Reproduction Review

Reproduction Review

HormonesSecreted from anterior pituitaryFSH and LHBind to receptors located on the membrane of follicle cellsFSH Development of oocyte in the follicle ( ovary)Thickening of follicle wallSecretion of follicular fluidSecretion of estrogen by follicle wallMore hormonesLHCompletion of meiosis in oocytePartial digestion of the follicle wall allowing it to burst open (ovulation)Ovarian HormonesEstrogenThickening of endometriumBlood vessel growth in endometriumIncrease in FSH receptors in follicleInhibition of FSH secretion and stimulation of LH secretion when estrogen levels are high.

Explain how hormones control the menstrual cycle in human females.(Total 8 marks)

FSH stimulates the development of follicles;FSH stimulates estrogen secretion (by the developing follicle);estrogen stimulates the repair of the uterus lining;estrogen stimulates LH secretion;LH causes ovulation;LH causes the development of the corpus luteum;LH causes secretion of progesterone;progesterone causes thickening of the uterus lining / prepares uterine lining for implantation;progesterone / estrogen inhibits the secretion of LH / FSH;falling progesterone levels at the end of the cycle allow FSH production / menstruation;feedback control;8 max

HormonesProgesteroneMaintenance of thickening of the endometrium with many blood vesselsInhibition of FSH and LH secretion

Outline the process of in vitro fertilization (IVF).(Total 6 marks)

(IVF) is fertilization outside body / "in glass";(drug) stops normal menstrual cycle;(inject FSH) to stimulate ovaries / stimulate production of eggs;(HCG) matures the follicles;eggs are removed from follicles / ovaries / mother;male provides sperm / sperm donor;washing / capacitation of sperm;eggs are mixed with sperm;23 embryos are implanted into uterus;pregnancy test is done to see if implantation / pregnancy has occurred;[6]

Discuss the ethical issues of in vitro fertilisation (IVF) in humans.(8)Arguments against (IVF):fertilized egg has potential to become a person / some view a fertilizedegg as having special status;IVF requires the production of multiple embryos;fate of extra embryos is ethical concern;ethics of long-term storage;stem-cell research is blurring issue as other cells now have the possibility of becoming a person;procedure may result in multi-embryo pregnancy which places stresson the family resources / unwanted children;issues of equity of access / expensive;high rates of failure;ownership / responsibility for stored embryos an issue;religious opposition / playing God;

Arguments favouring (IVF):only way some couples can have children / helps infertile couples;allows for genetic screening;allows for surrogate mothers;8 maxFor full marks at least two of the points should include the counter-argument,otherwise [6 max].

Spermatogenesis

Oogensis

Describe the structure and function of the placenta.(Total 6 marks)

structure: [3 max]placenta is composed of fetal and maternal tissues;villi increase surface area;vascularization / capillaries within placental villi;intervillous spaces through which maternal blood flows;function: [4 max]secretes estrogen to maintain uterine lining;secretes progesterone to maintain uterine lining;gas / nutrient exchange for fetus;removes waste products;acquiring passive immunity / antibodies cross placenta;secretes HCG;[6]