Unit 2 Flashcards - Production of gametes, biological control of fertility, screening
Name the cells that gametes are produced by?
Germline cells
Name the organs that produce sperm.
Testes
Name the tissue within the organ that produces sperm.
Seminiferous tubules
What hormone does the interstitial cells produce?
Testosterone
What does the prostate gland and seminal vesicles secrete?
They secrete fluids that maintain the mobility and viability of the sperm
What do the ovaries contain?
Immature Ova in various stages of development
What is each ovum surrounded by?
A Graafian follicle that protects the ovum and secretes hormone.
Where does fertilisation take place?
The Oviduct
What is a zygote?
A fertilised egg
What hormone is released to begin puberty?
Releaser hormone
Name the organ which releases releaser hormone.
Hypothalamus
What does releaser hormone stimulate?
The pituitary gland to release FSH and ICSH in males and FSH and LH in females
What does FSH in males stimulate?
Sperm Production in the seminiferous tubules and activate the prostate gland and seminal vesicles
What does ICSH stimulate in males?
The interstitial cells to produce testosterone
What do high levels of testosterone cause?
The inhibition of the pituitary gland which prevents the release of FSH of ICSH
This is negative feedback and brings the testosterone levels back to set point
Sperm production decreases until a low level is detected. At that point, the pituitary gland begins to release FSH and ICSH again.
How long does an average menstrual cycle take?
28 days
What day is regarded as the first day of the menstrual cycle?
Day one. This is the first day of a girls period.
What is the function of FSH in females?
Stimulates the development of the Graafian follicle and production of oestrogen by the follicle and ovarian tissue.
What is the function of oestrogen?
Stimulates the proliferation of the endometrium preparing it for implantation and affects the consistency of cervical mucus making it more easily penetrated by sperm.
What do peak levels of oestrogen stimulate?
A surge in secretion of LH
What does LH stimulate?
Ovulation
What day does ovulation typically occur on?
Day 14
What is day 1-13 typically referred to as?
The folicular phase
What is day 15-28 typically referred to as?
The luteal phase
After ovulation, what does the graafian follicle develop into?
Corpus Luteum
What causes the graffian follicle to develop into this structure?
LH
Which hormone does the corpus luteum secrete?
Progesterone
What is the function of progesterone?
To thicken the endometrium and cause vascularisation of the endometrium, preparing it to receive a blastocyst if fertilisation occurs.
What does high concentrations of progesterone cause?
The inhibition of the pituitary gland from secreting FSH and LH, which prevents further follicles from developing.
What does the the lack of LH cause?
The degeneration of the corpus luteum with a subsequent drop in progesterone levels leading to menstruation.
Is female fertility cyclical or continuous?
Cyclical. Females are only fertile for 2-3 per month. Males are continually fertile.
How can female infertility be treated?
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 in vitro fertilisation (IVF) programmes.
Stimulating ovulation. Ovulation stimulated by drugs that prevent the negative feedback effect of oestrogen on FSH secretion.
Name two processes which females can fall pregnant without having sexual intercourse
Artificial insemination or IVF
What does artificial insemination involve?
Collecting samples of the male’s sperm over time (preserved by freezing) and depositing them in the female reproductive system (artificially). The act of sexual intercourse does not take place.
Under what circumstance can artificial insemination be used?
If male’s have a low sperm count. If a man is sterile, a donor who has a normal sperm count can be used.
Describe 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.
Describe the process of IVF
- The female is given hormonal treatment to stimulate multiple ovulation
- Eggs are removed from her ovary
- The eggs and sperm are mixed in a culture dish of nutrient medium to allow fertilisation to occur.
- The eggs are incubated in the medium for 2-3 days to allow cell division to occur and form embryos of 8 or more cells
- Two or three embryos are chosen and then inserted via the vagina into the mothers uterus.
- The remaining embryos are frozen and stored in case a second attempt at implantation is required.
Before the embryos are inserted in the vagina of the female, what can be removed?
Cells to be be tested for genetic abnormalities.
