Defence-Immune System 1 Flashcards
Define specific defences.
They are adaptive mechanisms that protect against specific targets.
What are lymphoid tissues?
Essential parts of the defence system e.g. Thymus, bone marrow, spleen, lymph nodes.
Define lymph.
Lymph consists of fluids that accumulate outside of the bloodstream in the lymphatic system.
Define lymphatic system.
A branching system of tiny capillaries connecting larger vessels.
Name the two main types of white blood cell.
Phagocytes and lymphocytes.
What is the function of phagocytes?
To engulf and digest foreign materials.
Describe lymphocytes.
Most abundant white blood cell consisting of two types: T cells and B cells.
What is the function of T cells?
They migrate from the circulation to the thymus where they mature.
What is the function of B cells?
Circulate and also collect in lymph vessels, and make antibodies.
What is the function of platelets?
Initiate blood clotting.
What are T cell receptors?
Cell surface receptors that bind nonself substances on the surface of other cells.
What is major histocompatibility complex (MHC) proteins?
Exposed outside cells of mammals - these proteins help to distinguish self from nonself.
What are cytokines?
Soluble signal proteins released by T cells. They bind and alter the behaviour of their target cells.
What three defences do complement proteins provide?
- Attach to microbes helping phagocytes recognise and destroy them
- Activate inflammation response and attract phagocytes to infected site
- They lyse invading cells.
Define interferons.
They are produced by cells that are infected by a virus. They increase neighbouring cell resistance to the same or other viruses.
Name the different types of phagocyte.
- Neutrophils
- Monocytes/macrophages
- Eosinophils
- Dendritic cells
- Natural killer cells.
What is the function of neutrophils?
Attack pathogens in infected tissue.
What is the function of monocytes?
They mature into macrophages. They live longer and consume more pathogens than neutrophils.
What is the function of eosinophils?
They kill parasites such as worms that have been coated with antibodies.
What is the function of dendritic cells?
Have highly folded plasma membranes that can capture invading pathogens.
What is the function of natural killer cells?
They are a class of nonphagocytic white blood cells. They can initiate the lysis of virus-infected cells and some tumour cells.
What is the inflammatory response?
It is used when dealing with infection or tissue damage.
What are basophils?
Mast cells and white blood cells which produce histamine, which triggers inflammation.
Define antigens.
Organisms/molecules that are specifically recognised by T cell receptors and antibodies.
