1.) What do you understand by the term “endothelium-dependent” vasodilation?  Explain.

Endothelium-dependent vasodilation is due to substances that induce vasodilation but are synthesised by the endothelium.  Stimuli found in the endothelium cells cause NO synthesis, and NO causes vasodilatation.  

2.) When we talk about the NOS enzyme, what is meant by “constitutive” and “inducible” enzymes and what are the pathological and physiological implications thereof?

Constitutive enzymes are always present and produced at a constant rate, thus it is not dependent on the substrate concentration.  Inducible enzymes is only produced when it s exposed to a substrate or when they add adaptive value.

Constitutive enzymes are constantly present and thus they are more likely to be affected by pathology.

3.) Explain how NO contributes to the fatal pathology of septic shock.

Septic shock causes a NO inflammatory response to the infection.  Endotoxins released by the septic shock leads to the synthesis of iNOS.  A rapid and big increase in NO can lead to hypertension or even death. 

4.) Which autacoids’ mechanism of action depends on effects on the guanylyl cyclase-cGMP system?

Nitric Oxide.

5.) NO may be toxic to the cell.  Which mechanisms are available to the body to counter this detrimental effect of NO?

NO can be inactivated by the reaction with oxygen to form nitrogen dioxide.

6.) Name a way in which NO can act pro-inflammatory.  Give examples of where it will have advantages or disadvantages.

NO causes vasodilation and it plays a role in prostaglandin synthesis in the COX2 pathway, this results in an inflammatory response.  The inflammatory response contributes to erythema, vascular permeability and oedema that is associated with acute inflammation.

Advantage:  NO also appears to play an important protective role in the body via immune cell function.

Disadvantage : Excessive secretion of NO can worsen tissue injury and have an influence on disease pathology. 

7.) In which possible neurological and psychiatric diseases is NO involved? 

Stroke.

Parkinson's disease.