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Fertilization & Pregnancy. Pregnancy —time from fertilization until infant is born —developing offspring —period of time from fertilization until week.

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Presentation on theme: "Fertilization & Pregnancy. Pregnancy —time from fertilization until infant is born —developing offspring —period of time from fertilization until week."— Presentation transcript:

1 Fertilization & Pregnancy

2 Pregnancy —time from fertilization until infant is born —developing offspring —period of time from fertilization until week 8 —week 9 until birth --date of last period until birth (approximately 280 days)

3 Journey to Fertilization The oocyte is viable for hours after are viable for hours after ejaculation For fertilization to occur, sexual intercourse must occur no more than and no later Sperm cells must make their way to the for fertilization to be possible

4 Journey to fertilization When sperm reach the oocyte break down the follicle cells of the corona radiata around the oocyte Once a path is cleared, sperm undergo an (acrosomal membranes break down and in the oocyte membrane) on an oocyte pull in the head of the first sperm cell to make contact

5 Occurrence of fertilization The does not permit a second sperm head to enter The oocyte then undergoes its to form the ovum and a polar body Fertilization occurs when the of a sperm combines with that of an oocyte to form a zygote

6 Zygote First cell of a new individual The result of the fusion of DNA from sperm and egg The zygote begins cell divisions The zygote stage is in the, moving toward the

7 Cleavage… not what you think Rapid series of that begins with the zygote and ends with Zygote begins to after fertilization 3 to 4 days after ovulation, the pre embryo reaches the uterus and floats freely for 2 to 3 days Late blastocyst stage—embryo implants in (day 7 after ovulation)

8

9 Embryonic Development —period of time from fertilization until week 8 —16-cell stage (chorionic vesicle)—hollow, ball- like structure containing about 100 cells

10 The Embryo The embryo first undergoes division without growth The embryo enters the uterus at the 16-cell state ( ) about 3 days after ovulation The embryo floats free in the uterus temporarily Uterine secretions are used for

11 The Blastocyst Ball-like circle of cells Begins at about the ___________________ Secretes (hCG) to induce the corpus luteum to continue producing hormones The late implants in the wall of the uterus (by day 14)

12 Development after Implantation (projections of the blastocyst) develop Cooperate with cells of the uterus to form the placenta —fluid-filled sac that surrounds the embryo __________________ Blood vessel-containing stalk of tissue Attaches the embryo to the placenta

13 Placenta Forms a barrier between (blood is not exchanged) Delivers _____________________________ from embryonic blood Becomes an (produces hormones) and takes over for the corpus luteum (by end of second month) by producing Estrogen Progesterone Other hormones that maintain pregnancy

14 The Fetus Fetus–week 9 until birth All organ systems are formed by the end of the __________ Activities of the fetus are specialization This is a stage of tremendous growth and change in appearance

15 12-week fetus (90 mm) Fertilization 1-week conceptus 3-week embryo (3 mm) 5-week embryo (10 mm) 8-week embryo (22 mm) Embryo

16 Effects on Female Body Anatomical changes Enlargement of the _______________ Accentuated ______________(lordosis) Relaxation of the and ___________due to production of relaxin

17 Physiological changes Gastrointestinal system Morning sickness is common due to ____________ _____________ _______________ is common because of organ crowding by the fetus Constipation is caused by declining motility of the digestive tract

18 Physiological Changes Urinary system Kidneys have additional _________ _________________ The uterus compresses the bladder, causing stress incontinence

19 Physiological Changes Respiratory system Nasal mucosa becomes ________________Vital capacity and respiratory rate increase Dyspnea (_______________) occurs during later stages of pregnancy

20 Physiological Changes Cardiovascular system Blood volume increases by ______ percent __________________________increase Varicose veins are common


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