Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
McKenzie Health Science 20 NAME:_________________ Lesson 15.4 Pregnancy Objectives: 1. Describe how a zygote develops and implants in the uterus. 2. Describe the physiological changes that occur in the mother and developing child during pregnancy. 3. Explain the sequence of events involved in childbirth. 4. Explain how breast milk is produced and secreted. Saskatchewan Outcome: “I can analyze the anatomy and physiology of a healthy human” Saskatchewan Indicators: “I can describe the anatomy (structure) and physiology (function) of the reproductive system” Before this lesson, try to answer the following questions: 1. Where is the oocyte fertilized and where does it go after it’s fertilized? ANSWER:____________________________________________________________________ 2. What is the placenta, and how does it help the embryo and fetus develop? ANSWER:____________________________________________________________________ 3. What are the stages of labour? ANSWER:____________________________________________________________________ Key Terms: Amniotic fluid Dilation Fetus lactation placenta References: Notes & handouts Textbook Pages: 550 – 559 Study Guide Pages: 231 – 233 Blastocyst Embryo hCG let-down reflex prolactin Delivery of the placenta Expulsion implantation oxytocin Umbilical chord McKenzie Health Science 20 NAME:_________________ Reproduction 5: Pregnancy Out of a total of about 400 million ejaculated from the penis, only about 3000 make it to the oviduct. Of these 3000, only about 50 will make it to the mature egg. The egg is only fertile for 10 to 15 hours and a sperm lives for about 48 hours. Only one sperm can fertilize an egg and fertilization occurs in the OVIDUCTS. The sperm and egg are gametes which contain 23 chromosomes. (Normal body cells have 46). When the nuclei of the gametes fuse, a ZYGOTE with 46 chromosomes is formed. The zygote undergoes a number of mitotic divisions to become an EMBRYO which travels down the oviduct to the uterus. Inside the uterus, the embryo will undergo IMPLANTATION. Implantation marks the beginning of PREGNANCY. During implantation, the PLACENTA forms. The placenta not only provides the embryo with nourishment and oxygen and removes metabolic wastes, but it also produces HUMAN CHORIONIC GONADOTROPIC HORMONE. HUMAN CHORIONIC GONADOTROPIC HORMONE prevents the degeneration of the CORPUS LUTEUM The corpus luteum remains in the ovary and secretes even larger quantities of ESTROGEN and PROGESTERONE. The maintenance of high levels of estrogen and progesterone provide negative feedback and prevent the secretion of GONADOTROPIC RELEASING HORMONE. This effectively “shuts down” the anterior pituitary and maintains low levels of FOLLICLE STIMULATING HORMONE and LEUTEINIZING HORMONE. Low levels of FSH and LH prevent follicular maturation, ovulation and menstruation. The corpus luteum will eventually degenerate (after about 5 months). Estrogen and progesterone production is taken over by the maturing placenta. McKenzie Health Science 20 NAME:_________________ Oxytocin: Positive feedback control. Recall: Oxytocin is a hormone produced in the HYPOTHALAMUS but stored and secreted by the POSTERIOR PITUITARY gland. Oxytocin has two functions: 1. Stimulation of uterine contractions. 2. Release of milk by the mammary glands. Uterine Stimulation The number of oxytocin receptors in the uterus increase substantially during pregnancy. Although there is no increase in the amount of oxytocin in the blood, the increased number of receptors eventually makes the uterus so sensitive to oxytocin, strong uterine contractions begin. Strong, coordinated uterine contractions exert a POSITIVE FEEDBACK effect by stimulating the hypothalamus which signals the posterior pituitary to release more oxytocin. More oxytocin causes more contractions which cause more oxytocin secretions (positive feedback) until childbirth occurs. Milk Let-Down Milk LET-DOWN does not refer to milk production. Milk is secreted into sacs called ALVEOLI. However, milk must be moved into the MAMMARY DUCTS that lead to the nipples. This is milk let-down. Milk let-down is accomplished by contraction of the cells surrounding the alveoli. These cells are stimulated to contract by OXYTOCIN. The baby suckling the breast stimulates nerves in the breast. These nerve impulses travel to the hypothalamus which stimulates oxytocin release by the posterior pituitary. More oxytocin promotes more milk let-down which makes the baby happier. The baby suckles more and POSITIVE FEEDBACK occurs. Complete the Lesson 1. VIDEO: Watch https://www.healthyfamiliesbc.ca/home/articles/video-about-labour-and-birth 2. Read p. 550 – 558 3. Complete #1-10, p. 558 4. Study Guide pages 231 and 233 (handout)