Topic 2C- Cells and the Immune System Flashcards
What is the definition of antigens?
Where are antigens usually found?
What are antigens referred to as that aren’t normally found in the body?
What happens to these antigens?
What is the definition of pathogens?
What do all pathogens have on their surface?
What are these identified as and what happens to them?
What do cancerous or pathogen-infected cells have and what does this trigger?
Molecules (usually proteins) that can generate an immune response when detected by the body
They are usually found on the surface of cells, including body cells
Foreign antigens
It’s these antigens that the immune system usually responds to
Organisms that cause disease (eg bacteria, viruses and fungi)
All pathogens have antigens on their surface
These are identified as foreign by immune system cells, which then respond to destroy the pathogen
Have abnormal antigens on their surface, which trigger an immune response.
What are toxins?
What are and aren’t toxins described as?
What two things can the immune system respond to?
What happens when you receive cells from another person and give two examples of this?
When would this not be the case?
What do these foreign antigens trigger?
What does this then lead to?
What are the most important antigens for blood transfusions and describe these?
Toxins are poisons
Toxins are molecules, not cells
The immune system can respond to toxins as well as the pathogens that release them
(such as in an organ transplant or blood transfusion), those cells will have some antigens that are different to your own
Unless the donor is genetically identical to you
An immune response
The rejection of transplanted organs if drugs aren’t taken to supress the recipient’s immune system
The ABO blood group antigens- if the donated blood contains A or B antigens that aren’t recognised by the recipient’s immune system, they will generate an immune response.
What is the definition of lysis?
What is a phagocyte and give an example?
Where are they found?
What are these cells the first to do?
What is the definition of phagocytosis?
What is a T-cell?
What do T-cells have on their surface and what do these do?
What does this then do to the T-cell?
What is the function of helper T-cells (Th cells)?
What is the function of cytotoxic T-cells (Tc cells)?
What do helper T-cells also activate?
When the cell membrane is broken open, killing the cell
A type of white blood cell that carries out phagocytosis (engulfment of pathogens), eg a macrophage
Found in the blood and in tissues
They’re the first cells to respond to an immune system trigger inside the body
The engulfment of pathogens
(also called a T-lymphocyte) is another type of white blood cell
Receptor proteins on its surface that bind to complementary antigens presented to it by phagocytes
This then activates the T-cell
Release chemical signals that activate and stimulate phagocytes and cytotoxic T-cells (Tc cells)
Kill abnormal and foreign cells
Helper T-cells also activate B-cells, which secrete antibodies.
Describe the first stage of phagocytosis?
Describe the second stage of phagocytosis?
Describe the third stage of phagocytosis?
Describe the fourth stage of phagocytosis?
Describe the fifth stage of phagocytosis?
- A phagocyte recognises the foreign antigens on a pathogen
- The cytoplasm of the phagocyte moves round the pathogen engulfing it
- The pathogen is now contained in a phagocytic vacuole (a bubble) in the cytoplasm of the phagocyte
- A lysosome (an organelle that contains enzymes called lysozymes) fuses with the phagocytic vacuole. The lysozymes break down the pathogen
- The phagocyte then presents the pathogen’s antigens- it sticks the antigens on its surface to activate other immune system cells. The phagocyte is acting as an antigen-presenting cell.
What are B-cells?
What are B-cells covered with; what are they and what do they form?
What does each B-cell has that’s different and so what does each B-cell do?
What does a B-cell bind to (full description)?
What activates a B-cell?
What is this process known as?
What does the activated B-cell then do?
(also called B-lymphocytes) are a type of white blood cell
They’re covered with antibodies- proteins that bind to antigens to form an antigen-antibody complex
Each B-cell has a different shaped antibody on its membrane, so different ones bind to different shaped antigens
The antibody on the surface of a B-cell binds to a complementary shaped antigen
This binding and substances released from helper T-cells activates the B-cell
Clonal selection
Then divides into plasma cells.
What are plasma cells?
What do plasma cells secrete and what are these called?
What do these do and what do they form?
What does an antibody have and what does this mean?
What does this mean can happen to the pathogens?
What is this called?
What do phagocytes then do to the antibodies?
What does this process lead to?
Plasma cells are identical to B-cells (they’re clones)
They secrete loads of antibodies specific to the antigen. These are called monoclonal antibodies
They bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes
Two binding sites, so can bind to two pathogens at the same time
This means that pathogens become clumped together
Agglutination
Phagocytes then bind to the antibodies and phagocytise many pathogens at once
The destruction of pathogens carrying this antigen in the body.
What are antibodies and what are they made up of?
What does the specificity of an antibody depend on?
What do these form?
What does each antibody have?
What do they have that’s unique and why
What do all antibodies have that’s the same?
Proteins- they’re made up of chains of amino acids
It’s variable regions
These form the antigen binding sites
Each antibody has a variable region
With a unique tertiary structure (due to different amino acid sequences)
All antibodies have the same constant regions.
What is a lysosome?
What is a vacuole?
What is a phagocyte called when it displays the antigens?
What does the pathogen now do?
What do antibodies act as in B-cells?
What can antibodies also be released as and why?
How is the shape of an antibody made to be complementary?
Describe step 1 of humoral immunity?
Describe step 2 of humoral immunity?
What do steps 1 and 2 do to the B-cells?
Describe step 3 of humoral immunity?
What do the plasma cells then do?
What do the memory cells then do?
An organelle that contains enzymes called lysozymes, they digest the microbe
A membrane bound sac in the cytoplasm
An Antigen-Presenting Cell (APC)
The APC communicates with other cells in the immune system to aid the destruction of other similar microbes
They are essentially receptor found on the surface of B-cells
Antibodies can also be released as free agents that are free to form antigen-antibody complexes
Due to its primary structure- this refers to the specific sequence of amino acids in the protein
- B-cells, with antibodies on their surface which are complementary to the antigens, bind to them
- T-helper cells with complementary receptors to the same antigen also bind
Steps 1 and 2 activate the B-cells
- Now they divide by mitosis. Some of the B-cells formed are called plasma cells and others are memory cells
The plasma cells produce large quantities of antibodies
The memory cells remain in the body to aid a more rapid response to the next infection.
What is and describe the cellular immune response?
The T-cells and other immune system cells that they interact with (eg phagocytes) form the cellular response.
What is and describe the humoral immune response?
B-cells, clonal selection and the production of monoclonal antibodies form the humoral response.
