29 Questions
What is the primary function of the first line of defense?
To provide nonspecific resistance to infection
What type of immunity is acquired through exposure to a foreign substance?
Adaptive immunity
What is the role of the second line of defense?
To produce interferons and activate phagocytosis
What is the characteristic of innate defenses?
Nonspecific and present at birth
What is the primary function of Toll-like receptors in macrophages?
To stimulate an immune response
What is the result of the third line of defense?
Production of protective antibodies and creation of memory cells
What is the role of physical barriers in the first line of defense?
To keep microbes from penetrating sterile body compartments
What is the classic sign of inflammation characterized by increased fluid escaping into the tissue?
Swelling
Which of the following is NOT a function of the second line of defense?
Surveillance of the body
What is the result of increased blood flow during an inflammatory response?
Warmth
What is the primary function of phagocytosis in the immune response?
Destruction of foreign entities
What is the process by which phagocytic cells engulf and destroy foreign substances?
Phagocytosis
Which type of immunity involves the activation of T and B cells?
Acquired Immunity
What are the molecules that react with antibodies or T cells?
Antigens
What is the process by which a phagocytic cell engulfs a foreign substance, forming a phagosome?
Engulfment
Which type of immunity involves the production of antibodies?
Humoral Immunity
What are the molecules that can induce an immune response in the host?
Immunogens
What is the primary function of neutrophils in the body?
To react early to bacteria and other foreign materials, and to damaged tissue
What is the benefit of fever in inhibiting the multiplication of microorganisms?
It inhibits the multiplication of temperature-sensitive microorganisms
What is the origin of endogenous pyrogens?
Liberated by monocytes, neutrophils, and macrophages during phagocytosis
What is the role of macrophages in the immune response?
To scavenge and process foreign substances to prepare them for reactions with B and T lymphocytes
What is the result of the increased body temperature during a fever response?
Increased metabolism and immune reactions
What is the primary function of eosinophils in the immune response?
To be attracted to sites of parasitic infections and antigen-antibody reactions
What is the function of the stomach acid in the body's defense mechanism?
To kill pathogens
What is the purpose of the mucous coat in the body's defense mechanism?
To impede the attachment and entry of bacteria
What is the function of lysozyme in the body's defense mechanism?
To hydrolyze the cell wall of bacteria
What is the term for the study of the body's second and third lines of defense?
Immunology
What is the function of the sebaceous glands in the body's defense mechanism?
To produce fatty acids
What is the purpose of the blinking reflex in the body's defense mechanism?
To flush out pathogens
Study Notes
Host Defenses
- Innate, nonspecific defenses: present at birth, provide nonspecific resistance to infection
- Adaptive immunities: specific, must be acquired
First Line of Defense
- Physical barriers: skin, mucous membranes, and epithelial cells
- Chemical barriers: lysozyme, acidic pH, hydrochloric acid, digestive juices, and bile
- Functions: prevent microbes from penetrating sterile body compartments
Second Line of Defense
- Cellular and chemical system
- Recognizes foreign material, stimulates inflammation, and destroys foreign entities
- Includes: phagocytosis, complement, and interferons
Recognition of Foreign Cells
- Protein receptors (Toll-like receptors) within macrophage cell membranes
- Detect foreign molecules and signal the macrophage to produce chemicals to stimulate an immune response
Inflammatory Response
- Characterized by: redness, warmth, swelling, and pain
- Results in the formation of pus, which prevents the spread of infection
Phagocytosis
- Process of engulfing and destroying foreign substances by phagocytic cells
- Steps: chemotaxis, adhesion, engulfment, phagosome formation, killing, and destruction of bacterial cells
Leukocytes
- Phagocytic cells that engulf and destroy foreign substances
- Include: neutrophils, eosinophils, and macrophages
Acquired/Adaptive Immunity
- Antigen-specific, acquired through exposure to foreign substances
- Produces protective antibodies and creates memory cells
- Includes: cell-mediated immunity (T cells) and humoral immunity (antibodies)
Inflammatory Response
- Fever: initiated by circulating pyrogens, increases body temperature, and stimulates immune reactions
- Benefits of fever: inhibits multiplication of temperature-sensitive microorganisms, impedes nutrition of bacteria, and stimulates immune reactions
Phagocytosis and Phagocytes
- Phagocytes: neutrophils, eosinophils, and macrophages
- Functions: survey tissue compartments, ingest and eliminate foreign matter, and extract immunogenic information
Test your understanding of the host defense mechanisms, including innate and adaptive immunities, and how the immune system protects the body against pathogens. This quiz covers the first line of defense and the various barriers that block invasion.
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