Host Defenses I: Overview and Innate Immunity

These flashcards cover key concepts and vocabulary related to host defenses and innate immunity based on the provided lecture notes.

First line of defense

Barriers that block invasion at the portal of entry. Does not involve recognition of foreign substances.

Second line of defense

Internalized system of protective cells and fluids including inflammation and phagocytosis.

Third line of defense

Acquired defenses that are specific to each microbe through the action of specialized white blood cells.

Innate immunity

The non-specific first and second lines of defense that are present at birth.

Adaptive immunity

The specific third line of defense that is developed uniquely for each foreign agent.

Lymphatic system

Network of vessels, cells, and organs that help transport and filter lymph.

Lymph

Plasma-like liquid carried by the lymphatic circulation containing white blood cells.

Cytokines

Signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.

Phagocytosis

The process by which certain cells engulf and digest microbes or cellular debris.

Neutrophils

Type of white blood cell that responds rapidly to infection and is major component of pus.

Macrophages

Phagocytic cells that can process foreign materials and present them to lymphocytes.

Dendritic cells

Cells that capture and present antigens to T lymphocytes to initiate an immune response.

Antigens

Molecules on the surface of cells that are recognized by the immune system as self or non-self.

Self

Cells and substances recognized by the immune system as part of the body.

Nonself

Foreign entities like pathogens that are recognized as harmful by the immune system.

Inflammation

Local reaction of tissues to injury or infection characterized by redness, heat, swelling, and pain.

Edema

Swelling due to excess fluid in tissues, often as a result of inflammation.

Pyrogens

Substances that induce fever by acting on the hypothalamus, raising body temperature.

Fever

An abnormally elevated body temperature associated with infection and inflammation.

Immunogenicity

The ability of a substance to provoke an immune response.

Autoimmune disorders

Conditions where the immune system mistakenly attacks the body’s own cells.

Pattern recognition receptors (PRRs)

Receptors on immune cells that identify pathogen-associated molecular patterns (PAMPs).

PAMPs (pathogen-associated molecular patterns)

Molecular patterns common to many pathogens recognized by the immune system.

Complement system

A group of blood proteins that work together to destroy pathogens and signal immune responses.

Natural killer cells

Type of lymphocyte that can kill tumor cells and virally infected cells.

Gamma-delta T cells

A subset of T cells that respond to specific antigens and PAMPs.

Cytotoxic T cells

T cells that destroy infected or cancerous cells by inducing apoptosis.

Helper T cells

T cells that help activate B cells and other immune cells.

B lymphocytes

White blood cells that differentiate into plasma cells to produce antibodies.

Plasma cells

B cells that have differentiated to produce antibodies.

Antibodies

Proteins produced by B cells that specifically bind to antigens.

Serum

Clear liquid that separates from clotted blood, often used in immune testing.

Interferon

Proteins produced by host cells that help in defense against viruses and regulate immune responses.

Antimicrobial peptides

Short proteins that disrupt bacterial membranes, part of the innate immune response.

Histamine

Chemical released by mast cells that causes vasodilation and increases vascular permeability.

Vasodilation

Widening of blood vessels to increase blood flow to an area.

Chemotaxis

The directed migration of cells towards the site of infection in response to chemical signals.

Toll-like receptors (TLRs)

A type of PRR that initiates immune responses when recognizing PAMPs.

Microbiota

The community of microorganisms that live in and on the body, contributing to immunity.

Mucous membranes

Linings of body cavities that produce mucus to trap pathogens and protect underlying tissues.

Sebaceous glands

Glands in the skin that secrete oils with antimicrobial properties.

Lysozyme

An enzyme found in secretions like tears and saliva that breaks down bacterial cell walls.

Saliva

Fluid in the mouth that contains enzymes and antimicrobial agents contributing to oral immunity.

Mast cells

Tissue cells that release histamine during inflammatory responses.

Eosinophils

White blood cells that respond to parasitic infections and play roles in allergy responses.

Basophils

Type of granulocyte that plays a role in allergic reactions and inflammatory responses.

Agranulocytes

A type of white blood cell that lacks granules in its cytoplasm.

Granulocytes

A type of white blood cell characterized by the presence of granules in their cytoplasm.

Hemostasis

The process of stopping bleeding, which involves blood clotting and vessel constriction.

Antigen-presenting cells (APCs)

Cells that display antigens on their surface to activate T cells.

Spleen

Organ that filters blood and recycles iron; plays a role in immune response.

Lymph nodes

Small, bean-shaped structures that filter lymph and house immune cells.

Thymus

Organ where T cells mature before they migrate to the bloodstream.

Bone marrow

Tissue where hematopoiesis occurs, producing all blood cells, including lymphocytes.