Male Sexual Function and Dysfunction (7.4)

Question 1

Describe the sexual response cycle phases during coitus

Answer 1

Excitement: Initiated by erotic stimuli (physical, visual, chemical, foreplay etc.)

Physical changes: Stiffening of the penis (increased length and diameter); urethral opening widening; testes elevation (via cremateric muscle); scrotum becomes congested and thickened; nipples may erect; skin may redden

HR, RR and BP increase

Plateau: Occurs due to continued erotic stimuli (allows for continued growth)

Physical changes: Glans penis increases in size & colour deepens; urethral bulb enlarges (limits blood flow out of the penis); bulbourethral secretions released*; testes elevate (more), rotate and lie closer to the groin; prostate gland enlarges

HR, RR and BP increased further

*Acts to lubricate and to neutralise any remaining urine

Orgasm:!NOT THE SAME AS EJACULATION! Loss of voluntary control of muscles leading to rhythmic contraction. Smooth muscle contractions allows for emission and ejaculation.

Testes at ‘maximum elevation’.

HR, RR and BP all peak.

Males only - Refractory: The ‘system’ is not receptive to new stimuli. Cannot initiate and maintain an erection. This time period increases with age.

Resolution: Some ‘integration’ with the refractory phase. Sees the return to ‘resting’ state.

Physical changes: Loss of engorgement; decrease in penis size

HR, RR and BP quickly decrease (5 minutes)

Complete resolution may take up to 2 hours (final size reduction, scrotal relaxation, descent of testes).

The resolution phase may be lengthened (e.g. physical contact) or shortened (urination).

Question 2

Describe male sexual function with respect to the organs comprising the male reproductive system

Answer 2

Erection: Can have various stimuli.

Sees sinusoidal relaxation, helicine artery relaxation and venous compression (ischiocavernous and bulbospongiosus).

Increased intracavernous pressure causes erection. Contraction of the ischiocavernous muscle creates further pressure (+ pelvic floor muscles and bulbospongiosus).

NT release allows for smooth muscle relaxation - Cholinergic (ACh) and direct stimulates (NO)

Blood flow to penis increases due to vessel and sinusoidal dilation. Venous return is also decreased through skeletal muscle contraction.

Ejaculation - Emission:

Smooth muscle contraction in the seminal vesicles and ductus deferens allows for the movement of spermatozoa. Closure of the internal urethral sphincter prevents retrograde ejaculation. Sympathtic mediated (cavernous nerve, T11-L2).

Prostate secretions - 10 %

PSA (increases ‘fluidity’), citric acid, zinc. fructose

Ductus deferens - 10 %

Seminal vesicles - 80%

Alkalinises the ejaculate

Ejaculation - Expulsion:

*Minor expulsion from the bulbourethral glands seen before main ‘expulsion’*

Question 3

Describe erectile and ejaculatory dysfunction

Answer 3

Erectile dysfunction: The inabilty to attain or sustain an erection satisfactory for sexual intercourse. Prevalence increases with age. Can be an indicator of a more serious condition.

Primary: Never had an erection

Secondary: Previously had erections but fails to do so now, > 25 % of the time

Risk factors: Hypertension, dyslipidaemia, diabetes, CV disease. Commonly linked to endothelial dysfuntion.

Ejaculatory dysfunction: Absence of ejaculation

Primary absence: Obstruction, insufficient ejaculatory fluid production, retrograde ejaculation

Premature ejaculation: Ejaculation with minimal sexual stimulation and before the person wishes it. Clinical definition is < 1 minute after penetration. Most common male sexual dysfunction. May be:

Primary/lifelong: Persists throughout life

Secondary/acquired: Not as ‘severe’ and not consistent

Question 4

Describe the pathophysiology of erectile dysfunction and premature ejaculation

Risk factors

Answer 4

Erectile dysfunction: May be indicative of a more serious underlying pathology

Treatment: PDE-5 inhibitors (↑ cGMP levels for relaxation of arteriole smooth muscle)

• Commonly linked to endothelial dysfunction
• Hypertension
• Dyslipidaemia
• Diabetes (↑ circulating glucose, ↑ ateriolosclerosis, ↑ hyaline deposition, ↑ endothelial dysfunction)
• Obesity
• CV disease

Premature ejaculation: A complex multifactoral aetiology

• Genetic factors, decreased neural inhibitory control, psychological and environmental factors lead to ejaculation prior to the individual wishing to do so

Question 5

Define libido and describe conditions affecting libido (hypoactive)

Answer 5

Libido: Desire/drive for sex and the intensity/frequency of sexual thoghts

Hypoactivity may result from:

Hypogonadism; depression; hyperprolactinaemia; anger/anxiety; androgen receptor antagonists (e.g. spironolactone); CNS active drugs (SSRIs, TCA)