WGU Microbiology C453 Module 3
Phagocytes - ANSWER: a type of leukocyte within the body that engulfs and absorbs bacteria and other small
cells and particles. They patrol, destroying dead cells and cellular debris. Attack microbes and other foreign
material at portals of entry.
adaptive defenses - ANSWER: Respond to antigens by producing protein antibodies
-Humoral immunity (B cells)
-Cellular immunity (T cells)
innate defenses - ANSWER: those that act against any type of invading agent (physical, chemical, cellular,
molecular, fever, inflammation)
fever - ANSWER: elevation of body temperature to kill invading agents and/or inactivate their toxic products.
molecular defenses - ANSWER: interferon and complement, that destroy or impede invading microbes
cellular defenses - ANSWER: cells that engulf or phagocytize invading microorganisms
chemical barriers - ANSWER: antimicrobial substances in body fluids such as saliva, mucus, gastric juices, and
the iron limitation mechanisms
overactivity of innate responses - ANSWER: can lead to diseases such as autoimmune problems of lupus,
rheumatoid arthritis, and others
non-specific resistance - ANSWER: Defense mechanisms that provide general protection against a wide range
of disease producing organisms. Present at birth, act rapidly, provide general protection.
specific resistance - ANSWER: Immunity defense against a specific pathogen. 3rd line of defense. Cell or
antibody mediated immunity. Take time to build up, develop in response to a specific antigen, very specific.
, Interferons - ANSWER: proteins (cytokines) secreted by T cells and other cells to aid and regulate the immune
response. They inhibit cell division, combat bacterial and parasitic infections, and promote or impede
differentiation of cells. They also provide a potential therapy for viral infections and tumors (hairy cell
leukemia)
alpha interferon (INF-a) - ANSWER: source: leukocytes AFTER infection
stimulated by: viruses
Effects: production of antiviral proteins in neighboring cells
beta interferons (INF-b) - ANSWER: source: fibroblasts AFTER infection
stimulated by: viruses
Effects: same as INF-a
gamma interferon - ANSWER: source: T-lymphocytes and NK cells
stimulated by: viruses and other antigens
Effects: activates tumor destruction and killing of infected cells
antiviral proteins - ANSWER: enzymes that disrupt various stages of viral multiplication; specifically effective
against RNA viruses
complement system - ANSWER: more than 20 large regulatory proteins that play a key role in host defense.
They are produced by the liver and circulate in plasma in an inactive form. These proteins account for about
10% (by weight) of all plasma proteins.
General functions: (1) enhance phagocytosis by phagocytes; (2) lyse microorganisms, bacteria, and enveloped
viruses directly; and (3) generate peptide fragments that regulate inflammation and immune responses.
classical pathway - ANSWER: begins when antibodies bind to antigens, such as microbes, and involves
complement proteins C1, C4, and C2 (C stands for complement).
lectin pathway - ANSWER: begins when macrophages complete phagocytosis, releasing cytokines that cause
the liver to produce lectin proteins. The lectins bind to carbohydrates such as mannose, which are part of a
characteristic pattern of carbohydrates found on bacteria and some viruses. This then activates C4 and C2
Phagocytes - ANSWER: a type of leukocyte within the body that engulfs and absorbs bacteria and other small
cells and particles. They patrol, destroying dead cells and cellular debris. Attack microbes and other foreign
material at portals of entry.
adaptive defenses - ANSWER: Respond to antigens by producing protein antibodies
-Humoral immunity (B cells)
-Cellular immunity (T cells)
innate defenses - ANSWER: those that act against any type of invading agent (physical, chemical, cellular,
molecular, fever, inflammation)
fever - ANSWER: elevation of body temperature to kill invading agents and/or inactivate their toxic products.
molecular defenses - ANSWER: interferon and complement, that destroy or impede invading microbes
cellular defenses - ANSWER: cells that engulf or phagocytize invading microorganisms
chemical barriers - ANSWER: antimicrobial substances in body fluids such as saliva, mucus, gastric juices, and
the iron limitation mechanisms
overactivity of innate responses - ANSWER: can lead to diseases such as autoimmune problems of lupus,
rheumatoid arthritis, and others
non-specific resistance - ANSWER: Defense mechanisms that provide general protection against a wide range
of disease producing organisms. Present at birth, act rapidly, provide general protection.
specific resistance - ANSWER: Immunity defense against a specific pathogen. 3rd line of defense. Cell or
antibody mediated immunity. Take time to build up, develop in response to a specific antigen, very specific.
, Interferons - ANSWER: proteins (cytokines) secreted by T cells and other cells to aid and regulate the immune
response. They inhibit cell division, combat bacterial and parasitic infections, and promote or impede
differentiation of cells. They also provide a potential therapy for viral infections and tumors (hairy cell
leukemia)
alpha interferon (INF-a) - ANSWER: source: leukocytes AFTER infection
stimulated by: viruses
Effects: production of antiviral proteins in neighboring cells
beta interferons (INF-b) - ANSWER: source: fibroblasts AFTER infection
stimulated by: viruses
Effects: same as INF-a
gamma interferon - ANSWER: source: T-lymphocytes and NK cells
stimulated by: viruses and other antigens
Effects: activates tumor destruction and killing of infected cells
antiviral proteins - ANSWER: enzymes that disrupt various stages of viral multiplication; specifically effective
against RNA viruses
complement system - ANSWER: more than 20 large regulatory proteins that play a key role in host defense.
They are produced by the liver and circulate in plasma in an inactive form. These proteins account for about
10% (by weight) of all plasma proteins.
General functions: (1) enhance phagocytosis by phagocytes; (2) lyse microorganisms, bacteria, and enveloped
viruses directly; and (3) generate peptide fragments that regulate inflammation and immune responses.
classical pathway - ANSWER: begins when antibodies bind to antigens, such as microbes, and involves
complement proteins C1, C4, and C2 (C stands for complement).
lectin pathway - ANSWER: begins when macrophages complete phagocytosis, releasing cytokines that cause
the liver to produce lectin proteins. The lectins bind to carbohydrates such as mannose, which are part of a
characteristic pattern of carbohydrates found on bacteria and some viruses. This then activates C4 and C2
