Question

12) Imagine a pulmonary embolus breaking up and entering the pulmonary artery supplying blood to an entire lobe of the left lung, blocking 75% of the pulmonary arterioles in that lobe. Describe the effects on the arterioles and bronchioles in this lobe in response to this event.

13) Elevated potassium levels in the body (hyperkalemia) is a serious condition, resulting in a severely decreased ability for muscle fibers and neurons to reploarize. The adrenal cortex can respond to this. However, very high osmolarity shuts down this response. Explain this incongruity, by describing the response mechanism of the adrenal cortex. (6 pts)

16) ) A vaccine for Coronavirus is likely to take a longer time than imagined, because the most obvious target of the vaccine should be the external spike protein on the envelope of this enveloped virus. The cellular attachment protein on epithelial cells, which the virus binds to for entry into the epithelial cell, is known to be ACE2, a receptor enzyme. Explain why the production of a vaccine targeting the coronavirus spike protein (S1), is not likely to be successful.

Answer 1

12. An embolus can be any foreign substance floating in the blood or it can be intravascular solid or liquid or gaseous mass that is carried by the blood away from its site of origin. This process of transportation of embolus by the blood and get lodged in blood vessels which are narrower causing obstruction is called embolism.

• Pulmonary embolism is common in human beings. Here the emboli from veins of the legs can reach the right side of the heart and from there to the pulmonary artery or to its branches, thus can occlude pulmonary artery leading to serious consequences.
• This occlusion of the pulmonary artery which is supplying to the entire lobe of the left lung cause infarction.
• An infarct is an area of ischaemic necrosis caused by the occlusion of an end artery that is the artery without collateral branches.
• So ischemic necrosis occurs in the tissue of the lungs due to the lack of oxygen supply and glucose to the tissue with the lack of the blood supply to the tissue.
• The type of the infarct that occurs in spongy organs like lung is red/hemorrhagic infarct as the loose spongy organs permit the blood to collect in the infarct thus forming red/hemorrhagic infarct.
• The arterioles of the lungs begin to dilate in an attempt to increase the blood supply and become engorged with blood but not sufficient enough to keep the affected part alive.
• The endothelium of the blood vessels also damage thus cause edema and hemorrhage. So the area is stuffed with blood and is red in color and so it is known as red/hemorrhagic infarct.
• Then the red cells undergo hemolysis and Hb diffuses into the surrounding tissues. So the infracted area becomes pale/anemic infarct.
• These dead cells cause the release of the inflammatory mediators such as macrophage, thus lead to phagocytosis and removal of these necrotic tissues.
• There will be increased alveolar dead space, decreased supply of the oxygen and there is increased ventilation.
• The release of serotonin causes constriction of bronchioles and increases airway resistance.
• This all leads to the increase in the pulmonary artery pressure thus the work of the right ventricle is increased to compensate this but this will result in the right ventricular failure. And finally lead to shock.