Immune System Flashcards
Describe the external features of the innate immune system
Skin - acts as a physical barrier
Mucus membranes - line surfaces that are externally exposed
Enzymes that attack bacteria in the saliva
Describe the internal features of the innate immune system
Fever, swelling, pain all caused by phagocytes:
Neutrophils are the first thing attracted to an infectious agent
Macrophages come from monocytes and the engulf and digest pathogens
Natural Killer Cells - travel in blood and lymph, recognise infected cells by the lack of usual MHC presenting on cell surface, triggers apoptosis
Which cells trigger the inflammatory response?
Mast cells, which send out histamines
Macrophages
Describe the symptoms that arise in the inflammatory response and how these fight pathogens
Increase in temperature caused by macrophages releasing pyrogens to trigger the hypothalamus
Also causes body to withhold iron and zinc, preventing bacterial growth.
Increase in blood vessel permeability, causing swelling and for the excess fluid to be drained away and cleaned by the lymphatic system. Triggers clotting and attracts phagocytes via cytokines.
Describe the function of the adaptive immune system
The adaptive immune system is a systemic (whole body) defence, which has to be introduced to a pathogen and recognise that it’s a threat
What are the two types of adaptive immunity
Humoral and cell mediated
What do b lymphocytes carry on their surface
Thousands of membrane bound antibodies each unique to that particular b lymphocyte, each individual one specific to an antigen. Millions of antibodies present in the b lymphocyte population. High odds of matching a pathogen
Where are b lymphocytes produced and matured?
Bone marrow
When a b lymphocyte finds an antigen that it carries the matching antibody for what happens?
It binds to the antigen and summons the humoral immune response. The b-cell clones itself.
What two types of b lymphocyte do they clone themselves into in the humoral immune response
Effector cells and memory cells
Effector b lymphocytes have an increased amount of RER. Why?
Increased peptide production rate, therefore increased rate of production of antibodies
Describe how the effector B cell antibodies neutralise the antigens?
They block the binding site on viral and bacterial toxins so they cannot bind and infect healthy tissues
What is agglutination?
When the effector B cells bind multiple antigens at once and make a cluster of them, making it harder for them to travel around the body, and targeting them for destruction by macrophages, innate immune phagocytes and specialised leukocytes
How is active humoral immunity gained?
Naturally, via experiencing and encountering an antigen
Artificially, via vaccination
Passive humoral immunity is gained how?
Passive immunity it the transfer of pre synthesised antibodies, it doesn’t require them to be synthesised in response to exposure.
Babies gain passive immunity from their mother in utero and via breast milk.
Immunity can be gained by serums made from the blood plasma of an immune donor.
These don’t last as long as active immunity
Cell mediated immunity is defence using what sort of lymphocytes, and where are they synthesised?
T lymphocytes, produced in the thymus. They defend cells that are infected
All cells carry major histocompatability complexes, what are these?
MHCs bind to fragments of endogenous protein presented on the surface of cells
How do MHCs allow T cells to target foreign cells
MHCs bind fragments of exogenous antigen. When a phagocyte engulfs an antigen, it presents proteins on the surface of the cell, via MHCs. T cells identify cells to attack by the presence of fragments of antigen, as they can’t recognise whole antigens.
Which class of MHCs bind which type of T cell
Class I MHCs bind cytotoxic T cells
Class II MHCs bind helper T cells
What are the types of T cell
Helper T cells:
1) Effector
2) Regulatory
3) Memory
Cytotoxic T cells
What is the role of cytotoxic T cells in cell mediated adaptive immunity
They roam the blood and lymph recognising cells presenting antigen fragments on class I MHCs and signalling apoptosis
How do T helper cells help mature B effector cells
B cells engulf any pathogen it matches to as an antigen. The B cell presents the antigen fragments on its surface. It then stops and waits for the T helper cell to bind and recognise the presented antigen, and trigger the full B cell, humoral mediated response by releasing cytokines
It acts as a safeguarding hyperactive immune system, and gives us self tolerance to our own tissues
Name some diseases that happen when self tolerance goes wrong and the immune system attacks the body cells
Diabetes type I
Multiple sclerosis
What is the role of a regulatory T cell?
A regulatory T cell releases inhibitory cytokines to signal to other immune cells to stop attacking once the pathogen is eliminated.
