Male sexual function Flashcards
What are the 4 phases of the sexual response cycle?
- Excitement
- Plateau
- Orgasm
- Resolution
- Males also have a refractory period straight after orgasm phase.
What is the excitement phase?
- Initiated by erotic stimuli (Physical, visual, chemical, proceptive behaviour)
- Penis stiffens and increases in length and diameter - tumescent
- Urethral opening widens
- Scrotal skin becomes congested and thickened (scrotal diameter reduced)
- Testes elevated by contraction of cremaster muscle
- Nipples become erect (60%), reddened skin ‘sex flush’ (50-60%)
- Increased HRM breathing depth and rate, and BP
WOMEN:
- Uterus elevates
- Vaginal lubrication appears
- Clitoris enlarges
- Labis minora swell
What is the plateau phase?
- Occurs due to continued presence of erotic stimuli
- Slight increase in size of glands, deepened colour (greater blood supply)
- Urethreal bulb enlarges (X3)
- Preorgasmic emision from Cowper’s gland (lubricates penis tip and urethra). Alkanalises the environment to protect sperm
- Testes more elevate, rotate and lie closer to groin
- Prostate gland enlarges
- Further increase in HR, breathing depth and rate, and BP
- Redness spreads and increases in intensity (if present)
WOMEN:
- Uterus elevates further
- Upper part of the vagina expands
- Vaginal walls swell
- Colour of labia darkens
What is the orgasmic phase?
- Loss of voluntary control of muscles
- Testes at maximum elevation
- HR (180 bpm), respiratory rate (41 breaths/min), BP (200/110) all peak
- Redness peaks in intensity and distribution if present
- Smooth muscle contractions expel ejaculatory fluid into urethral bulb (emission)
- Rhythmic contractions of surrounding musculature result in forceful expulsion
- Contractions approx . 0.8s apart - 1st 3-4 are the most forceful and expel the majority of fluid
WOMEN:
- Contractions in uterus
- Rhythmic contractions in vagina
- Rectal muscle contracts
What is the refractory period?
- Immediately after ejaculation
- Erotic stimuli are not effective at initiating/maintaining an erection
- Refractory period tends to increase with age.
What is the resolution phase?
- occurs during and after the refractory period if no effective erotic stimulus is present
- Arousal mechanisms return to a resting state
- 50% of penis size is lost rapidly
- Muscle tension and redness disappear
- HR, resp, rate and BP will decrease within 5 mins
- Final reduction in penis size, relaxation of scrotum, decent of testes and loss of nipple erection take longer
- Entire resolution phase - up to 2 hrs
- Can be lengthened (physical contact) or shortened (urination)
WOMEN:
- Uterus lowers
- Vagina returns to normal
- Labia return to normal size and colour
What is the physiology of erection I?
- Various stimuli:
- Psychogenic- erotic stimuli- limbic system
- Reflexogenic/ tactile - direct genital stimulation - afferent nerves
- Nocturnal - no external stimulus
- Flaccid state :
- Corpora cavernosa smooth muscle and arterial wall smooth muscle contracted
- This allows a small amount of blood flow for nutrition
- Main changes during erection:
- Sinusoidal relaxation
- Arterial relaxation
- Venous compression
What is the physiology of erection relating to blood supply?
- Dialation of arteries and arterioles leading to increased blood flow
- Trapping of incoming blood by expanding sinusoids
- Compression of subtunical venular plexuses between the tunica alubginea and peripheral sinusoids leading to reduced venous outflow
- Stretching of the tunica which occludes veins between the inner circular and outer longitudinal layers leading to further decrease in venous outflow
- Increase intracavernous pressure raises penis to the erect state
- Further pressure increase with contraction of ischiocavernosus muscles.
What is the physiology of ejaculation?
- Forcible ejection of seminal fluid from urtheral meatus that commonly acoompanies sexual climax and orgasm
- Process divided into emission and expulsion
- Minor expulsion from teh Cowper’s gland (bulbourethral gland) can occur before main expulsion
- Contains spermatozoa at a similar concentration - pregnancy despite coitus interrupts
What is the process of emission in ejaculation?
- Closure of bladder neck- sympathetic innervation at the base of the bladder
- Prostatic secretions ( acid phosphatasem citric acid, zinc) mix with spermatozoa from the vas degerens - ejected into proststic urethra
- Seminal vesicle fluid (fructose) alkalinises the final ejaculatory product
- Minor contributions by Cowper’s glands and periurethral glands
- Total contribution :
- Prostate - 10%
- Vas Deferens - 10%
- Seminal Vesicle - 75-80%
What is expulsion?
- Discharge of ejaculatory fluid from the urethra
- Relaxation of external urethral sphincter (bladder neck still closed)
- Rhythmic contractions of prostate, bulbospongiosus and ischiocavernosus muscles , pelvic muscles (levator ani & mtransverse perineal)
- Afferent signal is not clear
- Efferent signal from pudenedal nerve (somatic)
What is the physiology of an orgasm?
- can occur without ejaculation - ‘dry orgasm’ and vice versa
- Hyperventilation (up to 40 breaths/min), tachycardia, high bp
- Powerful pelvic muscle contractions - particularly ischiocavernosus and bulovavernosus
- Quality and intesity varies - androgen level, build-up time, fluid volume increases
- Oxytocin and Prolactin levels shown to be increased after orgasm
What is an erectile dysfunction?
- Inability to attain or sustain an erection satisfactory for sex
- Impotenence - inaccurate/ undesirable term = implies lack of fertility
Primary : man has never had an erection
Secondary : had erections before but now fails to more than 25% of the time - Prevelance increases with age ( smooth muscle level decreases, age-related vascular leak)
What is the aetiology and risk factors of erectile dysfunction?
Psychogenic
* Poor health, obesity,
sedentary life-style
* Nicotine
* Alcohol abuse
* Drug addiction
* Age
Iatrogenic
Post-operative
Post-radiation
Endocrine
Hypogonadism
Thyroid disorders
Cardiovascular
Hypertension
Dyslipidaemia
Diabetes (l & Il)
Coronary artery disease
Peripheral arterial
occlusive disease
Cavernous
Veno-occlusive dysfunction
Myopathy
Fibrosis after priapism
Peyronie’s disease
Penile fracture
Neurogenic
* Parkinson’s disease
Stroke
Spinal cord
transection/tumour
Drug-induced
*
Antihypertensives (esp. BB
and thiazide diuretics)
Antidepressants
Antipsychotics
Antiandrogens
Antihistamines
Recreational drugs
Spinal cord
Antidepressants
What are common risk factors of erectile dysfunction?
- Can often be an indication of a more serious, treatable disorder
Common risk factors:
Hypertension (68% men with hypertension had ED to some degree)
Dyslipidaemia (60% of men with ED had dyslipidaemia)
— Diabetes
— Cardiovascular disease (56% of men with ED had a positive stress test, 40% had
significant coronary occlusions) - Common link — endothelial dysfunction
