Coitus, Fertilisation and Contraception Flashcards
What is coitus?
Coitus is when the erect penis is introduced into the vagina (intromission) during sexual intercourse/copulation. When ejaculation occurs semen is released into upper part of vagina (insemination) so that sperm can travel to appropriate site for fertilisation (ampulla of uterine tube)
What is the fascia of the penis?
The erectile tissues are surrounded by different layers of fascia. Venous plexus forms a network of veins over surface of columns of tissues. Lacunae are the spaces in between columns of erectile tissue, supported by smooth muscle which blood fills into during erection
What happens to the fascia during erection?
During erection they press against layers of fascia (tissues fill up with blood) which pushes against venous plexus minimising blood flow back out of penis. Tunica albuginea around corpus cavernosum and another one around corpus spongiosum. Spongiosum is not as erectile as cavernosum hence tunica albugenia is not as dense nor fibrous around spongiosum as it is around cavernosum
Comparative structures of clitoris and penis
Structure of the clitoris and penis share developmental origins, tissues of clitoris are erectile as in the penis
Why is the gonad artery high up?
Gonadal artery (female = ovaries, male = testes) is high up on branch as, as migration (growing) takes place and gonads moves down so does the vascular supply
What is the internal pudendal artery?
Internal pudendal artery feeds perineum and external genitalia including penis, branches to the penis include: artery to bulb, urethral artery, dorsal artery and deep (cavernosal) artery
What is the nerve supply is the penis?
Penis richly innervated by sensory and motor neurons. Includes sensory fibres responsive to touch, pressure, temperature. Pudendal nerve supplies sensory and somatic motor innervation to perineum and external genitalia including penis (dorsal nerve). Autonomic innervation to penis derived from pelvic plexus
Nerves involved in erection?
Parasympathetic nervous system stimulates production of nitric oxide (vasodilator - relaxes and widens vessels) by deep arteries of the penis. Deep arteries dilate and fill lacunae in corpora cavernosa
Nerves involved in ejaculation?
Sympathetic nervous system stimulates contraction of smooth muscle (ductus deferens and urethra), reproductive ducts and accessory glands (seminal vesicle and prostate)
Somatic motor system stimulates contraction of skeletal muscles and bulb of penis
What is the process of erection?
Erection of the penis is controlled by the parasympathetic nervous system (can be psychogenic or physical stimulation), arteries in erectile tissue dilate, erectile tissue becomes engorged with blood. Bulbourethral gland secretes bulbourethral fluid to help lubricate urethra and remove any urine that is present. Erect penis can be inserted into vagina
What is the process of emission?
Emission is a sympathetic response, smooth muscle of ductus deferents contracts to move sperm into ampulla (peristaltic contractions), smooth muscle of ampulla, seminal vesicles and prostate gland contract moving sperm and seminal fluid into urethra. Release of secretions from seminal vesicles and prostate gland
What is the process of expulsion?
Semen in urethra activates somatic and sympathetic reflexes, contractions of urethral smooth muscles, pelvic floor muscles contract and semen is ejected. Additional secretions from accessory glands, closure of internal urethral sphincter
What is the process of resolution?
Blood flow to penis is reduced, penis becomes flaccid. Trabecular contract and remove blood from erectile tissue. Refractory period where males cannot have another erectile period
What happens in the female sexual response?
Engorgement (increased blood flow) of clitoris, labia and vagina in response to autonomic stimulation (can be psychogenic or direct). Lubricating fluid secreted through vaginal wall; secretion of mucus into vestibule. Increased width and length of vagina, uterus elevates upwards. Rhythmic contraction of vaginal, uterine and perineal (pelvic floor) muscles
What happens after insemination?
Semen released into upper part of vagina, sperm travel to uterine tube for fertilisation, sperm fuse with secondary oocytes oocyte completes meiosis II. Fertilised oocyte now a zygote, zygote initiates cleavage (~7days) and travels towards the uterus for implantation