1. Briefly describe the process of inflammation in an area that has been traumatized.
Inflammation is one of the body's nonspecific defense mechanisms. Different pathogens, abrasions, chemical irritations, distortion/disturbances of cells, and extreme temperatures cause inflammation. However, the inflammatory response remains the same. This response has three basic stages: (1) vasodilation and increased permeability of blood vessels, (2) emigration (movement) of phagocytes from the blood into the interstitial fluid, and (3) tissue repair.
For the first stage, vasodilation allows more blood to flow through the damaged area, while increased permeability allows defensive proteins (i.e. antibodies and clotting factors) to enter the damaged area from the blood. This stage helps remove toxins and dead cells.
After an hour, the inflammatory process starts once phagocytes appear on the scene. This starts the second stage called the emigration of phagocytes from the blood to the interstitial fluid. As blood accumulates in the area, neutrophils start to move toward the inner surface of the endothelium of the blood vessels. The neutrophils start to break through the blood vessel wall. After, neutrophils attempt to destroy the microbes through phagocytosis. However, neutrophils immediately die in the early stages of infection. Once the neutrophils die, monocytes turn into wandering macrophages that add to the phagocytic activity of the fixed macrophages that are already there. Eventually, they also die. Within a few days, dead phagocytes and damaged tissue form, forming pus. Pus formation continues until the infection subsides.
2. Choose one type of Immunity (Innate and Humoral) and explain how its mechanism protects our body.
Innate immunity is the defense system that we were born with. It protects us against all antigens. This type of immunity depends on a group of proteins and phagocytic cells that recognize the features of each pathogen and destroy these invaders.
In this type of immunity, the skin and mucous membranes are considered our first line of defense against the entry of these pathogens. When pathogens pass through the physical and chemical barriers of the skin and mucous membranes, they encounter a second line of defense - our internal defenses, which include antimicrobial substances, natural killer cells and phagocytes, inflammation, and fever. Antimicrobial substances help inhibit the growth of pathogens. These substances include interferons, complement systems, iron-binding proteins, and antimicrobial proteins. Natural killer cells and phagocytes attack and kill pathogens and defective cells in the body. After that, inflammation helps our body to dispose of toxins and foreign materials at the site of the injury and prepares the site for tissue repair. Fever may also be experienced since it is a mechanism that intensifies the antiviral effects of interferons, inhibits the growth of some microbes, and speeds up body reactions that aid repair.
References:
Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. Innate Immunity. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26846/
Tortora, G. J., & Derrickson, B. H. (2020). Principles of Anatomy and Physiology (16th ed.). Wiley.