Hormonal control of Reproduction Flashcards
State the site of gamete production in males
Sperm are produced by seminiferous tubules in the testes.
How can seminiferous tubules produce sperm?
The tubules are lined with specialised germline cells which can carry out meiosis - a special type of cell division that produces gametes only.
State the site of testosterone production
Testosterone (the male sex hormone) is produced by interstitial cells, in the testes. Interstitial cells are found in-between the seminiferous tubules.
What is fertilisation
Fertilisation is the fusion of two haploid gamete nuclei to form a diploid zygote - this depends on the mobility of the sperm (their ability to swim and having fluid to swim in)
What is the function of the seminal vesicles and the prostate gland?
The fluid secreted by both the seminal vesicle and prostate gland maintains the mobility and viability of sperm.
These fluid, along with the sperm, make up the liquid called semen.
What is the term for cells which divide to form gametes?
Germline cells
What are the stages of the hormonal control of reproduction in males?
1) The hypothalamus produces a releaser hormone which triggers the onset of puberty.
2) The pituitary gland produces FSH and ICSH.
3) FSH and ICSH travels through the bloodstream to locate their target tissues at the testes.
4) FSH promotes sperm production in the seminiferous tubules. ICSH promotes testosterone production in the interstitial cells.
What are the roles of testosterone?
As the male sex hormone, testosterone has two roles to play.
1) Stimulates sperm production same as (FSH).
2) Activates the prostate gland and seminal vesicles to produce secretions that maintain the mobility and viability of sperm.
How is hormone production in males regulated?
Testosterone production is regulated by negative feedback control.
How does negative feedback control regulate testosterone levels?
1) High levels of testosterone inhibits FSH and ICSH production at the pituitary gland, leading to a decrease in testosterone production.
2) Low levels of testosterone stimulates FSH and ICSH at the pituitary gland, leading to an increase in the production of testosterone.
What are the phases of the menstrual cycle?
These are a series of events lasting approximately 28 days - day 1 of the cycle if the first day of menstruation.
Phase 1) The follicular phase (days 1-14 approx)
Phase 2) The Luteal Phase (days 14-28 approx)
What are the stages of the hormonal control of puberty and the menstrual cycle?
1) The hypothalamus produces a releaser hormone which triggers the onset of puberty.
2) The pituitary gland produces FSH and LH.
The Follicular Phase
3) FSH travels through the bloodstream to locate its target tissue at the ovary.
4) FSH stimulates the development of a follicle (becomes a mature follicle) inside the ovary, oestrogen is produced from the follicle.
The luteal phase
5) LH travels through the bloodstream to locate its target tissues at the ovaries.
6) LH stimulates ovulation (around day 14 of the cycle) and the development of the empty mature follicle into a corpus luteum which secretes progesterone until menstruation (the ovum will be shed along with the endometrium.), if fertilisation does not take place.
What allows the luteul phase phase of the menstrual cycle to begin ?
Peak levels of oestrogen stimulates a surge in the production of LH in the pituitary gland, this surge in LH triggers ovulation, allowing the luteal phase of the menstrual cycle to begin.
What is the role of oestrogen?
As the primary female sex hormone, oestrogen has two roles to play:
1) Stimulates the proliferation of the endometrium, preparing it for implantation.
2) Thins the cervical mucus, making it more easily penetrated by sperm.
What is the role of progesterone ?
As the secondary female sex hormone, progesterone has one role to play:
1) Promotes further proliferation and vascularisation of the endometrium, preparing it for implantation.
How is the production of ovarian hormones regulated?
Ovarian hormone production is regulated by negative feedback control.
How does negative feedback control regulate the production of ovarian hormones.
High levels of oestrogen inhibits FSH production at the pituitary gland, preventing further follicles from developing leading to a decrease in the production of oestrogen.
High levels of progesterone inhibits LH production at the pituitary gland, causing the corpus luteum to degenerate , leading to a decrease un the production of progesterone and the onset of menstruation.
What happens, during the menstrual cycle, if fertilisation takes place?
If fertilisation takes place:
-Corpus luteum does not degenerate
-Progesterone levels remain high
-Menstruation does not occur
Which structure provides protection for a developing ovum?
The follicle
Where is the site of fertilisation ?
The oviducts
State the term for a fertilised egg?
A (diploid) zygote
What causes menstruation ?
A fall in the level of progesterone due to the corpus luteum degenerating.
What is ovulation?
Ovulation is the release of a mature ovum from a follicle into the oviduct. After this, the mature ovum may be fertilised by sperm to form a zygote at the oviduct, travels down an implants in the endometrium.
Explain target tissues and hormones
Each hormone has a specific target tissue which means when a hormone reaches a specific target tissue, it brings about its specific effect.
What are the male pituitary hormones ?
Follicle Stimulating hormone (FSH) and Interstitial Cell Stimulating Hormone (ICSH)
What are the female pituitary hormones ?
Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH)
What are the ovarian hormones
Oestrogen and Progesterone
