Karteikarten
Reproduction
Karten in diesem Stapel (31)
- 1Draw the side and front view of the female and male reproductive systemsPicture
- 2What are the 3 roles of testosterone in the male?1. Pre - natal development of the male genitalia
2. Development of secondry sexual characteristics (pubic hair, lower voice, muscle mass)
3. Maintainance of the sex drive - 3What are the 3 phases of the menstrual cycle?1. Follicular Phase
2. Ovulation
3. Luteal Phase - 4What happens in the follicular phase of the menstrual cycle?1. Follical stimulating hormone (FSH) stimulates the growth of several follicles, only one develops
2. This dominant follicle secretes oestrogen that inhibits FSH and stimulates development of endometrium and stops other follicle growth - 5What happens in the ovulation phase of the menstrual cycle?1. A surge in lutenising hormone (LH) causes ovulation - the egg is released from the follicle
2. LH causes follicle cell to secrete less oestrogen and more progesterone and the follicle ruptures and creates the corpus luteum - 6What happens in the luteal phase of the menstrual cycle?1. The corpus luteum secretes more progesterone, stimulating the development of endometrium
2. Oestrogen and progesterone inhibit LH and FSH and the corpus luteum degrades and progesterone levels drop so the endometrium is not maintained
3. Endometrium is sloughed away (menstruation)
4. FSH is no longer inhibited so menstrual cycle starts again - 7What is the function of the epididymis in the testes?Where sperm mature and develop the ability to swim
The testicular fluids are removed and, concentrating the sperm - 8What is the function of the seminal vesicle in the testis?Adds nutrients (fructose/ amino acids) for respiration since sperm have high energy requirements
Secretes prostaglandins that cause contractions in the female system helping sperm move towards the egg - 9What is the function of the prostate gland in the testis?Secretes and alkaline fluid to neutralise vaginal acids which aids sperm mobility
Vaginal fluids are acidic as to stop infections and kill pathogens - 10Annotate a light micrograph of testis tissue to show location and function of interstitial cells, germline epithelial cells, developing spermatozoa and sertoli cellspicture
- 11What are testes composed of?Seminifoerous tubules surrounded by basement membrane
Lined by germline epithelium cells - they divide by MITOSIS to produce primary spermatocytes
Primary spermatocytes divide my MEIOSIS to make spermatozoa
Sertoli cells nourish the spermatozoa
Outside of the tubules are blood capillaries and interstitial (leydig) cells that produce testesterone - 12What happens in spermatogenesisSpermatogenoesis is the production of sperm in the seminiferous tubules of the testes
1. The germline epithelial cells divide by mitosis to produce diploid cells that grow larger tp ,make primary spermatocytes
2. Each primary spermatocyte carries out the first division of MEIOSIS to produce two haploid secondary spermatocytes
3. Each secondary spermatocyte divides by secondary division of meiosis to produce two spermatids
4. Spermatids associate with sertoli cells that nourish developing spermatids as they differentiate to become spermatozoa (sperm)
5. Sperm detach from sertoli cells and go into the centre of the seminiferous tubule (lumen) and carried out into the fluid - 13What are the hormones that are involved in spermatogenesis?ANDROGENS
1. LH (Pituitary gland) - Stimulates Leydig cells to produce testosterone
2. FSH (Pituritary gland) - Stimulates first meiotic division of spermatogonia
3. Testosterone (leydig cells) - Stimulates the second meiotic division of spermatogonia and the differentiation of spermatozoa - 14Draw the mature sperm and eggPicture
- 15Annotate a diagram of the ovaryPicture
- 16What is in the ovary?The ovary contains follicles in various stages of development
Egg cells with primordial follicles have been arrested in prophase 1 and have yet to undergo meiotic division
Egg cells within mature follicles have begun meiotic division and released from the ovary as secondary oocytes (arrested prophase 2)
The ruptured follicle develops into a corpus luteum that will degenerate into corpus albicans
The germline epithelium functions as an epithelial layer separating ovarian tissue from the rest of the body (not involved in oocyte development) - 17What does the ovary consist of?A central area (medulla) surrounded by a cortex
Outer layer is germline epithelium - 18What happens during oogenesis?1. In the ovaries of a female foetus, germinal epithelium cells divide by mitosis to form diploid cells that grow to form primary oocytes
2. Primary oocytes start the first meiosis division but are arrested at prophase 1 until puberty. The primary oocyte and a single layer of follicle cells form a primary follicle (when a baby is born it contains around 400,000 primary follicles)
3. Every menstrual cycle, few primary follicles start to develop. The primary oocyte completes first division of meiosis, forming two haploid nuclei of different sizes. The bigger is the secondary oocyte, the smaller, the polar body that will then degenerate
4. The secondary oocyte starts second division of meiosis and stops at prophase 2 it is released from the ovary and the ruptured follicle develops into the corpus luteum
5. The secondary oocyte will not complete meiosis 2 unless it is fertilised. The second meiotic division will produce an ovum and a second polar body, which degenerates - 19Compare and contrast oogenesis and spermatogenosisSIMILARITIES:
- Both result in haploid gamates
- Both involve mitosis, growth and meiosis
DIFFERENCES:
- LoCaTiOn - testis/ovary
- NuMbEr Of GaMaTeS - lifelong (millions)/ 400 mature
- GaMaTeS pEr CeLl - Four/ one
- BeGiNiNg Of PrOcEsS - Puberty/ foetal development
- EnD oF pRoCeSs - Lifelong fertility/ menopause
- TiMiNg Of GaMaTe ReLeAsE - any time/ once a month
- MeIoTiC dIvIsIoN - Uninterrupted/ arrested - 20What is the process of fertilisation?1. The sperm enters the female tract and it finally matures - capacitation
2. The sperm is attracted to the egg due to chemical signals from secondary oocyte
3. The first sperm that breaks through the layer of the follicle cells binds to the pellucida and triggers the
4. The acrosome reaction - the sperm makes contact with the zona pellucida (glycoprotein coat) and contents of the acrosome is released. The enzymes relesaed break down the coating and the sperm forces its way through with vigouros tail beating
5. Proteins in the sperm can bind to the egg membrane and sperm and egg membranes fuse. The sperms nucleus (and centriole) enter the egg - FERTILISATION
6. This causes the cortical reaction - It prevents other sperm from penetrating the fertilised egg by making cortical granules near the surface to release their contents by exocytosis - causing zona pellucida to become impenetrable
7. Now fertilised, the nucleus of the secondary oocyte completes meiosis 2 and the egg and sperm nuclei fuse to form a diploid zygote - 21How does the early embryo develop?1. After fertilisation, the zygote undergoes several mitotic divisions to create a solid ball of cells - a morula (at 4 days)
2. Unequal divisions cause a fluid- filled cavity to form in the middle, making a blastocyst (at 5 days)
3. The blastocyst is transported down the oviduct to the uterus and at around 7 days, it implants in to the endometrium in the uterus wall to grow and develop
4. The embryo continues to grow and at 8 weeks, it starts to develop bone tissue and then on is the foetus - 22What does a blastocyst consist of?1. An inner cell mass (the embryo)
2. An outer layer - the trophoblast (the placenta)
3. A fluid filled cavity - the blastocoele - 23What is the structure and function of the placenta?The placenta is disc-shaped and nourishes the developing embryo
It forms from the development of the trophoblast upon implantation and eventually invades the uterine wall
The umbilical cord connects fetus and placenta and maternal blood pools via open ended arterioles (uterine arteries and veins) into intervillous spaces (lacunae)
Chorionic villi extend into these spaces and facilitate the exchange of material between maternal blood and fetal capillaries
Nutrients, oxygen and antibodies are taken up by the foetus and CO2 and waste products are removed
The placenta is expelled from the uterus after childbirth - 24What is the role of hormones in pregnancy?HCG prevents the degeneration of the corpus luteum and stimulates it to grow and continue secreting oestrogen and progesterone
The placenta takes over hormonal control of the ovary at around 12 weeks and the corpus luteum degenerates
Oestrogen stimulates growth of the muscles of the uterus (myometrium) and the development of mammary glands
Progesterone maintains the endometrium as well as reducing uterine contractions and maternal immune response
Both oestrogen and progesterone levels drop at time of birth - 25What is the amniotic sac?The amniotic sac and the amniotic fluid protects and supports the foetus, acting as a shock absorber
Sample of the fluid can be taken via amniocentesis, as they contain fetal cells that can be cultured for division and these chromosomes can be tested for abnormalities such as downs syndrome - 26What is exchanged via the placenta between maternal and fetal blood supplies?Maternal to fetal includes:
Oxygen, glucose, lipids, water, vitamins, antibodies, hormones and amino acids
Fetal to maternal includes:
Carbon dioxide, urea, hormones and water
Maternal blood is in the intervillous space and capillary carrying fetal blood is separated by the chorion - a placental barrier that controls what goes in and out - 27What happens during childbirth, and what are the hormones that control it?After the 9 months, the foetus is fully grown and stretches the uterine walls releasing prostoglandins that cause myometrial contractions and, causing a signal to be sent to the posterior pituitary to release oxytocin
Oxytocin inhibits progesterone, which would inhibit uterine contractions and it also stimulates the smooth muscle of the uterine muscle to contract
This causes further stretching, releasing more oxytocin (positive feedback)
The contractions make the cervix relax and become wider
The amniotic sac will burst and amniotic fluid is released
Contractions then only stop once the baby is born and placenta is expelled as there is no more stretching of the wall - 28What is meant by infertility?Pregnancy is not achieved even when sex occurs at the right stage of the menstural cycle
- 29What happens during IVF?1. Drugs are injected to stop menstrual cycle
2. Large doses of FSH hormone injected to stimulate follicle developments
3. HCG is injected to loosen eggs in follicles to make them mature
4. Semen is ejaculated into a jar and sperm are concentrated for the healthiest
5. Multiple eggs are extracted
6. Eggs are mixed with sperm in jars and kept in an incubator in hope of fertilisation
7. Two or three embryos are selected and placed into the uterus
8. Pregnancy tests are done to see if any have implanted
9. Scans for pregnancy - 30What are the advantages of IVF?Allows couples to have children
Genetic screening of embryos could reduce the occurrence of genetic diseases
Spare embryos can be stored for future attempts or stem cell research
Embryos that are killed through IVF feel no pain as there is no developed nerves - 31What are the disadvantages/ ethical issues against IVF?It is expensive, so not available to all
Low success rate - stress
Lead to gender choices
Multiple pregnancies that are often unwanted and pose extra risks
Issue of disposing of unwanted embryos
Cultural and religious objections to creation
Inherited forms of infertility could be passed onto children
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- IB Biology Karteikarten am Reproduction, erstellt von P H am 15/03/2015.
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- P H
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