Lymphatic and Immune Systems

Immune System

A functional system that defends against foreign materials through two main mechanisms: innate (nonspecific) and adaptive (specific).

Innate Immunity

The nonspecific defense mechanisms that protect against a variety of invaders and respond immediately.

Adaptive Immunity

The specific defense system that fights invaders that get past the innate system, requiring specificity for each type of invader.

Inflammatory Response

Triggered when body tissues are injured, characterized by redness, heat, pain, and swelling.

Phagocytes

Cells such as neutrophils and macrophages that engulf foreign material through phagocytosis.

Complement Proteins

A group of plasma proteins activated to attack pathogens and enhance the inflammatory response.

Interferons

Small proteins secreted by virus-infected cells that help inhibit virus multiplication in healthy cells.

Antigens

Any substance that can excite the immune system and provoke an immune response.

B Lymphocytes

Cells that produce antibodies and oversee humoral immunity.

T Lymphocytes

Cells that constitute the cell-mediated arm of adaptive defenses; they do not produce antibodies.

Active Immunity

Immunity that occurs when B cells encounter antigens and produce antibodies.

Passive Immunity

Immunity obtained from antibodies acquired from another source, providing short-lived protection.

Monoclonal Antibodies

Antibodies produced from a single cell line, used for clinical testing and treatment.

Antibody Structure

Composed of four polypeptide chains, with variable regions for antigen binding and constant regions determining antibody class.

Helper T Cells

T cells that recruit other cells to fight invaders and release cytokines to activate more leukocytes.

Cytotoxic T Cells

Specialized T cells that kill infected cells by inserting toxic chemicals like perforin and granzymes.

Self-Antigens

Proteins and carbohydrates on human cells that do not trigger an immune response in the individual.

Haptens

Incomplete antigens that do not elicit an immune response unless bound to a carrier protein.

Memory Cells

Long-lived B cells that provide a rapid response against previously encountered antigens in subsequent infections.

Immunocompetence

The capability of lymphocytes to respond to specific antigens by binding to them with antigen-specific receptors.

Humoral Immune Response

Response where B lymphocytes produce antibodies in response to a specific antigen.

Antibody Functions

Include mechanisms like neutralization, agglutination, and complement fixation to inactivate antigens.

T Cell Activation

Occurs when a T cell recognizes a nonself antigen presented by an antigen-presenting cell (APC).

Antigen-Presenting Cells (APCs)

Cells that engulf antigens and present them on their surface to activate T cells.