Coitus And Fertilisation Flashcards
Approximately how long does it take from spermatogonium to mature spermatozoa?
74 days
Which cells secrete androgen binding protein?
Sertoli cells
If the pituitary gland was removed, what would we need to give to initiate spermatogenesis?
FSH and testosterone
Giving testosterone directly bypasses need for LH
What is the role of oestrogen in males?
Increases sperm viability
Which cells secrete inhibin?
Sertoli cells
What is spermiogenesis?
The process from spermatid to spermatozoan
What happens during spermiogenesis?
Head undergoes nuclear condensation Acrosome develops Mitochondria packed around contractile filaments Flagellum produced by microtubules Gains motility and becomes 'fertile'
What happens in epididymis during sexual arousal?
Contraction of epididymal wall
Expel spermatozoa into vas deferens
Non-expelled sperm undergo phagocytosis
How many phases of coitus are they and what are they?
4 Excitement Plateau Orgasmic Resolution
Describe the male excitement phase
Sensory and psychological stimulation of limbic system
Activate sacral PNS (inhibit SNS)
NO production and arteriolar vasodilation in corpora cavernosa
Increased penile blood flow, testes elevate and engorge
(Erection reversible at this stage)
Describe male plateau phase
Sacrospinous reflex
Contraction of ischiocavernosus - engorgement of penis
Increased penile pressure
Accessory glands secrete - Cowper’s and Littre’s
Loss of erection unlikely
What are the 2 parts that the male orgasmic phase is divided into?
Emission
Ejaculation
What happens in the emission phase?
SNS reflex
Contraction of SM in vas deferens, ampulla, seminal vesicle and prostate
Internal and external urethral sphincters contract
Semen pooled in urethral bulb
What happens in the ejaculation phase?
Spinal reflex with cortical control SNS L1 and L2 Contraction of glands and ducts and IUS Filling of urethra stimulates pudendal nerve -> contraction EUS relaxes
What happens in the resolution phase for males?
SNS pathway Contraction of SM in corpora cavernosa - increase venous return Detumescence and flaccidity Refractory period Testes descend and shrink
What happens in female excitement phase?
Sensory and psych stimulation - activated sacral PNS, inhibit SNS
Vaginal lubrication begins - increased blood flow
Clitoris engorges with blood
Uterus elevates
Increased muscle tone, HR and BP
Inner 2/3 vagina lengthens and expands
Describe the plateau phase for females
Further increase in tone, HR and BP
Labia minora deepen in colour
Clitoris withdraws
Bartholin’s glands secrete vestibule for entry of penis
Orgasmic platform forms in lower 1/3 vagina
Uterus fully elevated
Describe the orgasm phase in females
Orgasmic platform contracts rhythmically 3-15 times
Uterus contracts, anal sphincter contracts
Clitoris remains retracted
No refractory period - multiple orgasms possible
Uterine contractions beginning at top and moving down
Describe resolution phase in females
Clitoris descends and engorgement subsides
Labia return to unaroused size and colour
Uterus descends
Vagina shortens and narrows
Describe the changes in breast during excitement phase
Breast size increased
Nipples erect
Veins more distinct
Describe changes in breast in plateau/orgasm phase
Greater size increase
Areola size increase
Sex flush on breasts and upper abdo
Describe changes in breast in resolution phase
Return to unaroused size
Disappearance of sex flush
What is the G spot?
Female equivalent of prostate
Area of erotic sensitivity located in anterior wall of vagina
What affect does ageing having on female sexual habits?
Decreased desire
Decreased vasocongestion response so less lubrication
Vagina and urethra lose elasticity
Length and width of vagina decrease
Decreased number of orgasmic contractions
More rapid resolution
