Week 6: Immune Disorders Flashcards
Define the immune system.
A collection of mechanisms that protect against disease by identifying and killing pathogens and tumour cells. It also protects against microbial toxins and is the body’s defence mechanism against microorganisms and their products.
Define immunology.
The science that examines the structure and function of the immune system.
Define pathogens.
Viruses, bacteria, mycobacteria, parasites, and fungi.
Define recognition.
The ability to distinguish between normal self, altered (damaged) self and non-self (foreign material).
Define specificity.
The ability to inactivate, destroy and remove the “offending” material, without damaging normal tissues in the vicinity of the reaction, i.e. the reaction must be target-specific.
Define regulation.
The immune system is able to control the type, intensity and duration of the reaction and has the ability to prevent immune reaction (suppression).
Define amplification.
The effector (attack) phase of the immune reaction is mediated through multiple pathways which act synergistically for optimal effect. Each pathway has built-in amplification systems, too. All these systems have different triggering points and each may be triggered independently, but eventually involve the other systems.
Define memory.
The identity of the foreign material (antigen) which led to the first (primary) immune response is remembered so that the next episode involving the same antigen will result in an accelerated reaction (secondary immune response), which by-pass several initial steps that the primary immune response has to go through. Immunological memory is what confers long-term immunity against infections.
List the five characteristics of immunity.
Recognition, specificity, regulation, amplification, and memory.
How does the immune system defend against microbial invasion?
Using the innate and acquired immune systems.
Explain the innate immune system.
It does not require prior exposure to a microbe to mount an immune response and is always present and ready to attack. We are born with it, it is not specific to any particular antigen, and it does not require prior exposure. Innate immunity:
Epithelial barriers → physical barrier
Phagocytes, neutrophils, etc
Natural killer cells, the complement system
Innate immunity is fast and does not require time to react to a specific antigen.
Explain acquired immunity.
A more advanced system that requires previous exposure to an antigen in order to become active against microbes which have evaded the innate system.
Acquired immunity:
Antibodies by B-cells
T-cells → helper (CD4+) and cytotoxic (CD8+)
Adaptive immunity requires time to react; it often requires days.
State the characteristics of the innate immune system
- Exposure leads to immediate maximal response
- It is non-specific
- It does not require a previous exposure to an offending agent (antigen)
- Found in nearly all forms of life
State the characteristics of the adaptive immune system
- Pathogen- and antigen-specific response
- Lag time between exposure and maximal response
- Cell-mediated and humoral (antibody) components
- Cell-mediated and humoral components (of inflammatory response)
- Exposure leads to immunological memory
- Found only in jawed vertebrates
What initiates the innate immune response?
When microorganism breaks through the normal epithelial barriers of the skin, GI, and respiratory tract
