ED and BPH Pathophysiology Exam 3 Flashcards
function of corpora cavernosa
control the sinusoidal blood capacity
function of corpora helicine arteries
supply blood to the sinusoids of the erectile tissue
function of corpora subtunical veins
collect blood from the sinusoids
function of corpora circumflex veins
collects blood from the subtunical veins
function of corpora cavernosal veins
drains the proximal portions of the corpora cavernosa
Parasympathetic role in erection
Principal mediators of erection
Sympathetic role in erection
Principal mediators of ejaculation and detumsecence
Testosterone
- Normal serum concentration is 300 to 1100 ng/dL
- stimulates libido and increases levels of nitric oxide and cGMP
- Free testosterone accounts for 2% of blood levels and is the active form
What is the key modulator of erection?
the tone of the smooth muscle walls of the helicine arteries and the trabecular spaces
The tone of an erection is controlled by what?
level of intracellular calcium in the smooth muscle cells
Which neurotransmitters influence intracellular calcium levels?
- Nitric oxide (NO)
- Vasoactive intestinal polypeptide (VIP)
- Prostaglandin E1 (PGE1)
- Norepinephrine (NorEpi)
- Acetylcholine
Acetylcholine
indirectly enhances arterial flow to the corpora
Nitric oxide (NO)
- Most important NT for erection
- Released from the endothelium stimulated
- Testosterone enhances the release of nitric oxide
- ACh enhances release of nitric oxide
- Activates guanylate cyclase to convert guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP)
phosphodiesterase-5 (PDE5)
brakes down cGMP which ends the erection
Vasoactive intestinal polypeptide (VIP)
- Simulates the production of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP)
- Reduction in intracellular calcium
Prostaglandin E1 (PGE1)
- Stimulates the production of cAMP from ATP
- Reduction in intracellular calcium
Norepinephrine (NorEpi)
- Released from sympathetic nerves within the corpora cavernosa and activates alpha1receptors on the smooth muscle cells
- increased intracellular calcium which causes contraction / vasoconstriction
psychogenic process of erection
- Audiovisual stimuli or fantasy may initiate erection
- also contains tactile stimulation
- Spinal erection center sends messages to cavernosal nerves
Parasympathetic Stimulation
- Dilation of the cavernosal and helicine arteries, increasing blood flow into the lacunar sinusoidal spaces
- Relaxation of cavernosal smooth muscle, opening the vascular lacunar spaces
- Expansion of the lacunar spaces which decreasing venous outflow and producing a rigid erection
- called the veno-occlusive mechanism
psychogenic ED
- Performance anxiety
- Relationship problems
- Loss of attraction for a partner
- Stress
- Depression
organic ED
- Neurogenic
- Hormonal
- Vasculogenic
- Drug-induced
- Other
organic ED: neurogenic
- Failure of the body to initiate nerve impulses needed for erection or when there is an interruption of the neural transmission needed to initiate and sustain an erection
- Results from: stroke, Alzheimer’s disease, spinal cord injury, radical pelvic surgery, diabetic neuropathy, pelvic injury, intervertebral disc lesion, multiple sclerosis, serious cyclists, and trauma
organic ED: hormonal
- Inadequate hormonal activity for erection
- low testosterone levels, high hormone-binding globulin, high prolactin levels -> hypogonadotropic hypogonadism
organic ED: vasculogenic
- damaged blood vessels -> inadequate arterial blood flow to initiate and maintain an erection
- Associated conditions include: atherosclerosis, hypertension, diabetes, trauma, Peyronie’s disease, pelvic irradiation, and hyperlipidemia
