FUNCTION
• Fights pathogens to prevent infections and disease
• Works with the lymphatic system (collects fluid and returns it to the blood)
STRUCTURES
• Bone marrow: produces blood cells
• Lymphocytes: wbc • Thymus: mature wbc• Lymph nodes: stores wbc• Spleen: contains wbc that clean
out pathogens as blood filters through
WHITE BLOOD CELLS (wbc)• Also called leukocytes• Type of wbc present indicates specific
disease or have specific job
IE. Neutrophils respond to bacteria
INITIATING THE IMMUNE SYSTEM
• pathogens: cause disease
- viruses: protein shell containing DNA or
RNA
- bacteria, protists, fungi
FIRST LINE OF DEFENSE
• Skin: block entry• mucous membranes: trap
pathogens and move them out of the body
• stomach acids: destroys pathogens
SECOND LINE OF DEFENSE• Inflammatory response
1. Injured cells release a chemical signal
called histamine to increase blood flow to
area
2. platelets cause clotting trapping pathogens
3. Area swells, becomes warm, and
macrophages/phagocyte (wbc) move in and
engulf bacteria
Top Related