andrology (see DM) Flashcards
what are sertoli cells
cells in the testes where spermatogenesis takes place
what are leydig cells
the primary source of testosterone or androgens in males
what is erectile dysfunction
persistant inability to attain and maintain an erection sufficient to permit satisfactory sexual performance
what are the cylindircal structures of the penis
- paired corpora cavernosa
- corpus spongiosim
what is the tunica albuginea
a two layered fibrous envelope that extends the length of the corpus cavernosum penis and corpus spongiosum penis
what are the 2 layers of the tunica albuginea + function
- inner layer bundles -> support and contain the cavernous tissue
- outer layer bundles -> orietnated longitudionally from glans penis to proximal crurua and insert into the inferior pubic rami
what areas fill with blood during an erection
the central and peripheral sinusoids, located in the tunica albuginea
preservation of what artery during prostatectomy surgery allows for preservation of sexual function
the accessory pudendal artery during radical retropubic prostatectomy
what is the arterial supply to the penis
internal pudenal artery
what is the venous drainage of the penis
tiny venules from the peripheral sinusoids travel in the trebeculae and form the subtinical venous plexus -> drained by:
1. deep dorsal vein
2. circumflex vein
3. periutheral vein
4. cavernous vein
5. crural vein
-> these go on to form the periprostatic plexus and internal pudendal vein
what is dutemescence
subsidence or diminution of swelling or erection
what are the erectile tissues of the penis (2)
- cavernous smooth musculature
- smooth muscles of the arteriolar and arterial walls
what changes occur to produce/maintain and erection (6)
- dilation of the arterioles and arteries resulting in increased blood flow
- trapping of blood by expanding sinusoids
- compression of the subtunical veins, reducing venous outflow
- stretching of the tunica results on occlusion of emissary veins and decreases venous outflow further
- an increase in pO2 and intracavernous pressure
- contraction of the ischiocavernosus muscle -> further pressure increase (rigid erection phase)
what is tumescence
the swelling of the penis for sexual activity
what neural pathways govern tumescence
sympathetic pathway -> T11-L2
what neural pathways govern detumescence
parasympathetic pathway:
S2,3,4 -> pelvic nerves -> pelvic plexus
“point and shoot”
P - parasympathetic - point (erection)
S - sympathetic - shoot - subsidation of erection
what nerves innervates the penis (2)
- cavernous nerves - can be damaged in surgery
- pudendal nerve -> S2-4 root, innervates ischiocavernosus and bulbocavernosus muscles
how does nitric oxide mediate the erection pathway (4)
- NO is a gaseous molecule produced by the vascular endothelium and parasympathetic nerve
- NO acts as a NT on the parasympathetic system to increase the production of cGMP
- cGMP results in cavernous smooth muscle relaxation -> increased blood flow in sinusoids
- venous compression against hard tunica albugenia
in contrast symp stim results in NA release causing muscle contraction and reduced blood flow to the sinusoids
phases of the erectile process (6)
0 - flaccid phase (cavernosal smooth muscle contracted, sinusoids empty)
1 - latent filling phase (increase pudendal artery flow, penile elongation)
2 - tumescent phase (rising intracavernosal pressure, erection forming)
3 - full erection phase (increased cavernosal pressure causes penis to become fully erect)
4 - rigid erection phase (further increases in pressure + ischiocavernosal muscle contraction)
5 - detumescence phase (following ejaculation, sympathetic discharge resumes -> smooth muscle contraction and vasoconstriction, reduced arterial flow)
if a man with ED still has erections at night what is the likely cause
psychogenic -> situational ED
what other organ system can ED be linked to
cardiovascular -> men with heart disease, diabetes or hypertension are 4x more likely to develop complete ED
erections are vascular
what factors of metabolic syndrome contribute to erectile dysfunction
- endothelial dysfunction
- low testosterone
side effects of PGE5 inhibitors (sildenafil etc.)
- headaches
- flushing
side effects of penile prosthesis (3)
- infection
- erosion
- mechanical malfunction
on which side are varicoceles usually seen and why (4)
left, due to:
1. vertical drainage into the renal vein -> renal/adrenal metabolites cause vasodilation
2. the the vein being longer compared to the right resulting in higher hydrostatic pressure
3. “nutcracker” effect of vein between SMA and aorta
4. incompetent or absent valves more common on left side
what is the hudson classification
classification of varicoceles
1 - palpable only on valsalva
2 - palpable on standing
3 - visible
how does cystic fibrosis lead to infertility in men
abnormal development of the vas deferens, epididymis, and seminal vesicles -> sperm cannot reach semen
is there a relationship between Mumps and infertility
of mumps causes orchitis there can be shrinking of the testicles and a lower sperm count -> this is a rare complication
what drugs can impair spermatogenesis (5)
- sulphasalazine
- nitrofurantoin
- methotrextate
- colchicine
- chemotherapy
what drugs can suppress the pituitary causing infertility
- testosterone injections
- GnRH analogues
what drugs can result in ejaculation failure (3)
- alpha blockers
- antidepressants
- phenothiazines
what drugs can result in erectile dysfunction
- beta blockers
- thiazide diuretics
- metoclopramide
what recreational drugs can result in male infertility
- anabolic steroids
- cocaine
- cannabis
- heroin
what is priapism
a pathological condition of erection of the penis which is prolonged (beyond 4 hrs) and devoid of sexual stimulation or excitement
what are the 2 types of priapism
- low flow - venous blood, ischaemic, painful, requires urgent treatment
- high flow - arterial blood, non ischaemic, painless
what condition is priapism commonly seen in
sickle cell disease -> low flow, ischaemic priaprism is seen
also other haem causes such as thalassemia
priapism mgx
- aspiration -> drainage of blood from the cavernosa
- flushing with saline (removes oxygen poor blood)
- intracavernosal injection of a sympathomimetic agent, such as phenylephrine (if aspiration doesn’t work)
- surgical shunt between the corpus cavernosa and glans is fashioned (if above manouvers don’t work)
priapism investigations
corporeal blood gas
ischaemic - acidotic + raised lactate
non ischaemic - normal pH and normal lactate
what is a complication of priapism >24hrs
erectile dysfunction
what is peyronie’s disease
a benign lesion of the penis leading to curvature of the erect penile shaft due to formation of fibrous tissue plaques within the tunica albugenia
what extra-urological symptom is peyronie’s disease associated with
dupuytrens contracture
acute phase peyronie’s disease presentation (3)
- painful erections
- penile deformity
- lasts 1-6 months
chronic phase peyronie’s disease presentation (3)
- painless
- plaque stabilisation
- erectile dysfunction
what is the pathophys of peyronie’s disease
- micro tear/autoimmune disease to the penis
- scar tissue (plaque) forms under the skin of the penis
- The plaque builds up inside tunica albuginea
- As it develops, the plaque pulls on the surrounding tissues and causes the penis to curve or bend
peyronie’s disease mgx (4)
- injections -> Collagenase, verapamil, Interferon-alpha 2b
- surgery -> corporoplasty, nesbitt’s procedure
- mechanical traction and vacuum devices
- shockwave therapy of plaque
what is a vasectomy
male sterilisation -> the removal of a small section of vas from both sides with interposition of tissue between the divided ends to prevent recanalisation
risks/side effects of vasectomy (6)
- scrotal bruising/swelling for a few days
- seepage of yellow fluid from wound after a few days
- blood in semen for first few ejaculations
- chronic testicular pain or sperm granuloma
- inflammation/infection of testis/epididymis
- significant bleeding requiring further surgery
what test is mandatory post vasectomy
post vasectomy semen analysis to confirm azoospermia -> disappearance of spermatozoa from ejaculate can be slow and some men can have non-motile sperm for months/years after vasectomy
3 mechanisms of erection initiation
- Psychogenic erections - occur in response to afferent sensory stimulation (T11-L2 and S2-S4) to trigger central dopaminergic erection from the pre-optic area
- Reflexogenic erections - often preserved in men with spinal cord injury above the sacral level, occur following genital stimulation, and are mediated in the spinal cord and autonomic nuclei
- Nocturnal erections - occur during rapid eye movement sleep probably result from suppression of inhibitory sympathetic outflow by the pontine reticular formation and amygdala
