N3 Anatomy and Physiology AY 2023-2024

The process of inflammation occurs in three stages: (1) vasodilation and increased permeability of blood vessels, (2) phagocyte emigration, and (3) tissue repair. There would be an increase in diameter of arterioles and increased permeability of capillaries allowing more blood to flow through the damaged area and permitting antibodies and clotting factors to enter the injured area from the blood, respectively. An hour following the inflammatory process begins, and phagocytes show up. As a significant volume of blood builds up, neutrophils adhere to the blood vessel's endothelium to reach the damaged area. Monocytes enter the contaminated area with neutrophils as the inflammatory response progresses. After entering the tissue, monocytes change into macrophages that enhance the fixed macrophages' phagocytic activity. Lastly, a pocket of dead phagocytes and injured tissue forms in a few days; this collection of fluid and dead cells is known as pus. Eventually, it will reach the body and surface and gradually destroyed.

Humoral immunity or antibody-mediated immunity works against extracellular pathogens that are in body fluids outside cells. It involves antibodies binding to antigens in body humors or fluids. Lymphocytes secrete antibodies that eliminate extracellular microbes. It is carried out by the B cell-derived plasma cells' secretion of antibody molecules. An antigen stimulates B-cell activation and differentiation into plasma cells that secrete antibodies when it interacts to the B-cell antigen receptor. Three key functions of antibodies in immunity are to neutralize the pathogen, stop bacterial toxins from penetrating cells, and aid in the pathogen's uptake by phagocytic cells, which are specialized in eliminating ingested germs. Antigen activates B cells, which then differentiate into plasma cells. Helper T cells are typically needed for this process.