Department of Physiology & Neurobiology
PNB 2264 Exam I
Unlike the abdominal viscera, the thoracic viscera are separated into two cavities by an area called the mediastinum. What is the clinical importance of this compartmental arrangement? The clinical importance of this compartmental arrangement is that the mediastinum region contains a lot of major and essential parts of the human body. The mediastinum contains the pericardial cavity, thymus, trachea, esophagus, and major blood vessels. The fact that it’s placed in a sort of central space of the upper body provides these major parts with a protective barrier of tissues and serous membranes. Even though the mediastinum itself doesn’t have a serous membrane most of the thoracic cavity does. Also this region encloses the heart by two layers of pericardium; serous membrane. The mediastinum creates a barrier in between the two compartments which enclose the lungs. This is clinically beneficial to the human body because if one lung gets injured, diseased, or infected, the other one may remain functional due to the protective barrier of the mediastinum (McKinley). The process of hemostasis is associated with positive feedback. Describe the specific events that confirm this statement.Homeostasis is the state of equilibrium, or constant internal environment, in the body (McKinley).The specific event that confirms that positive feedback is in-fact associated with homeostasis is how positive feedback brings the body back to homeostasis after an injury. Due to injury, homeostasis of the body is thrown off and positive feedback leads to speeding up of blood clotting where the injury occurred. The process consists of platelet plug formation, coagulation, vascular spasm, and arterial dilation. Out of this process the step that shows the most positive feedback is the platelet plug formation. In this step in damaged tissue, platelets aggregate to form a plug that seals off the broken blood vessel in undamaged tissue,...
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