Presentation on theme: "11.4.7 Outline the role of the epididymis, seminal vesicle and prostate gland in the production of semen."— Presentation transcript:
Outline the role of the epididymis, seminal vesicle and prostate gland in the production of semen.
Sperm produced in seminiferous tubules In the epididymis, sperm are stored and gain motility On arousal, millions of sperm travel along the vas deferens – Near the bladder, seminal vesicle glands add a large volume of fluid (high fructose concentration) – Prostate adds more fluid (alkaline) to help spermatozoa survive female’s vagina
Compare the processes of spermatogenesis and oogenesis, including the number of gametes and the timing of the formation and release of gametes
How are the alike? Both begin with – mitosis Both make use of – LH and FSH Both include – 2 meiotic reduction divisions
How are they different? TIming Development into sperm between puberty & death Development into eggs between puberty & menopause Location Testis Oviduct Haploid/Diploid 4 haploid sperm cells 1 haploid egg cell
How are they different? Amount Millions of sperm are produced every day Typically, one secondary oocyte is ovulated per mentrual cycle Size Very small Very large Release During ejaculation Secondary oocyte released during ovulation
Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction
Fertilization Not as simple as “sperm meets egg” How does the sperm get through the zona pellucida? What causes meiosis of the egg to finish? How does the egg prevent further entry of sperm cells (polyspermy)
Outline the role of HCG in early pregnancy
HCG When the blastocyst implants into the endometrium, it starts to release HCG hormone.
HCG HCG concentration continues to rise for 8-10 weeks. HCG causes the corpus luteum to secrete estrogen & progesterone Progesterone and estrogen inhibit FSH and LH – so no more eggs are released
HCG Progesterone maintains the endometrium, where the blastocyst develops into a fetus and the placenta forms.
HCG Secondary oocyte left an outer ring of follicle cells within the ovary This layer begins mitotically dividing & secretes estrogen and progesterone This is a temporary endocrine gland (corpus luteum) If no fertilization, the corpus luteum secretes progesterone for about 14 days
Outline early embryo development up to the implantation of the blastocyst.
Early Embryonic Development Fertilization = zygote Start mitotic division 1 st division usually 24 hours after fert. Dividing and still moving down the fallopian tube getting closer to the uterus Approx. 100 cells by the time it reaches the uterus (4 -5 days later) Ready to implant – a blastocyst
Blastocyst Characterized by – Surrounding layer of cells called the trophoblast (helps with the fetal portion of the placenta) – A group of cells on the interior known as the inner cell mass and located toward one end of the “ball” (Inner cells become body of embryo) – A fluid-filled cavity
Explain how the structure and function of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy
HCG and the Placenta Large human ovum – contains nutrients needed for early development 1 st 2 weeks after fertilization – no true growth bc. embryo is still size of original egg Nutrients used for metabolism, not growth When embryo implants into the endometrium it is running out of food Embryo & maternal endometrium begin to create the placenta
Progestins Progesterone is a progestin with 2 major roles – Support the endometrium – provide an environment conducive to fetal survival. If the endometrium is deprived of progestins, the pregancy will be terminated – Suppression of contractility in uterine smooth muscle.
Estrogens Stimulate growth of the myometrium and antagonize the myometrial-suppressing activity of progesterone. Stimulate mammary gland development.
State that the fetus is supported and protected by the amniotic sac and amniotic fluid.
State that materials are exchanged between the maternal and fetal blood in the placenta
Blood supply 2 fetal blood vessels within the umbilical cord carry fetal blood to the placenta Blood within these 2 vessels is deoxygenated and carries waste products Fetal blood exchanges materials with the maternal bloodstream and another fetal blood vessel returns the blood to the fetus Returning blood is oxygenated and nutrients have been added while in the placenta
Blood mixing? At NO TIME does the blood of the fetus and the blood of the mother actually mix – exchange of material only
Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback
Hormonal control of Birth
Major events of vaginal childbirth Major hormone changes Opening of the cervix to 10 cm The most typical position for the baby is head- first, face down The shoulders of the baby are typically the widest part to pas through the birth canal The afterbirth is the name for the expelled placenta, occurring after the baby is born Lactation begins soon after birth
TWINS!!!! 30% of twins are identical 70% of twins are fraternal