Pathophysiology Q&A | Pathophysiology
1. Which of the following is an example of a physical barrier in the innate
immune system?
A) Antibacterial fatty acids in sebum
B) Lysozymes in tears
C) Epithelial cells lining the skin
D) Earwax (cerumen)
Correct Answer: Epithelial cells lining the skin
Rationale: Physical barriers include epithelial cells that line the skin and
mucous membranes, providing a mechanical barrier against pathogen entry.
Antibacterial fatty acids, lysozymes, and earwax are considered biochemical,
not physical, barriers.
2. Which statement accurately describes the inflammatory response?
A) It is the third line of defense and is highly specific.
B) It relies exclusively on cellular components.
C) It generates a nonspecific response in vascularized tissue.
D) It occurs only in nonvascular tissue.
Correct Answer: It generates a nonspecific response in vascularized tissue.
Rationale: The inflammatory response is the second line of defense. It is
nonspecific (innate) and involves both vascular and cellular components,
occurring in vascularized tissue to allow plasma proteins and leukocytes to
reach the injury site.
3. Which receptor, expressed on macrophages, facilitates the recognition and
phagocytosis of bacterial pathogens?
A) Complement receptors
B) Scavenger receptors
C) Toll-like receptors (TLRs)
,D) Pattern recognition receptors (PRRs)
Correct Answer: Pattern recognition receptors (PRRs)
Rationale: PRRs are expressed on macrophages and other innate immune
cells. They recognize pathogen-associated molecular patterns (PAMPs) on
pathogens, facilitating recognition and phagocytosis. Toll-like receptors are a
specific type of PRR.
4. Histamine causes all of the following EXCEPT:
A) Vasodilation
B) Increased vascular permeability
C) Vasoconstriction
D) Increased blood flow to the site of injury
Correct Answer: Vasoconstriction
Rationale: Histamine is a potent vasodilator that increases blood flow and
vascular permeability, leading to erythema and swelling at the injury site. It
does not cause vasoconstriction.
5. What is the primary function of chemotactic factors in the inflammatory
response?
A) To induce fever
B) To attract leukocytes to the site of inflammation
C) To activate the complement cascade
D) To promote vasodilation
Correct Answer: To attract leukocytes to the site of inflammation
Rationale: Chemotactic factors are chemical signals that attract leukocytes
(such as neutrophils and macrophages) to the site of injury or infection, a
process known as chemotaxis.
6. A patient presents with urticaria, rhinitis, and angioedema after exposure
to peanuts. This reaction is classified as which type of hypersensitivity?
,A) Type I (Anaphylactic)
B) Type II (Cytotoxic)
C) Type III (Immune complex-mediated)
D) Type IV (Delayed-type)
Correct Answer: Type I (Anaphylactic)
Rationale: Urticaria (hives), rhinitis, and angioedema are classic
manifestations of a Type I hypersensitivity reaction, which is IgE-mediated
and occurs rapidly after exposure to an allergen.
7. A patient with systemic lupus erythematosus (SLE) has antibodies against
DNA and nuclear proteins. This autoimmune disease is primarily classified as
which type of hypersensitivity?
A) Type I
B) Type II
C) Type III
D) Type IV
Correct Answer: Type III
Rationale: SLE is a classic Type III hypersensitivity disorder. Autoantibodies
form immune complexes with self-antigens, which deposit in tissues (e.g.,
kidneys, skin) and activate complement, leading to inflammation and tissue
damage.
8. Which type of hypersensitivity reaction is mediated by T cells and typically
takes 24-72 hours to develop?
A) Type I
B) Type II
C) Type III
D) Type IV
Correct Answer: Type IV
, Rationale: Type IV hypersensitivity is a delayed-type reaction mediated by T
cells, not antibodies. It typically takes 24-72 hours to develop, as seen in
contact dermatitis (e.g., poison ivy) and tuberculin skin tests.
9. A patient with a blood transfusion reaction experiences hemolysis of
transfused red blood cells. This is an example of which type of
hypersensitivity?
A) Type I
B) Type II
C) Type III
D) Type IV
Correct Answer: Type II
Rationale: A transfusion reaction is a Type II (cytotoxic) hypersensitivity.
Antibodies (IgG or IgM) bind to antigens on the surface of transfused red
blood cells, leading to complement activation and cell lysis.
10. Which immunoglobulin (Ig) is primarily responsible for mediating Type I
hypersensitivity reactions?
A) IgA
B) IgE
C) IgG
D) IgM
Correct Answer: IgE
Rationale: IgE is the immunoglobulin responsible for Type I hypersensitivity
reactions. It binds to Fc receptors on mast cells and basophils, and cross-
linking by an allergen triggers degranulation and the release of inflammatory
mediators.
11. What is the role of mast cells in Type I hypersensitivity reactions?
A) To produce antibodies