4.1.5- Secondary Non Specific Defences Flashcards
What is a neutrophil?
A type of WBC that engulfs foreign matter and traps it in a large vacuole (phagosome) that fused with lysosomes to engulf the foreign matter.
What is an opsonin?
Proteins that bind to the antigen on a pathogen and then allows the phagocytes to bind to the pathogen.
What is an antigen presenting cell?
A cell that isolated the antigen from a pathogen and places it on the plasma membrane so that it an be recognised by other cells in the immune system.
Define what clonal selection?
Selection of a specific B or T cell that is specific to the antigen.
What are secondary responses?
They are used to combat pathogens that entered the body already.
An _______ is on the surface of a pathogen.
Antigen.
When a pathogen enters a body, how is it recognised?
By the antigen (chemical markers) on its membrane.
Antigens are…
Specific to the organism.
Opsonins are a type of _________.
Antibody.
What is the role of an opsonin?
They enhance the ability of the phagocyte to bind to and engulf the pathogen.
What is the first line of secondary defence?
Phagocytosis.
What is the most common type of phagocyte for phagocytosis?
Neutrophils
Neutrophils are manufactured where?
In the bone marrow.
What type of nucleus does a neutrophil have?
Multi lobed nucleus.
What happens to phagocytes after they engulf a few pathogens?
They die and may collect in an area of infection to form pus.
Briefly explain the whole process of phagocytosis.
The neutrophil binds to the opsonin that’s attached to the antigen on the pathogen and the pathogen is engulfed by endocytosis- forming a phagosome. Lysosomes fuse to the phagosome and release hydrolytic enzymes into it and the pathogen is digested. After this, the harmless waste products are absorbed into the cell.
List six ways in which phagocytes are specialised for their function.
- many lysosomes w/lysin
- many mitochondria- release energy glucose
- ribosomes- synthesise enzymes needed
- lobed nucleus- can squeeze through narrow gaps
- plasma memb receptors that bind to opsonin or specific pathogen
- well developed cytoskeleton- cell can change shape to engulf pathogen and move organelles around in cell
What are macrophages?
Larger cells that are manufactured in the bone marrow and travel in the blood as monocytes m before settling in body tissues.
Macrophages and neutrophils are produced where?
In the bone marrow.
Macrophages travel in the blood as ____________.
Monocytes.
Explain how a macrophage and a pathogen interact.
The macrophage partially digests the pathogen and a special protein complex is formed on the surface of the cell and the macrophage comes an antigen presenting cell.
What advantage does the special protein complex of the macrophage have?
It ensures the APC (macrophage) is not mistaken for a foreign cell and is attachments by other phagocytes.
What is a cytokine?
A hormone like molecule that is used in cell signalling to stimulate the specific immune response.
