Non-specific Immune Response Flashcards
What makes up the immune system?
Consists of a collection of cells/molecules that work together to protect the body
Cells found in blood, organs and tissues around the body
What are the 4 main functions of the immune system?
1) protect body against infection from microbes
2) destroy/neutralise non-living foreign matter eg dust
3) ‘immune surveillance’- destroy any abnormal cells appearing in the body
4) remove old/damaged cells from the body
What are the 4 features of a good defence system?
1) provision of physical barriers, limiting invasion of the body by pathogens
2) ability to detect cells which are infected
3) ability to recognise infinite number of pathogens
4) distinguish between ‘self’ and ‘non-self’
What is the specific immune system?
Recognises various antigens and will remember then again once it has been encountered
What is the non-specific immune response?
More general reaction to infection and injury
What are the features of a non-specific immune response?
Present at birth (innate)
No memory- elicits same response to every pathogen no matter how many previous encounters
Makes up the 1st and 2nd line of defence
Protects well against bacteria and viruses
Includes barriers, phagocytosis, inflammation, protective proteins and fever
Important cells- neutrophils, macrophages and natural killer cells
What are the features of a specific immune response?
Built up over time
Memory- can remember specific pathogens so when encountered again bigger/faster stacks are made
Makes up the 3rd line of defence
Protects well against bacteria and fungi
Important cell- T and B lymphocytes
Includes- cell mediated immunity and humoral immunity
What makes up the 1st line of defence?
Skin, mucous membranes, chemicals
Physical barriers
What makes up the 2nd line of defence?
Phagocytosis, inflammatory process, protective proteins
What makes up the 3rd line of defence?
Specific immunity (B and T cells), lymphocytes and antibodies
What does phagocytosis mean?
Part of the non-specific response
Process by which cells of the immune system recognise, engulf and digest foreign cells and particles
What is the process of phagocytosis?
1) macrophage/neutrophil attaches to the bacteria
2) macrophage flows around and engulfs the bacteria
3) vesicle is formed- Phagosome
4) lysosomes fuse with the phagosome- Phagolysosome
5) enzymes contained within the lysosomes are released destroying the bacteria
6) digested products are expelled from the cell or presented (antigen-presenting cells) to lymphocytes
What is the function of Opsonins?
Coat foreign particle, making it easier for phagocytes to recognise and engulf it
Enhance phagocytosis
E.g. Antibodies
What is the process of antigen presentation?
1) once phagocyte has digested the bacteria, displays breakdown products of bacteria on cell surface
2) products- epitopes
3) macrophage- Antigen presenting cell
4) antigen presented to helper T cell to initiate specific immune response
What are the 4 main types of protective proteins?
Complement proteins, interferon, iron-binding proteins and anti-microbial proteins
What is the function of complement proteins?
Some act as opsonins
Complement System- collection of proteins in blood, which can be activated in cascade reaction (e.g. clotting cascade)
Once activated they can:
1) destroy foreign cells- punches holes in cell membranes so fluid/electrolytes can flow into foreign cells, causing it to burst
2) enhance phagocytosis
3) chemotaxis- recruit other cells of immune system to site of infection
4) promote inflammation
What is the function of interferons?
Group of proteins produced by lymphocytes/macrophages when infected by virus
Interfere with viral replication
Activate natural killer cells/macrophages
What is the function of iron binding proteins?
Inhibit microbial growth- reduces amount of iron available to certain bacteria
What are the functions of antimicrobial proteins?
Destroy a range of microorganisms
Attract other cells involved in inflammation e.g. Mast cells
What are natural killer cells?
Type of lymphocyte
Destroy any abnormal cells in body
Cause altered cell to burst
What is inflammation?
Tissue response preventing spread of infectious agents into nearby tissues
Involves: dilation of capillaries and increase in permeability, increase no. of WBC, phagocytosis to remove debris and cell division to replace injured cells
Clotting may also occur
What are the effects of histamine released from mast cells?
1) increase blood flow to infected area- Bring WBC to area
2) increase capillary permeability- easier fro WBC/fluid to leave blood capillaries and enter infected area
3) more heat (body defences more active)
4) phagocytes activates- microorganisms engulfed
5) complement system/specific immune defences activated
What are the symptoms/signs of inflammation?
Redness
Swelling
Heat
Pain
