What is the role of mast cells in the immune system?
Mast cells are proteins produced to bind with antigens.
Mast cells destroy antigens, cancer cells, and viruses.
Mast cells release chemical mediators like histamine.
Mast cells are antibodies that attack the body's tissues.
The Correct Answer is C
Rationale:
A. Proteins that bind to antigens are antibodies (immunoglobulins). Mast cells are cells, not proteins, and their primary role is not to directly bind to antigens.
B. Direct destruction of pathogens or abnormal cells is the role of phagocytes, cytotoxic T cells, and natural killer cells. Mast cells do not directly kill pathogens, but instead orchestrate the immune response by releasing chemical signals that recruit other immune cells.
C. The primary function of mast cells is to release preformed chemical mediators stored in granules, including histamine, heparin, prostaglandins, and cytokines. Histamine causes vasodilation and increased capillary permeability, allowing immune cells to move into tissues. Cytokines recruit additional immune cells, such as neutrophils and eosinophils, to the site of infection or injury. Prostaglandins and leukotrienes contribute to inflammation, pain, and bronchoconstriction. Mast cells are central to allergic reactions, such as urticaria (hives), asthma, and anaphylaxis, because the rapid release of mediators can cause tissue swelling, redness, itching, and airway constriction. They also help in defense against parasitic infections.
D. Antibodies are immunoglobulin proteins, not cells. Mast cells release chemical signals rather than directly attacking tissues. While mast cells can contribute to tissue damage during allergic or autoimmune reactions, they themselves are not antibodies.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Rationale:
A. This describes a fissure, which is a linear tear or crack in the skin, often caused by dryness, trauma, or infection. Fissures are not flat and involve disruption of the skin surface, unlike a macule.
B. A macule is a small, flat, non-palpable area of skin that is different in color from the surrounding tissue. Examples include freckles, flat moles, or certain rashes. Macules are usually less than 1 cm in diameter and do not involve elevation or fluid accumulation.
C. This describes a vesicle, which is raised and fluid-filled. Vesicles are seen in conditions like chickenpox, herpes simplex, or contact dermatitis. Unlike macules, vesicles are palpable and elevated.
D. This describes a papule or nodule, which is solid, raised, and can vary in size. Examples include warts or small skin tumors. Macules are flat and non-palpable, so this description does not fit.
Correct Answer is C
Explanation
Rationale:
A. B-memory cells are derived from B lymphocytes, not basophils. Basophils do not participate directly in antibody production or memory formation.
B. Basophils are not phagocytic cells. Phagocytosis is primarily performed by neutrophils, macrophages, and dendritic cells. Basophils function mainly in mediating inflammatory responses, especially allergic reactions.
C. Basophils are granulocytes that circulate in the blood and play a key role in type I hypersensitivity reactions (allergic reactions). They bind to IgE antibodies on their surface. Upon exposure to an allergen, cross-linking of IgE triggers degranulation, releasing histamine, leukotrienes, and other inflammatory mediators. This causes vasodilation, increased vascular permeability, smooth muscle contraction, and the classic symptoms of anaphylaxis, such as swelling, hives, and airway constriction.
D. Monocytes, not basophils, leave the bloodstream to differentiate into macrophages in tissues. Basophils remain as circulating granulocytes and do not transform into other cell types.
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