Introduction to Immunology and Immune System Activation

Vocabulary flashcards covering key concepts, definitions, cells, pathways, and organs involved in innate and adaptive immunology based on the lecture material.

Immunology

The study of physiological mechanisms that humans and animals use to defend their bodies from invading organisms such as bacteria, viruses, fungi, toxins, and parasites.

Immune system

A complex system of organs, cells, and proteins whose primary purpose is to identify and fight against foreign (non-self) substances.

Immune tolerance

The ability of the immune system to determine friend from foe (self from non-self).

Immunity

The state of being immune from, insusceptible to, or protected from a particular disease.

Immune response

A reaction of the body in response to the presence of a foreign substance for the purpose of defending against exogenous factors.

Antigen

Any substance that is capable of inducing an immune response when introduced into an organism.

Immunologic memory

The ability of the immune system to respond more quickly and more effectively to pathogens to which it has been previously exposed.

Specificity

The degree to which an immune response discriminates between antigenic variants.

Autoantigens

Markers on cells inside animal bodies that the immune system attacks even though it shouldn't.

Tumor antigens

Markers on the surface of tumors that are expressed by host cells, typically expressed at a very low or zero level in normal tissues.

Innate immunity

The rapid-acting host defense mechanism present from birth ('always on') that has universal specificity, lacks immunologic memory, and does not improve upon secondary exposure.

Adaptive immunity

The long-term, specific immune defense developed and activated by antigens, involving T cells and B cells, with slow onset, significant memory, and improved effectiveness upon secondary exposure.

Sentinel cells

Immune cells predominantly found in tissues (such as macrophages, dendritic cells, and mast cells) that monitor and clear dangerous and foreign material.

Phagocytosis

A process meaning 'cell eating' by which certain immune cells bind, internalize, and destroy invading substances.

Phagocytes

Cells capable of phagocytosis, including neutrophils, macrophages, and dendritic cells.

Pathogen-Associated Molecular Pattern (PAMP)

Small molecular motifs conserved within a class of microbes that are not present in the host, such as bacterial cell wall structures or viral double-stranded RNA.

Lipopolysaccharide (LPS)

A pathogen-associated molecular pattern (PAMP) found in the cell wall of Gram-negative bacteria.

Lipoteichoic acids (LTA)

A pathogen-associated molecular pattern (PAMP) found in the cell wall of Gram-positive bacteria.

Pattern Recognition Receptor (PRR)

Proteins, mostly expressed on immune cells, capable of recognizing PAMPs and DAMPs to initiate immune signal transduction and cytokine expression.

High Endothelial Venules (HEV)

Specialized blood vessels through which T cells and B cells enter the lymph node.

Red pulp

The functional region of the spleen that filters blood to remove aging and damaged blood cells, immune complexes, and opsonized microbes.

White pulp

The functional region of the spleen that initiates adaptive immune responses to blood-borne antigens.

Cellular immunity

Adaptive immunity mediated by T cells through direct lysis of target cells or production of cytokines that activate infected cells, eliminating intracellular microbes.

Humoral immunity

Adaptive immunity mediated by antibodies produced by B cells, targeting whole or fractionated extracellular antigens and toxins.

Primary lymphoid organs

Organs that regulate the development and maturation of lymphocytes, including the thymus for T cells, and bone marrow, bursa of Fabricius, or Peyer's patches for B cells.

Secondary lymphoid organs

Organs where mature lymphocytes encounter antigens and initiate adaptive immune responses, including lymph nodes, spleen, and tonsils.

Spleen

Organ that filters antigens from blood

Red Pulp & White Pulp

Red Pulp: Filters blood to remove aging/damaged blood cells

White Pulp: Initiates adaptive immune responses to blood borne antigens

What are the two Adaptive Immunity mechanisms?

Cellular Immunity & Humoral Immunity

What are the characteristics of Humor Immunity?

• Production of antibodies by B Cells

• Antibodies bind to either whole or fractions of antigens outside cells

• Eliminate extracellular microbes or toxins

What are the characteristics of Cellular Immunity?

• Direct lysis (destruction) of target cells

• Production of cytokines (proteins secreted by immune cells)

• Eliminate intracellular microbes

• Driven by T Cells produced in bone marrow

What are Lymphocytes?

B Cells & T Cells

What are Primary lymphoid organs? Where are these located within humans and animals?

Organs that regulate the development of lymphocytes.

T Cells in Humans: Thymus

B Cells: Bone marrow (in humans) & Bursa of Fabricius (In birds) & Peyer’s Patch (in pigs & horses)

What are the Secondary lymphoid organs?

Tonsils, Spleen & Lymph nodes

What are the key cells in the Innate Immune System?

Sentinel Cells, Circulating Cells & Tissue Cells

What are some examples of Circulating Cells?

Neutrophils, Monocytes, Eosinophils & Lymphocytes

What are some examples of diferent types of tissue?

Epithelial, Connective, Nervous & Muscle