Erectile dysfunction and the anatomy of the penis

All about ED and penis

What is erectile dysfunction/impotence?

• Inability to achieve or sustain an erection sufficient in rigidity or duration for sexual intercourse which is president for a minimum of 6 months

• is not considered a normal part of the aging process

What are the organic cause of ED?

1. Vasculogenic → failure to fill

   1. HTN → inadequate blood supply due to atherosclerosis and damage to the blood vessels → atherosclerosis is due to the buildup of the atheromatous plaques → this can harden the arteries supplying the penis

   2. DM → high levels of glucose can cause hyaline arteriosclerosis in the small arterioles in the penis → making it harder to dilate

   3. CVD, hyperlipidemia, smoking

2. Neurogenic → failure to initiate (disorders of the autonomic fibers to the penis)

   1. SCI → no impulse transmission to the penis

   2. Hypoxia → Vasculogenic cause may lead to neurogenic cause → atherosclerosis plaques may build up in the capillaries causing the basement membrane to thicken → making it harder for oxygen to efficiently move from the vascular space to the tissues → thus hypoxia

3. Endocrinology → failure to initiate (lower levels of testosterone are associated with low NO synthase)

   1. Hypogonadism → ↓ GnRH → ↓ LH → ↓ testosterone

   2. Hyperprolactinemia → inhibits GnRH

What are the pathophysiology of ED?

May result from 3 basic mechanisms:

• Failure to initiate (psychogenic, endocrinologic, or neurogenic)

• Failure to fill (arteriogenic)

• Failure to store adequate blood volume within the lacunar dysfunction

What are the drugs causing impotence?

1. Beta blockers → ex atenolol and propanolol

2. SSRIs → ex fluoxetine and sertraline

3. Antipsychotics → eg haloperidol and fluphenazine

4. Benzodiazepines → eg lorazapam and diazepam

5. TCAs → eg amitriptiline and nortriptiline

6. SNRIs → venlafaxine

7. MAOIs → eg selegeline and phenelzine

What is peyronie disease?

• mechanical cause of impotence

• physical problems

• Fibroproliferative disorder that affects the tunica albuginea of the penis, causing abnormal curvature of the penis

What are the psychogenic cause of impotence? → 10%

• Depression

• Anxiety (performance related)

• Relation issues

• PTSD

• Stress

What are the treatment of ED?

1. Psychotherapy → counseling

2. medical therapy

   1. First line → phosphodiesterase-5 (PDE-%) inhibitors → sildenafil and tadalafil

   2. MOA → PDE5 inhibition → ↓ breakdown of cGMP → ↑ cGMP → ↑ smooth muscle relaxation in reaction to nitrous oxide activation → pulmonary vasodilation, penile smooth muscle relaxation and increased blood flow

What are the layers of the urogenital triangle of the male?

1. Skin

2. Subcutaenous tissue

   1. superficial fatty → camper’s fascia

   2. Deep membranous → colle’s fascia

3. superficial perineal space (pouch) → the pelvic floor

   1. ischiocavernosus membrane and crura of the penis

   2. bulbospongiosus membrane and the bulb and the root of the penis

   3. perineal body → the anterior portion

   4. greater vestibular (bartholins gland in female)

4. perineal membrane

5. deep perineal pouch

   1. bulbo-urethral (cowper’s) gland

   2. contains the urethra, which runs through the penis and allows for the passage of urine and semen.

   3. The deep perineal pouch also houses muscles like the external urethral sphincter and the transverse perineal muscles, which assist in controlling urination and ejaculation.

What are the layers of the testes?

• Tunica vaginalis

• Extraperitoneal fat

• Cremater muscle 

• External spermatic fascia

• Dartos muscle

What muscle is inside the scrotum?

cremaster muscle

_____________ is a cutaneous sac consisting of two layers, skin and underlying subcutaneous layer which contain ___________ (smooth muscle) responsible for the wrinkled appearance of the scrotum.

1. Scrotum

2. dartos muscle

What happens to the scrotum when its cold?

• When it is cold, cremaster and dartos muscle contract.

•  The contraction of cremaster muscle moves testis closer to the body, where they can absorb body heat.

•  Contraction of dartos muscle causes the scrotum to become tight, which reduces heat loss.

•  Exposure to warm temperature reverses these actions. 

  • Muscles relax and the testes hangs freely.

Where is the location of testes?

hang inside the scrotum

What are the 2 main function of the testes?

1. sperm production which fertilize the egg

2. produce testosterone → male sex hormone

What is the tunica vaginalis, and how is it formed?

The tunica vaginalis is a serous membrane derived from the peritoneum that forms during the descent of the testis. It partially covers the testis.

Which layer lies directly internal to the tunica vaginalis?

The layer internal to the tunica vaginalis is the tunica albuginea.

Where is the interstitial cells of he leydigs located and what are the function?

The interstitial cells of Leydigs that secrete testosterone are located in the connective tissue between the seminiferous tubules.

What are the two types of cells found in the seminiferous tubules?

The two types of cells in the seminiferous tubules are

1. spermatogenic cells (sperm-forming cells)

2. Sertoli cells → much bigger than spermatogenic cells and provide nutrients and supports

What is the function of the seminiferous tubules?

The seminiferous tubules function as sperm-forming factories, where sperm is produced.

After sperm is produced in the seminiferous tubules, where does it go next?

Sperm empties into the rete testis and then travels to the epididymis.

What are the function of sertoli cells?

• They protect the sperms. 

• They produce fluid for sperm transport.

• The release hormone inhibin.

• They have a nutritive function

What is the role of the epididymis in sperm development?

The epididymis is a tightly coiled structure where sperm matures as it travels through to the vas deferens.

• Sperm matures here

How does sperm become semen as it travels through the male reproductive system?

• As sperm travels through the vas deferens, it gains protective and nourishing fluids, combining with these secretions to form semen.

• Sperm + Secretions = semen

What structure in the male reproductive system functions as an erectile organ and contains the penile urethra?

The penis functions as an erectile organ and contains the penile urethra for conducting semen and urine.

what are the 2/3 and 1/3 of the prostate gland?

• The glandular part constitutes around two-thirds of the prostate.

• While the remaining third is fibromuscular.

What are the anatomical part of the prostate gland?

1. base

2. apex

3. four surfaces → anterior, posterior and 2 inferolateral

What the 5 traditional lobes of the prostate?

1. anterior lobe → anterior to the urethra

2. median lobe → between the urethra and the ejaculatory ducts

3. posterior lobe →inferior to the ejaculatory ductcs

4. left and right lateral lobe