Unit 3: Immunology Flashcards
Define “immunity”.
the ability of the body to protect itself
Define “non-specific defense” and “specific immune response”.
non-specific: innate; not specific to any one pathogen
specific: acquired immunity; develop when exposed to pathogen; adaptive - different each time.
Describe the physical and chemical barriers of the first line of defense.
Provide some examples.
physical- skin, mucosae, mucus, secretions
chemical- enzymes, antibodies, pH
also mechanical- flushing, fluid flow
Describe the different components of the second line of defense:
NON-SPECIFIC.
[5]
Phagocytes: can envelop pathogen by endocytosis and ingest it > cellular digestion
Inflammation/Fever: will draw fluid and phagocytic WBC into infection area & enhance capacity for stopping infection at this site through focal attack
Complement system: a series of proteins that work as a cascade to eventually form open holes on any bacterial cell membranes & enveloped viral particles > cell lysis/inflammation/opsonization
Interferon: decrease transcription/translation > protect against viruses
Natural Killer/ NK Cells: lymphocyte type; interact with infected cells and release toxin (perforin) that will perforate pathogenic cell & disrupt membrane > cell lysis
Describe the characteristics that define a specific immune response.
a. Specific
b. Recognition of Self
c. Memory
d. Versatility
Specific- WBC and antigen fit together perfectly like lock and key
Recognition of self- cells recognize themselves to prevent WBC attack against our own healthy cells
Memory- once you made multiple WBC copies unique to a pathogen, easier to make more copies during future exposure
Versatility- potential for antigen recognition is almost unlimited
Define and describe “antigen” and “antibody”.
antigen: usually a protein; foreign substance, ( like virus, bacterium..) that can stimulate an immune response in the body.
antibody: AKA immunoglobulin; protein produced by the immune system in response to the presence of an antigen.
~designed to specifically target and neutralize antigens, helping the immune system defend the body against infections and diseases.
Describe the cells of specific immunity. What is their structure, where do they originate, what is their role in specific immune reactions?
- Antigen presenting cell APC
AKA macrophage in tissue/ monocyte in blood
~aggresive phagocyte
~capture, process, and present antigens to helper T cells - T-lymphocytes [cell-mediated]
~derive from stem cell lymphocytes
~differentiate into 3 subtypes
a. cytotoxic/ killer T lymphocyte- bind to antigens and secrete perforins
b. helper cells - activate other lymphocytes to enhance response
c. Regulatory/suppressor cells- suppress lymphocytes to prevent excessive immune response - B-lymphocytes (humoral immunity)
~split into 2 types
a. plasma cells (produce antibodies > immunological response)
b. memory cells (prolonged immunity to pathogen exposure)
Compare and contrast cell-mediated and humoral immunity.
Cell-Mediated Immunity:
Involves T lymphocytes
works against cellular pathogens (bacterial cells, not against viruses, but works with virus-infected cells).
Humoral Immunity:
Involves B lymphocytes
Provides immunity against cellular and non-cellular pathogens including viruses
Describe the predominant way in which T-cells are activated
Via macrophage or infected cell
APC will digest pathogen, take antigenic pieces and place them inside cell membrane; Helper T cells latch on and produce a chemical signal that will stimulate any other T cells that also recognized the antigen
Describe the different T-cell types produced during the proliferative phase:
a. Helper T-Cells
b. Cytotoxic T-Cells
c. Suppressor T-Cells
d. Memory T-Cells
a. Helper T-Cells- multiply and secrete cytokines that summon macrophages and cytotoxic T cells to the infected site.
b. Cytotoxic T-Cells- kill toxic/target cells
c. Suppressor T-Cells- stopping an autoimmune response once the threat has been eliminated.
d. Memory T-Cells- critical role in long-term immunity. They “remember” previous encounters with specific antigens and respond more rapidly and effectively upon re-exposure to the same pathogen.
Describe the mechanism for T-cell destruction of pathogens.
What type of pathogens are T-cells effective against?
~Effective against intracellular pathogens (bacterial cells, not against viruses, but works with virus-infected cells).
T cells can wipe out infected/cancerous cells; also direct immune response by helping B lymphocytes eliminate invading pathogens.
Describe the two predominant ways in which B-cells are activated (T-cell dependent and independent).
T-Cell-Dependent Activation:
B cells need help from Helper T cells, which recognize the antigen presented by B cells and provide cytokines (signaling molecules) that activate B cells
T-Cell-Independent Activation:
B cells can activate themselves when they directly bind to simple antigens.
Describe the mechanism for B-cell destruction of pathogens.
What type of pathogens are B-cells effective against?
~Primarily effective against extracellular pathogens (viruses, bacteria, toxins..)
B cells create APCs/ antibodies >antibodies bind to pathogens/foreign substances, such as toxins, to neutralize them.
Compare and contrast active and passive immunity.
active- body exposed to pathogen and produces own antibodies
[getting sick or vaccination]
passive- we acquire antibodies made by another organism
[through placenta/breastfeeding or immunotherapy]
what is the immune system?
Our defensive system
defending us against foreign materials (pathogens) - [bacteria, viruses, etc.]
