BIOS 242 EXAM 3 COMPREHENSIVE STUDY
QUESTIONS AND ANSWERS
◉ how do physical barriers help with immunity?
Answer: inhibits pathogen growth and blocks the pathogen from
entry into the body
skin: tightly packed epithelial cells, keratin, low pH
mucous membranes: trap microbes, cilia move them out
mechanical removal: tears, saliva, earwax, urine; pushes pathogen
out of the body
◉ how do chemical barriers help with immunity?
Answer: lysozyme (tears, saliva, sweat): breaks down peptidoglycan
in bacterial walls
sebum: oily secretions that inhibit microbes
acidic environments: stomach acid, vaginal pH; most pathogens not
able to survive
◉ how does the body's microbiota help with immunity?
Answer: normal flora outcompete pathogens for survival
◉ immune system second line of defense
,Answer: nonspecific, internal
-cellular defenses: macrophages, natural killer cells
-inflammation, fever, complement system, interferons
◉ cellular defenses of the 2nd line of defense (phagocytes & NK
cells)
Answer: phagocytes:
neutrophils- 1st responder; engulf bacteria
macrophages- long term clean up; phagocytize foreign pathogens &
dead cells
dendritic cells- capture antigens & present to T cells; bridge to
adaptive immunity
natural killer cells: lymphocyte; kills virus infected cells; use
perforin & granulocytes to induce apoptosis
◉ inflammation
Answer: redness, heat, swelling, pain, loss of function
-Increases blood flow, recruits immune cells to the infected area
◉ fever
Answer: systemic increase in body temperature, inhibits microbes
and boosts metabolism
,◉ complement system
Answer: a group of plasma proteins that work together in a cascade
to fight infections
-classical, alternative, and lectin pathways; leads to end product
(membrane attack complex or MAC)
◉ classical pathway
Answer: triggered by antibodies binding to microbial invaders
◉ alternative pathway
Answer: begins when complement proteins bind to normal cell wall
and surface components of microorganisms
◉ lectin pathway
Answer: mannose-binding lectin binds to sugars on microbes
◉ Membrane Attack Complex (MAC)
Answer: end product of each pathway
forms pores in microbial membranes; results in lysing/bursting of
bacteria
◉ interferons
, Answer: -Produced by virus-infected cells.
-Warn neighboring cells to produce antiviral proteins.
-the infected cell is sacrificed
◉ immune system 3rd line of defense
Answer: adaptive and specific
- T cells, B cells, antibodies, antigen recognition
◉ what are the types of T cells
Answer: Cytotoxic T cells
Helper T cells
Memory T cells
◉ Cytotoxic T cells (CD8)
Answer: release perforin + granzyme → directly kill infected cells by
inducing apoptosis
recognize MHC Class 1 antigens
◉ Helper T cells (CD4)
Answer: secrete cytokines, which activates B cells & cytotoxic T cells.
QUESTIONS AND ANSWERS
◉ how do physical barriers help with immunity?
Answer: inhibits pathogen growth and blocks the pathogen from
entry into the body
skin: tightly packed epithelial cells, keratin, low pH
mucous membranes: trap microbes, cilia move them out
mechanical removal: tears, saliva, earwax, urine; pushes pathogen
out of the body
◉ how do chemical barriers help with immunity?
Answer: lysozyme (tears, saliva, sweat): breaks down peptidoglycan
in bacterial walls
sebum: oily secretions that inhibit microbes
acidic environments: stomach acid, vaginal pH; most pathogens not
able to survive
◉ how does the body's microbiota help with immunity?
Answer: normal flora outcompete pathogens for survival
◉ immune system second line of defense
,Answer: nonspecific, internal
-cellular defenses: macrophages, natural killer cells
-inflammation, fever, complement system, interferons
◉ cellular defenses of the 2nd line of defense (phagocytes & NK
cells)
Answer: phagocytes:
neutrophils- 1st responder; engulf bacteria
macrophages- long term clean up; phagocytize foreign pathogens &
dead cells
dendritic cells- capture antigens & present to T cells; bridge to
adaptive immunity
natural killer cells: lymphocyte; kills virus infected cells; use
perforin & granulocytes to induce apoptosis
◉ inflammation
Answer: redness, heat, swelling, pain, loss of function
-Increases blood flow, recruits immune cells to the infected area
◉ fever
Answer: systemic increase in body temperature, inhibits microbes
and boosts metabolism
,◉ complement system
Answer: a group of plasma proteins that work together in a cascade
to fight infections
-classical, alternative, and lectin pathways; leads to end product
(membrane attack complex or MAC)
◉ classical pathway
Answer: triggered by antibodies binding to microbial invaders
◉ alternative pathway
Answer: begins when complement proteins bind to normal cell wall
and surface components of microorganisms
◉ lectin pathway
Answer: mannose-binding lectin binds to sugars on microbes
◉ Membrane Attack Complex (MAC)
Answer: end product of each pathway
forms pores in microbial membranes; results in lysing/bursting of
bacteria
◉ interferons
, Answer: -Produced by virus-infected cells.
-Warn neighboring cells to produce antiviral proteins.
-the infected cell is sacrificed
◉ immune system 3rd line of defense
Answer: adaptive and specific
- T cells, B cells, antibodies, antigen recognition
◉ what are the types of T cells
Answer: Cytotoxic T cells
Helper T cells
Memory T cells
◉ Cytotoxic T cells (CD8)
Answer: release perforin + granzyme → directly kill infected cells by
inducing apoptosis
recognize MHC Class 1 antigens
◉ Helper T cells (CD4)
Answer: secrete cytokines, which activates B cells & cytotoxic T cells.
