Chpt 14 Host Defense Flashcards
Host Defense
Protects the body against pathogens
Innate (natural) defenses
- Provide nonspecific resistance to infections
- Present at birth
Adaptive Immunities
-Specific immunities that must be acquired
First Line of Defense
- Any barrier that blocks invasion at the portal of entry.
- Limits access to the internal tissues of the body
- ie. Skin, Mucous membranes, etc.
- Physical, Chemical, or Genetic
Second Line of defense
- More internalized system of protective cells and fluids
- Includes Phagocytosis and inflammation
Third Line of Defense
-Highly specific, is adaptive and aquired on an individual basis as each foreign substance is encountered by WBC
Nonspecific (1st line) Chemical Barriers
- Skin and Mucous membrane secretions have antimicrobial effects
- Tears and saliva have Lysozyme (enzyme which hydrolyzes peptidoglycan wall) and defensins (peptide which damages cell membranes–lyse bacteria and fungi)
Pattern recognition receptors (PRRs)
-Variety of surface receptor which serve as “feelers” for foreign substances
Pathogen-Associated molecular patterns
Molecules on the surface of many pathogens that serve as “red-flags” for WBCs
B-cells
- Contribute to humoral immunity (protective molecules carried in the fluids of body)
- Active b-cells produce antibodies
Granulocytes
- Neutrophils- Phagoctyes (engulf and kill bacteria)
- Basophils- Inflammation and Allergies
- Eosinophils- Worm and Fungal infections, allergies and inflammation
Agranulocytes
- Monocytes- Blood Phagocytes, Leave circulation and mature into macrophages and dendritic cells
- Macrophages- largest, specific immunity, ingest and kill foreign substances
- Dendritic cells-early immune reactions
- B-Cells- Differentiate into plasma cells- antibody production
- T-cells- specific immune responses- cell-mediated immunity
Monocytes
- Blood phagocytes
- leave circulation and mature into macrophages and dendritic cells
T-cells
-Cell-mediated immunity
Second line of defense
-Inflammation
4 signs of Inflammation
- Rubor- Redness (increased circulation and vasodilation)
- Calor- Increased warmth
- Tumor- Swelling (increased extracellular fluid)
- Dolor- Pain (stimulation of nerve endings from pressure of swelling)
Functions of Inflammation
- Mobilize and attract immune components to injury
- Set in motion mechanical repair and clear away harmful substances
- Destroy and block microbes
Major Phagocytes
Neutrophils, Monocytes, and Macrophages
Benefits of a Fever
- Inhibits multiplication of temp-sensitive microbes
- impedes the nutrition of bacteria by reducing availability of iron
- Increases host metabolism and stimulates immune reactions
