Immune System Flashcards
What is the main role of the human immune system?
The immune system protects the body against bacteria, viruses, and other invading organisms or substances.
In other words, the immune system helps protect against foreign, often disease-causing agents.
Define:
leukocyte
A leukocyte, also known as a white blood cell, is a cell involved in immune function.
Leukocytes are a broad category of cells, including neutrophils, monocytes, and lymphocytes, among others.
Name the most abundant leukocyte found in the blood.
The most abundant leukocytes are neutrophils, which constitute 50-70% of all white blood cells by number.
As one of the first cell types to reach the site of an infection, neutrophils are the main component of pus. Like macrophages, they can perform phagocytosis.
Define:
pathogen
A pathogen is a disease-causing organism. The purpose of the immune system is to protect against pathogens, foreign particles, and the body’s own damaged cells.
Pathogens can include bacteria, viruses, and fungi.
What is the difference between innate and specific immunity?
Innate immunity provides a broad line of defense against foreign material. Its response to pathogens is general, not specific to the identity of the pathogen.
Specific immunity is highly specialized, using immunological memory of previous infections to respond to certain pathogens.
Macrophages, neutrophils, mast cells, and other cell types are involved in innate immunity. T and B lymphocytes are involved in specific immunity.
Give another name for innate immunity.
Innate immunity is also known as nonspecific immunity.
Other than the skin and mucous membranes, name three components of the innate immune response.
Three main components of the innate (nonspecific) immune response are:
- The inflammatory response
- Phagocytosis
- Interferons
What large organ covers most of the body and serves as an early line of defense against pathogens?
The skin
Remember, the skin is technically an organ! Skin serves as an innate protective mechanism against many pathogens and foreign substances.
Which structures secrete a thick fluid that helps protect the digestive and respiratory tract against pathogens?
Mucous membranes
These membranes (or linings) secrete mucus, a protective fluid that can coat pathogens and foreign particles, trapping them in place. Mucus often contains enzymes that act to damage microbes (bacteria and viruses).
What enzyme is found in tears and catalyzes the breakdown of bacterial cell walls?
Lysozyme
Specifically, lysozyme catalyzes the breaking of glycosidic linkages within peptidoglycan molecules. This role is part of the innate immune system.
Which of the following is not directly involved in the innate immune response?
- Macrophages
- Skin
- B lymphocytes
- Mucus in the respiratory tract
B lymphocytes do not play a major role in innate immunity. The other choices all provide a first line of defense against a wide variety of pathogens.
B lymphocytes, on the other hand, produce antibodies. These products are highly specialized to recognize certain antigens, and form a large part of specific immunity.
What is phagocytosis?
Phagocytosis is the engulfment of a foreign particle by an immune cell, or phagocyte. The particle is taken up in a vesicle and can then be degraded.
This process can often involve chemotaxis, a form of movement in which a cell is drawn toward or away from specific chemical substances.
Which of the following cells cannot perform phagocytosis?
- Monocytes
- Erythrocytes
- Macrophages
- Neutrophils
Erythrocytes cannot perform phagocytosis. Erythrocytes are red blood cells, which do not serve a major function in the immune system.
Neutrophils, monocytes, and macrophages all perform phagocytosis as an important part of innate immunity.
Describe three main effects of the inflammatory response.
- Capillary permeability increases, allowing immune cells to access the infected site. This results in redness and swelling.
- The infected area becomes warm.
- The infected area is often painful due to swelling and the presence of certain chemicals.
Diphenhydramine, an allergy medication, functions as an antihistamine. Which immune response is likely to be inhibited by the administration of diphenhydramine?
Diphenhydramine will inhibit the inflammatory response.
Histamine is a chemical that functions as part of the inflammatory response. Specifically, it increases capillary permeability and can lead to many common allergy symptoms.
Which type of pathogen do interferons combat?
Interferons, a subtype of cytokines, are generally associated with viral infection. However, they can also be activated by bacterial infection or cancerous growth.
As signaling molecules, interferons do not directly kill infected cells; instead, they activate surrounding immune cells.
In what part of the body are lymphocytes synthesized?
Lymphocytes (B and T cells) are synthesized in the bone marrow.
B lymphocytes also remain in the bone marrow to mature, while T lymphocytes move to the thymus for maturation.
Give another name for specific immunity.
Specific immunity is also known as adaptive or acquired immunity.
Which of the following is not directly involved in the specific immune response?
- T lymphocytes
- Macrophages
- B lymphocytes
- Antibodies
Macrophages do not play a direct role in specific, or acquired, immunity.
Specific immunity involves cells that specialize to recognize and attack a limited class of antigens. In contrast, macrophages phagocytose a wide variety of pathogens and foreign particles.
Name the two types of specific immunity.
The two types of specific immunity are cell-mediated and humoral immunity.
A certain virus inhibits the functioning of cytotoxic T cells. Which type of specific immunity would be limited in this case?
Cell-mediated immunity would be inhibited.
Cell-mediated immunity involves cytotoxic T lymphocytes, as well as other immune cells. Specifically, it allows the destruction of body cells that have been marked for destruction after viral infection or other damage.
Which type of specific immunity involves B lymphocytes?
Humoral immunity
Humoral immunity involves antibodies, which are produced by B lymphocytes to recognize specific bloodborne antigens. It also involves the differentiation of plasma and memory B cells upon exposure to a pathogen.