Intro to RDA Flashcards
Functions of male reproduction system
androgens and production of mature sperm
The two important cells of the testis and roles
Sertoli cells: form the seminiferous tubule and produce sperm
Lyedig cells: Produce Testosterone and androgens and release into circulation
Function of the epididmys
Store of mature sperm
Route of sperm during ejaculation
Epidiymis, vas deferens, +semen, The fluid then leaves the ejaculatory duct, and passes into the urethra where it mixes with secretions from the prostate gland.
Which glycoprotein is produced by sertoli cells
Androgen Binding Protien
Explain which hormones lead to spermatogenesis
GnRH->FSH&LH. FSH acts on ABP. LH acts on Lyedig to produce testosterone, which also acts on ABP. Testostrone and Inhibin act on negative feedback
Spermatogenesis steps
Germ Cell 44xy, primary spermatocyte 44xy, secondary spermtocyte 22x22y, spermatid 22x22y, spermatozoa 22x22y, released into lumen
Functions of the ovaries
gametogenesis, oestrogen and progesterone production
Revise the anatomy of the uterus and surrounding structures
including zones of the uterus, ligaments, parts of the fallopian tubes
What are the gonadotrophin independent stages of follicle growth
primordial follicle -> primary follicle -> pre-antral follicle
What are the gonadotrophin dependent stages of follicle development
Small antral follicle -> Large antral follicle -> Pre-ovulatory follicle
Why do not all germ cells reach follicular stage
Atresia
Which cells are responsible for oestrogen production
thecal cells
Which cells are responsible for oestrogen production during the second half of the ovarian cycle
granulosa-luteal cells
Describe expected variences from the 28 day cycle
Normal range of 21-25. When menses starts can be longer eg. 45 days. at menopause, more irregular and more frequent
What are the endometrial cycle phases
Menstrual (days 1-5)
Repair and proliferative (9 days)
Secretory phase (13 days)
What happens in each of the endometrial cycle phases
Menstrual: Shedding of previous endometrium
Repair and Proliferation: 17b-oestradiol causes proliferation of endometrial cells
Secretory phase: Production of nutrients and widening of endometrial glands, increased coiling of arteries (progesterone and oestrogen)
What are the stages of ovarian cycle
follicular: 14 days -> Growth of the follicle, thecal and granulosa cells produce oestrogen, this switches from negative to positive feedback and so LH and FSH surge occurs and ovulation occurs. This is oestrogen mediated.
Luteal phase: 14 days -> follicle produces oestrogen and progesterone
When does oestrogen have negative feedback effectds
early, mid follicular phase and luteal
When does oestrogen have positive feedback effect
late follicular phase
What happens to body temperature during the luteal phase
it increases
When is the first meiotic division of folliculogenesis
first meiotic division is completed during the formation of the Secondary follicle, linked to the LH surge
When is the second meiotic division
Meiosis II follows immediately after this, but pauses in metaphase II
How long does folliculogenesis take
56 days, therefore roughly a month each ovary. Ovaries have follicles at all stages of development inside them occurring simultaneously
What is the dominant follicles pathway
becomes a secondary graffian follicle
How many primordial follicles are there at the time of birth
2 million
How many follicles are released in a lifetime
roughly 400
Describe the course of meiosis and the timing of the cell cycle in oogenesis
Meiosis I starts during embryonic development, but halts at the diplotene stage of prophase I (primary follicle); this persists until puberty when meiosis resumes as secondary follicles develop. Only a sub-population of follicles become secondary follicles, and these undergo another pause in meiosis at the metaphase stage of Meiosis II. Only fertilisation can cause the completion of meiosis in a human oocyte.
what is sexual reproduction
Produces offspring that differ genetically from both parents.
What is the purpose of sexual intercourse
Required for sexual reproduction
Sexual activity
Sexual pleasure
Human bonding
How is the brain involved in sexual reproduction
Mesolimbic pthway for reward and pleasure
Nigrostriatal tract: movement
HPaxis -> necessary hormones
Describe how an erection occurs
Initiated by: increased parasympathetic activity to smooth muscle of pudendal artery
Increases the activity of Nitric Oxide Synthase (NOS), and hence nitric oxide (NO)
NO increases production of cyclic GMP which induces dilatation of arterial smooth muscle.
counteracts sympathetic-maintained myogenic tone
increases blood flow in corpus cavernosum
which compresses the dorsal vein, restricting the outflow of blood
The urethra is protected from increased pressure by surrounding corpus spongiosum (less turgid)
Explain the link between viagra and cGMP
Cyclic GMP is normally de-activated by a phosphodiesterase enzyme, and this will reverse the changes leading to penile erection. Viagra inhibits the phosphodiesterase, thus potentiating the effects of cyclic GMP.
Describe the events leading to fertilisation
Deposition of sperm within female system following sexual intercourse.
Sperm are deposited near cervix
Cervical mucus is normally hostile to sperm
This forms a physical barrier to sperm
Cervical mucus changes at mid-cycle
This change permits sperm to enter uterus
Passage of sperm through uterus
Passage of sperm into Fallopian tube
Swim from there to Fallopian tube ampulla
~30 µm/sec average speed; 2 mm/min; 12 cm/hour
Survival of the fittest (a few days)
Capacitation – takes time within uterus
Capacitation is essential preparation before the sperm meet the oocyte
Meeting of egg with sperm
Fusion of egg and one sperm (within 24 hours post ovulation)
Acrosome reaction: penetration of Zona Pellucida (& Coronal cells)
Calcium flux
Resumption of meiosis, release of 2nd polar body
Alignment of maternal and paternal chromosomes to generate zygote.
Change in Zona Pellucida to prevent additional sperm fusing with zygote.
Initiation of mitotic (cleavage) divisions in embryo.
Whats the name of the hardening of the zona pelucida
cortical reaction
