The Immune System Flashcards
(22 cards)
What can the immune response be broken up into?
Innate immunity and adaptive immunity.
What is innate immunity and adaptive immunity referred to as?
Innate: natural immunity
Adaptive: acquired immunity
What are natural barriers to infectious diseases?
- intact skin
- normal flora in gastrointestinal tract, in upper respiratory tract and on skin can compete with the pathogens and afford some protection.
- mucous membrane: site of secretion of various substances that contribute to the barrier function
- e.g lysozyme in saliva, sweat, tears and other secretions breaks down cell walls of many bacteria, acidity of stomach secretion inhibits growth of microorganisms.
What does the immune responses depend on?
The activity of white blood cells or leukocytes.
Where does white blood cell and leukocytes originate?
In bone marrow and many of them develop and mature there.
Where do white blood cells and leukocytes migrate to?
Peripheral tissues where some of them reside, while others circulate in the blood stream and in the lymphatic system, which drains extracellular fluid and frees cells from the tissues, transport the through the body as lymph and eventually delivers them back into the blood.
What are some examples of cells of the immune system (leukocytes)?
Neutrophils, eosinophils, mast cells, monocytes, macrophages, dendritic cells, natural killer cells, T lymphocytes (=T cells), B lymphocytes (= B cells) and plasma cells.
What are cytokines?
- A group of chemical substances that act as messengers within the immune system and between the immune system and other systems of the body.
- the language of the immune response
- protein molecules that are secreted by a range of cells and allow each of these cells to communicate with each other.
What are the importance of cytokines ( interleukin 2, chemokine, interferons)?
- interleukin 2: they stimulate the growth of lymphocytes
- chemokine: they control the movement of cells throughout the body
- interferons: important for activating macrophages and natural killer cells
Describe innate immunity
- non specific
- includes natural, mechanical, chemical and biological barriers to infection
- an extremely active process based around a set of receptors found on cells such as neutrophils and macrophages
- receptors recognise patterns such as sugars on the surface of bacteria as well as components of complement and antibodies that have attached to their respective antigens.
What are the components of innate immunity?
consists of:
- cellular defences: cells like phagocytes and natural killer cells
- non-cellular defences
- other defences include inflammation and complement
What is phagocytes and phagocytosis?
- phagocytosis: process whereby cells such as granulocytes and macrophages will destroy foreign antigens. There is orderly process of chemotaxis, where the cells are attracted to the site of inflammation followed by the adherence of the receptors on the surface of the phagocytic cells to the target antigen. This adherence is enhanced by the process of opsonisation by antibodies or complement. The particle is ingested into a phagocytic vesicle which then fuses with a lysosomal vesicle to digest the particle.
- Macrophages and dendritic of foreign antigens which are partly broken down and presented on the surface of these cells in association with MHC class II antigens. This is an extremely important process that results in the activation of helper T- cells.
What are natural killer cells?
- part of the innate lymphoid cells
- capable of destroying a variety of targets such as tumour cells, infected cells and damaged cells
- they identify changes on the surface of abnormal cells via a complex system of receptor cells
- insert protein molecules, call perforins, into the cells’ membrane, which creates a pore, allowing the NKs to insert toxic substances into the cells and thereby killing them.
What is the major function of inflammation?
- clear the injured site of cellular debris and foreign material such as pathogens, thereby repairing the site for the healing process
What are the four main signs of inflammation?
Redness, heat, swelling and pain
What is the complement system?
- group of plasma proteins that are present in the blood in an inactive state.
- when activated for example by infection, the complement proteins enhance the inflammatory response and can destroy foreign cells (e.g bacteria and viruses)
Describe adaptive immunity
- specific for the particular foreign agent
- if the host is re-exposed to the same agent, the response will be massively increased (memory).
- The ultimate immune response, where we adapt to change be producing new receptors that recognise antigens
- these receptors are found on T cells and B cells.
- on T cells they are referred to as T cell receptors
- on B cells they are antibody molecules attached to the outside of the cells.
What is tolerance?
- the immune response must be capable of differentiating between self and non-self.
- the ability to recognise self and not react
What are antigens?
- referred to as compounds that are capable of provoking an immune response
- most are large and complex
- individual components that are recognised by antibodies and T-cells receptors are referred to as epitopes.
What are the type of lymphoid organs?
Primary and secondary
What are primary lymphoid organs?
- where lymphocytes develop
- the critical process is that T cells and B cells develop the new receptors associated with the adaptive immune response.
- they rearrange receptor genes in these primary lymphoid organs.
What are secondary lymphoid organs?
- Are those in which naive T cells and B cells encounter their antigen and undergo proliferation. Cells that do not encounter their antigens are lost because they die due to lack of stimulation.
