3.2.4 Immunity Flashcards
What is the specific immune response?
Rcognising foreign cells and targeting pathogentic cells
What are antigens used to recongnise? (4)
Pathogenic cells
Abnormal body cells
Toxins
Cells from other individuals of the same species
What is the importance of antigens in defending againts pathogens?
Antigens are used as a binding site by surface proteins of phagocytes.
The pathogen is engulfed and digested
the antigen on the pathogen is complimetary to surface receptor of the phagocyte
It then recruits cells of the immune system leading to a specific immune response
How are antigens produced?
By organisms own body cells and are self-antigens
What are non-self antigens?
Antigems not produced by the body’s own cells
Why do some pathogens exhibit antigen variablity?
Antigens present on their surface change frequently due to gentic mutations.
Why is antigen variability a problem for the immune system?
Antigens on pathogens change shape due to gene mutations creating new strains, so vaccine or prior infection no longer provides immunity. B memeory cell receptors cannot recognis r bind to changed antigen on secondary response. Specific antibodies are no ,onger complementary
What molecules on outer surface membranes act as antigens?
Glycolipids
Glycoproteins
How are phagocytes stored and distributed?
Stored in bone marropw and distributes through the blood.
What are the two types of phagocytes?
Neutrophils
Macrophages
How do Neutrophils leave the blood?
By squeezing through the capillary walls to patrol the body tissues
Describe neutrophils mode of action.
-The chemicals released by pathogens and in the body attract neutrophils to the site where pathogens are reacted.
-They move toward pathogen and antibodies of surface of pathogen triggers attack as receptors on its surface recognise antibody.
-The surface cell memebranes surround and engulf trapping pathogen with phagocytic vacuole.
-The process is know as endocytosis.
What is the response to chemical response in neutrophils known as?
Chemotaxis
What is endocytosis?
The process of surrunding and engulfing a pathogen in a phagocytic vacuole.
What is a phagososme?
Phagocytic vacuole formed around a pathogen once engulfed by a neurophil.
Describe what are lysosomes?
Membrane organelles that contain digestive enzymes called lysozomes which digest unwanted material in a cell.
What is the function of lysosmes in pahgocytosis?
It fuses with the membrane of the phagososme to form a phagolysome.
It then releases lysozomes to digest pathogen
These digestive enzymes destroy the pathogen
What is secreted as a sign of a dead neutrophil?
Pus
List the 6 stages of phagocytosis.
Chemostasis
Recognise and attach
endocytosis
Bacteria with phogocytic vacuole
Lysosmes fuse with phagosome
Killing and digestion
Acronym for remebering stages of phgocytosis
Cant reveal everything because love kills
State two differences in the physical propeties and life span between neutrophils and macrophages
Macrophages are long lived and larger whereas nuetrophils are smaller and short lived.
What do macrophages do instead of staying in the blood?
They move into organs - lungs, liver, spleen, kidney
After leaving the blood, what do macrophages travel as?
Monocytes- type of white blood cell
State two ways in which macrophages carry out phagocytosis differently than neutrophils
-Dont destroy the pathogen completely and cuts it up instead
-It displays its antigens on their surface so recognised by lymphocytes
Where/When are T-lymphoctes produced?
In the bone marrow before birth
What are the physical properties of T- lymphocytes?
Smaller than phagocytes
Large nuclues that takes up most of cell
Where do immature T-lymphotes leave bone marrow to mature?
In the thymus- gland in the chest
Name the receptors on the surface of T- lymphoctes
T cell receptors
What are the two types of T-cellls?
Helper T-Cell
Cycotoxic T-cell (KILLER)
When are T cells activated?
When they encounter and bind to specific antigen presented by host cells.
What are the function of antigen presenting cells?
-They recruit other cells to produce specific immune response
-T-cells bing to complimentary antigen on these cells become sensitivised and divies to clone cells
What are the 2 most common antigen presenting cells?
Macrophages
Dendritic cells
Describe the response and function of T lymphocytes to a foreign antigen
Specific T lymphocytes with complementary receptors bind to antigen on antigen presenting cell. They are activated and divide by mitosis to form clones which stimulate:
Cytotoxic T cells- Kill innfected cells/tumour cells
Specific B cells- Humoral response
Phagocytes-E ngluf pathognes by phagocytosis
develop into memory cells- enable rapid response in future
Where to B lymphocytes mature and spread to?
They remain in bone marrow until mature then spread through body concentrating liver and spleen.
Why are millions of B lymphocytes produced?
As they mature, the genes coding for antibodies are changed to code for different antibodies.
How many types of antibody molecule can B lymphocytes make?
One type of antigen
What two types of cells do B lymphocytes differentiate into?
Plasma Cell
Memory Cell
What type of molecule does an antibody molecule form that combines with one type of antigen?
Glycoprotein receptor