Answer the following questions:
1. Briefly describe the process of inflammation in an area that has been traumatized.
Inflammation is a nonspecific response to tissue damage, which aims to destroy and prevent the spread of pathogens, toxins, and other foreign substances located at the site of injury. Altogether, this process is vital in defending and healing the body to restore homeostasis. The specific mechanisms of this response are as follows:
Vasodilation and Increased Blood Vessel Permeability.
Once an injury occurs, the blood vessels present in the site of the wound immediately respond by increasing both the diameter of arterioles’ walls (vasodilation) and the permeability of capillaries. First, as the permeability of capillaries are higher, cells involved in the body’s defense are easily able to enter the site of injury, thus eliminating unwanted materials and initiating tissue repair. In addition, vasodilation aids these cells by allowing an increase in the flow of blood that enters the damaged tissue. Hence, repair of damage and removal of microbes are aided.
Emigration of Phagocytes.
Within the first hour of the inflammatory process, phagocytes start to migrate from the blood into the site of injury. As vasodilation triggers an influx in the amount of blood that accumulates, neutrophils stick to the blood vessels’ lining, then squeeze through the vessel walls to reach the damaged tissue. Once they reach the location of the wound, neutrophils digest or phagocytize microbes, toxins, and dead cells to defend the body against pathogens. Moreover, neutrophils are also aided by macrophages (from monocytes) which also phagocytize unwanted substances. After a few days, the dead phagocytes and damaged tissue collect and form a pus.
Tissue Repair.
As days go by, the damaged tissue is slowly repaired to return back to its normal function. Tissue repair is characterized by: 1) the formation of new blood vessels in the damaged area, 2) attachment of a temporary extracellular matrix (collagen and fibronectin) by fibroblasts, 3) re-epithelialization or the stretching of epithelial cells around the wound, and 4) contraction of myo-fibroblasts to decrease the size of the damaged tissue. Once the wound closes, the cells involved in the inflammatory process disappear, and the damaged tissue is restored back to normal.
2. Choose one type of Immunity (Innate and Humoral) and explain how its mechanism protects our body.
Our body has two types of immunity mechanisms as defense against different classifications of disturbance or stress. Responses classified under innate or nonspecific immunity are all the same; they are able to defend the body against all types of pathogens, unlike those in adaptive immunity where particular instructions are stored and done only to specific infections. Innate immunity involves both external and internal barriers to prevent infections and diseases from occurring. Furthermore, should damage be already done, these chemicals and structures pave the way for healing and repair. There are two types of innate defenses: the first line of defense (skin and mucous membranes), and the second line of defense (internal defenses).
First Line of Defense: Skin and Mucous Membrane.
The skin and mucous membranes are recognized as the first line of defense due to its special physical features that specialize in defensive functions: 1) the epidermis that serves as the body’s very own physical barrier, 2) mucous membranes that inhibit microbes from entering the body, 3) mucus that traps pathogens present in the respiratory and digestive tracts, 4) hairs and cilia that filter, trap, and remove microbes, 4) lacrimal apparatus (tears) that wash away irritants, 5) saliva, urine, defecation, and vomiting that expels microbes away from the body. To add, chemical factors such as sebum (skin’s acidic film), lysozyme, gastric juices, and vaginal secretions also protect the body against pathogens.
Second Line of Defense: Internal Defenses.
Should microbes enter the body, various internal mechanisms are present to prohibit their invasion. First, different antimicrobial substances each play a role to protect the body; these include: 1) interferons that serve as protection against viral infections, 2) complement system that promote cytolysis and phagocytosis, 3) iron-binding proteins that decrease the body’s iron supply to inhibit certain bacterial growth, and 4) antimicrobial proteins that attract dendrites and mast cells. In addition, Natural Killer Cells and phagocytes are also present to attack and digest foreign substances. Lastly, processes such as the inflammatory response and fever also take effect to inhibit and destroy microbes, as well as to initiate and catalyze tissue repair.