1 - reproductive physiology Flashcards
Distinguish between biological sex, sexual reproduction and sexual intercourse
Biological sex - identifies gender, as a result of chromosomes (XX or XY), determines gonads which produce mature gametes
Sexual reproduction - process that produces offspring that differ genetically from both parents
Sexual intercourse - sexual activity requited for sexual reproduction. Associated with pleasure and human bonding
Recognise brain pathways associated with pleasure, the contribution to procreation and role in human bonding and parental behaviours
Mesolimbic dopaminergic system - reward pathway in brain
Pleasure, reward, fertility, reproduction and parenting pathways all linked
Activation of the pleasure pathway encourages intercourse — survival of human race
regulation of penile erection controlled by the brain
what occurs during erection
Controlled via the spinal cord efferent nervous system
Tactile stimulation – afferent system – pudendal nerve
during erection, there is increased parasympathetic activity to the SM of the pudental artery
Increased NOS – increased NO – increased cGMP – dilation of arterial SM – increased blood flow and compressed venous outflow — increased size of penis/ clitoris
Male gonads - what they do seminiferous tubules Leydig cells Sertoli cells Epididymis
Seminiferous tubules - produce sperm
Leydig - responsive to LH, produce testosterone, important for spermatogenesis and sexual differentiation
Sertoli - responsive to FSH, support spermatogenesis, regulate environment of seminiferous tubules
Epididymis - where sperm cells are stored prior to ejaculation
At ejaculation, sperm cells are released into the contractile…. and then pass through the….
during ejaculation sperm are mixed with fluid from the….
vas deferens
urethra
seminal vesicles and prostate gland
Female gonads - what they do
ovary
fallopian tube
uterus
Ovary - produce mature oocytes monthly, produces steroids needed for female reproductive function - progesterone and oestrogen
Fallopian tube - where oocyte is fertilised - path through which fertilised oocyte reaches uterus
Uterus - where conceptus implants and is supported
What is a follicle and what happens inside it
significance of granulosa and thecal cells
An oocyte in the ovary surrounded by granulosa cells
As the follicle develops, the granulosa cells proliferate
Thecal cells produce oestrogen for first half of cycle and the granulosa-luteal cells produce oestrogen and progesterones during the second half of the cycle
Hormonal control of the menstrual cycle (HPO axis)
Hypothalamus – GnRH which stimulates the pituitary gland
Pituitary secretes LH and FSH which stimulate the thecal and granulosa cells in the ovaries to secrete oestrogen and progesterone
These inhibit further LH/FSH secretion from the pituitary
3 stages of the ovarian cycle and what occurs in them
Follicular
- development of several follicles - only 1 stimulated to ovulate
- stimulated by FSH
- leads to an increased production of oestrogen which inhibits FSH and LH secretion
Pre-ovulatory
- follicle grows and produces more oestrogen
- dominant follicle selected for ovulation
- oestrogen switches and stimulates LH and FSH secretion leading to LH surge in ovulation
Luteal
- after ovulation, follicle develops into the corpus luteum
- corpus luteum produces progesterone
How are the ovarian cycle and endometrial cycle linked
the steroids (E and P) produced by the ovaries act on the endometrium
3 stages of the endometrial cycle and what occurs in them (which days)
Menstrual
- day 1-5
- shedding of blood and endometrial lining of the uterus
- remaining basal endometrium is v thin
Proliferative and repair
- Day 5-14
- stimulation of endometrial cell proliferation, increase in thickness, increase and number and length of glands, increase in length of arteries
Secretory
- Day 15-28
- production of nutrients and other factors
- epithelial glands widen, endometrium thickens, coiling os sprial arteries
- lining maintained by progesterone
Importance of progesterone and what produces the progesterone if there is pregnancy
Progesterone maintains the endometrial lining.
If there is no pregnancy, P drops and endometrium sheds
If there is a pregnancy, the corpus luteum maintains P levels – no menses
Gametogenesis in male
occurs in seminiferous tubules in the testis
T secretion from Leydig cells
Nutritional and hormonal support for Sertoli cells
Meiotic divisions to form a haploid gamete
Spermatogonium – 1 spermatocyte – 2 spermatocyte – spermatids — spermatozoa
Gametogenesis in female
occurs in the ovary supported by follicles
Oogonium – 1 oocyte (pauses here until puberty) – first meiotic division – 2 oocyte + first polar body (pauses here until fertilisation) – second meiotic division – ovum + second polar body
1st meiotic division completed after the LH surge (ovarian cycle), this only occurs in the ovulated oocyte —- in teenagers who have started menstruating
Second meiotic division ONLY completed after fertilisation (ovulated diploid)
the process of fertilisation
sexual intercourse - sperm deposited near cervix
survival of the fittest (acidity, cervical mucus, distance)
- acidity activates acrosome reaction
- mid cycle after ovulation the cervical mucus changes to increase chance of fertilisation
- capacitation of sperm (acrosomal cap altered so acrosome reaction possible, cell membrane changes so receptors are made available through glycoprotein layer)
- egg and sperm meet
- acrosome reaction - release of enzymes from sperm to break down zona pellucida
- calcium influx into oocyte:
- resumes meiosis (2nd division occurs) and forms the female pronucleus and 2nd polar body
- cortical reaction- zona pellucida hardens so no more sperm fertilises it
- sperm head undergoes decondensation
- —–both pronuclei are haploid at this stage
- DNA of both pronuclei are duplicated (2n of paternal and maternal)
- maternal and paternal chromosomes align to prepare for the first mitotic division
