C3 Immunology Flashcards
Name all the natural barriers to infection:
Skin
Skin flora
Blood clotting
Inflammation
Phagocytosis
Mucous membranes
Acid and lysozyme
How does skin act as a natural barrier to infection?
Forms a tough barrier (collagen) to prevent entry
Vitamin C is required to maintain the barrier
How does skin flora act as a natural barrier to infection?
Compete with pathogenic bacteria preventing them from growing
The gut and other areas also have their own flora
How does blood clotting prevent infection?
Seal wounds to prevent entry of pathogens
How does inflammation stop disease spreading?
Cells surround the site of infection to prevent the spread of disease
How does phagocytosis stop infenction>
Invading microbes are engulfed and destroyed
What do mucous membranes do?
Mucus and ciliated cells trap microbes and help remove them
How does acid and lysozyme stop infection?
Stomach acid kills bacteria
Lysozyme in tears and saliva hydrolyse the peptidoglycan in bacterial cell walls
What are the signs of inflammation?
Redness
Swelling
Heat
Pain
What are the main functions of inflammation?
Increases blood flow to the area
Destroy the cause of infection
Repair/replace damaged tissue
Describe the process of phagocytosis:
Lysosomes fuse with the vacuole and release toxic compounds which destroy the ingested microbes
These compounds include enzymes and hydrogen peroxide
The debris is released, and antigens from the microbes are presented on the surface of the macrophage
These are antigen-presenting cells
The antigens can stimulate lymphocytes
What are the two main cell types of the immune system?
Phagocytes and lymphocytes
What are phagocytes?
Cells which engulf and destroy microbes and dead cells
e.g. macrophages and neutrophils
What are lymphocytes?
Involved in the specific immune response and come in two main types
What are the two main types of lymphocytes?
B-lymphocytes and T-lymphocytes
What are B-lymphocytes?
Mature in the spleen and lymph nodes and produces antibodies
What are T-lymphocytes?
Mature in the thymus and come in 2 main types:
T helper and T killer
What is the specific immune response and how does it come about?
Response to an antigen involving lymphocytes
What is an antigen?
A molecule that elicits an immune system, usually they are parts of proteins
Recognised as foreign by immune system
Have a specific shape and stimulate an immune response
Describe the Humoral response involving B lymphocytes and antibodies
B lymphocytes produce antibodies
B lymphocytes are produced from stem cells in the bone marrow and mature in the spleen and lymph nodes
Each B lymphocyte has a different antigen receptor or binding site
Each one will make antibodies similar to this receptor which will attach to this specific antigen
When a B lymphocyte is stimulated by their specific antigen on an antigen-presenting cell they develop into 2 types of cells
What 2 types of cells are produced when a B lymphocyte is stimulated?
Plasma cells - Produce antibodies and die shortly after
Memory cells - Remain in the body for months or years in case the same antigen appears in the body
Where are antigens found?
On the surface of bacteria or virus
On cell surface of foreign tissue such as organ transplants and transfused blood cells
Or be free molecules such as toxins released by microbes
Describe the Antibody structure:
Antibodies are quaternary globular proteins
They have a Y shape made of 4 polypeptide chains
Chains are held together by disulphide bonds
There are 2 antibody binding sites which are specific to the antigen
Phagocytes can bind to the constant region, this helps phagocytosis
How do antibodies work in phagocytosis?
Antibodies bind to antigens on microbes
Phagocytes have receptors which enable them to bind to and engulf the microbes coated with antigen
Also known as opsonisation
