Anatomy and Physiology Week 14

This week we started discussing the digestive system. It is an open portal system that is highly guarded by WBC's. There are four layers to the system. The mucosal layer is made of simple columnar epithelium. It is avascular and is constantly shed and replaced. The Submucosal layer is made up of dense irregular connective tissue. It is vascular and has specialized cells that protect from pathogens. The muscularis layer has a circular layer and a longitutinal layer. Peristalsis is regulated by the parasympathetic nervous system by the vagus nerve which constricts first the circular muscularis then the longitudinal muscularis. The last layer is the serosa layer. It is composed of areolar connective tissue and is vascular. It is really interesting thinking about the different layers that have to work together to help get rid of toxins from the body. The fact that the circular and longitudinal layer have to constrict at certain times to cause peristalsis to happen. I know I says this after every blog but I have a hard time believing and understanding everything that has to go right for our bodies to run correctly.

Anatomy and Physiology Week 13

This week we discussed the inflammation process. In response to injury, damaged tissue cells(mast cells in connective tissue, basophils in blood) release histamine, increasing blood flow to the area. Kinins then induce vasodilation and serve as chemotactic agents for phagocytes. Prostaglandins are released by damaged cells and intensify the effects of histamine and kinins. Phagocytes engulf bacteria, dead cells, and debris. Componenets of the complement system stimulated the release of histamine and the promotion of phagocytosis. The increased permeability of capillaries allows the leakage of blood clotting factors into the tissue. the clotting sequence is set into motion and fibrogen is converted to the thick meshwork of fibrin that traps invading microbes and prevents their spread. It is hard to imagine that all these things happen just to have an inflammatory response. I know next time I get a burn or something that causes inflammation I will have to think about all the things that go on to cause it.