Please enable JavaScript.
Coggle requires JavaScript to display documents.
Cell recognition and the immune system - Coggle Diagram
Cell recognition and the immune system
Phagocytosis
Lysosomes move towards the phagosome and fuse with it, forming a phagolysosome.
Lysozymes destroy the pathogen by hydrolysis of cell components.
The phagocyte engulfs the pathogen, forming a phagosome.
Soluble products of hydrolysis are absorbed into the cytoplasm.
Phagocytes have receptors that attach to antigens on the pathogen.
Phagocytes present the antigens of the pathogen on their cell-surface membrane to become an antigen-presenting cell.
Phagocytes move towards a pathogen down a concentration gradient of chemicals released by the pathogen.
Cell-mediated response
This attachment activates the Th cell to divide rapidly by mitosis (clone).
The cloned Th cells:
Stimulate more phagocytes to engulf pathogens by phagocytosis.
Stimulate B-lymphocytes to divide and secrete specific antibodies.
Differentiate into memory cells to ensure a rapid response to future infection.
Activate Tc cells.
A receptor on a Th cell fits exactly onto antigens on an APC.
Humoral immune response
Some B cells develop into plasma cells, which produce antibodies specific to the antigen, however these cells only last a few days.
Some B cells develop into memory cells, which have specific antibodies attached to their cell-surface membrane.
This stimulates the B cells to divide by mitosis.
Memory cells remain in the blood and can divide by mitosis into more plasma cells and memory cells in response to the same antigen again.
Th cells present processed antigens (from cell-mediated response) to B cells, which have a specific receptor for the antigen.
Primary and secondary immune response
Primary
When the immune system encounters and antigen for the first time.
The number of antibodies produced is fewwe, and takes longer.
Develop symptoms of disease, then recover.
Secondary
When the immune system encounters the same antigen again.
The number of antibodies produced is greater and much quicker.
Don't develop symptoms, not infectious, and don't realise you have the disease.
This is immunity.
Defence mechanisms
Lymphocytes need to distinguish between the body's own cells and molecules and those that are foreign.
Non-self antigens include
Non-self cells, e.g. from another organism of same speecies
Toxins produced by bacteria
Pathogens
Abnormal cells, e.g. cancer cells
Specific
Cell-mediated response (T-lymphocytes)
Humoral response (B-lymphocytes)
Non-specific
Physical barriers
Phagocytosis