What role do basophils play in immunity?
Basophils are humoral immunity cells that become B-memory cells.
Basophils are a nonspecific defense used for phagocytosis.
Basophils bind to IgE and release histamine in anaphylaxis.
Basophils travel from the blood to tissues to become macrophages.
The Correct Answer is C
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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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Rationale:
A. Histamine release during an allergic reaction typically causes vasodilation and increased capillary permeability, which can lead to tachycardia as the heart compensates for hypotension. Bradycardia is not expected in a typical allergic reaction.
B. Histamine release usually causes vasodilation, redness, and edema, not dryness. Dry skin is unrelated to the acute effects of histamine in allergic reactions.
C. Pallor results from reduced blood flow or vasoconstriction, which is opposite to histamine’s effect. Histamine causes dilation of blood vessels, leading to redness, not pallor.
D. Urticaria, or hives, is a classic manifestation of histamine release. Histamine increases capillary permeability, allowing fluid to leak into the surrounding tissues, producing raised, itchy, red wheals. This is a hallmark feature of type I hypersensitivity reactions, such as allergic responses to foods, medications, or insect stings.
Correct Answer is A
Explanation
Rationale:
A. Cellulitis is a bacterial infection of the skin and subcutaneous tissue that can occur when a pressure ulcer breaks the skin barrier. Open wounds provide a pathway for bacteria, most commonly Staphylococcus aureus or Streptococcus species, to enter underlying tissues, leading to redness, swelling, warmth, pain, and potentially systemic infection. This makes cellulitis a common and serious complication of pressure ulcers if not treated promptly.
B. While chronic blood loss or poor nutrition can contribute to anemia, it is not a direct complication of a pressure ulcer. Anemia may be present in patients with multiple comorbidities but is not caused specifically by pressure injuries.
C. Osteoarthritis is a degenerative joint disease unrelated to pressure ulcers. While immobility from severe pressure injuries could worsen joint function, osteoarthritis is not a direct complication.
D. Diabetes is a risk factor for developing pressure ulcers due to poor circulation and impaired wound healing, but it is not caused by pressure ulcers.
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