Microbiology

Microbiology Study Guide

resist the entry of pathogens in the host. The sebaceous glands in the skin produce an oily substance known as sebum that acts as a protective coating over the surface of the skin. Further, this sebum is rich in unsaturated fatty acids that provide protection against the growth of bacteria in the skin. Perspiration on the skin surface is effective enough to break down, thereby inhibiting the growth of cell walls of the bacteria, as they contain the enzyme lysozyme. Mucous Membranes Mucous membranes are the special epithelial linings in different parts of the body that act as a protective shield against microorganisms so they cannot penetrate the body structure and cause infections. The epithelial linings generate a lubricated fluid that contains mucin, a sticky form of protein, which traps the microbes on a continuous basis and stops them from entering the body from the external environment. For instance, the linings of the digestive, respiratory, and urogenital systems, as well as the conjunctival lining of the eyes, all act as a defensive non-specific resistance factor. Lysozyme Lysozyme is an enzyme that can break down gram-positive bacteria cell walls. It is found in perspiration, tears, saliva, and nasal secretion. Phagocytosis Types of Phagocytes Phagocytosis is a non-specific defense mechanism in which various phagocytes engulf and destroy the microorganisms of disease. The most important types of phagocytes are the neutrophils and monocytes, which are the white blood cells circulating throughout the body. These monocyte cells turn into phagocytic cells in the tissues and are then known as macrophages. These macrophages circulate throughout the cells of the body and perform the function of phagocytosis and finally, destroy the parasites invading the host function. These all form part of the reticuloendothelial system of the body. Phagocytes are also responsible for initiating the immune system of the body, which has the ability to defend the organisms against infections and disease. When microbes enter the body, the phagocytosis attaches itself and digests these microorganisms, forming a bubble-like organelle known as a phagosome. The phagosome attaches to the lysosome that is responsible for contributing enzymes, and it transforms into a phagolysosome . Once this fusion takes place, the microorganism causing infections and diseases is destroyed in no time and ejected from the body through the egestion process. Antigenic determinants, which represent the chemical portions of the microorganism, are displayed over the surface of the phagocyte inside the immune process and help stimulate the immune process. The reactions of the immune system stimulate the complement system that completes the defensive system by circulating the proteins in the bloodstream and encouraging phagocytosis in the body structure.

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