menstrual cycle

Question 1

what does the pituitary gland produce

Answer 1

-FSH
-LH
-gonadotrophins

Question 2

what does FSH do

Answer 2

-stimulates the development of the follicle in the ovary and
-stimulates follicles to produce oestrogen
-released on day 1 of menstrual cycle

Question 3

what does oestrogen do

Answer 3

-low levels of oestrogen can repair the uterus lining after menstruation
-it inhibits FSH and LH
-high levels stimulates the production of FSH and LH by the pituitary gland.
-released on day 6/7 of menstrual cycle

Question 4

what does LH do

Answer 4

-causes ovulation
-ruptures the follicle so it can develops into the corpus luteum
-and stimualtes corpus luteum to produce progesterone.
-released on day 12 of menstrual cycle

Question 5

what does progesterone do

Answer 5

• maintain the lining of the uterus
• inhibits the production of FSH
• inhibits the production of LH
  -released on day 15 of menstrual cycle

Question 6

what is an exmaple of negative feedback in menstrual cycle

Answer 6

-increase in LH
-LH stimulates the corpus luteum to produce progesterone
-increase in progesterone conc
-progesterone inhibits production of LH

Question 7

what is an example of positive feedback in mesntrual cycle

Answer 7

-increase in FSH
-increase in oestrogen (from follicle stimulated by FSH)
-stimulates further release of oestrogen

Question 8

describe the process of fertilisation

Answer 8

-sperm binds to receptors on the zona pellucida of the egg
-acrosome releases enzymes to breakdown through egg
-sperm reach the outer surface of the zona pellucida
-another enzyme breaks down through the surface
-sperm fuses with microvilli and penetrates the cytoplasm
-zona pellucida thickens and hardens cortical reaction
- The ovum is produced after the second meiotic division of the secondary oocyte
-pronuclei is formed
-pronuclei of male and female fuse to form a zygote (fertilisation)

Question 9

what does the HCG hormone do

Answer 9

-secreted by the trophoblastic cells
-stops the breakdown of the corpus luteum
-the corpus luteum then carries on secreting oestrogen and progesterone and so the uterus lining builds up
-lining of endometrium is not lost so period doesnt occur
-the placenta takes over from corpus luteum where it then secretes oestrogen and progesterone
-miscarriage occurs when corpus luteum fails before placenta takes over.
-HCG is what forms the basis of pregnancy test as it can be detecetd in pregnancy