Human Immune System and Innate Immunity Overview

Comprehensive vocabulary flashcards covering the Human Immune System, including innate and adaptive immunity, cell types, protein systems, and disease classifications.

Pathogens

Harmful microorganisms that cause disease.

$$Leukocytes$$

White blood cells that serve as the primary cells of the immune system.

$$Lymphocytes$$

White blood cells that originate from bone marrow and are primarily found in lymphatic organs, including B cells, T cells, and natural killer (NK) cells.

$$T \text{ cells}$$

Lymphocytes that mature in the thymus.

$$B \text{ cells}$$

Lymphocytes that mature in the bone marrow.

Innate Immune System

The first line of defense that generates a nonspecific (generalized) immune response.

External immunity

Physical and physiological barriers, such as skin, hair, cilia, mucous membranes, chemical secretions, and symbiotic bacteria, that prevent pathogen entry.

Internal immunity

Internal defenses activated to neutralize pathogens that have entered the body, composed of the inflammatory response, complement proteins, phagocytic cells, and natural killer cells.

$$Mast \text{ cells}$$

Leukocytes sitting in tissue that release histamine and heparin in response to injury to initiate the inflammatory response.

$$Histamine$$

A chemical that dilates blood vessels and increases their permeability, allowing immune cells to enter the tissue.

$$Heparin$$

An anticoagulant released by mast cells that prevents blood clotting.

$$SLIPR$$

A mnemonic for the inflammatory response standing for Swelling, Loss of function, Increased heat, Pain, and Redness.

Diapedesis

The process by which cells move from capillaries to the tissues in order to fight pathogens, directed by chemokine signaling.

$$Chemotaxis$$

The movement of white blood cells following a chemical trail/gradient toward a site of injury.

Granulocytes

Cells in the innate immune system with specific granules in their cytoplasm, including neutrophils, eosinophils, basophils, and mast cells.

Neutrophils

The most common leukocyte found in the blood ( > 50 \text{%}) and one of the first cells recruited to a site of inflammation.

$$Natural \text{ killer (NK) cells}$$

Innate immune cells that attack virally infected and cancerous cells using perforin to create holes and granzymes to stimulate apoptosis.

Macrophages

The mature form of monocytes that function as phagocytes and antigen-presenting cells (APCs) after undergoing diapedesis.

Eosinophils

Innate immune cells with granules released specifically to kill pathogens, particularly parasites.

Basophils

The least numerous leukocyte, containing granules with histamine and heparin; they circulate as mature cells while mast cells circulate as immature cells.

Dendritic Cells

Innate immune cells that scan tissues using pinocytosis and phagocytosis, acting as antigen-presenting cells to activate adaptive immunity.

$$Toll \text{-like receptors (TLRs)}$$

Receptors used by macrophages and dendritic cells to recognize conserved parts of microbes, triggering phagocytosis.

Interferons

Molecules secreted by virally or bacterially infected cells that bind to non-infected cells to prepare them for potential attack.

Platelets

Anucleate cell fragments involved in blood clotting and the activation of the innate immune system.

Complement System

A group of approximately $30$ proteins that activate a cascade to aid immune cells in fighting pathogens via protease activity.

Opsonization

The process by which complement proteins tag antigens for phagocytosis.

$$Membrane \text{ attack complex (MAC)}$$

A structure formed by complement proteins that pokes holes in and lyses pathogens.

Adaptive Immune System

A specific immune response that targets specific antigens.

Antigen

An immunogenic foreign molecule that is the target of an immune response.

Epitope

The specific portion of an antigen that is recognized by immune cells.

$$Major \text{ histocompatibility complex (MHC)}$$

Molecules on immune cells that allow the system to recognize foreign cells and antigens.

$$MHC \text{ class I}$$

Surface molecules on all nucleated cells that present intracellular antigens; they are unique to each individual.

$$MHC \text{ class II}$$

Surface molecules on antigen-presenting cells (dendritic cells and macrophages) that present extracellular antigens.

Humoral Immunity

Antibody-mediated immunity controlled by B cells.

Plasma cells

B cells that have differentiated to produce and secrete antibodies.

Memory B cells

B cells that lie dormant after an initial attack and are the key to vaccinations for massive antibody production upon reactivation.

Antibodies

Immunoglobulins consisting of light and heavy chains linked by disulfide bonds, featuring a variable region for antigen recognition and a constant region.

$$IgM$$

The largest, pentameric antibody; it is the first to be produced and activates the complement system.

$$IgA$$

A dimeric antibody found in bodily secretions and breast milk, providing passive immunity to newborns.

$$IgE$$

A monomeric antibody on basophils and mast cells that triggers histamine release and allergic reactions.

$$IgG$$

The most abundant monomeric antibody in circulation; the only class that crosses the placenta to provide passive immunity to a fetus.

Cell-mediated immunity

Immunity controlled by T cells which directly act on cells rather than releasing antibodies.

$$Cytotoxic \text{ T cells (CD8+)}$$

T cells activated by MHC I that kill infected cells using perforin and granzymes.

$$T \text{ helper cells (CD4+)}$$

T cells activated by MHC II that release interleukins to boost both innate and adaptive immunity.

Passive Immunity

Immunity gained from receiving antibodies from another organism, such as through the placenta or breast milk.

Active Immunity

Immunity gained from being infected by a pathogen or through vaccination (artificial immunity).

Bacterial Diseases

Infections including Tuberculosis, Gonorrhea, Leprosy, Syphilis, and E. coli.

Viral Diseases

Infections including Influenza, Hepatitis, Herpes, Chicken pox, HPV, HIV, Measles, and Polio.

Genetic Diseases

Conditions including Down syndrome, Cystic fibrosis, Huntington’s disease, Sickle cell, and Tay-Sachs.

Parasitic Diseases

Infections such as Malaria and Tapeworms.

Fungal Diseases

Infections such as Yeast infections and Athlete's foot.