WGU Microbiology C453 Module 3 A+
Phagocytes - ✔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 - ✔Respond to antigens by producing protein antibodies
-Humoral immunity (B cells)
-Cellular immunity (T cells)
innate defenses - ✔those that act against any type of invading agent (physical,
chemical, cellular, molecular, fever, inflammation)
fever - ✔elevation of body temperature to kill invading agents and/or inactivate their
toxic products.
molecular defenses - ✔interferon and complement, that destroy or impede invading
microbes
cellular defenses - ✔cells that engulf or phagocytize invading microorganisms
chemical barriers - ✔antimicrobial substances in body fluids such as saliva, mucus,
gastric juices, and the iron limitation mechanisms
overactivity of innate responses - ✔can lead to diseases such as autoimmune problems
of lupus, rheumatoid arthritis, and others
non-specific resistance - ✔Defense mechanisms that provide general protection against
a wide range of disease producing organisms. Present at birth, act rapidly, provide
general protection.
specific resistance - ✔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 - ✔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) - ✔source: leukocytes AFTER infection
stimulated by: viruses
Effects: production of antiviral proteins in neighboring cells
, beta interferons (INF-b) - ✔source: fibroblasts AFTER infection
stimulated by: viruses
Effects: same as INF-a
gamma interferon - ✔source: T-lymphocytes and NK cells
stimulated by: viruses and other antigens
Effects: activates tumor destruction and killing of infected cells
antiviral proteins - ✔enzymes that disrupt various stages of viral multiplication;
specifically effective against RNA viruses
complement system - ✔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 - ✔begins when antibodies bind to antigens, such as microbes, and
involves complement proteins C1, C4, and C2 (C stands for complement).
lectin pathway - ✔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
alternative pathway - ✔activated by contact between complement proteins and
polysaccharides at the pathogen surface.
Opsonization - ✔An immune response in which the binding of antibodies to the surface
of a microbe facilitates phagocytosis of the the microbe by a macrophage
dendritic cells - ✔cells with long membrane extensions that resemble the dendrites of
nerve cells, hence their name. These cells are phagocytic and are involved in initiating
the adaptive defense response. Dendritic cells in the skin, known as Langerhans cells,
produce immune tolerance to good bacteria, preventing overreaction of our immune
system.
Neutrophils - ✔50-70% of total leukocytes, also called polymorphonuclear leukocytes
(PMNLs), guard blood, skin, and mucous membranes against infection. These cells are
phagocytic and respond quickly wherever tissue injury has occurred. Contain oxidized
chemicals to kill internalized microbes
Phagocytes - ✔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 - ✔Respond to antigens by producing protein antibodies
-Humoral immunity (B cells)
-Cellular immunity (T cells)
innate defenses - ✔those that act against any type of invading agent (physical,
chemical, cellular, molecular, fever, inflammation)
fever - ✔elevation of body temperature to kill invading agents and/or inactivate their
toxic products.
molecular defenses - ✔interferon and complement, that destroy or impede invading
microbes
cellular defenses - ✔cells that engulf or phagocytize invading microorganisms
chemical barriers - ✔antimicrobial substances in body fluids such as saliva, mucus,
gastric juices, and the iron limitation mechanisms
overactivity of innate responses - ✔can lead to diseases such as autoimmune problems
of lupus, rheumatoid arthritis, and others
non-specific resistance - ✔Defense mechanisms that provide general protection against
a wide range of disease producing organisms. Present at birth, act rapidly, provide
general protection.
specific resistance - ✔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 - ✔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) - ✔source: leukocytes AFTER infection
stimulated by: viruses
Effects: production of antiviral proteins in neighboring cells
, beta interferons (INF-b) - ✔source: fibroblasts AFTER infection
stimulated by: viruses
Effects: same as INF-a
gamma interferon - ✔source: T-lymphocytes and NK cells
stimulated by: viruses and other antigens
Effects: activates tumor destruction and killing of infected cells
antiviral proteins - ✔enzymes that disrupt various stages of viral multiplication;
specifically effective against RNA viruses
complement system - ✔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 - ✔begins when antibodies bind to antigens, such as microbes, and
involves complement proteins C1, C4, and C2 (C stands for complement).
lectin pathway - ✔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
alternative pathway - ✔activated by contact between complement proteins and
polysaccharides at the pathogen surface.
Opsonization - ✔An immune response in which the binding of antibodies to the surface
of a microbe facilitates phagocytosis of the the microbe by a macrophage
dendritic cells - ✔cells with long membrane extensions that resemble the dendrites of
nerve cells, hence their name. These cells are phagocytic and are involved in initiating
the adaptive defense response. Dendritic cells in the skin, known as Langerhans cells,
produce immune tolerance to good bacteria, preventing overreaction of our immune
system.
Neutrophils - ✔50-70% of total leukocytes, also called polymorphonuclear leukocytes
(PMNLs), guard blood, skin, and mucous membranes against infection. These cells are
phagocytic and respond quickly wherever tissue injury has occurred. Contain oxidized
chemicals to kill internalized microbes
