Physiology of Pregnancy and Labour PHG 224 by Dr Agbaraolorunpo F.M

What is pregnancy marriage sex agbaraolorunpo

Ovulation Ejaculation Fertilization Cell division Implantation pregnancy agbaraolorunpo

Physiology of pregnancy Release of 400 millions of sperm into vagina Swimming of sperm → vagina → cervix →→uterus → fallopian tube About 50-100 sperms reach the ovum agbaraolorunpo

Takes place in the midportion of the fallopian tube. Fertilization= a single egg fuses with a single sperm to form a cell refer to as zygote Takes place in the midportion of the fallopian tube. Ovum releases chemical that attract the sperm to its. Sperm swims towards ovum in the fallopian tube The first sperm penetrate the Zona Pellucida of ovum via ZP 3 receptors. agbaraolorunpo

Mixing of genetic make up of sperm and ovum =zygote=embryo Acrosomal reaction takes place:acrosin in the head of the sperm (acrosome) bore hole in the zona pelllucida for the sperm to penetrate into the ovum Fusion of sperm and ovum facilitated by fertilin from the head of sperm Mixing of genetic make up of sperm and ovum =zygote=embryo Polysmermy is prevented agbaraolorunpo

Initiation of signals that brings about development of the embryo 3-5days Zygote Within 24 to 36 hours of fertilization the singe cell divides into two cells,after the next 12 hours to four cells and after another 12 hours to eight cells Initiation of signals that brings about development of the embryo Division of zygote →two cells→four cells→eight cells The Zygote continually divides to form a clusters of cell called morula agbaraolorunpo

The morula moves into the uterus after 3-4 days of fertilization Zygote The morula moves into the uterus after 3-4 days of fertilization The morula form a cell with cavity known as blastocyst The blastocyst burrow into the wall of uterus, a process know as implantation agbaraolorunpo

Implantation of blastocyst in the endometrium agbaraolorunpo

From zygote to fetus=amazing wonder of creation agbaraolorunpo

Implanted blastocyst develop into fetus and grow for 37-42 week before delivery agbaraolorunpo

Fetus growing in the uterus agbaraolorunpo

Identify the following states its function and its mportance agbaraolorunpo

Human Chorionic Gonadotropin (hCG) Placenta hormones Human Chorionic Gonadotropin (hCG) Human Chorionic Somatomammotropin (hCS) Estradiol Progesterone Relaxin agbaraolorunpo

placenta The placenta take over corpus luteum function after six weeks of conception The function of corpus luteum decline after 8 weeks of conception but persist throughout pregnancy agbaraolorunpo

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Functions of placenta Nutritive Excretory Respiratory Edocrine function agbaraolorunpo

hCG Effect on corpus luteum Is Glycoprotein Preservation and secretory activity of corpus luteum Progesterone and estrogen secreted by corpus luteum= maintenance of pregnancy. Absence of hCG within 2 months of pregnancy →involution of corpus luteum →abortion Is Glycoprotein Secreted by syncytiotrophoblast Has effect similar to LH Action is luteinizing Can be detected in blood 6days after conception Detected in urine as early as early as 14 days after conception Not specific to pregnancy .i.e seen in other several tumor as tumour marker agbaraolorunpo

Effect of hCG on fetal testes Similar to the effects of LH on adult testes Stimulates the interstitial cells of leydig→secretion of testosterone→development of male sex organs agbaraolorunpo

Human Chorionic Somatomammotropin Also called human placental lactogen(hPL) Secreted by syncytiotrophoblast of placenta Similar to growth hormone and prolactin Believe to act on mammary glands and to enhance the growth of fetus by influencing metabolic activities Act as maternal growth hormone of pregnancy to bring about nitrogen, potassium and calcium retention, mobilization of lipid, protein and glucose from mother to fetus decreased→ glucose utilization. It increases the amount of glucose and lipid in maternal blood which are transfer to the fetus Amount secreted is proportional to placenta size(normally weight one-sixth of fetus) Low hCS indicates placenta insufficiency agbaraolorunpo

Estrogen Uterus:enlargement of uterus to accommodate the growing fetus Breast: enlargement of breast and growth of breast system External genitalia:enlargement Pelvis:relaxation of pelvic ligament-for facilitation of fetal passage in the birth canal during labour agbaraolorunpo

progesterone Endometrium of uterus: increase secretory activity by stimulating decidual cells→nutrition of embryo during the early stage of conception Myometrim of uterus: inhibit contraction of uterus to prevent abortion.decreases the activity of oxytocin, estrogen and uterus sensitivity. Breast-development lobules and alveoli of breast=further breast enlargement =readiness for lactation agbaraolorunpo

Inhibits myometrial contraction Secreted by both corpus luteum Relaxin Inhibits myometrial contraction Secreted by both corpus luteum Also secreted by placenta at the time of labour agbaraolorunpo

Possible changes in reproductive system during pregnancy agbaraolorunpo

Physiological changes during pregnancy Ovaries: suppression of follicular development due to inhibition of LH and FSH secretion→suppression of menstruation/menstrua cycle Uterus and vagina size increase Cervix-soft and closed by mucus plug Mammary glands:enlarges Body weight: increases Metabolic activities increase:increase in protein metabolism, blood glucose→pregnancy induced diabetes(Gestational Diabetes) agbaraolorunpo

Physiological changes in pregnancy 7. Blood volume increases by 20% or 1L due to fluid retention→dilutional aneamia 8. Cardiac output increases in first trimester 9. Blood pressure remain unchanged with the tendency to increase during 3rd trimester Pre-eclampsia(toxeamia of pregnancy) in 3-4% of pregnant women during 3rd trimester Cause:autoimmune reaction to placenta or fetus,substance release by placenta agbaraolorunpo

Eclampsia-severe form of pre-eclampsia characterise by Severe hypertention ,convulsion, coma,kidney failure,heart failure,liver failure 10.urine formation and output increases due to increase RBF and GFR GIT: Morningsickness, nausea,vomiting,indigestion due to hormonal imbalance CNS:Psychological imbalance:change in mood,excitement,depression agbaraolorunpo

PARTURITION -LABOUR agbaraolorunpo

parturition Is the expulsion of fetus from the uterus at the end of pregnacy. Occur through a process called labour agbaraolorunpo

labour Preceded by Braxton Hicks contraction/false labour:weak, irregular, short and often painless True labour involves Descending of presenting part(head) in the pelvis Strong ,Regular, uterine contraction Dilatation of cervix from 0cm to 10 cm Shortening of length of cervix(effacement) Softening of Cervix agbaraolorunpo

Stages of labour Stage 1:dilation of cervix Stage 2:fetus descend through the birth canal Stage 3: expulsion of placenta agbaraolorunpo

STAGES OF LABOUR agbaraolorunpo

Parturition(neuroendocrine reflex) It is a positive feedback mechanism The head of the baby is the stimulus that stimulate the stretch receptors in the cervix Neural signal is conducted to the brain which is communicated to pituitary gland This result in oxytocin release from posterior pituitary glands Oxytocin causes the contraction of myometrium of the uterus The fetus is pushed further towards the cervix The head of the fetus further stimulate the receptor and the process continues until the fetus is expelled from the womb agbaraolorunpo

Hormone that participates in labour progesterone↓ estrogen↑ Oxytocin**(maternal↑↑ Cortisol Cathecholamines relaxin agbaraolorunpo

Congratulation agbaraolorunpo

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