MCAT Biological and Biochemical Foundations of Living Systems Flashcards: 3b Blood Composition Gas Transport

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This deck focuses on 3b Blood Composition Gas Transport, giving you a quick way to review the definitions, rules, and examples that matter most for MCAT Biological and Biochemical Foundations of Living Systems.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What vitamin is required for hepatic synthesis of several clotting factors?

Answer: Vitamin K. It enables gamma-carboxylation of glutamate residues in factors II, VII, IX, and X for calcium binding.

Flashcard 2: What is the main form of $CO_2$ transport in blood?

Answer: Bicarbonate ($HCO_3^-$) in plasma. Carbonic anhydrase converts $CO_2$ to bicarbonate in erythrocytes for efficient transport to lungs.

Flashcard 3: What immunoglobulin class mediates type I hypersensitivity via mast cells?

Answer: IgE. It triggers degranulation upon allergen binding, releasing histamine for allergic responses.

Flashcard 4: What immunoglobulin class is a pentamer and best at complement activation?

Answer: IgM. Its structure allows efficient agglutination and classical complement pathway initiation.

Flashcard 5: What immunoglobulin class is most abundant in serum?

Answer: IgG. It provides long-term protection through opsonization, neutralization, and placental transfer.

Flashcard 6: What is the defining specificity of an antibody (immunoglobulin)?

Answer: Binds a particular epitope (antigenic determinant). The variable region confers high-affinity binding to unique molecular structures on pathogens.

Flashcard 7: Which MHC class presents exogenous antigens to $CD4^+$ T cells?

Answer: MHC class II. It presents phagocytosed antigens to initiate helper T cell-mediated immune responses.

Flashcard 8: Which MHC class presents endogenous antigens to $CD8^+$ T cells?

Answer: MHC class I. It displays intracellular peptides to enable immune surveillance of infected or cancerous cells.

Flashcard 9: What is the primary function of helper T cells ($CD4^+$)?

Answer: Coordinate immune response via cytokine signaling. They release cytokines to activate B cells, macrophages, and cytotoxic T cells in adaptive immunity.

Flashcard 10: What is the primary function of cytotoxic T cells ($CD8^+$)?

Answer: Kill virus-infected and malignant cells. They induce apoptosis in target cells via perforin and granzymes upon MHC I recognition.

Flashcard 11: What is the primary function of B lymphocytes in adaptive immunity?

Answer: Differentiate into plasma cells that secrete antibodies. Activated B cells produce immunoglobulins for humoral immunity against specific antigens.

Flashcard 12: Which leukocytes differentiate into macrophages in tissues?

Answer: Monocytes. Monocytes migrate to tissues and transform into phagocytic cells for pathogen clearance.

Flashcard 13: Which leukocyte releases histamine and heparin in allergic responses?

Answer: Basophil (and tissue mast cells). They degranulate to release mediators promoting inflammation in hypersensitivity reactions.

Flashcard 14: Which leukocyte is most associated with parasitic infections and allergy?

Answer: Eosinophil. Eosinophils release major basic protein and other mediators to combat helminths and allergens.

Flashcard 15: What is the most common leukocyte type in peripheral blood?

Answer: Neutrophils. They constitute 50-70% of white blood cells and act as primary phagocytes against bacteria.

Flashcard 16: What enzyme converts fibrinogen to fibrin during coagulation?

Answer: Thrombin. This serine protease cleaves fibrinogen in the common pathway of coagulation to stabilize clots.

Flashcard 17: What is the immediate precursor protein cleaved to form fibrin in clotting?

Answer: Fibrinogen. It is converted by thrombin into fibrin monomers that polymerize to form clot meshwork.

Flashcard 18: What is the function of platelets (thrombocytes)?

Answer: Hemostasis: platelet plug formation and clotting support. Platelets aggregate at vessel injury sites and release factors to initiate coagulation.

Flashcard 19: What is hematocrit?

Answer: Fraction (percent) of blood volume occupied by erythrocytes. It indicates oxygen-carrying capacity and is measured by centrifuging blood to separate components.

Flashcard 20: What is the biconcave shape of erythrocytes best suited to increase?

Answer: Surface area-to-volume ratio for gas exchange. The discoid shape maximizes diffusion efficiency for oxygen uptake and carbon dioxide release.

Flashcard 21: What is the primary function of erythrocytes in blood?

Answer: Transport $O_2$ (and some $CO_2$) via hemoglobin. Hemoglobin within erythrocytes binds oxygen in lungs and releases it in tissues for cellular respiration.

Flashcard 22: What are the main plasma proteins responsible for clotting?

Answer: Fibrinogen and prothrombin (clotting factors). These proteins participate in the coagulation cascade to form fibrin clots and stop bleeding.

Flashcard 23: What is the main protein in plasma that maintains oncotic pressure?

Answer: Albumin. It exerts colloidal osmotic pressure to regulate fluid balance between blood and tissues.

Flashcard 24: What are the two major components of whole blood by volume?

Answer: Plasma and formed elements. Whole blood consists of liquid plasma and cellular formed elements, separated by centrifugation.

Flashcard 25: What are the three major formed elements of blood?

Answer: Erythrocytes, leukocytes, and platelets (thrombocytes). These cellular components are suspended in plasma and perform oxygen transport, immune defense, and hemostasis functions.