BSCI202 Exam 1 Study Guide: Blood, Lymph, and Immune System

Vocabulary flashcards covering blood components, hemostasis, immune defenses, blood typing, and the lymphatic system.

Hematocrit

The percentage of total blood volume composed of erythrocytes (RBCs), which averages approximately $45\%$ in a healthy individual.

Albumin

The main plasma protein responsible for maintaining osmotic balance and buffering pH in the blood.

Serum

The liquid portion of blood that remains after clotting factors have been consumed by clot formation.

Hemocytoblast (Hematopoietic Stem Cell)

The progenitor stem cell located in red bone marrow from which all formed elements of the blood originate.

Oxyhemoglobin

Hemoglobin bound to oxygen ($O_2$) immediately after loading in the lungs, giving blood a ruby red color.

Carbaminohemoglobin

Hemoglobin bound to carbon dioxide ($CO_2$) on its globin chains, transporting approximately $20\%$ of blood $CO_2$.

Erythropoietin (EPO)

A hormone released mainly by the kidneys in response to hypoxia that stimulates red bone marrow to produce erythrocytes.

Pernicious Anemia

An autoimmune condition targeting stomach parietal cells, preventing the production of intrinsic factor required for vitamin $B_{12}$ absorption.

Sickle-Cell Anemia

A genetic disorder caused by a single amino acid mutation in beta-globin ($HbS$), causing red blood cells to deform into a sickle shape, block vessels, and rupture easily.

Vascular Spasm

The initial step of hemostasis in which smooth muscle in the damaged blood vessel wall contracts to narrow the vessel and limit blood loss.

Platelet Plug Formation

The second step of hemostasis where platelets aggregate at exposed collagen via von Willebrand factor and release chemicals ($ADP$, serotonin, thromboxane $A_2$, and $Ca^{2+}$) to recruit more platelets.

Intrinsic Pathway

A slower coagulation pathway triggered by contact with collagen or activated platelets inside the damaged blood vessel.

Extrinsic Pathway

A rapid coagulation pathway triggered by Tissue Factor released by damaged cells outside the blood vessel.

Plasmin

An active fibrin-digesting enzyme formed from plasminogen that dissolves blood clots during fibrinolysis.

Thrombus

A blood clot that develops and remains attached to the intact wall of a blood vessel.

Embolus

A blood clot or intravascular mass that breaks free from its site of origin and travels through the bloodstream.

Thrombocytopenia

A condition defined by a diagnostic platelet count below $50,000/\mu L$, leading to petechiae and spontaneous bleeding.

Agglutinogen

A surface antigen on red blood cells (such as A, B, or D) that determines blood type and can react with specific antibodies.

Agglutinin

An antibody dissolved in plasma (such as anti-A or anti-B) that causes clumping (agglutination) when binding to matching red blood cell antigens.

Erythroblastosis Fetalis

Hemolytic disease of the newborn caused when maternal anti-Rh $IgG$ antibodies cross the placenta in a subsequent pregnancy to destroy $Rh^+$ fetal red blood cells.

Neutrophils

The most abundant leukocytes ($50\text{--}70\%$ of WBCs), serving as highly phagocytic, short-lived responders in innate immunity.

Monocytes

Agranular leukocytes ($3\text{--}8\%$ of WBCs) that migrate from blood into tissues to transform into chief phagocytic cells known as macrophages.

Natural Killer (NK) Cells

Cytotoxic innate lymphocytes that identify and destroy target cells missing normal self surface markers without requiring MHC presentation.

Diapedesis

The process by which leukocytes squeeze between endothelial cells of capillary walls to leave the bloodstream and enter injured tissue.

Pyrogen

A fever-inducing chemical released by leukocytes or pathogens that acts on the hypothalamus to raise body temperature.

Immunocompetence

The functional maturation of a lymphocyte allowing it to recognize and bind to one specific antigen.

Self-Tolerance

The state in which mature lymphocytes are rendered unreactive to the body's own self-antigens.

Major Histocompatibility Complex (MHC)

A set of cell surface proteins used for self-recognition; $MHC\text{-}I$ occurs on all nucleated cells, whereas $MHC\text{-}II$ occurs exclusively on antigen-presenting cells.

Helper T Cells ($T_H$)

$CD4^+$ T lymphocytes that direct immune responses by activating B cells, T cells, and driving cell proliferation.

Cytotoxic T Cells ($T_C$)

$CD8^+$ T lymphocytes that directly attack and destroy infected or cancerous body cells presenting foreign antigens on $MHC\text{-}I$.

IgM

The pentameric antibody class produced first during a primary immune response, effective at complement activation and agglutination, but incapable of crossing the placenta.

IgG

The most abundant plasma antibody class, dominant in secondary immune responses, capable of crossing the placenta and granting passive immunity.

IgE

An antibody class that binds mast cells and basophils, triggering histamine release responsible for allergic reactions, asthma, and anaphylaxis.

Active Immunity

Long-lasting immunity established when an individual's own B and T cells encounter antigens and generate an active response with immunological memory.

Passive Immunity

Short-term immunity conferred by receiving pre-formed antibodies from another source without activating memory cell production.

Opsonization

The process of coating a pathogen with antibodies or complement proteins to enhance its recognition and phagocytosis by leukocytes.

Primary Lymphoid Organs

Anatomical sites where lymphocytes originate and mature, consisting of red bone marrow for B cells and the thymus for T cells.

Secondary Lymphoid Organs

Tissues where mature, immunocompetent lymphocytes encounter antigens and launch adaptive responses, including lymph nodes, spleen, and tonsils.