Reproductive physiology Flashcards
Summarise the male reproductive system including the testis and the epididymis:
Provision of androgens (mainly testosterone) + the formation of the male phenotype through the mature sperm.
The testis have the seminiferous tubules which will form the sperm and the leydig cells which form the testosterone.
the epdidymis - there are two (one in each scrotal sac)- the sperm is made in the seminiferous tubules and it will stay there until ejaculation. Here it goes through the two vas deferns to the seminal vesicle where it is mixed and to the urethra where it is mixed with secretions of the prostate gland.
Describe the regulation of the male hormonal system:
FSH causes the release of inhibin A + B from the testis and sperm from the seminfereous tubules. There will then be spermatogenesis.
LH causes the releasse of testosterone from the leydig cells.
They are controlled by the release of GnRH.
There is a negative feedback mechanism.
Summarise the process of spermatogenesis:
Primordial germ cell –> spermatagonium –> primary spermatocyte –> secondary spermatocyte –> spermatotids –> mature sperm
This occurs in the seminiferous tubules. It occurs from the start of puberty to lifetime. The quality and number of sperm will detrioate as the man gets older but he can still have children at the age of 70.
Describe the regulation of the female hormonal system:
LHRH is released by the hypothalamus this leads to the pituitary releasing FSH and LH.
This leads to the release of oestrogen and progesterone.
What are the main organs in the female reproductive system?
Ovaries act at the testes do as they produce the gametes and the steroids.
The fallopian tubes have the right environment to sustain the oocyte.
Implants inside the uterus.
What cells produce the oestrogen and progesterone in the female reproductive system?
Thecal cells in the developing ovary will produce the oestrogen. FSH will stimulate 17-B oestradiol synthesis.
Luteal cells will produce oestrogen/progesterone in the second half of the ovarian cycle. LH will stimulate the luteal cells to form progesterone.
Describe the changes in the female HPO cycle:
At the start there is negative feedback exerted by the oestradiol - this is the follicular phase.
After this there is a positive feedback effect by the oestridiol leads to an increase in FSH and LH. (oestradiol rises mid-cycle leading to the LH surge)
There is then an LH surge (this drives ovulation)
Following this there is the luteal phase where it goes back to negative feedback. The progesterone remains high but LH, FSH and oestradiol will begin to decrease.
IN PREGNANCY THE WHOLE MENUSTRAL CYCLE IS HALTED AND PROGESTERONE REMAINS HIGH.
How does the menstrual cycle vary as a woman ages?
During puberty the periods can last longer than 28 days up to 45.
As a woman approaches menopause she gets more irregular periods.
What is the role of oestrogen on the endometrium?
This will thicken the endometrium alongside progestrone to get ready for implantation.
Describe the process of oogenesis before fertilisation?
primordial germ cell –> oogonium (this has no germ cells left) –> first polar body (this is essentially a nucleus as half of the chromosomes are taken away) –> stops at the production of the primary oocyte. The eggs are in meiosis and they are halted until puberty.
at puberty the follicles will grow and one of them will grow faster (dominant follicle) this will enter the second stage of development to form the secondary oocyte + 1st polar body. meiosis is then halted after metaphase II.
MEIOSIS IS ONLY COMPLETED UPON FERTILISATION.
THE LONGER THE EGGS ARE HELD THE POORER THE DNA HENCE THE ISSUES WITH LATE PREGNANCIES.
What happens during fertilisation?
The sperm swims through the fallopian tube to the ovary.
This sperm is detected by the ovum that will form corneal follicles around it.
The sperm will then undergo the acrosome reaction as it binds to the zona pellucida and this will digests into the ovum
As soon as this happens the nucleus will expand + de-condense to form a male pro-nuclei that it haploid. The ovum will then complete meiosis forming an ovum and a second polar body –> will also expand to form a female pro-nuclei.
they then replicate immediately and line up on the spindle and fuse then separate to give 2 2n genetically identical daughter cells.
Why are pleasure pathways activated during sex?
this links the reproduction and parenting to increase the bond and this will lead to an increase in sexual intercourse and so an increase in reproduction.
Describe the changes that occur during an errection:
this partly controlled by the brain and the pudendal nerve.
Parasymp increases activity down the pudendal nerve which then leads to an increase in the NOS. this increase NO and so leads to an upregulation of cAMP. this counteracts the symp myogenic tone. This dilation increases the blood flow in the corpus cavernosum.
Urthera is protected by the corpus spongiosum.
What happens to the clitoris during stimulation?
It will also increase in size through the same mechanisms as the penis through the NO.
