Question

Distributive shock is the result of whole-body vasodilation and increased vascular permeability. The most common form of distributive shock results from a severe whole-body allergic reaction called anaphylaxis, or a severe infection in the blood known as sepsis. In addition to constriction of the airways, chemicals such as histamine and cytokines which are released during the reaction cause systemic vasodilation and increased blood vessel permeability.

a. Describe how this would be dangerous to the survival of brain tissue. Your answer should include the consequences of respiratory impact, systemic vasodilation, and vascular permeability. (75-125 words)

b. During prolonged steroid treatment, the adrenal glands drastically reduce cortisol production. One of the many roles of cortisol is to upregulate alpha-1 receptors in the body. How could distributive shock occur if a patient who had been on long-term steroids was suddenly taken off them? (2-3 sentences)

Answer 1

A) Respiratory ipac of carbondioxide mediated has has a profound and reversible impact on blood flow to brain tissues. Hypercapnia causes dilation of cerebral arteries and arterioles and hence increased blood flow, whereas hypocapnia causes viceversa. Low perfusion pressure lower than critical perfusion pressure to the brain results in decreased blood flow to the brain tissues. Inadequate tissue perfusion caused by distributive shock or vasodilatory shock leads to decreased blood flow to the brain. When increased vascualr permeability in the brain evade the vascular strong barrier of the brain called as the blood–brain barrier (BBB) casues detrimental edema in brain parenchymal cells often associated with leakage of larger molecules and cells.

B) Long term usage of corticosteroids have great impact in decreasing the cortisol production often leads to cortisol insufficiency. Cortisol is critical for activation of α₁-adrenergic receptors in vascualr smooth cells responsible for vasoconstriction and these receptors are profoundly seen inthe skin, the sphincters of gastrointestinal system, renal artery and brain. Decreased cortisol induced by long term sterooids affects the activation of receptors and hence cause systemic vasodilation and ultimately the distributive shock.