2011 Pregnancy, Delivery and Birth Control

2011 Pregnancy, Delivery and Birth Control - Dr. Kennon...

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E-116 Dr. Kennon Garrett PREGNANCY, DELIVERY AND BIRTH CONTROL Reading: Vander et al., Human Physiology, 12 th ed. pp. 614-627. Behavioral Objectives 1. List steps that occur during fertilization. 2. List steps that occur during implantation. 3. Know anatomy and functions of the placenta. 4. Know hormones produced during pregnancy and their function. 5. Know adaptations that occur to the mother and fetus during pregnancy. 6. List steps that occur during parturition. 7. List adaptations in the neonate after birth. 8. Know how lactation occurs and is regulated. 9. Know the 4 mechanisms of birth control and the examples for the mechanisms. I. Fertilization (Fig. 17-25). A. Ovum transport 1. Movement of cilia on fimbria (fringe on tube opening) 2. Uterine tube smooth muscle contracts and cilia beat. 3. Ovum take 4 days to reach uterus B. Sperm transport 1. Transport from vagina to uterus Fluid pressure of ejaculation and movement of cervical cilia 2. Transport through uterus and uterine tubes Transport is mainly by swimming of sperm. Some transport by uterine smooth muscle contractions. Contractions are stimulated by prostaglandins in the seminal fluid and by oxytocin released by posterior pituitary during intercourse. Sperm can be found in uterine tubes from 5 to 60 minutes after ejaculation.
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E-117 3. Hormonal regulation of sperm transport a. estrogen – secreted in abundance in the late follicular phase helps prepare the female reproductive tract for efficient sperm transport creates an acidic vaginal environment which increases sperm motility and facilitates passage through the cervical canal creates watery secretions from cell lining the cervical canal which allows sperm to pass through the canal b. Progesterone In the secretory phase, progesterone causes the cells lining the cervical canal to secrete a thick fluid which prevents sperm from moving into the uterus. This thick mucous also prevents bacteria from entering the uterus and causing infections during pregnancy. 3. Sperm mortality Of approximately 100 – 600 million sperm deposited in the vagina, only 100,000 reach the uterus and only 50-100 reach the egg. Mortality due primarily to acidic vaginal environment. C. Sperm undergo capacitation . (Fig. 17-9) 1. Change in flagella to whip like movement 2. Acrosome membrane begins to dissolve to allow fusion with ova 3. Capacitation is caused by secretions from female reproductive tract capacitation takes several hours
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E-118 D. Fertilization 1. Many sperm bind to receptors on zona pellucida and undergo acrosomal activation; still motile. Enzymes in acrosome digest path through zona pellucida to reach the egg. 2. 1st sperm fuses with the egg membrane. The egg responds by a. Blocking fertilization by other sperm (polyspermy). b.
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2011 Pregnancy, Delivery and Birth Control - Dr. Kennon...

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