MCB2010 Chapter 15: Leukocytes & Immune Defense Terms

First line of defense

intact skin, mucous membranes and their secretions, normal microbiota

Epidermis

outermost layer of skin

Dermis

Inner layer of skin; collagen fibers help with resistance

Sebum

oily substance secreted by the sebaceous glands of the skin that lowers pH

Epithelium

cells covering external and internal surfaces of the body

Epithelium functions

protection, absorption, filtration, excretion, secretion, sensory reception

upper respiratory tract

consists of the nose, mouth, pharynx, epiglottis, larynx, and trachea

lower respiratory tract

trachea, bronchi, lungs

lacrimal apparatus

the structures that produce, store, and remove tears

microbial antagonism

bacterial flora benefit host by preventing overgrowth of harmful microbes

antimicrobial peptides

Short peptides act against a variety of microbes

second line of defense

protective cells, chemical, and processes acted upon infection

Plasma

Fluid portion of blood

Serum

plasma without clotting factors

Leukocytes (White Blood Cells)

Any of the blood cells that are colorless, lack hemoglobin, contain a nucleus, and include the lymphocytes, monocytes, neutrophils, eosinophils, and basophils.

Granulocytes

A group of leukocytes containing granules in their cytoplasm; neutrophils, eosinophils, basophils.

Agranulocytes

A group of leukocytes without granules in their nuclei; lymphocytes, monocytes.

Basophils

release histamine, play role in inflammation; stained blue with basic dye methylene blue

Neutrophils

A type of white blood cell that engulfs microbes by phagocytosis; bacterial infection; stained lilac

Eosinophils

play role in parasitic (worms) infection and allergy; stained red with acidic dye eosin; secrete toxins that weaken or kill the helminth. Produce proteins that can also kill bacteria.

Monocytes

An agranular leukocyte that is able to migrate into tissues and transform into a macrophage.

Diapedesis

cell (walking) migration from circulatory system to lymphatic system, monitoring foreign pathogen

Lymphocytes

The two types of white blood cells that are part of the body's immune system: B lymphocytes form in the bone marrow and release antibodies that fight bacterial infections; T lymphocytes form in the thymus and other lymphatic tissue and attack cancer cells, viruses, and foreign substances.

Show increase in viral infection.

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells; second line of defense

Stages of phagocytosis

chemotaxis, adhesion, ingestion, maturation, killing, elimination

Natural killer cells

A type of white blood cell that can kill tumor cells and virus-infected cells.

Toll-like receptors (TLRs)

transmembrane protein of immune cells that recognizes pathogens and activates an immune response directed against those pathogens

PAMP

pathogen associated molecular patterns

NOD proteins

Cytosolic proteins that bind PAMPs

Trigger inflammation, apoptosis, and other innate responses

Mechanism of action still being researched

Inteferons

body defenses that inhibit viral replication and activate nearby cells with antiviral actions; type I (alpha and beta) and type II (gamma)

Complement proteins

a plasma protein that helps defend against invading microbes by tagging the microbe for phagocytosis, puncturing cell membranes, or triggering the formation of a mucous coating

Protein cascade

A series of reactions in which a signal is passed on to downstream proteins within the cell by sequential protein phosphorylation and activation of the cascade components

Lectin pathway

mannose-binding lectin binds to pathogen surface

Classical pathway of complement activation

One of three pathways of complement activation. It is activated by antibody bound to antigen, and involves complement components C1, C4, and C2 in the generation of the C3 and C5 convertases. See also alternative pathway of complement activation; lectin pathway of complement activation.

Alternative pathway of complement activation

one of three pathways of complement activation. It is triggered by the presence of infection but does not involve antibody. The early stages leading to cleavage of C3 involve C3b, factor B, and factor D.

Inflammatory response

nonspecific defense against infection, characterized by redness, heat, swelling, and pain

Inflammatory Response Phase

Dilation, migration of phagocytes, and tissue repair

Vasodilation

The enlargement of blood vessels to increase blood supply

Fever

a rise in the temperature of the body as host response

Pyrogens

substances that cause fever