Lymphatic System Vocab

Lymph

Excess tissue fluid not returned via the venules that must be filtered before being returned to the subclavian veins

Lymph node

Tissue found at the junctions of lymphatic vessels that filter infectious organisms and debris out of lymph

Spleen

Extracts old or defective blood blood cells and platelets from blood; also removes debris, foreign matter, bacteria, viruses, and toxins

Thymus

Releases hormones to facilitate T cell maturation

Tonsils

Small lymphoid organs that gather and destroy bacteria inhaled in air or food

Red bone marrow

Where all lymphocytes (T cells, B cells) develop

Appendix

Stores beneficial gut bacteria and generates lymphocytes to combat infections

Peyer’s patches

Clusters of mucosa-associated lymphoid tissue (MALT) in the intestines with WBCs that identify and destroy pathogens

Lysozyme

Enzyme that destroys bacteria by digesting their cell walls; found in saliva

Phagocyte

Cell that can surround and engulf a particle or cell

Macrophage

Irregularly shaped phagocyte that identify, engulf, and destroy pathogens

Kupffer cells

Macrophages in the liver

Alveolar macrophage

Macrophages in the lungs

Histiocytes

Macrophages in connective tissue

Monocyte

Circulating precursor cell that differentiates into either a macrophage or dendritic cell

Neutrophil

Phagocytic granulocyte that is attracted to infected tissues via chemotaxis and release enzymes and chemicals to kill pathogens and signal other immune cells to the infection site

NK cells

Lymphocyte that induces lysis in cancerous cells or intracellular pathogens

Perforin

Protein that forms pores in the membranes of infected cells

Granzyme

Protein-digesting enzyme that enters the cell via perforin pores and triggers apoptosis

Heat, redness, pain, and swelling

4 cardinal signs of inflammation

Cytokine

Signaling molecule that allows cells to communicate over short distances; triggers pro- or anti-inflammatory reponses

Chemokine

Soluble chemical mediator that attracts cells from longer distances

Mast cell

White blood cell that releases inflammatory mediators such as histamine and heparin

Histamine

Causes vasodilation and increases the permeability of local capillaries; causes swelling

Heparin

Anticoagulant that prevents the formation of blood clots to maintain accessability for immune cells; and works as an anti-inflammatory chemical

Leukotrienes

Attracts neutrophils via chemotaxis and increases vascular permeability

Prostaglandins

Relaxes vascular smooth muscle to cause vasodilation; major cause of pain

Complement system

Series of circulating proteins in the blood plasma that enzymatically alter and fragment later proteins in the series

Opsonization

Binds to the cell membrane of pathogens and labels them for phagocytosis

Membrane-attack complex (MAC)

Inserts damaging pores into pathogen plasma membranes to disrupt their osmotic balance; causes water to rush into the cell and it to lyse

Alternate pathway

When interacting with foreign materials, C3 protein splits apart

C3a

Diffuses from site of activation and attracts phagocytes to the site of infection

C3b

Binds to the pathogen surface, marking it for destruction by phagocytic cells

Classical pathway

C1 protein binds two antibodies and then acts as an enzyme that splits C3

Interferons

Inhibits viral replication and assists in activating natural killer cells

Interferon alpha

Produced by viral-infected cells to attract NK cells

Interferon beta

Secreted by fibroblasts to slow inflamation

Interferon gamma

Secreted by T cells and NK cells to help stimulate macrophages

Interleukins

Chemical activators that send signals throughout the body to increase the immune response

Pyrogens

Interleukins that raise the body’s set-point temperature in the hypothalamus

Antigen

Any substance that can be recognized by the immune system

Antibody

Y-shaped protein secreted by the immune system that can recognize, bind, and neutralize antigens

Complete antigen

Large, complex molecule capable of triggering an immune response

Haptens

Small molecules that cannot induce an immune response alone; becomes immunogenic when binding to larger proteins

Antigenic determinant/epitope

Small region of an antigen that an antibody can bind

Carbohydrate antigens

Found on bacterial cell walls and red blood cells (ABO blood groups)

Protein antigens

Complex 3D antigens found in viruses and worm parasites

Chemical specificity

Precise interaction where an antibody recognizes and binds an epitope on an antigen