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42 Cards in this Set
- Front
- Back
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What are gametes produced from and where? |
Gametes are produced from germline cells. Gamete production in the testes. Gamete production in the ovaries. |
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Where are the seminiferous tubules and the interstitial cells and what do they do? |
Testes produce sperm in the seminiferous tubules and testosterone in the interstitial cells. |
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What does the prostate gland and seminal vesicles do? |
The prostate gland and seminal vesicles secrete fluids that maintain the mobility and vitality of the sperm. |
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What do ovaries contain? |
The ovaries contain immature ova in various stages of development. |
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What happens to the ova when it leaves the ovary? |
The ovum is surrounded by a follicle that protects the developing ovum and secretes hormones. Mature ova are released into the oviduct where they may be fertilised by sperm to form a zygote. |
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What do hormones control? |
Hormone control the onset of puberty, sperm production and the menstrual cycle. |
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Describe the hormonal onset of puberty. |
Pituitary gland is stimulated to release follicle stimulating hormone (FSH), luteinising hormone (LH) or interstitial cell stimulating hormone (ICSH) by a releaser hormone produced in the hypothalamus. |
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Describe the hormonal control of sperm production. |
FSH promotes sperm production and ICSH stimulates the production of testosterone. Testosterone also stimulates sperm production and activities the prostate gland and seminal vesicles. Negative feedback control of testosterone by FSH and ICSH. |
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How long is the menstrual cycle? |
The menstrual cycle takes approximately 28 days with the first day of menstruation regarded as day one of the cycle. |
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What does FSH do in the follicular phase? |
FSH stimulates the development of a follicle and the production of oestrogen by the follicle in the follicular phase. |
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What does oestrogen do in the follicular phase? |
Oestrogen stimulates proliferation of the endometrium preparing it for implantation and affects the consistency of cervical mucus making it more easily penetrated by sperm. Peak levels of oestrogen stimulate a surge in the secretion of LH which triggers ovulation. |
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What happens to follicle during the luteal phase? |
In the luteal phase the follicle develops into a corpus luteum and secretes progesterone. |
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What does progesterone do in the luteal phase? |
Progesterone promotes further development and vascularisation of the endometrium preparing it to recieve a blastocyst if fertilisation occurs. |
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What does the negative feedback effect of the ovarian hormones do in the luteal phase? |
The negative feedback effect of the ovarian hormones on pituitary gland and the secretion of FSH and LH prevent further follicles from developing. |
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What leads to menstruation? |
The lack of LH leads to degeneration of the corpus luteum with a subsequent drop in progesterone levels leading to menstruation. |
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What are infertility treatment based on and what problems are associated with them? |
Infertility treatments and contraception are based on the biology of fertility. Risks and ethicss associated with fertility treatments. |
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Describe fertility in men and women and how they can be used. |
Continuous fertility in males. Cyclical fertilitly in females leading to a fertile period. Calculation of fertile periods and their use. |
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Name the four main treatments for infertility? |
Stimulating ovulation, artificial insemination, intra-cytoplasmic sperm injection (ICSI) and in vitro fertilisation (IVF). |
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Explain stimulating ovulation. |
Ovulation stimulated by drugs that prevent the negative feedback effect of oestrogen of FSH secretion. Other ovulatory drugs mimic the action of FSH and LH. These drugs can cause super ovulation that can result in multiple births or be used to collect ova for IVF programmes. |
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Explain artificial insemination. |
Several examples of semen are collected over a period of time. Artificial insemination is particularly useful where the male has a low sperm count. If a partner is sterile a doner may be used. |
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Explain intra- cytoplasmic sperm injection. |
If mature sperm are defective or very low in number ICSI can be used- the head of the sperm is drawn into a needle and injected directly into the egg to achieve fertilisation. |
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Explain IVF. |
Surgical remove of eggs from ovaries after hormone stimulation. The eggs are mixed with sperm in a culture dish. The fertilised eggs are incubated until they have formed at least eight cells and are then transferred to the uterus for implantation. |
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Why is IVF used in conjunction with PGD? |
The use of IVF in conjunction with Pre-implantation Genetic Diagnosis to identify single gene disorders and chromosomal abnormalities. |
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What are the two different types of methods of contraception? |
Physical and chemical. |
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Name four common physical methods of contraception? |
Physical methods such as barrier methods, avoiding fertile periods, intra uterine devices and sterilisation procedures. |
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What are chemical contraceptives based on and what are two different types? |
Chemical contraceptives are based on combinations of synthetic hormones that mimic negative feedback preventing the release of FSH/LH. Some prevent implantation ('morning after pills') or causing the thickening of cervical mucus ('progesterone only pill'). |
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How is the health of the mother and developing fetus monitored? |
A variety of techniques can be used to monitor the health of the mother and developing fetus. |
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What does antenatal screening identify? |
The risk of a disorder so that further tests and a prenatal diagnosis can be offered. |
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What may anomaly scans detect? |
Serious physical problems. |
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What are dating scans for, what are they used with, and what is a potential problem with this? |
Dating scans, for pregnancy stage and due date, are used with tests for marker chemicals which vary normally during pregnancy. Measuring a substance at the wrong time could lead to a false result. |
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What do biochemical tests detect? |
They detect the normal physiological changes of pregnancy. |
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What other normal tests are carried out on the mother? |
Blood pressure, blood type and general health checks (including routine blood and urine tests). |
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What can detect medical condiditions? |
A range of marker chemicals that indicate a condition but need not necessarily be part of the condition. |
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What happens after routine screening for medical conditions? |
As a result of screening or for individuals in high risk categories, further tests can be offered. In deciding to proceed with these tests, the element of risk will be assessed as will the decisions the individuals concerned are likely to make if a test is possible. |
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What are the types of diagnostic testing and their advantages and disadvantages? |
Tests may include amniocentesis and CVS from the placenta. CVS can be carried out earlier in the pregnancy than amniocentesis. Although it has a higher risk of miscarriage, CVS karyotyping can be performed on the fetal cells immediately. |
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How is a karyotype produced? |
Cells from samples can be cultured to obtain sufficient cells to produce a karyotype to diagnose a range of conditions. |
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Generally, what kind of immune response do mothers show to their fetus? |
They usually show no immune respone to their fetus although sensitisation to Rhesus antigens can occur. |
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What type of antibodies are given to what kind of mother after what event? |
Anti-rhesus antibodies are given to rhesus-negative mothers after the sensitising event of birth. |
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Postnatally, what happens to individuals whith high levels of phenylalanine? |
They are placed on a restricted diet. |
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Postnatally what kind of disorders are tested for? Give an example. |
Diagnostic testing for metabolic disorders, including phenylketonuria (PKU) an inborn error of metabolism. |
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What are pedigree charts for? |
The use of pedigree charts to analyse patterns of inheritance in genetic screening and councelling. |
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Name the four patterns of inheritance for single gene disorders. |
Autosomal recessive, autosomal dominant, incomplete dominance and sex-linked recessive single gene disorders. |
