Flashcards
Human reproduction
Flashcards do conjunto (38)
- 1Fill in the boxes of the diagram of a male reproductive system
- 2What is the function of the testes?Produce spermatozoa and makes testosterone which stimulates changes during puberty
- 3What is the function of the scrotum?A sac which protects the testes and holds them outside the body to keep them cool as sperm cannot be developed or stored above 37 degrees
- 4What is the function of seminal vesicles?Secrete mucus into the vas deferens. The mucus contains a mixture of chemicals including fructose for energy. The mucus makes it easier for the sperm to move and prevents them sticking together
- 5What is the function of the epididymis?Matures and stores sperm in coiled tubules
- 6What are the vas deferens?Carry sperm from testes to the urethra
- 7What's the function of the prostate gland?Sectretes prostate fluid including Zinc, and nourishes and protects the sperm
- 8What is the function of the urethra?Carries urine and sperm out of the penis but not at the same time
- 9What is the function of the penis?Delivers sperm to the vagina for fertilisation by ejaculation.
- 10Name the key features of the female reproductive system
- 11What is the function of the ovary?Produces the hormones oestrogen and progesterone. Site of ovum development
- 12What are the functions of the oviducts?Carry the ovum from ovary to uterus
- 13What is the function of the uterus?Site of implantation. Protects and accommodates the embryo as it develops
- 14What is the function of the endometrium?Innermost layer of the uterus wall. It is a mucous membrane, well supplied with blood. It builds and sheds in a monthly cycle.
- 15What is the cervix?A narrow ring of connective tissue. Dilates during childbirth and produces lubrication for sperm
- 16What is the function of the vagina?Receives sperm from the penis and produces fluid for lubrication
- 17What are the steps of spermatogenesis?Cells of the germinal epithelium are diploid. They divide by mitosis to produce spermatogonia and more germinal epithelial cells. Spermatogonia divide many times by mitosis and enlarge, making diploid primary spermatocytes and more spermatogonia. The primary spermatocytes then undergo meiosis I, making secondary spermatocytes which are haploid. Secondary spermatocytes undergo meiosis II, making haploid spermatids. Spermatids mature to become spermatozoa
- 18Where does spermatogenesis occur?In the seminiferous tubules
- 19What are the functions of the Leydig and Sertolli cells?Sertolli cells provide nourishment and protection of the developing spermatogonia. Leydig cells produce testosterone triggered from LH to stimulate the process of spermatogenesis
- 20Name the key features of this diagram
- 21What is the function of the sperm head?Nucleus contains the DNA for fertilisation. Acrosome Contains enzymes to break down the outer layer of the egg cell
- 22What is the function of the middle of the sperm?Contains many mitochondria which provide ATP for movement
- 23What is the function of the flagellum of the sperm?To propel the sperm forwards towards the uterus. They are not motile until they have been modified in the epididymis
- 24Describe the process of Oogenesis before birthDiploid cells in the germinal epithelium of the ovary divide by mitosis to produce more germinal epithelial cells and Oogonia. The Oogonia divide many times by mitosis and enlarge to produce diploid primary oocytes. The primary oocytes begin meiosis I but stop at prophase I. Germinal epithelium cells divide to form diploid follicle cells, which surround the primary oocytes, making primary follicles
- 25Describe Oogenesis from puberty onwardsHormones stimulate the primary follicles to develop further. Just before ovulation, a primary oocyte completes meiosis I, making a secondary oocyte. The other product is a much smaller cell and is called the first polar body. The secondary oocyte and polar body are both haploid.
The primary follicle develops into a secondary follicle, which is called the Graafian follicle when it is mature. Only one Graafian follicle is developed every month. The secondary oocyte begins meiosis II but stops at metaphase II unless fertilisation takes place. In ovulation, the Graafian follicle bursts, releasing the secondary oocyte. - 26What is the corpus luteum?The Graafian follicle becomes the Corpus luteum after releasing the secondary oocyte. If fertilisation occurs, it produces progesterone
- 27What is the structure of the secondary oocyte?A clear carbohydrate layer called the zona pellucida surrounds the cell membrane of the secondary oocyte. The chromosomes in the secondary oocyte are at metaphase II, so the chromosomes are attatched to the spindle fibres. On the periphery of the cytoplasm are cortical granules, which are secretory organelles which stop more than one sperm entering. Corona Radiata cells surround the secondary oocyte and provide nutrients
- 28What are the steps of fertilisation?capacitation, acrosome reaction, cortical reaction, completion of fertilisation
- 29What occurs during capacitation?Capacitation increases permeability of the membrane in front of the acrosome by removal of cholesterol and glycoproteins by the membrane. This makes it more permeable to Ca+.
- 30What occurs during the acrosome reaction?Acrosome releases proteases to digest Corona Radiata. Proteases then digest Zona Pellucida. Then cell membranes of secondary oocyte + sperm fuse. Secondary oocyte is now ovum
- 31What is the cortical reaction?Smooth ER in the Ovum releases Ca+ into the cytoplasm making cortical granules which fuse with cell membrane + release enzymes by exocytosis. Zona pellucida hardens to prevent polyspermy
- 32What happens in the completion of fertilisation?Entry of sperm= completion of meiosis II in ovum nucleus. Polar body is expelled. Mitosis occurs so genes from parents combine to make diploid cells. Formation of zygote. After first mitotic division it becomes an embryo.
- 33What occurs in implantation?Zygote undergoes repeated mitotic divisions called cleavage to form a ball of cells called the blastocyst. The blastocyst is moved to the uterus where it attatches and sinks into the endometrium. A placenta forms between the tissues of the mother and the foetus
- 34What is the process of the menstrual cycle hormones when pregnancy does not occur?1. FSH (Follicle stimulating hormone) is secreted by the anterior pituitary gland and stimulates the maturation of a follicle and releases oestrogen
2. Oestrogen rebuilds the endometrium ready for implantation and inhibits FSH from negative feedback but stimulates LH
3. LH (lutenising hormone) Peaks at around day 12, where it causes the Graafian follicle to release a secondary oocyte.
4. The remaining Graafian follicle turns into the corpus luteum, which secretes oestrogen and progesterone, which maintain the endometrium ready for implantation and inhibit secretion of FSH and LH so eventually their conc drops.
5. If no implantation occurs, the corpus luteum degenerates so progesterone and oestrogen drops and the endometrium sheds - 35What occurs to the corpus luteum when implantation occurs?Just before and following implantation, the developing embryo secretes HCG (Human Chorionic Gonadotrophin) which maintains the corpus luteum for the first 16 weeks of pregnancy
- 36(Make sure you can interpret this graph)
- 37What are the hormonal changes in pregnancy?Pregnancy- Placenta secretes oestrogen and progesterone after the corpus luteum has degenerated. Oestrogen inhibits FSH and stimulates the growth of mammary glands and the uterus to accommodate the growing foetus. Progesterone inhibits LH and suppresses the uterine wall's ability to contract
At birth- Just before birth oestrogen levels increase and progesterone levels decrease, allowing the uterine wall to contract. Oxytocin secreted by the posterior pituitary gland stimulates the contraction of the uterine wall, which stimulates the secretion of more oxytocin (positive feedback)
Prolactin is also secreted by the anterior pituitary gland to stimulate the production of milk by the mammary glands - 38What is the structure of the placenta?
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- AS level Biology (Unit 4- Griff) FlashCards sobre Human reproduction, criado por Seren Jones em 12-04-2018.
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- Seren Jones
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