Coition Flashcards
What is the EPOR model for human sexual responses?
- Excitement
- Plateau
- Orgasm
- Resolution
What is excitement?
In response to psychogenic or somatogenic stimuli
Increasing sexual arousal or tension
What is plateau?
Arousal is maintained and intensified
Increased pelvic haemodynamics
What is orgasm?
A few seconds of involuntary climax
Tension relieved by wave of intense pleasure
What is resolution?
Arousal dissipated
Pelvic haemodynamics resolve
What causes penile erection?
Changes in blood flow in erectile tissue
Increased pressure in corpora cavernosa
Pressure in corpus spongiosum remains low to prevent compression of urethra and allow ejaculation
How is flaccidity maintained?
Arterial input to corpora cavernosa blocked by smooth muscle mounds
Keeps pressure in corpora lower than in artery
What is tumescence?
Stimulation of pelvic nerve causes increased blood flow through penis
After 20-30 seconds, increased pressure in corpus cavernosum leading to engorgement
How is erection maintained?
Relaxation of smooth muscle mounds at arterial input allows full arterial input and high pressure but reduced blood flow
Reduced venous drainage due to occlusion by flaps of smooth muscle keeps pressure high
What is detumescence?
Contraction of smooth muscle causes arterial flow to decrease and increases venous outflow
Which autonomic system regulates erection?
Parasympathetic
Pelvic nerve - S2, 3, 4
Which autonomic system regulates detumescence?
Sympathetic
T12 - L3 via hypogastric nerves
What causes smooth muscle relaxation?
Prostacyclin
VIP
NO
How does viagra work?
PDE5 inhibitor
Maintains level of cGMP
Causes smooth muscle relaxation
What is the bulbospongiosus reflex?
Ischiocavernosus muscle contracts and compresses proximal part of corpus cavernosum to increase penile rigidity
Triggered by pressing on glans penis
Mediated by pudendal nerve S2, 3, 4
What are the organic causes of erectile dysfunction?
- Neurogenic
- Arteriogenic
- Drugs
- Endocrine
What is the treatment for erectile dysfunction?
- Sex therapy
- Hormone replacement
- Injection of smooth muscle relaxants
- Viagra
How does sperm travel through vasa efferentia?
Passively in bulk flow
Sperm are non-fertile and immotile
How does sperm travel through vas deferens?
Muscular contractions move sperm along
90% fluid reabsorbed
What are the vasa efferentia?
Connect seminiferous tubules to epididymis
What occurs in the epididymis?
Sperm maturation
- Nuclear condensation and acrosome remodelling complete
- Loss of cytoplasmic droplet
- Rise in cAMP in tail allows movement
- Membrane lipid composition becomes more fluid
- Surface coated with stabilising glycoproteins
- Sialic acid levels rise
What causes seminal emission?
Contraction of smooth muscle in prostate, vas deferens and seminal vesicle
Controlled by sympathetics from lumbar splanchnics via α-adrenergic fibres
What provides nutrition in sperm?
Fructose
What is the role of prostaglandins?
Muscle stimulants
Which antioxidants are present in semen?
- Ascorbic acid
2. Hypotaurine
What causes ejaculation?
Rhythmic contractions of urethra and bulbospongiosus and ischiocavernosus at orgasm
Controlled by pudendal nerve
What prevents retrograde ejaculation?
Urethral sphincter at neck of bladder
Where do the ejaculate contributions come from?
Early - prostate - 30%
Mid - vas deferens - 10%
Late - seminal vesicle - 60%
What are Cowper’s glands?
Produce lubricant in ejaculate and pre-ejaculate
What do corpora cavernosa do in the female?
Enlargement of clitoris
What do corpora spongiosa do in the female?
Enlargement and eversion of labia
What lubricates the vaginal orifice?
Greater vestibular glands
Bartholin’s duct
Cervical secretions
What is transudation?
Lubrication of vagina and vestibule through vascular engorgement of walls
What is the tenting effect?
Dilatation of upper part of vagina caused by increased stimulation
What is uterine elevation?
Uterine and vaginal contractions at orgasm
What are the characteristics of the cervix during oestrogen dominance?
Watery secretion
Os open
Good for sperm
What are the characteristics of the cervix during progesterone dominance?
Thick secretion
Os closed
What is spinnbarkeit?
Elasticity of cervical secretion
How does the cervix act as a filter?
- Prevents pathogens ascending female tract during non-receptive phase of cycle
- Filters out abnormal sperm
- Separates sperm from seminal fluid
How many sperm are inseminated?
~350,000
How quickly do first sperm arrive at oviduct?
5 mins
What is sperm capacitation?
Acquisition of capacity to fertilise eggs
- Loss of membrane cholesterol to albumin in uterine fluid
- Loss of glycoproteins by glycosidase enzymes in uterine fluid
- Increases fusogenicity with oocyte
- Influx of calcium causes increase in cAMP and PKA
Where does capacitation occur?
In uterus during passage to oviduct
How can sperm capacitation be reversed?
By seminal fluid
How is the oocyte transported?
- Ovulated oocyte and cumulus cells picked up by fimbriae
2. Cilia beat in direction from ovary to uterus
What is Mittelschermz pain?
Bleeding into peritoneal cavity from ovulation
Which hormone stimulates cilia to beat?
Oestrogen
Where does fertilisation occur?
Ampulla of oviduct
