Comprehensive Pathophysiology Review 2026: Questions and Rationales for High Performance

What is the primary function of red blood cells? a) To fight infections b) To form blood clots c) To transport oxygen and carbon dioxide d) To regulate body temperature Rationale: Red blood cells contain hemoglobin which carries oxygen from the lungs to tissues and returns carbon dioxide to the lungs. White blood cells fight infections, platelets help clotting, and temperature regulation is done by the circulatory system as a whole. Which blood component is essential for clot formation? a) Red blood cells b) Platelets c) Plasma proteins d) White blood cells Rationale: Platelets are responsible for initiating blood clotting by forming a plug at the site of injury. Red and white cells do not participate directly in clotting, and plasma proteins are only supportive. Which of the following is a common symptom of iron deficiency anemia? a) Jaundice b) Fatigue and pallor c) Excessive bleeding d) Bruising easily Rationale: Iron deficiency anemia leads to low hemoglobin, causing fatigue and pale skin. Jaundice is seen in hemolytic anemia, bleeding and bruising are more related to platelet disorders. What is the normal lifespan of a red blood cell? a) 10–20 days b) 120 days c) 365 days d) 5–7 days Rationale: A red blood cell circulates in the bloodstream for about 120 days before being destroyed by the spleen. The other time spans are incorrect for erythrocytes. Which skin layer contains blood vessels and nerve endings? a) Epidermis b) Stratum corneum c) Dermis d) Hypodermis only Rationale: The dermis houses blood vessels, nerves, hair follicles, and glands. The epidermis is avascular and primarily protective, while the hypodermis stores fat. Which condition is characterized by chronic redness, scaling, and silvery plaques on the skin? a) Eczema b) Acne c) Psoriasis d) Dermatitis herpetiformis Rationale: Psoriasis presents as well-defined red plaques with silvery scales due to rapid skin cell turnover. Eczema is more itchy and weepy; acne involves sebaceous glands; dermatitis herpetiformis is linked to celiac disease. What is the most abundant plasma protein? a) Globulin b) Fibrinogen c) Albumin d) Prothrombin Rationale: Albumin accounts for about 60% of plasma proteins, maintaining osmotic pressure and transporting substances. Globulins are immune-related, fibrinogen aids in clotting, and prothrombin is a clotting factor. Which white blood cell type is primarily responsible for allergic reactions and parasitic infections? a) Neutrophils b) Eosinophils c) Basophils d) Lymphocytes Rationale: Eosinophils increase during allergies and parasitic infections. Neutrophils fight bacteria, basophils release histamine, and lymphocytes are involved in immunity. Which vitamin is essential for proper blood clotting? a) Vitamin C b) Vitamin B12 c) Vitamin K d) Vitamin D Rationale: Vitamin K is necessary for the synthesis of clotting factors like prothrombin. Vitamin C supports collagen formation, B12 helps RBC production, and D is for bone health. Which skin condition is caused by autoimmune destruction of melanocytes? a) Albinism b) Vitiligo c) Melasma d) Psoriasis Rationale: Vitiligo leads to patchy loss of skin pigment due to immune attack on melanocytes. Albinism is genetic absence of melanin, melasma is hormonal hyperpigmentation, and psoriasis is inflammatory. What type of anemia results from a deficiency of intrinsic factor? a) Iron deficiency anemia b) Hemolytic anemia c) Pernicious anemia d) Aplastic anemia Rationale: Pernicious anemia occurs due to lack of intrinsic factor, leading to poor absorption of vitamin B12. Iron deficiency anemia is due to low iron, hemolytic anemia is caused by RBC destruction, and aplastic anemia is due to bone marrow failure. Which laboratory test measures the percentage of red blood cells in blood? a) MCV b) Hematocrit c) Hemoglobin d) ESR Rationale: Hematocrit measures the proportion of RBCs in total blood volume. Hemoglobin measures oxygen-carrying protein, MCV shows red cell size, and ESR indicates inflammation. Which dermatological condition is caused by Staphylococcus aureus or Streptococcus pyogenes and presents with honey-colored crusts? a) Psoriasis b) Eczema c) Impetigo d) Rosacea Rationale: Impetigo is a contagious bacterial infection with honey-colored crusts. Psoriasis shows silver scales, eczema is itchy and red, rosacea has facial flushing. What is the primary cause of sickle cell anemia? a) Iron deficiency b) Autoimmune response c) Bone marrow damage d) Genetic mutation in hemoglobin Rationale: Sickle cell anemia is inherited and caused by a mutation in hemoglobin, leading to sickle-shaped RBCs. The other options are unrelated causes. Which skin layer is responsible for keratin production? a) Dermis b) Hypodermis c) Epidermis (specifically the stratum basale) d) Stratum lucidum Rationale: The epidermis, particularly the basal layer, produces keratinocytes which form keratin. The dermis supports with blood vessels and nerves; the hypodermis stores fat. Which test is used to measure the rate at which red blood cells settle in a tube over one hour? a) Hemoglobin test b) ESR (Erythrocyte Sedimentation Rate) c) Platelet count d) Coagulation profile Rationale: ESR detects inflammation by measuring RBC settling rate. Hemoglobin measures oxygen-carrying capacity, platelet count detects clotting issues, and coagulation profile evaluates clotting factors. A patient presents with petechiae and prolonged bleeding. Which blood component is most likely deficient? a) Red blood cells b) Platelets c) Plasma enzymes d) Neutrophils Rationale: Platelet deficiency leads to petechiae and bleeding. RBC deficiency causes anemia symptoms, plasma enzymes do not control bleeding, neutrophils are involved in infection control. Which skin condition is characterized by comedones, papules, and pustules due to blocked sebaceous glands? a) Dermatitis b) Acne vulgaris c) Psoriasis d) Cellulitis Rationale: Acne is caused by blocked sebaceous glands. Dermatitis is inflammation, psoriasis is autoimmune, cellulitis is bacterial infection of deeper skin layers. Which hematologic disorder results in excessive production of white blood cells? a) Anemia b) Leukemia c) Thrombocytopenia d) Polycythemia vera Rationale: Leukemia involves uncontrolled production of abnormal WBCs. Anemia is low RBCs, thrombocytopenia is low platelets, polycythemia vera is high RBCs. Which pigment gives the skin its color and protects it from UV radiation? a) Keratin b) Collagen c) Melanin d) Elastin Rationale: Melanin is produced by melanocytes and provides pigmentation and UV protection. Keratin strengthens skin, collagen provides structure, and elastin offers flexibility. What condition results from destruction of red blood cells leading to excess bilirubin? a) Iron deficiency anemia b) Hemolytic anemia c) Aplastic anemia d) Pernicious anemia Rationale: Hemolytic anemia occurs when RBCs are destroyed faster than they are produced, releasing bilirubin. Other anemias involve impaired production, not destruction. Which white blood cell is primarily responsible for allergic reactions and fighting parasites? a) Neutrophil b) Lymphocyte c) Eosinophil d) Monocyte Rationale: Eosinophils combat parasitic infections and mediate allergic responses. Neutrophils fight bacteria, lymphocytes target viruses, and monocytes become macrophages. Which dermatologic disorder is characterized by silver-white scales on red plaques? a) Psoriasis b) Eczema c) Impetigo d) Urticaria Rationale: Psoriasis produces silvery scales from rapid skin cell turnover. Eczema causes itching, impetigo causes crusting, and urticaria presents with hives. A patient with chronic renal failure develops pale conjunctiva and fatigue. What type of anemia is most likely? a) Hemolytic anemia b) Pernicious anemia c) Anemia of chronic disease d) Aplastic anemia Rationale: Kidney failure decreases erythropoietin production, causing anemia of chronic disease. Other types result from vitamin deficiency or marrow damage. Which layer of the skin contains blood vessels, nerves, and connective tissue? a) Epidermis b) Dermis c) Hypodermis d) Stratum corneum Rationale: The dermis houses vessels, nerves, and glands. The epidermis is avascular, the hypodermis stores fat, and the stratum corneum is only the outer keratinized layer. Which laboratory value would be decreased in a patient with iron deficiency anemia? a) White blood cell count b) Platelet count c) Hemoglobin concentration d) ESR Rationale: Iron deficiency reduces hemoglobin synthesis. WBCs and platelets remain normal; ESR may be slightly raised but not diagnostic. A child presents with thickened skin and erythematous lesions in flexural areas. What is the most likely diagnosis? a) Psoriasis b) Atopic dermatitis (eczema) c) Acne vulgaris d) Rosacea Rationale: Eczema is common in children, involving itchy red lesions in folds. Psoriasis affects extensor surfaces, acne affects the face, and rosacea affects adults. Which test is most useful in diagnosing iron deficiency anemia? a) Serum ferritin level b) ESR c) Platelet count d) WBC differential Rationale: Ferritin reflects iron stores; low levels confirm iron deficiency. ESR indicates inflammation, platelet count checks clotting, and WBC differential measures immune response. A butterfly-shaped rash across the nose and cheeks is characteristic of which condition? a) Eczema b) Rosacea c) Systemic lupus erythematosus d) Psoriasis Rationale: Lupus causes a malar (butterfly) rash. Rosacea may mimic it but lacks systemic signs. Eczema and psoriasis have different patterns. Which hematologic disorder is characterized by pancytopenia (low RBCs, WBCs, and platelets)? a) Aplastic anemia b) Hemolytic anemia c) Sickle cell anemia d) Thalassemia Rationale: Aplastic anemia results from bone marrow failure causing all blood cell lines to decrease. Other anemias affect primarily red cells.