Host Defenses and Immune System Overview

These flashcards cover key terms and concepts related to nonspecific and specific immune responses, including the body's defenses against pathogens.

Nonspecific immunity

The first and second lines of defense against pathogens, including physical barriers like skin and mucous membranes, and inflammatory responses.

Phagocytosis

The process by which certain cells (like neutrophils and macrophages) ingest and eliminate pathogens and debris.

Complement system

A series of blood proteins that work together to destroy bacteria and viruses through a cascade reaction.

Interferon

A small protein produced by certain white blood cells and tissue cells, used in therapy against specific viral infections and cancer.

Diapedesis

The process through which leukocytes move out of the bloodstream to the site of infection or injury.

Microbiome

A community of microorganisms that inhabit the body, competing with pathogens and providing protective benefits.

Antimicrobial peptides (AMPs)

Small molecules secreted by the body that have antibacterial and antifungal properties.

Inflammation

A localized response to injury or infection characterized by redness, heat, swelling, and pain.

Chemotaxis

The movement of cells towards the site of infection or injury in response to chemical signals.

Natural Killer (NK) Cells

Immune cells that destroy virus-infected cells and cancer cells by inducing apoptosis.

Mucous membranes

Moist barriers that line various tracts in the body (like the digestive and respiratory tracts) and impede the entry of pathogens.

Chemical defenses

Substances in body fluids (like lysozyme in tears and saliva) that help destroy pathogens.

Acute inflammation

A rapid and short-lived response to injury, often beneficial in combating infections.

Chronic inflammation

A prolonged inflammatory response that can lead to tissue damage.

Barriers at the portal of entry

Physical structures, like skin and mucous membranes, that serve as the first line of defense against pathogens.

Pathogen-associated molecular patterns (PAMPs)

Molecular signatures found on pathogens recognized by pattern recognition receptors (PRRs) in the immune system.

Cytotoxic T cells

A type of T cell that kills infected cells or cancer cells.

B cells

Lymphocytes that produce antibodies as part of the humoral immune response.

Helper T cells

A type of T cell that helps activate B cells and cytotoxic T cells.

Lymphatic system

A network of vessels and nodes that transport lymph, assists in immune responses, and returns extracellular fluid to the bloodstream.

Fever

An abnormally high body temperature often as a response to infection that aids in fighting pathogens.

Skin

Cells compacted, cemented together, & impregnated with keratin

Salivary flow & Swallowing

carry microbes to harsh environment of stomach

Tears

flush eyes of irritants

Peristalsis

evacuate noxious substances or microbes from body

Coughing & Sneezing

ejects irritants

Defense Behaviors

Examples include: Salivary flow &

Swallowing, Tears, Peristalsis, and Coughing & Sneezing

Nonspecific Chemical Defenses

Stomach, Intestines, Proteases in the digestive track, Other (Semen has antimicrobial chemicals, V*gina has a protective acidic pH maintained by normal biota)

Thymus

Site of T-cell maturation

Lymph nodes

filter out materials that have entered the lymph

Spleen

Filters pathogens from the blood for

phagocytosis by macrophages