29 Questions
What controls the degree of tone of the penile vasculature and the smooth muscle in the physiology of an erection?
The balance between contractant (flaccid) and relaxant (erection) factors
What is the physiological function of the corpora cavernosa in the context of an erection?
The cavernosal spaces make up the corpus cavernosum.
Name three neurotransmitters involved in penile vasculature and smooth muscle physiology related to erection.
Acetylcholine (ACh), Noradrenaline, Dopamine (DA)
What are the two functional states of the penis determined by the balance of contractant and relaxant factors?
Detumescence (return to flaccid state) and flaccidity, Tumescence (being swollen) and erection
What role do cerebral sex centers play in the physiology of an erection?
They are not needed to know for the physiology of an erection.
What is the role of cGMP-specific protein kinase (Protein Kinase G) in the process of achieving an erection?
Bringing calcium ions (Ca2+) to the endoplasmic reticulum and decreasing calcium ions (Ca2+) to induce smooth muscle relaxation.
How does the inhibition of PDE-5 contribute to the mechanism of achieving an erection?
Inhibiting PDE-5 leads to the promotion of cGMP, which activates Protein Kinase G, resulting in smooth muscle relaxation and erection.
Explain the role of Potassium (K+) in the process of erection.
Potassium (K+) is stimulated to move out of smooth muscle by Protein Kinase G, contributing to smooth muscle relaxation and erection.
What is the significance of Phosphatase in the process of achieving an erection?
Phosphatase activated by Protein Kinase G removes phosphate groups, leading to muscle relaxation and erection.
How do PDE5 inhibitors work to treat erectile dysfunction?
PDE5 inhibitors hyperpolarize the membrane, inhibiting depolarization and the opening of Calcium Ion Channels, promoting smooth muscle relaxation and erection.
What is the main tissue localization of PDE (Phosphodiesterase) in the context of erection?
Corpus cavernosum, vascular smooth muscle, platelets, lung, esophagus, and brain.
What is the role of Acetylcholine (ACh) in the penile vascular smooth muscle relaxation?
Increase the production of Nitric Oxide (NO)
In the flaccid state, what is involved in smooth muscle contraction?
Circumflex vein, Venular plexus, Corpus cavernosum, Cavernous artery, Helicine arteries, Trabecular smooth muscle
What is the main mechanism of penile vascular smooth relaxation during erection?
Nitric Oxide/C-GMP pathway
What is the more common name for the 'cGMP-specific kinase' depicted in green in the illustration?
Protein Kinase G (PKG)
What is the role of Cialis in penile vascular smooth muscle relaxation?
Stimulates the cavernous nerve and the endothelial cell to produce Nitric Oxide (NO)
What is the washout time for Cialis?
48 hours
What is the role of Protein Kinase G in the vascular smooth muscle cell?
Increases sequestration of Ca++ in the Endoplasmic Reticulum and activates Myosin Light Chain Phosphatase leading to detachment of myosin head from actin.
How does Protein Kinase G affect the potassium channels in the plasma membrane of vascular smooth muscle cells?
Opens the potassium (K+) channels, hyperpolarizing the smooth muscle cell.
What is the 'Kick In' time for Tadalafil (Cialis)?
15 - 30 minutes
How long does Tadalafil (Cialis) work for?
Up to 36 hours
How does food affect the absorption of Tadalafil (Cialis)?
Absorption is not affected by food; it can be taken with food.
Which PDE5 inhibitor has the shortest 'Kick In' time?
Avanafil (15 - 30 minutes)
What enzyme degrades cGMP and essentially prevents smooth muscle relaxation, leading to erection?
Phosphodiesterase (PDE)
What is the main effect of PDE5 inhibitors like Viagra and Levitra?
Mostly vasodilation effects
What are some common side effects of PDE5 inhibitors?
Heartburn, sinus pressure, headache, flushing, visual effects
What is NAION, a condition associated with PDE5 inhibitors?
Non-arteritic anterior ischemic optic neuropathy
Why should nitrates be avoided after taking PDE5 inhibitors like Tadalafil, Sildenafil, or Vardenafil?
Nitrates can potentiate the vasodilatory effects
What does Protein Kinase G do in smooth muscle?
Activates myosin (light chain) phosphatase and promotes smooth muscle relaxation
Explore the physiological processes involved in the erection of penile vessels and the smooth muscle of the Corpora Cavernosa. Learn about the neurotransmitters, hormones, and molecular factors that contribute to the mechanism of erection.
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