U2 KA 1-4

Created by

Murray

Cards (65)

what is the role of the testes
site of sperm production and the manufacture of testosterone
where is sperm produced
from germline cells in seminifererous tubules
where is testosterone produced
by the interstitial cells located in the tissue between the seminiferous tubules
what do the secretions from the seminal vesicles and prostate gland do together
maintain the mobility and viability of the sperm
what do the ovaries contain 
the ovaries contain immature ova in various stages of development
what protects ova in the ovaries
each ovum is surrounded by a follicle that protects the developing ovum and secretes hormones
what happens in fertilisation
mature ova are released into the oviduct where they may be fertilised by sperm to form a zygote
how is puberty triggered
- the pituitary gland is stimulated by a release hormone produced in the hypothalamus
- pituitary gland releases Follicle Stimulating Hormone (FSH), Luteinising Hormone (LH) or Interstitial Cell Stimulating Hormone (ICSH)
- this triggers the onset of puberty
role of FSH in males
promotes sperm production in the seminiferous tubules
role of ICSH 
stimulates production of testosterone in the interstitial cells
role of testosterone 
stimulates sperm production and activates the prostate gland and the seminal vesicles
negative feedback control of testosterone by FSH and ICSH
- as testosterone conc. builds up, it reaches a level that inhibits secretion of FSH and ICSH
- leads to decrease in testosterone conc, which stimulates pituitary gland to increase FSH and ICSH secretion
how long does the menstrual cycle last
takes approx. 28 days
what is day 1 of the menstrual cycle regarded as
the first day of menstruation
role of FSH in women
stimulates the development of a follicle and the production of oestrogen by the follicle in the follicular phase
role of oestrogen 
- stimulates proliferation of the endometrium, preparing it for implantation
- also affects consistency of cervical mucus making it more easily penetrated by sperm
what do peak levels of oestrogen trigger
a surge in LH secretion, which triggers ovulation
what is ovulation and when does it occur 
the release of an egg from a follicle in the ovary, occurs around mid-point of menstrual cycle
describe a graph comparing FSH and LH levels
Day 1-10
- LH decreases slightly then begins to increase a lot while FSH increases then decreases
Day 11 - 28
- LH increases a lot peaking at day 14
- FSH also increases peaking just before LH, does not peak as high
- both begin to decrease
describe a graph comparing oestrogen and progesterone 
- progesterone stays low until after day 14 (surge in LH)
- oestrogen increases, peaking high at day 14 before decreasing after
- after day 14, progesterone increases, peaking at day 21 before decreasing
what happens to the follicle after ovulation (in the luteal phase)
the follicle develops into a corpus luteum which secretes progesterone
role of progesterone 
promotes further development and vascularisation of the endometrium preparing it for implantation if fertilisation occurs
what happens in the luteal phase if fertilisation occurs
the corpus luteum does not degenerate and progesterone levels remain high
what happens to the corpus luteum if fertilisation does not occur
- lack of LH (from neg. feedback of oestrogen) leads to degeneration of corpus luteum with a subsequent drop in progesterone levels
- leading to menstruation
why don't more follicles develop after ovulation
negative feedback effect of ovarian hormones on pituitary gland and secretion of FSH and LH prevent further follicles developing
what is cyclical fertility
- women show cyclical fertility leading to a fertile period
- women are only fertile for a few days during each menstrual cycle
what is continuous fertility 
- men show continuous fertility
- continually produce sperm in their testes
how to identify fertile period in women
- body temperature rises by around 0.5°C after ovulation
- cervical mucus becomes thin and watery
how does stimulating ovulation work (infertility treatments)
ovulation can be stimulated by drugs that prevent negative feedback effect of oestrogen on FSH secretion
other ovulatory drugs (super ovulation) 
other ovulatory drugs mimic 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
process of artificial insemination and why is it useful
insertion of semen into female tract by some means other than sexual intercourse
- several samples 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 donor may be used to provide semen
Intra-cytoplasmic sperm injection (ICSI)
- 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
what is in-vitro fertilisation and the process 
surgical removal of eggs from ovaries after hormone stimulation, then incubation of zygotes and uterine implantation
- eggs are mixed with sperm in a culture dish
- the fertilised eggs are incubated until they have formed at least eight cells
- then they are transferred to uterus for implantation
pre-implantation genetic diagnosis (PGD) 
- used in conjunction with IVF to identify any single gene disorders and chromosomal abnormalities
- embryos screened for diseases before implantation
what is contraception 
the intentional prevention of conception
how do barrier methods of contraception work
physically blocks the ability of sperm to reach an ovum
how does an intra-uterine device (IUD) work
- a t-shaped structure that is fitted into the uterus
- prevents implantation of an embryo into the endometrium
- copper IUD works as a spermicide, others release hormones or thicken cervical mucus
sterilisation procedure in men
vasectomy
- involves cutting and tying of two sperm ducts, prevent sperm being released
- sperm produced undergo phagocytosis, destroyed
- highly effective, sometimes irreversible
sterilisation procedure in women
tubal ligation
- cutting and tying of the 2 oviducts to prevent eggs meeting sperm and reaching uterus
- highly effective, irreversible
how does the oral contraceptive pill work
- contains a combination of synthetic oestrogen and progesterone
- mimics negative feedback preventing the release of FSH and LH from the pituitary gland
- follicle development inhibited