What is Adaptive/Acquired immunity?
Specific response to the invader, marked by an enhanced response on repeated encounters with the same invader (immunological memory)
What is the purpose of Helper T cells?
They help to regulate the immune response
What are the two types of T cells?
1. Cytotoxic 2. Helper
What are Mucosal Immune System/ Mucosal Defences?
The special defences that are found at mucosal surfaces- such as the respiratory, GI and genitourinary tract (at the surface)
What is important about the secondary response?
It is much faster, and is stronger and better
What does Innate/Natural immunity mean?
This refers to broadly-directed protection from the genetic constitution of the host, which is not effected or improved by repeat encounters with the same invader
What is the purpose of Cytotoxic T cells?
They are important to viral infections, when T cells must kill cells that have been 'taken over' by the virus. They release cytokines, which help them to regulate the actions of other cells. Cytokines are cell mediators that help to encourage the immune response
What are B cells?
A type of lymphocyte formed in the bone marrow that is responsible for producing antibodies, which fight bacteria. They are situated in the lymph nodes, where they recognise antigens, and where clonal selection occurs. The proliferation of cells through clonal selection leads to swelling of lymph nodes
Does the adaptive immune response improve over time?
What is the simple process of phagocytosis?
1. Migrating to the site of infection 2. Attaching to the invader 3. Engulfing the invader 4. Destroy the invader 5. Process engulfed pieces of invader, and present them to the adaptive immune system
What are microbial virulence factors?
Factors that contribute to the ability of a microorganism to evade defences and cause disease
What is phagocytosis?
The engulfment of foreign material (cell eating) carried out by WBCs
What are System Immune System/ Systemic Defences?
Defends other tissues, including the blood. WBCs (leukocytes) are cells of the immune system
Describe the process of Clonal Selection
On each of the millions of B cells in our body, there are around 250,000 antibody molecules which are expressed and act as antigen receptors. The antigen selects a specific cell by binding to the surface antibody. This results in cell activation, and the B cell divides and results in the formation of an ARMY of clones of specific B cells with that useful antibody.
- Some of these clones will pump out free antibody (plasma cells), while others develop into memory cells with antibodies on their cell surface.
- Progeny can get better through mutation!
What WBCs undergo phagocytosis?
1. Macrophages 2. Neutrophils (most common WBC in the blood)
What are the components of Innate Immunity (The first line of defence)?
1. Physical barriers, eg. the skin
2. Mechanical processes (including reflexes)
3. Biochemical defences
4. Cellular defences
5. Acute inflammatory response (!!)
What are antibodies?
Molecules produced by B lymphocytes in response to the presence of antigens, which bind directly to the antigen that caused their initial formation. These are also called Immunoglobulins (Ig)
What does the term self mean?
A term used to describe the molecular makeup of the host. We do not normally mount an immune response against ourselves- self-tolerance
What does the term non-self mean?
The term used to describe the molecular makeup of the universe outside of out bodies, which the body does not naturally recognise. The immune system recognises and responds to molecules that are foreign to the body
What is the adaptive immune system?
The adaptive immune system, also called acquired immunity, uses specific antigens to strategically mount an immune response. Unlike the innate immune system, which attacks only based on the identification of general threats, the adaptive immunity is activated by exposure to pathogens, and uses an immunological memory to learn about the threat and enhance the immune response accordingly. The adaptive immune response is much slower to respond to threats and infections than the innate immune response, which is primed and ready to fight at all times.
What are antigens?
Foreign macromolecules which are 'seen' by the immune system, leading to the production of cells and molecules that specifically target the antigens.
What proportion of lymphocytes is B cells and T cells?
2/3 T cells 1/3 B cells
What are the effects of antibodies?
When an antibody binds to an antigen, It 'flags' the antigen to be dealt with by the immune system, including phagocytic cells, which can then engulf and destroy the immune complex. This binding to form an immune complex triggers the complement cascade. It also forms steric hindrance (getting in the way!)