S2 EXAM- REPRODUCTION SYSTEM Flashcards
What does the follicle stimulating hormone do?
- From pituitary gland, targets the ovaries
- Stimulates the development and maturation of ovarian follicles
- Increases oestrogen
Luteinising hormone?
- from pituitary gland, targets ovaries
- promotes final maturation of ovarian follicle
- formation of corpus luteum, which secretes prog amd oest
Oestrogen?
From ovarian follicle, targets brain
Increases sexual maturation
Progesterone?
From corpus luteum, targets the brain
As prog increases, luteinising hormone decreases. Stops periods from coming
Human chorionic gonadotropin?
From placenta, targets the corpus luteum
Maintains the corpus luteum during the early stages of pregnancy
Oxytocin
From pituitary gland, targets the uterus and breasts
Causes uterine contractions amd promotes movement of milk In the breasts
Day 1-5 of cycle
Reduced oestrogen and progesterone causes the shedding of endometrium lining
Day 6-13
Follicles continue to divide and enlarge due to FSH. Secretes follicular fluid that protects and nourishes the oocyte. Forms mature follicle. FSH reduces.
The endometrium lining builds up, increasing blood vessels and mucous glands.
Day 14
Ovulation.
Mature follicle bursts, secondary oo the releases.
Most fertile phase- increased oestrogen causes increased FSH and massive spike in luteinising hormone
Day 15-25
Corpus luteum causes progesterone and oestrogen to increase. Lasts 8-10 days. If fertilisation, HcG produced by embryo maintains the corpus luteum to continue producing prog. Endometrial lining is maintained , secretes watery mucous to sustain possible embryo.
Oogenesis
Before birth- millions of oogonia develop. Finite number. Primary oocyte begins prophase 1.
At birth- 1000 still remain
At puberty- luteinising hormone and follicle stimulating hormone are released from pituitary gland. FSH acts on follicle cells, producing and releasing oestrogen. Oestrogen starts meiosis 1, primary oocyte becomes secondary oocyte, starts meiosis 2 but stops at day 14.
Ovulation - if no fertilisation, secondary oocyte remains dormant. If fertilisation, meiosis 2 is completed to produce mature ovum.
Spermatogenesis
Spermatogia begins dividing at puberty by mitosis. Some become primary spermatocytes. These undergo meiosis 1 and become secondary spermatocytes. These undergo meiosis 2 and become spermatids. Spermatids mature in spermatozoa.
Reproductive hormones in men
FSH- stimulates testes to create sperm
LH- stimulates testes to secrete testosterone
Testosterone- development of immature sperm into mature spermatozoa.
Oxytocin- movement of sperm, production of testosterone.
Infertility methods
Gamete intra fallopian transfer (GIFT); sper and eggs collected in a lab and inserted into a woman
In vitro fertilisation (IVF); hormones to stimulate ovaries and prepare uterine lining. Eggs and sperm mixed, embryo interred into uterus.
Surrogacy; another woman carries baby and gives it to couple.
Fertilisation
Occurs at top third of Fallopian tube. Enzymes in sperm head breaks down the corona radiata to enter ova. Only the head enters, fertilisation barrier forms around ovum so no other sperm an enter. Secondary oocyte completes meiosis 2 to form mature ovum.
Pronuclei fuse to make a diploid zygote—> starts mitosis to multiply
Contraceptive methods
Abstinence
Withdrawal
Spermicides- kills sperm
IUD- releases prog, mucous thickens
Condom
Mini pill- prog. Mucous thickens so sperm cant enter
Nuva ring- oest and prog. In for 3 weeks, out for period
Implanon- stick into skin under arm. Lasts 3 years
Morning after pill- prog. Prevents ovulation. Sperm cant reach egg
Reproductive technologies
Surgery- uterine tubes can be opened, sperm ducts ca be opened
Ovulation tracking- blood tests, hormones on-site red
Ovulation induction- medications taken to increase FSH to induce the development of follicles
How is placenta formed?
The yolk sac develops further to become the placenta after 12 weeks
Formation of Amniotic sac?
Amniotic fluid eventually forms sac around embryo and fuses with the chorion. Provides nourishment to foetus
What does van deferents do
Joins the urethra. A duct that transports sperm. If cut- vasectomy
What does the prostate gland do
Surrounds the urethra and secretes a thin, milky alkaline fluid.
Development of foetus
The 3 germ layers
Ectoderm; nervous system
Mesoderm; muscle and connective tissues
Endoderm; gut and internal organs
Changes to baby after birth
Forman ovale closing; increasing pressure, stimulating pumping an breathing
Lungs; blood flow in ductus arteriosus decreases. Blood now flows to lungs is pulmonary artery
Liver; blood flow in ductus venosus decreases. Blood now flows through liver and returns to heart via inferior vena cava.
