2.4 Immunology Flashcards
What are the 2 types of cells of the immune system?
leukocytes
stem cells
Where do leukocyres come from?
derived from bone marrow stem cells
What are stem cells?
undifferentiated cells that can continually divide
What does totally potent mean?
stem cells can differentiate into any type of cell
What does multi-potent mean?
can differentiate into a certain type of cells
what are the 2 types of stem cells?
embryonic
bone marrow
What are the 2 types of leukocytes?
phagocytes and lymphocyte
What do phagocytes do?
carry out phagocytosis - engulfs the pathogen
How can you identify a neutraphil?
e-shaped nucleus
How would you identify a macrophage?
c-shaped nucleus
How would you identify a lymphocyte?
nucleus takes up most of the cell
Why do phagocytes alone not provide immunity?
do not produce memory cells
What are the two types of phagocytes?
macrophages and neutraphils
What are the 2 types of lymphocytes?
B cells and T cells
What do lymphocytes do?
capable of self and non-self recognition
kills pathogens and remebers them so provides immunity
What type of cells are the non-specific immune response?
phagocytes
What type of cells are involved in the specific immune response?
lymphocytes
What do antigen presenting cells do?
once killed a pathogen, they can take the secretion of the antigen and present it to activate the immune system
What type of cells are antigen presenting cells?
macrophages
B cells and T cells
What antigen is on a B cell?
membrane-bound antibodies
What antigen is on a T cell?
membrane bound protein
What is an infection?
an interaction between the pathogen and the body’s various defence mechanisms
What is immunity?
the ability of organisms to resist infection by protecting against disease-causing microorganisms or toxins
What type of lymphocyte does cell mediated resposes involve?
T lymphocytes
What type of lymphocyte does the humoral resposne involve?
B lymphocytes
What can be identified from its antigens?
pathogens
non-self material
toxins
cancer cells
What is the issue with cell recognition and transplants?
the immune system recognises the transplant as non-self and attempts to destroy it
How do you minimise self cells attacking a transplant?
matching the transplant as close as possible to avoid tissue rejection
What drugs are used to minimise the immune response to a transplant?
immunosuppresant drugs
Why is there a lag time between exposure to pathogen and bodys defences?
clonal selection is occuring
What are the 2 non-specific responses?
physical / chemical barriers
phagocytosis
What are the 2 specific responses?
cell-mediated response
humoral response
What happens to lymphocytes that attach to the bodys own cells?
they either die or are suppressed
What is apoptosis?
programmed cell death
What are the 2 types of WBC?
lymphocytes and phagocytes
What is the process of phagocytosis?
- the phagocyte is attracted to the pathogens by debris or toxins from pathogen
- the phagocyte attaches to the pathogen by receptor binding points
- phaocyte changes shape to engulf pathogen
- lysosomes within phagocyte migrate towards pathogen to form a phagosome
- lysosomes release lysozymes into phagosome
- hydrolysis products are abosrbed by phagocyte
How is the phagocyte attracted to the pathogen?
by chemical products of the pathogen, it moves towards the pathogen down a conc grad
How does the phagocyte attach to the pathogen?
phagocyte has several receptors on its cell-surface membrane that attach to the chemicals on the pathogen’s surface
How do the lysosymes break down the pathogen in the phagosome?
they hydrolyse the cell walls of the bacteria forming soluble products
What is an antigen?
any part of an organism or substance that is recognised as non-self by the immune system and stimulates an immune response
Where is the B lymphocytes produced?
bone marrow
Where are the T cells produced?
thymus gland
How can T cells find invader cells?
phagocyte presents pathogen antigen
body cells presenting viral antigen
transplanted cells have different antigens
cancer cells antigens
What are antigen-presenting cells?
cells that display foreign antigens on their surface
What are the only antigens a T cell responds to?
antigens that are presented on a body cell
What is the process of cellular response?
- pathogens invade body cells/ taken in by phagocytes
- antigens are displayed on cell-surface of phagocyte
- receptors of a specific Th cells fits onto the antigens
- attachment activates the T cell to divide rapidly by mitosis - forms clones
- one clone will divide to form memory cells
- the other clone will secrete cytokenes to stimulate b cells
What do the cloned T cells do?
develop memory cells
stimulate phagocytes
stimulate B cells to divide and secrete antibodies
activates cytotoxic T cells (Tc cells)
What are Th cells?
T helper cells
What do T helper cells do?
their receptors bind to the antigens
What are Tc cells?
cytotoxic T cells
What do cytotoxic T cells do?
kills abnormal cells and body cells that are infected by pathogens
How do cytotoxic T cells kill cells?
produces a protein called perforin that makes holes in the cell-surface membrane
What do B cells do?
produces a specific antibody that responds to one specific antigen
How does the antigen enter the B cell?
by endocytosis
What is clonal selection?
The process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes.
What are the 2 types of cells that the B cell clones develop into?
plasma cells
memory cells
What do plasma cells do?
secrete antibodies into the blood plasma
How long do plasma cells survive?
a few days
What are the plasma cells responsible for?
the immediate defence of the body against infection
What is the primary immune response/
the initial production of antibodies and memory cells
Where do memory cells circulate?
in the blood and tissue fluid
What do memory cells do?
responsible in the secondary response - detect same antigen and divide rapidly into plasma cells and more memory cells
By what cell divison proces do B cells clone themselves?
mitosis
Describe the process of the humoural response?
- the surface antigens on pathogen are taken up by B cell - specific antibody receptors complementary to antigen
- B cell processes and presents antigen on surface
- Helper t cells - attach to antigen and activate B cell
- b cell divides by mitosis to give a clone of plasma cells others divide into memory cells
- the cloned plasma cells secrete antibodies that specifically combine with antigen
- some B cells develop into memory cells
What is an antibody?
a protein with a specific binding site synthesised by B cells
How does an antibody react with the antigens?
binds to them
How many polypeptide chains does an antibody have?
4
What are the long polypep chains in an antibody called?
heavy chains
What are the short polypep chains in an antibody called?
light chains
How does the antibody bind to the antigen?
by the antigen binding sites - complementary in shape to antigen
What is formed when an antibody binds to an antigen?
an antigen-antibody complex
What two regions are on a antibody?
variable region
constant region
What are the two ways an antibody prepares a bacteria cell for destruction?
causes agglutination of the bacterial cells
serve as markers
What is agglutination?
clumping together cells
Why does agglutination of cells make destruction of them easier?
easier for the phagocytes to locate them as they are less spread out in the body