

LACTATION n Ejection/let down process in milk secretion Function of oxytocin n Neurogenic reflex n Hormonal reflex When the baby suckles n Sensory impulses are transmitted thru somatic nerves from the nipples to mothers spinal cord then to her hypothalamus n n 16 -Sep-20 Male Reproductive System 22

LACTATION n Increased nerve signals n n Oxytocin n promote oxytocin secretion & cause prolactin secretion Increases contraction of myoepithelial cells surrounding the outer walls of alveoli Milk expressed from alveoli into ducts at a pressure of +10 to 20 mm. Hg 30 -60 seconds after a baby begins to suckle, milk begins to flow n 16 -Sep-20 Process called milk ejection/milk let down Male Reproductive System 23

LACTATION n milk production n Inhibition of milk ejection n Physical touch/suckling/fondling Psychic – baby cry Psychogenic factors Generalized sympathetic nervous system stimulation through out the mothers body Inhibit oxytocin secretion n 16 -Sep-20 Depress milk production Male Reproductive System 24

LACTATION n Milk composition n n Nutrients Antibodies n Against n E. coli Other anti-infection agents n Wbc n n Neutrophills macrophages n Macrophages against E. coli which cause lethal diarrhoea in newborns 16 -Sep-20 Male Reproductive System 25

LACTATION n Metabolic drain on the mother caused by lactation n n With this degree of lactation great quantities of metabolic substrates are lost from the mother For instance n n 16 -Sep-20 50 gm of fat per day 100 gm of lactose per day 2. 3 of ca 2 pho 4 per day Out put of calcium & phosphates by lactating mammals is greater than intake Male Reproductive System 26

LACTATION n n n 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 16 -Sep-20 Male Reproductive System 27