NSG 530 STUDY GUIDE Pathology TEST 1 Graded A+

Know how to differentiate between cell types (eosinophils, neutrophils, leukotrienes, monocytes, mast cells). In other words know what they each are responsible for. Eosinophils are a type of disease-fighting white blood cell. This condition most often indicates a parasitic infection, an allergic reaction or cancer. You can have high levels of eosinophils in your blood (blood eosinophilia) or in tissues at the site of an infection or inflammation (tissue eosinophilia). Eosinophils Defend against parasites, degrade vasoactive substances released by mast cells. ● Eosinophils Mildly phagocytic Defense against parasites and regulation of vascular mediators Eosinophils do many things, including: • fend off bacteria and parasites • kill cells • participate in allergic reactions • play a part in inflammatory responses • "respond" to areas of inflammation Although eosinophils are part of the immune system, some of their responses aren't always healthy for the body. Sometimes they play a part in conditions such as food allergies and inflammation in the body's tissues. Neutrophils – phagocytize microorganisms and cellular debris soon after injury; secrete chemicals that call in longeracting phagocytes ● Neutrophils Also referred to as polymorphonuclear neutrophils (PMNs) Predominate in early inflammatory responses Ingest bacteria, dead cells, and cellular debris Cells are short lived and become a component of the purulent exudate They are a type of white blood cell (WBC or granulocyte) that protect us from infections, among other functions. They make up approximately 40 percent to 60 percent of the white blood cells in our bodies and are the first cells to arrive on the scene when we experience a bacterial infection Neutrophils are a type of white blood cell that helps heal damaged tissues and resolve infections. Neutrophil blood levels increase naturally in response to infections, injuries, and other types of stress. They may decrease in response to severe or chronic infections, drug treatments, and genetic conditions. Neutrophils help prevent infections by blocking, disabling, digesting, or warding off invading particles and microorganisms. They also communicate with other cells to help them repair cells and mount a proper immune response. Inflammatory molecules called leukotrienes are one of several substances which are released by mast cells during an asthma attack, and it is leukotrienes which are primarily responsible for the bronchoconstriction. Leukotrienes are potent pro-inflammatory mediators that appear to contribute to pathophysiologic features of asthma. ● Leukotrienes Product of arachidonic acid from mast cell membranes Similar effects to histamine in later stages Monocytes are a type of leukocyte, or white blood cell. They are the largest type of leukocyte and can differentiate into macrophages and myeloid lineage dendritic cells. As a part of the vertebrate innate immune system monocytes also influence the process of adaptive immunity. Monocytes are a type of white blood cell. Like other white blood cells, monocytes are important in the immune system’s ability to destroy invaders, but also in facilitating healing and repair. Monocytes are formed in the bone marrow and are released into peripheral blood, where they circulate for several days. They comprise about 5-10 percent of the circulating white blood cells in healthy individuals. Monocytes are probably best known for their role in serving as something akin to reserve forces in the military. Some of them may be called up if needed, to form the precursors of two other types of white blood cells: tissue macrophages and dendritic cells. But monocytes also have other roles in infection and disease, some of which have nothing to do with tissue macrophages and dendritic cells. Mast cells are cells found in connective tissue throughout our bodies as part of our immune system. Mast cells are particularly prominent in tissues of our bodies that interact with our external world, such as those found on our skin and in our respiratory and digestive tracts. Mast cells can also be found in the organs and tissue of our circulatory and nervous systems. Mast cells play an important role in protecting our health by providing a line of defense against pathogens. Mast Cell Functions Release chemicals that initiate the inflammatory response ● Mast cells are cellular bags of granules located in the loose connective tissues close to blood vessels Skin, digestive lining, and respiratory tract Contain histamine, cytokines, and chemotaxic factors In response to exposure to a perceived pathogen, mast cells set off a rapid inflammatory response to outside invaders, such as germs, viruses, and parasites. Mast cells have the capacity to directly kill these organisms or to stimulate the production and release of substances that will destroy the pathogen. Mast cells play a prominent role in the activation of the allergy response. When a person has an allergy, mast cells are responding to harmless triggers as if they were a threat. In addition to their protective and immune system effects, mast cells are also involved in: • Homeostasis of blood vessels and bronchial functioning • Injury healing • Formation of new blood vessels • Regulate functioning of cells throughout the body • Regulation of bone growth