Immune responses Flashcards
What is a non-specific response?
It responds in the same way to all germs and foreign substances. This is useless after the pathogen enters the body.
What is a specific response?
This happens after the non-specific response and is an attack aimed at a particular antigen
What are the non-specific responses?
- Chemical barriers (This is the first line of defence. Stomach acid kills bacteria, enzymes in tears prevent eyes from getting infected, mucus traps pathogens and removes harmful particles).
- Physical barriers (The skin forms a protective barrier and the mucus membrane traps and removes harmful particles. These physically block pathogens).
- Inflammation (This is a natural response to injury and infection. There will be an increased blood flow to the area that is infected to bring white blood cells to fight off the pathogen. This causes redness, heat and swelling).
- Phagocytosis (White blood cells engulf and destroy pathogens by breaking them down with enzymes. The antigens are then presented to different white blood cells to begin the specific response).
What is the specific immune response ‘PTBA’?
- Phagocytosis (The white blood cells that carry out phagocytosis are found in the blood and tissue. They’re the first cells to respond to a pathogen in the body. A phagocyte will recognise an antigen on a pathogen and the phagocytes cytoplasm will move around the pathogen, engulfing it. The pathogen is now contained in the phagocytes vacuole, in the cytoplasm. Then lysosomes fuse with the vacuole of the phagocyte, the lysosomes enzymes then break down the pathogen. The phagocyte then presents the pathogens antigens and sticks the antigens on its surface to activate the other immune system cell).
- T cell activation (Lymphocytes (a type of white blood cell) have proteins on their surface that bind to the antigens presented to it by the phagocytes. This activates the T cells. Different types of T cells respond in different ways, some release substances to activate B cells and some attach to antigens on a pathogen to kill the cell).
- B cell activation and plasma cell production (B-lymphocytes (a type of WBC) are covered in antibodies 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).
- Antibody production (Plasma cells are identical to the original B cells, secrete loads of antibodies specific to the antigen. The functions of these antibodies include: Coating pathogens to make it easier for a phagocyte to engulf it, coating pathogens to prevent them from entering a host cell and binding to and neutralising toxins produced by a pathogen).
What is phagocytosis?
The process of WBC engulfing and destroying pathogens.
Explain the process of phagocytosis.
-The white blood cells that carry out phagocytosis are found in the blood and tissue. They’re the first cells to respond to a pathogen in the body.
- A phagocyte will recognise an antigen on a pathogen and the phagocytes cytoplasm will move around the pathogen, engulfing it.
- The pathogen is now contained in the phagocytes vacuole, in the cytoplasm.
- Then lysosomes fuse with the vacuole of the phagocyte. The lysosomes enzymes then break down the pathogen.
- The phagocyte then presents the pathogens antigens and sticks the antigens on its surface to activate the other immune system cell.
How are T cells activated?
- Phagocytosis takes place and then phagocytes present the pathogens antigens to activate other immune system cells.
- Lymphocytes have proteins on their surface that bind to the antigens presented to it by the phagocytes. This then activates T cells.
How are B cells activated?
- Different types of T cells respond in different ways. Some release substances to activate B cells.
What are the roles of antibodies produced by plasma cells?
- Coating pathogens to make it easier for a phagocyte to engulf it.
- Coating pathogens to prevent them from entering a host cell.
- Binding to and neutralising toxins produced by a pathogen.
What is a phagocyte?
A white blood cell that engulfs a pathogen.
What is a phagocytic vacuoles role?
Contains the engulfed pathogen.
What is a lysosomes role?
This breaks down the pathogen.
What is the 1st and non specific phase of the primary immune response?
- Pathogens covered in antigens arrive in the bloodstream.
- Phagocytes go around the body looking for cells with foreign antigens. When one is found it engulfs it via phagocytosis.
- The phagocyte breaks down the pathogen, killing it. It then pulls all the antigens off and displays them on its cell surface. This is called ‘antigen presentation’.
What is antigen presentation?
When a phagocyte pulls all the antigens off of a pathogen and displays them on its cell surface.
What is the 2nd and specific immunity phase of the primary immune response?
- The next two types of lymphocytes appear (B and T cells). T cells find the antigens presented by the phagocyte, they then take the antigens and clone themselves multiple times.
- The cloned T cell then do 3 things:
- Release chemicals which attract more
phagocytes to kill more pathogens . - They stimulate B cells to make the correct
antibody and release it. - They turn into memory cells for later.
- Release chemicals which attract more
- Loads of B cells, called plasma cells at this point, show up and release the specific antibodies, killing the pathogens. The rest of the B cells then turn into memory cells.
