Human Health and Physiology

6.6 Reproduction

6.6.1 Draw and label diagrams of the adult male and female reproductive systems.

 

6.6.2 Outline the role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinizing hormone), oestrogen, and progesterone.

FSH:

  1. Stimulates growth and development of follicle
  2. Stimulates the secretion of oestrogen by the follicle in the ovary

Oestrogen:

  1. Brings about repair and growth of uterine lining
  2. Stops FSH release (negative feedback)
  3. Stimulates production of LH

LH:

  1. Stops oestrogen release
  2. Stimulates follicle growth
  3. Triggers ovulation (egg is released from follicle to fallopian tube)
  4. Formation of the corpus luteum after ovulation
    1. Corpeus luteum secretes more oestrogen/progesterone

Progesterone:

  1. Maintains uterus lining/ thickening of endometrium
  2. Inhibits secretion of LH
  3. Inhibits production of FSH (in event of pregnancy)

Lowered level of progesterone due to degeneration of corpus luteum (if no embryo) leads to menstruation.

 

6.6.3 Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone levels and ovulation, menstruation and thickening of the endometrium.

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6.6.4 List three roles of testosterone in males.

  1. Pre-natal development of male genitalia
  2. Development of secondary sexual characteristics (armpit hair, development of muscles)
  3. Maintenance of sex drive

 

6.6.5 Outline the process of in vitro fertilisation (IVF)

  • Used in cases of blocked oviduct/ low sperm count/ need for genetic screening/ infertility/ cannot become pregnant/ need for donor embryo

 

  • Drugs used to down-regulate the menstrual cycle
  • FSH injected to stimulate many follicles to develop
  • HCG injected to cause the follicles to mature

 

  • Eggs are harvested/extracted from the follicles/ovaries
  • Semen sample produced/collected
  • Semen is processed to concentrate it/ healthy sperm selected (swim test)
  • ICSI where sperm is directly injected into egg when low numbers of motility is a factor
  • Semen is mixed with eggs in a dish to allow fertilization
  • Incubate at 37 degrees
  • Dish examined to choose healthiest embryo

 

  • Embryos placed in uterus/oviduct using long plastic tube/catheter
  • One to four embryos implanted
  • Pregnancy test used to see if procedure has been successful

 

6.6.6 Discuss the ethical issues associated with IVF

Pros:

  • Chance for infertile couples to have children
  • Decision to have children is clearly a conscious one due to difficulty of becoming pregnant
  • Genetic screening of embryos could decrease suffering from genetic diseases
  • Spare embryos can safely be stored for future pregnancies/ or stem cell research

 

Cons:

  • IVF is expensive and might not be equally accessible
  • Success rate is low and therefore it is stressful for the couple
  • Not natural/cultural/religious objections
  • Could lead to gender choice
  • Could lead to unwanted multiple pregnancies with associated risks
  • Production and storage of unused embryos/ legal issues for stem cell research
  • Inherited forms of infertility might be passed on to children

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