Physiology of Pregnancy PDF

Physiology of Pregnancy Presented by Dr. Lamis Kaddam Dr Lamis Kaddam PhD Physiology 1  Objectives After this lecture you should be able to: 1- describe the mode of sperm transport up the female genital tract to the mid-oviduct. 2- discuss the physiological changes that oc...

Physiology of Pregnancy Presented by Dr. Lamis Kaddam Dr Lamis Kaddam PhD Physiology 1  Objectives After this lecture you should be able to: 1- describe the mode of sperm transport up the female genital tract to the mid-oviduct. 2- discuss the physiological changes that occur in the sperm before the penetration of the ovum. 3- list endocrinal changes during pregnancy. 4- describe placental hormones & their functions. 2 Dr Lamis Kaddam PhD Physiology Pregnancy (Gestation) Overview: 1. Ovulation 2. Fertilization 3. Implantation 4. Embryo 5. Fetus Mid-oviduct 3 Dr Lamis Kaddam PhD Physiology Fertilization Involves: 1. Chemoattraction of the sperm to the ovum (effect of oxytocin, PGs, ovum chemotactic Fs). 2. Adherence to zona pellucida (Z.P.). 3. Penetration of Z.P. via acrosome reaction. 4. Fusion to cell memb. of the ovum → breakdown of the area of fusion → release of the sperm nucleus into the cytoplasm of the ovum. 4 Dr Lamis Kaddam PhD Physiology  CAPACITATION Sperm capacitation occurs in the tube i.e. ↑ motility + preparation for acrosome reaction. Occurs in the fluid media of female genital tract. Requires 2 to 3 hours. Sperm undergoes physiological & chemical changes to make it capable of fertilizing the ovum. Only capacited sperm can penetrate the outer covering of ova known as zona pellucida. 5 Dr Lamis Kaddam PhD Physiology Dr Lamis Kaddam PhD Physiology 6  Notes on Fertilization Acrosome reaction Penetration of sperm is done by disolution of external membranes of ovum i.e corona radiata & zona pellucida. The penetration occurs by hyluronidase which is liberated from acrosomal cap of hundreds of sperms. Soon after penetration entry of other sperms is prevented & immobilization is done by viteline block & zona reaction(hardening). 7 Dr Lamis Kaddam PhD Physiology  Implantation Implantation occurs in the endometrium of anterior or posterior wall of the body near fundus on the 6th day( 20th day of menstrual cycle). Endometrium is in the secretory phase. Dr Lamis Kaddam PhD Physiology 8  Implantation Involves: 1. Blastocyst moves in the tube to the uterus → 2. Contacts with endometrium → outer layer (trophoblasts) → erodes endometrium and the blastocyst burrows into it. 9 Dr Lamis Kaddam PhD Physiology  Placenta Placenta develops after implantation, and the trophoblast remains associated with it, where placental hormones are secreted to maintain pregenancy. Functions of the placenta: 1 Transfer gasses 2 Transport nutrients 3 Excretion of wastes 4 Hormone production – temporary endocrine organ –estrogen and progesterone 5 Formation of a barrier – incomplete, nonselectivenancy. 10 Dr Lamis Kaddam PhD Physiology  Endocrinal Changes During Pregnancy After implantation, syncytiotrophoblast secretes human chorionic gonadotropin (HCG, placental gonadotropin) → Enlargement of corpus luteum instead of degeneration → C.L. of pregnancy → secretes progesterone & relaxin → maintenance of pregnancy by inhibiting uterine contractions. 11 Dr Lamis Kaddam PhD Physiology  Endocrinal Changes During Pregnancy HCG has weak FSH actions, but strong LH actions (luteinizing and luteotropic for the first 6-8 weeks of pregnancy) → C.L. continues to secrete Progesterone. & Estrogen. After the 8th week of pregnancy, ↓ HCG→ ↓ progesterone & estrogen from C.L. but maintained by the placenta till end of the pregnancy (full term) 12 Dr Lamis Kaddam PhD Physiology  Endocrinal Changes During Pregnancy 13 Dr Lamis Kaddam PhD Physiology  Endocrinal Changes During Pregnancy 14 Dr Lamis Kaddam PhD Physiology HORMONES OESTROGEN Produced in corpus luteum Produced by placenta after 12 weeks Responsible for growth particularly of uterus and breasts Dr Lamis Kaddam PhD Physiology 15 progesterone Produced in corpus luteum and then the placenta Relaxes smooth muscle Inhibits uterine contractions until uterus is prepared for labour Regulates storage of body fat Dr Lamis Kaddam PhD Physiology 16  Human chorionic gonadotrophic HCG Secreted from trophoblast of the developing embryo Maintains corpus luteum until placenta takes over Used in tests to confirm pregnancy Dr Lamis Kaddam PhD Physiology 17 Human placental lactogen Alters maternal metabolism Diverts glucose to fetus Mobilises free fatty acids from maternal stores Dr Lamis Kaddam PhD Physiology 18  RELAXIN Released by corpus luteum then the Placenta Softens pelvic ligaments Reduces myometrial tone Dr Lamis Kaddam PhD Physiology 19 The Fetoplacental Unit The fetus and the placenta interact in the formation of steroids. 20 Dr Lamis Kaddam PhD Physiology Test your understanding Upon fertilization and implantation, the degeneration of the corpus luteum is slowed by which of the following hormones? A.) LH B.) Estradiol C.) Progesterone D.) HCG Dr Lamis Kaddam PhD Physiology 21 Dr Lamis Kaddam PhD Physiology 22