Week 3 - Infection and Immunity Flashcards
(31 cards)
3 things our immune system is designed to do
- prevent entry
- prevent spread/growth
- remove threat
What are the main components of the immune system?
- organs and tissues
- cells
- molecules/chemical mediators
What is a pathogen
a microorganism that can cause disease
What is pathogenicity
the capability of a microorganism to cause disease
What is an infection?
a pathogen has reproduced in the host’s body
How are infectious diseases caused?
caused by pathogens (microorganisms that invaded; multiply; cause damage)
Bacteria
- prokaryotic, single cell organisms, rigid cell wall
- contain DNA, RNA, and ribosomes (in cytoplasm)
- Can survive and divide outside a living host
- Named based on shape and characterisitics
Viruses
- small intracellular parasite
- requires a living host to replicate
- a protein coat with a core that contains RNA or DNA
- called virion when it is outside of a host
Fungi
- found everywhere in the environment
- eukaryotic single cells (yeast) or chains of cells (molds)
- can produce spores that become airborne (inhalation can trigger allergic reaction)
- only certain fungi are pathogenic (worse for people who are immunocompromised)
Protozoa
- parasites (pathogenic protozoa)
- complex eukaryotic organisms (unicellular, motile)
Prions
- don’t contain genetic material
- infection is transmitted by protein particles (prions) that are able to self-propagate (induces proteins in the brain to misfold -> nonfunctional -> neurodegeneration)
- systems are neuro-degenerative
Infection - modes of transmission
- direct contact
- indirect contact
- droplets
- aerosol
- vector-borne
Infection reservoir
the source carrying the infection
Innate immune response: defense mechanism
physical and chemical barriers, inflammatory response
Adaptive immune response: defense mechanism
kill the compromised cells (antibody tags the antigen)
Innate immune response characteristics
- immune cells are non-specific (what should/shouldn’t be in the body)
- molecular components are non-specific: chemical mediators involved in an inflammatory response
- fast, immediate response
- no memory
Adaptive immune response characteristics
- immune cells are specific for each invader
- molecular components: antibodies and chemical mediators
- initial response takes a few weeks
- immunologic memory
Leukocytes involved in the adaptive immune response
- natural killer cells
- antigen presenting cells (dendritic cells)
- B lymphocytes
- T lymphocytes
B lymphocyte roles in an adaptive immune response
- recognize specific antigens that have invaded the body before
- secrete antibodies (plasma cells do this)
T lymphocyte roles in an adaptive immune response
- recognize the specific antigen presented
- turn into helper T cells & Cytotoxic T cells
Helper T cells role in an adaptive immune response
secrete cytokines to help coordinate the immune response
Cytotoxic T cells role in an adaptive immune response
Kill target cells that present a specific antigen
Natural killer cells role in an innate immune response
- target cells infected with viruses and cancer cells
- trigger apoptosis in these cells
Initiation of the adaptive immune response
- dendritic cell phagocytizes a pathogen for the first time
- breaks up the pathogen into small peptides
- travels to the lymph node and ‘presents’ an antigen (fragment of the pathogen) to T cells
- T cells differentiate in specific mature T cell and reproduce
- antigen-specific B cells develop and reproduce; target specific pathogen and also turn into plasma cells once exposed to antigen; plasma cells secrete antibodies specific to the antigen
- antibodies attach to the specific pathogen and mark it for destruction
