Repro-L01-(A)-Physiology & Epidemiology of ED

What are the four components of normal male sexual function

Sufficient libido, ability to achieve and maintain penile erection, ejaculation, and detumescence.

What is libido influenced by

Visual, olfactory, tactile, auditory, imaginative, and hormonal stimuli, particularly testosterone.

What factors can diminish libido

Emotional context, systemic illness, hormonal disturbances, psychiatric disorders, and medications.

What leads to penile erection

Increased blood flow into the lacunar network and complete relaxation of arteries and corporal smooth muscle.

How is blood retained in the corpora during an erection

Compression of trabecular smooth muscle against the tunica albuginea passively closes the emissary veins.

Which spinal segments provide parasympathetic nerve fibers to the penis

S2-S4 sacral spinal segments.

Where does sympathetic innervation of the penis originate

T11-L2 spinal segments via the hypogastric plexus.

What induces vascular relaxation to promote erection

Nitric oxide (NO) synthesized from L-arginine by nitric oxide synthase (NOS).

How does nitric oxide promote smooth muscle relaxation

By increasing cyclic GMP production, which induces muscle relaxation.

What enzyme metabolizes cyclic GMP, and how is it inhibited

Phosphodiesterase type 5 (PDE-5); inhibitors like sildenafil, tadalafil, vardenafil, and avanafil block its action.

Why are PDE-5 inhibitors ineffective without nitric oxide

They facilitate the enzyme cascade but do not initiate nitric oxide production.

What prostaglandins are synthesized in cavernosal tissue, and what do they do

PGE1 and PGF2α; they increase cyclic AMP levels, leading to cavernosal smooth muscle relaxation.

What stimulates ejaculation

The sympathetic nervous system, causing contraction of the epididymis, vas deferens, seminal vesicles, and prostate.

What follows seminal fluid emission in ejaculation

Rhythmic contractions of the bulbocavernosus and ischiocavernosus muscles.

What characterizes the expulsion phase of ejaculation

Stereotypic rhythmic contractions of striated perineal muscles, leading to semen expulsion with the bladder neck closed.

What controls emission and expulsion in ejaculation

Autonomic (parasympathetic and sympathetic) and somatic spinal centers, respectively.

What coordinates synchronization of autonomic and somatic spinal centers in ejaculation

Interneurons forming the spinal ejaculation generator.

What commonly causes premature ejaculation

Anxiety or learned behavior.

How is premature ejaculation treated

Behavioral therapy or selective serotonin reuptake inhibitors (SSRIs).

What causes retrograde ejaculation (RE)

Failure of the internal urethral sphincter to close, often in men with diabetes or after bladder neck surgery.

What is anejaculation, and what commonly causes it

Failure of the emission process, often due to selective alpha blockers like tamsulosin or silodosin.

What mediates detumescence

Norepinephrine, endothelin, and smooth-muscle contraction via α-adrenergic receptors and Rho kinase activation.

What causes venous leak leading to premature detumescence

Insufficient relaxation of the corporal smooth muscle.

What is priapism, and what conditions are associated with it

A persistent, painful erection associated with sickle cell anemia, hypercoagulable states, spinal cord injury, or penile vasodilator injections.

Is erectile dysfunction (ED) considered a normal part of aging

No, but it is associated with physiological and psychological changes related to age.

What percentage of men in the MMAS reported some degree of ED

52%.

What percentage of men in the MMAS reported complete ED

10%.

How did the incidence of moderate or severe ED change between ages 40 and 70 in the MMAS

It more than doubled.

What percentage of men in the NHSLS reported being unable to maintain an erection

10%.

In which age group was the incidence of ED highest in the NHSLS

Men aged 50–59 (21%).

Which groups had a higher incidence of ED in the NHSLS

Poor (14%), divorced (14%), and less educated (13%) men.

What medical conditions are associated with a higher incidence of ED

Diabetes, obesity, LUTS/BPH, heart disease, hypertension, low HDL levels, and systemic inflammatory diseases.

What shared etiology do cardiovascular disease and ED have

Endothelial dysfunction.

Why is ED considered a "sentinel symptom"

It may indicate occult cardiovascular and peripheral vascular disease.

What lifestyle factor is a significant risk factor for ED

Smoking.

What treatments for medical conditions increase the risk of ED

Medications for diabetes and cardiovascular disease.

What medical procedures are associated with a higher incidence of ED

Radiation or surgery for prostate cancer.

What physical condition is linked to a higher risk of ED

Lower spinal cord injury.

What psychological factors can cause ED

Depression, anger, stress, anxiety, and stress-related causes.