Sexual Wellbeing Flashcards
What are the four phases of sexual response (defined by Masters and Johnson, 1966)?
- Excitement
- Plateau
- Orgasm
- Resolution
What are the anatomical components of the clitoris?
Corpus spongiosum
Corpus cavernosa
What supplies the smooth muscle and coropora cavernosa of the clitoris?
Cavernous nerves (uterovaginal plexus, from the inferior hypogastric plexus)
What is the sensory nerve supply to the clitoris?
Dorsal nerve, arising from the pudendal nerve
What is the arterial supply to the clitoris?
Dorsal artery of clitoris, a terminal brach of the internal pudendal artery
What is the function of the clitoris?
The receptor of sexual stimuli, as part of the sensory arm of the female orgasmic reflex
Why is the lower third of the vagina ‘tighter’ and ‘less capacious’ than the upper third?
The levator ani and perineal muscles
What is responsible for the ‘female ejaculate’?
The urethra is surrounded laterally and anteriorly by some erectile tissue - is is the response of the erectile tissue that causes the secretion of clear fluid from the urethra
Why is the lower vagina, clitoris and introitus more sensitive?
Supplied by the pelvic plexus of nerves (whereas the upper vagina, derived from Mullerian ducts, which have a poor sensory supply)
What is the most sensitive part of the vagina?
Anterior vaginal wall - high concentration of nerve plexuses and ganglia, especially along the mid-line
What are the two sensory arms of the female orgasmic reflex?
- Clitoris
- Anterior vagina
What are the different ways arousal can be mediated?
- Local genital areas - esp. clitoris and vagina, but also other sites e.g. the nipples
- Centrally
A. The nervous system - e.g. visual and olfactory stimuli are potent arousal senses (contributing psychological and environmental factors) - vasocongestion followed by myotonia fits with parasympathetic followed by sympathetic activity
B. Hormones = may act directly on genitalia to induce vasocongestion similar to a state of sexual arousal, and may increase sexual attractiveness by secretion of pheromones
What happens during the excitement phase of the sexual response?
- Initiated by psychological or physical stimuli, or both
- Vasocongestion of external genitalia occurs within 30 secs - clitoris and labia (and uterus) become engorged
- Labia majora, appears to flatten out
- Rapid development of transudate (production dependant on blood flow)
- Vasodilation leading to erection of nipples, flushing of skin etc.
What is the function of the transudate produced in the excitement phase?
- Reduction in friction
- Increases partial pressure of oxygen in the vaginal epithelium, providing more energy for sperm actvitity
What happens during the plateau phase of the sexual response?
- Continued lengthening of the vagina, with elevation of the uterus , with expansion of the proximal end of the vagina - ‘tenting’ or ‘ballooning’ (allowing complete filling of the ant or post fornix with the penis during SI)
- ‘Turgid cuff’ of the distal vagina continues (dilatation of the venous plexuses in vagina and vestibule)
- Retraction of the clitoris
What happens during the orgasm phase of the sexual response?
- Release of vasocongestion, brief contraction of the turgid cuff at the distal vagina (approx. 5), uterus and occasionally the anal sphincter
- Voluntary and involuntary contraction elsewhere - Can cause stress incontinence
- Transient hypertension, tachycardia, hyperventilation
What is the motor arm of the female orgasmic reflex?
A circum-vaginal muscular discharge manifested by contractions of the pubo-coccygeus muscle
What happens during the resolution phase of the sexual response?
If orgasm has not been achieved, resolution of vasocongestion may take several hours
How can pregnancy affect sexual response?
1st trimester - painful breasts at high arousal, wide variation in sexuality - may be more anxious, nauseated etc.
2nd trimester - increase in arousal, libido and performance - marked pelvic organ congestion and vaginal lubrication. Uterine contractions at orgasm may become increasingly uncomfortable throughout pregnancy
3rd trimester - sexual activity tends to decrease owing to non-hormonal factors e.g. fatigue, physical awkwardness etc.
What is the ‘Good Enough Sex’ Model?
Metz & McCarthy, 2007 - only about 15% of the total of our sexual encounters with our long-term partner will we consider to be great sex. 15% will be sexual encounters that are truly not good or perhaps dysfunctional, and the remaining 70% will be good/fine/mediocre
In a patient whom is able to sustain an erection, but is not able to ejaculate, a lesion at what spinal level might be responsible?
L1
What causes a hydrocele?
Fluid accumulating within the potential space between the visceral and parietal layers of the tunica vaginalis
What is the processus vaginalis?
A communication between the tunica vaginalis and the abdominal peritoneum, it is normally obliterated around the time of birth
Which of the accessory glands contributes the most to seminal fluid?
Seminal vesicles
What is the largest component of semen?
Fructose
Which part of the male reproductive system contributes zinc and citric acid to semen?
Prostate
Which cells form the BTB?
Sertoli cells
Is sexual stimulation required for sildenafil to work?
Yes
How long before sexual activity should sildenafil be taken?
1 hour
How does food effect the rate of onset of activity with sildenafil?
May be delayed compared to fasting state
In what medical conditions is sildenafil contraindicated?
- Severe hepatic impairment
- Hypotension (<90/50 mmHg)
- Recent history of stroke or myocardial infarction
- Known hereditary degenerative retinal disorders
- In those whom sexual activity in itself is not recommended - e.g. unstable angina and severe cardiac failure
Co-administration with what medications should be avoided in sildenafil?
Nitrates or nitric oxide donors, and guanylate cyclase stimulators - could potentiate hypotensive effects
What is the physiological mechanism responsible for erections?
Involves the release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation
NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood
Therefore how does sildenafil potentiate erections? (MOA)
Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) in the corpus cavernosum, where PDE5 is responsible for degradation of cGMP, therefore increased cGMP and so increased muscle relaxation
If you start someone on a PDE 5 inhibitor, when should they be reviewed?
6-8 weeks
What conditions would place a man at high cardiovascular risk (don’t Rx PDE 5 inhibitor, stop sexual activity, d/w cardiology)?
- Unstable or refractory angina
- Recent MI (within the last 2 weeks)
- Reduced EF HF (NYHA class IV)
- Uncontrolled HTN
- High-risk arrhythmia
- HOCM or other cardiomyopathy
- Moderate-to-severe VHD
If PDE 5 inhibitor therapy is initially not successful, what initial advice should be given?
Try each PDE-5 inhibitor 4–8 times at the max tolerated dose before switching to an alternative drug
Trial of at least two different PDE-5 inhibitors taken sequentially before being classed as a ‘non-responder’
What may a urologist suggest when PDE 5 inhibitor therapy has been unsuccessful?
- Vacuum erection assistance devices (VEDs)
- Alprostadil penile intracavernous injections (e.g. Caverject)
- Medicated urethral system for erection (MUSE®)
- Vascular surgery/angioplasty, or penile prostheses
Which muscles are responsible for maintaining an erection?
Bulbospongiosus and ischiocaverosus
Which nerves are responsible for bring about an erection?
Parasympathetic
Pelvic splanchnic nerves (to cavernous nerves)
S2-S4
Which nerves are responsible for bringing about ejaculation?
Sympathetic
Pudendal nerve (to dorsal nerve of penis)
S2-S4
