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Flashcards in Repro Session 7 Deck (80):

what happens to semen immediately after ejaculation?

coagulates due to action of clotting factors- fibrinogen and vesiculae


function of coagulating sperm immediately after ejaculation?

to prevent their physical loss from the vagina


what happens after coagulation of semen?

it then liquefies by action of enzymes derived from prostatic secretions- fibrinolysis


what maturational changes do sperm undergo on their passage through the uterus to the uterine tube?

capacitation and acrosomal reaction, which results in them acquiring a full capacity to fertilise ovum
changes first began during their transport from testis to epididymis, and continuing during their storage there until ejaculation


how are capacitation and acrosomal reaction induced in spermatozoa?

by an influx of calcium and rise in cAMP


describe the process of capacitation of sperm

removal of glycoprotein coat promotes changes in sperm cell membrane. Tail movements change from waves to whip-like thrashing movement, propelling sperm along, and they become responsive to signals from oocyte.


what marks the start of the acrosomal reaction?

the membrane fusion when a capacitated sperm come s in contact with the occyte zona pellucida


how is sperm helped to be moved along seminiferous tubules?

by fluid secreted from Sertoli cells


phases of coitus?

excitement- vasodilation
orgasmic- further stimulo
resolution (+/- refractory period)- vasoconstriction, no physiological refractory period in females where sex arousal can not occur for mins-hrs, latency


what haemodynamic changes causing erection occur?

Must be vasodilation via:

inhibition of S.arterial vasoconstrictor nerves
PNS activation- unique as PNS doens't normally act directly on blood vessels
activation of non-adrenergic, non-cholinergic AN nerves to arteries, releasing NO


importance of NO for erection?

ACh released from post-ganglionic PNS neurones onto endothelial cell and binds to M3 receptor- Gq- PLC activation, with IP3 release, acts on IP3 receptors to cause increase in IC Ca2+, which activates NOS and so forms NO, which then diffuses into vascular smooth muscle cell and causes relaxation through gunalyl cyclase stimulation, increase cGMP, PKG activation, decrease Ca2+.
NO also released directly from non-adrenergic, non-cholinergic neurones


mechanism of action of viagra?

inhibits cGMP bdown, so more around to activate PKG, and reduce IC Ca2+ conc within vascular smooth muscle cell, inducing relaxation, hence vasodilation


what is the female sexual response?

blood engorgement and erection: clitoris, vaginal mucosa, breast and nipples
glandular activity- vaginal vestibule
sex excitement as in male
with or without orgasm as not essential for fertilisation- only occurs with ejaculation in male- need orgasm
no physiological refractory period


efferents of penile erection?

pelvic nerve- PNS
pudendal nerve-somatic


causes of erectile dysfunction?

psychological- descending inhibition of spinal reflexes
tears in fibrous tissue of corpora cavernosa as unable to stop venous drainage necessary to maintain erection
vascular- arterial and venous e.g. diabetes
drugs e.g. anti-hypertensives, alcohol


factors which block NO?

diabetes, alcohol, anti-hypertensives


how does fibrous tissue of corpora cevernosa help maintain erection?

very tight to prevent venous drainage


why is withdrawl a poor method of contraception?

live sperm are present during emission as spermatozoa move from vas deferens into prostatic urethra, despite ejaculation having not yet took place, so some leakage of live sperm into female before ejaculation


describe processes involved in emission and its control

sperm from epididymis moves through vas deferens to prostatic urethra, via vas deferens peristalsis under SNS control

mainly SNS control, but PNS control of glandular secretions

accessory gland secretions e.g. bulbourethral- pre-ejaculate- alkaline, lubricates urethra and neutralises any acid, control via PNS


describe mechanism of ejaculation

spinal and cerebral reflex
SNS control- L1 and L2
contraction of smooth muscle of glands and ducts, bladder internal sphincter contracts- involuntary control- hypogastric nerve T10-L2 to prevent backflow of semen into bladder that could cause dry orgasm,
rhythmic striated muscle contractions- pelvic floor, ischiocavernosus, bulbospongiosus, hip and anal muscles
PNS may be involved


normal ejaculate volume?



normal sperm concentration of ejaculate?

20-200 million sperm per ml


within how long does liquefaction of sperm occur after ejaculation

1 hour


important clotting factor produced in seminal vesicle secretion?



importance of seminal vesicle secretion being alkaline?

neutralise acid in male urethra from urine, and female vagina, alkalinity better for sperm survival


typically, over which days of uterine cycle does uterine proliferation take place and why?

days 7-14
oestrogen increasing due to production from ovaries: FSH stimulates granulosa cells to produce aromatase which can convert androgens produced by theca interna under LH influence to oestrogens- oestradiol namely


how might oxytocin help sperm transport?

role in rhythmic uterine movements


why do numerous sperm need to reach fertilisation site?

in order to disperse zona pellucida


viable period for oocytes?



when is the fertile period and why?

up to 3 days before ovulation or day of ovulation= 14 days before menstruation occurs, as sperm viable for 48-72hrs and must allow time to travel to ampulla of fallopian tube for fertilisation


outer part of ovum that sperm must push through for fertilisation?

granulosa cells


which cells release hCG from conceptus?



what do proteins on sperm head bind to on ovum?

ZP3 proteins of zona pellucida, receptor= species specific


what does binding of proteins of sperm cell to ZP3 receptors trigger?

acrosomal reaction


why is polyspermy blocked after fertilisation?

cortical granules in oocyte cytoplasm, in cortical reaction, release chemicals which stop any further sperm as cause hardening of ZP


importance of cleavage not increasing size of cells from mitosis?

morula would be unable to get into the uterus as still passing along uterine tube


what may happen if blastocytst implantation is close to cervix?

early miscarriage


common implantation site of blastocyst?

2/3 of the way up the posterior uterine wall


how long does conceptus spend in uterine tube before implantation and why?

3 days
awaiting rise in progesterone that results in smooth muscle relaxation in fallopian tube, espec intramural segment, to allow movement into uterus


in an ectopic pregnancy, why does the embryo die?

insufficient blood and nutrient supply to embryo.
egg has failed to be transported


why can severe maternal bleeding occur with ectopic pregnancy?

conceptus invasion into local blood supply- ovarian and uterine arteries, ovarian- from abdominal aorta, uterine- from anterior division of internal iliac, so blood vessel rupture


during which days of uterine cycle is zygote to blastocyst stage?



how many days after ovulation does implantation commence?

6 days


what does conceptus have to wait for before implanting when floating in intrauterine fluid?

trophoblast to become sticky over inner cell mass by developing receptors.


stimulants of penile erection?

tactile- sensory afferents of penis and perineum


changes in female which facilitate coitus?

Vaginal lubrication- vaginal vestibule glandular activity
Swelling and engorgement of the external genitalia- blood- vasodilation
Internal enlargement of the vagina
Cervical Mucus
 Oestrogen – Abundant, clear, non-viscous mucous, aids sperm transport
 Progesterone + Oestrogen – Thick, sticky mucous plug


ischiocavernosus and bulbospongiosus innervation

Pudendal (S2-S4)


how many sperm penetrate ovum cytoplasm?

Only one sperm, and its nucleus fuses with the nucleus of the ovum. This forms the zygote.


main action of progesterone when used as a contraceptive?

production of thick, hostile, cervical mucus plug that prevents sperm entry into uterus


examples of natural contraception? what are the disadvantages?

coitus interruptus (or withdrawal)- may not be effective in preventing pregnancy as sperm present in pre-ejaculate that will enter vagina, also no protection against STIs
rhythm method- need regular cycle, would avoid coitus on days 7-16 of uterine cycle=fertile period


what method of contraception prevents sperm entering ejaculate?

vasectomy: vas deferens divided bilaterally, but must ensure ejaculate is free of sperm before relying on it for contraception, so check a few months later.
Sperm phagocytosed by epithelia of vas deferens and epididymis as unable to pass from tail of epididymis to prostatic urethra during peristalsis of vas deferns under SNS stimulation during emission


what are the barrier methods of contraception?

o Condoms- readily available and also protect against STIs
o Diaphragm- Lies diagonally across the cervix, needs correct fitting, does not completely occlude the passage of sperm, holds sperm in the acid environment of vagina and reduces survival time
o Cap- Fits across the cervix- physical barrier


what contraception can be used to prevent sperm passing through cervix?

combined OCP
depot progesterone- 3mnthly injectiona
progesterone only pill-low-dose
progesterone impant

main mode of action for POP and implant


contraception to inhibit ovulation?

Comb OCP
depot progesterone
POP- may inhibit ovulation
progesterone implants- may inhibit ovulation


effect of progesterone on GnRH release by hypothalamic neurones?

reduces frequency of GnRH pulses


what contaception can be used to inhibit sperm transport along uterine tube?

sterilisation: clips, rings, ligation


how can implantation be inhibited by contraception?

hormonal- affect receptivity of endometrium
post-coital contraception- combined oestrogen/progesterone high dose, or progesterone only, up to 72 hrs after intercourse, may disrupt ovulation, and may also impair luteal function.
intra-uterine device- copper coil, can be used post-cotal up to 5 days after ovulation


how does an intrauterine contraceptive device work?

inert or copper containing, or progesterone impregnated. Copper interferes with endometrial enzymes, assoc. FB reaction with many inflam. cells, and may also interfere with sperm transport into fallopian tubes, so interferes with implantation.
problems= infection, perforation


define infertility

failure to conceive within 1 yr when not using contraception


what is primary infertility?

infertility with no previous pregnancy


what is secondary infertility?

infertility having had previous pregnancy, whether successful or not


Anovulatory causes of infertility?

Hyperprolactinaemia, weight loss, exercise, stress= hypothalamus
Pituitary tumours- prolactinoma, necrosis- post-partum haemorrhage, insufficent blood to pituitary- sheehan syndrome, may present so many mnths-yrs after birth of child with now inability to conceive, no problems before this birth
Ovarian failure, menopause- premature- <40yrs, radiotherapy and chemotherapy gonadotoxic



how do you differentiate causes of anovultation?

look at hormone levels


how can hormone levels distinguish between PCOS and ovarian failure as causes of anovulation?

PCOS: increased LH:FSH, and normal oestrogen
ovarian failure: high LH, high FSH, low oestrogen


when is serum progesterone at its peak?

7 days after ovulation


how could POS be investigated?

ultrasound scan


how is anovulation diagnosed?

serum progesterone level in mid-luteal phase, approx. day 21 (7 days after ovulation)
usually >30, if no ovulation, no CL forms, no rise in progesterone


how can ovulation be induced in patients with anovulation?

anti-oestrogen: clomiphene or tamoxifen, reduce -ve fbk to hypothalamus/pit by preventing oestrogen from binding to receptors to inhibit gonadotropin release, so increase GnRH and FSH
gonadotropins- FSH administration
GnRH agonists- pulsatile to mimic normal secretion


examples of coital problems causing infertility?

poor erection- may give viagra- inhibit cGMP bdown


causes of tubal occlusion resulting in infertility?

sterilisation- ring, ligation
scarring from infection-salpingitis, PID, endometriosis- endometrial tissue outside uterus-increased PG prod. may promote inflammation ,adhesions and fibrosis


how can tubal occlusion be treated?

tubal surgery- reanastomosis
assisted conception


how is tubal occlusion diagnosed?

laparoscopy and dye insufflation
hysterosalpingogram- dye injected into neck of womb and can look at tubes via X-ray


causes of abnormal sperm production ,resulting in infertility?

testicular disease
duct obstruction- infection, vasectomy
hypothalamic/pit dysfunction


general investigation of infertility?

regualr unprotected intercourse?
ovulating?- regular menstrual cycle, day 21 progesterone?
patent tubes- history of infection/sterilisation?, dye insufflation or hysterosalpingogram
adequate sperm count?->20million per ml, >50% motility, >30% morphology


general tment of infertility?

induce ovulation e.g. anti-oestrogen like clomiphene
overcome tubal occlusion by surgery or IVF
inadequate sperm then artificial insemination by donor? or intracytoplasmic sperm injection


how might fibroids be responsible for infertility?

may distort uterine cavity if SM in location, or physically obstruct fallopian tubes. can be pedunculated


main aim of drugs designed to improve erectile function?

increase penile blood flow


normal range of length of menstrual cycle?

21-35 days


how can the uterine tubes be tested for patency?



how might you establish whether cervical sperm transport is disrupted?

post coital test- collect cervical mucus soon after copulation