Erectile dysfunction

Question 1

5 phases of an erection (0-5):

Answer 1

0 - flaccid phase 
1 - latent (filling) phase
2 - tumescent phase 
3 - full erection phase 
4 - rigid erection phase 
5 - detumescence phase

Question 2

mechanism of erection

Answer 2

cavernous artery dilates = muscle contracts

Question 3

causes of impotence

Answer 3

organic: vascular/arterial, neurogenic, anatomical, secondary to surgery
psychogenic: situational, general
drugs and substance use: alcohol, hypnotics, diuretics, alpha and beta blockers, SSRIs
riding bikes

Question 4

possible referrals for impotence

Answer 4

mental health services
cardiology
urology
endocrinology

Question 5

lifestyle changes to treat ED

Answer 5

weight loss 
regular exercise - avoid long-distance bike rides 
healthy diet 
moderate alcohol consumption 
smoking cessation

Question 6

3 treatment options for ED

Answer 6

Lifestyle changes
implants/ prosthesis surgery
medication

Question 7

Medication options for ED

Answer 7

PDE5 - 1st line (sildenafil, tadalafil, vardenafil)

prostaglandin (PG) injection - 2nd line (alprostadil)

Question 8

Physiology of erection

Answer 8

1. Pudendal nerve activates nitric oxide
2. This activates guanylate cyclase (converts GTP to cGMP)
3. cGPM activates protein kinase G (PKG)
4. PKG decreases intracellular Ca2+
5. Low Ca2+ decreases smooth muscle tone and vasodilation of penile arteries = erection

a. Adenylate cyclase converts ATP to cAMP
b. cAMP activates protein kinase A (PKA)
- PKA acts same as PKG in above process

PDE converts cGMP to GTP and cAMP to ATP