Nervous system ppt/question, Schemes and Mind Maps of Law

Download Nervous system ppt/question and more Schemes and Mind Maps Law in PDF only on Docsity!

Female Reproductive system_

Dr Reem Abraham

1. Describe the development of the placenta and determine the importance of this organ for steroid production during pregnancy./intercellular signal transduction/Sexual reproduction
2. Describe the hormonal changes that accompany pregnancy and parturition./intercellular signal transduction/neuro-endocrine regulation/Sexual reproduction
3. Describe the major hormones produced by the fetoplacental unit and explain the role of each during the course of pregnancy/intercellular signal transduction/Sexual reproduction
4. Outline the processes involved in lactation./intercellular signal transduction
5. Relate why during pregnancy, there is a high level of prolactin in the blood but no lactogenesis./intercellular signal transduction/Sexual reproduction

At the end of this lecture, students should

be able to:

Learning Objectives

• (^) After implantation of the conceptus (the embryo and its adjacent parts or associated membranes differentiation of the endometrial cells to form the decidua basalis (endometrium of pregnancy), with stimulation from progesterone
• (^) The stored nutrients in the decidua are used by the embryo for growth and development.
• (^) Trophoblastic cells proliferate and form the syncytiotrophoblast, which allows the blastocyst to penetrate deep into the endometrium
• (^) While the trophoblastic cords from the blastocyst are attaching to the uterus formation of blood sinuses, supplied with blood from the mother develop around the outsides of the trophoblastic Events of early pregnancy

• (^) The trophoblast cells and other adjacent cells (from the blastocyst and the uterine endometrium) proliferate rapidly, forming the placenta and the various membranes of pregnancy.
• (^) Blood capillaries grow in the trophoblastic cords.
• (^) 21 days after fertilization, blood starts to be pumped by fetal heart into the capillaries.
• (^) Maternal blood sinuses develop around the trophoblastic cords.
• (^) More and more trophoblast projections develop (placental Events of early pregnancy

Placenta

• (^) Fetus’s DEOXYGENATED blood flows through two umbilical arteries , then into the capillaries of the placental villi;
• (^) OXYGENTATED BLOOD flows back through a single umbilical vein, from the placenta into the fetus.
• (^) Mother’s blood flows from her uterine arteries into large maternal sinuses that

• (^) Human Chorionic Gonadotropin (hCG) 8
• (^) Source: syncytiotrophoblast cells of placenta

hCG has biological activity similar to LH

hCG levels peak at week 10 of gestation and then begin to decline until reaching a steady state around week 25 Hormones of pregnancy

10

• (^) Pregnancy test is based on the excretion of large amounts of hCG in urine , which are measurable.
• (^) hCG is detectable in blood 1 week after fertilization and on home urine tests 2 weeks after fertilization. Hormones of pregnancy

hCG  peaks at 10 weeks and then declines

• (^) At this time placental progesterone maintains pregnancy

11 Hormones of pregnancy

• (^) Progesterone rises throughout pregnancy
• (^) During the first trimester, MAIN source of progesterone  corpus luteum
• (^) After about 10 weeks or so  placenta becomes the main

1. Maintains decidual lining of uterus to provide nutrition for fetus 2. Decreases uterine myometrial excitability, Inhibits uterine contractions -- inhibits prostaglandin production and decreases sensitivity to oxytocin (increases threshold for uterine contractions)  Maintenance of pregnancy
2. Stimulates the development of breast lobules and alveoli Actions of progesterone in pregnancy

• (^) The placenta synthesizes pregnenolone and progesterone from cholesterol.
• (^) Progesterone enters the fetal circulation and provides the substrate for the formation of cortisol and corticosterone in the fetal adrenal glands
• (^) Pregnenolone enters the fetus
• (^) In the fetal adrenal gland pregnenolone is converted to dehydroepiandrosterone sulfate (DHEAS)
• (^) In the fetal liver, DHEAS --  16 α- hydroxydehydroepiandrosterone sulfate (16-OHDHEAS)
• (^) 16-OHDHEAS is transported back to the placenta,
• (^) 16 α -hydroxydehydroepiandrosterone sulfate (16α -OHDHEAS) forms estriol in the placenta
• (^) The principal estrogen formed is estriol, and since fetal 16-OHDHEAS is the principal Fetal adren al gland: Cortisol , Cortico st- erone The principal estrogen formed in placenta is estriol
• (^) The fetus and the placenta interact in the formation of steroid hormones. Fetoplacental Unit

16 Lactation: Milk ejection reflex

• (^) Source of oxytocin : synthesized by the hypothalamus, stored and secreted from posterior pituitary
• (^) Oxytocin STIMULATES uterine contractions
• (^) Oxytocin STIMULATES contraction of myoepithelial cells of breast causing ejection of milk (milk let-down)
• (^) Suckling or baby crying stimulates oxytocin and

17 Lactation

• (^) High Prolactin levels during pregnancy
• (^) High estrogen and progesterone levels during pregnancy
• (^) Estrogen stimulates prolactin secretion during pregnancy
• (^) But lactation does not occur during pregnancy ,

because high estrogen and progesterone blocks

the action of prolactin on breast

• (^) After parturition  low levels of estrogen and

19 Regulation of prolactin secretion

• (^) Prolactin is tonically inhibited by Prolactin inhibitory hormone (PIH)/DOPAMINE, secreted from the hypothalamus

20