Reproductive physiology Flashcards
what do the testis contain?
- seminiferous tubules: to produce sperm
- Leydig cells: produce testosterone
what is the epididymis? what’s stored in them?
- one within each scrotal sac
- sperm stored in them
- at ejaculation, sperm passed through vas deferens
- mixed with fluid from seminal vesicles
- fluid leaves duct and passes into urethra to mix with prostrate secretions
what do leydig cells release? what stimulates them?
- testosterone
- LH stimulated
what do sertoli cells release? what stimulates them?
- inhibin
- FSH stimulated
describe spermatogenesis
- Germ cells (44XY) mitotic division - primary spermatocyte (44XY) 1st meiotic division - secondary spermatocyte (22X, 22Y) 2nd meiotic division - spermatids (22X, 22Y) - spermatozoa (22X, 22Y)
what does the ovary produce?
- gametes
- steroids (oestrogens and progesterones)
what do the fallopian tubes do?
- sustains oocyte
- conceptus
what happens in the uterus?
- conceptus implants here
what do thecal cells release? What stimulates them?
- oestrogen and androgens
- LH stimulates
what do granulosa cells release? what stimulates?
- androgens –> oestradiol
- produce progesterone in second half of cycle
- FSH stimulates
what do progestogens and oestrogens do to endometrium?
- progestogens: maintain endometrium
- oestrogens: stimulate proliferation of endometrium
what 2 cycles is the menstrual cycle composed of?
- endometrial: menstrual, repair, proliferative, secretory phases
- ovarian: follicular, luteal phases
describe the hormonal changes that cause the movement between stages of the cyle
- FSH and LH stimulate follicular phase
- results in oestradiol production = endometrial proliferation - oestradiol (E2) production continues at greater pace. -ve feedback switches to +ve
- ovulation occurs - corpus luteum produces progesterone and E2
- endometrium enters secretory phase
describe the menstrual phase in the endometrial cycle
- day 1 of cycle
- shed blood and enometrial lining
- remaining basal endometrium is very thin
- lasts around 5 days
describe the repair and proliferative phase
- 9 days
- stimulation of endometrial cell proliferation
- inc. in thickness
- number and length of glands
- length of arteries
- stimulated by E2 from follicular phase
describe the secretory phase of endometrial cycle
- production of nutrients and other factors
- epithelial glands widen, endometrium thickens, inc. coiling of spiral arteroes
- stimulated by progesterone and E2 from luteal phase
describe the follicular phase of ovarian cycle
- around 14 days
- FSH causes growth of ovarian follicle
- FSH and LH causes thecal and granulosa cells to release 17-beta oestradiol
- follicles continue to grow, producing more and more E2
- mid cycle get ovaluation
describe the luteal phase of ovarian cycle
corpus luteum produces progesterone and E2
what hormone dominates the proliferative or follicular phase?
oestrogen
what hormone dominates the secretory or luteal phase?
progesterone
how thick is the endometrium?
- 2-4mm
- 7-16mm
what happens to basal body temp around ovulation?
inc
describe the steps to the menstrual cycle
- gradual rise of oestradiol by developing follicle
- follicles grow and -ve feedback on LH and FSH
- dominant follicle selected and produces lots of E2
- -ve feedback switch to +ve = LH surge
- ovulation
- corpus luteum produces E2 and progesterone –> -ve feedback on LH/FSH
- no fertilisation = E2 and progesterone fall, endometrium enters secretory phase
where does folliculogenesis occur?
inside ovum
describe the stages in folliculogenesis
- oogonia (44XX) mitotic division - primary oocytes (44XX) 1st meiotic division - secondary oocyte + polar body (22X, 22X) 2nd meiotic division - ovum + polar body (22X, 22X)
what is the 1st meiotic division linked to?
- LH surge
- meiosis 2 follows immediately after this
- but pauses in metaphase 2
what is the time needed for a primordial follicle to get to a secondary oocyte? how does this work?
- primordial follicle (immature) –> secondary oocyte is more than one month
- human ovary contain multiple follicles at ALL stages of development
- one dominant Graafian follicle at any one time
during meiosis when are the 1st and 2nd divisions paused
- meiosis 1 starts during embryonic development
- halts at diplotene stage of prophase 1 (primary follicle)
- arrested at puberty
- meiosis then resumes and 2nd follicles develop
- 2nd follicles undergo 2nd arrest until fertilization
how many primordial follicles do ovaries contain?
- around 6m at 20 weeks of development
- 1m at delivery of infant
- 400 released over lifetime
how much sperm does the testes produce?
100m sperm/day from puberty onwards
define sexual reproduction
produce genetically different offspring
define sexual intercourse
required for:
- sexual reproduction
- sexual activity
- sexual pleasure
- human bonding
define biological sex
- identifies gender
- result of chromosomes
- produces different gametes
describe 3 different brain pathways involved in sexual reproduction
- meso-limbic DA system: produce genetically different offspring
- nigro-striatal tract: control of movements
- neuro-endocrine pathways: regulating fertility and parenting
what are the penile erection pathways?
- sexy thoughts in brain or tactile stimulus to penis (limbic system)
- spinal cord - efferent to penis, afferent back (pudendal nerve)
describe the penile erection changes
- inc. PNS to SM of pudendal artery
- inc. activity of NOS and so NO release
- NO stimulates cGMP –> vasodilation
- couteracts SNS-mediated myogenic tone
- inc. blood flow in corpus cavernosum
state the 6 steps to fertilisation
- deposition of sperm near cervix
- passage of sperm through uterus and fallopian tubes
- sperm moves to fallopian tube ampulla
- eggs meets sperm, fusion of egg with sperm
- change in zona pellucida to stop additional sperm fusing
- initiation of mitotic divisionsin embryo
describe the relationship b/ the cervical mucous and sperm
- cervical mucous is hostile to sperm –> forms physical barrier
- cervial mucous changes at mid cycle to permit sperm to enter uterus
what happens as the sperm moves to fallopian tube ampulla?
- survival of fittest
- capacitation takes place within uterus which matures spermatozoa
what happens when the egg meets the sperm?
- acrosome reaction: penetration of zona pellucida
- Ca flux
- resumption of meiosis, release of 2nd polar body
- alignment of maternal and paternal chromosomes to generate zygote
what is the cortical reaction?
- hardening of zona pellucida
- exclusion of other sperm
