Immune Functions Flashcards
What are five types of invader cells?
- fungus
- cancer cells
- parasites
- virus
- bacteria
Outline the first line of defence
Non-specific immune responses including:
- mechanical barriers; skin, mucous membranes
- chemical barriers; tears, saliva, stomach acid, perspiration
- reflexes; sneezing, coughing, vomiting, diarrhoea
Outline the second line of defence
Non-specific immune responses including:
- phagocytosis
- inflammation & fever
- protective proteins
- natural killer cells (NK cells)
What is phagocytosis?
The leukocytes (WBCs) can ingest or “eat” and destroy pathogens. When a normal body cell is injured by a pathogen, they release chemicals which attracts the mobile phagocytes to the area (chemotaxis)
What is inflammation?
Caused by the injured cells releasing histamine causing the blood vessels to dilate, bringing more blood to the area causing heat and redness. It also causes fluid to leak out of the blood vessel walls causing swelling and putting pressure on pain receptors
Why is swelling protective?
The increased blood flow is good as it brings more phagocytes to the area
What is fever (pyrexia)?
As phagocytes do their job, they release chemicals which stimulate the hypothalamus to reset the body’s temperature to a higher setting
Why is a fever protective?
A higher setting is beneficial as:
- Phagocytosis is stimulated in hot environments
- Pathogens cannot multiply in hot temperatures
What is the function of compliment proteins?
Complement Proteins float around in the bloodstream. Once activated to attack a bacteria, they swarm all over it and punch holes into the bacteria. This allows fluid and electrolytes to flow into the bacteria causing it to explode.
What are the two types of protective proteins?
interferons and compliment proteins
What is the function of interferons?
The Interferons are secreted by body cells when infected by a virus. They move into surrounding cells preventing the virus to take over the host cell.
Outline the third line of defence
A set of Specific Immune Responses involving:
- T Cell Lymphocytes
- B Cell Lymphocytes
What are NK cells
Natural Killer Cells (NK) are a type of lymphocyte that roam the body looking for any cells that look unusual. They will kill any unusual cell.
What is an antigen?
A marker on the outside of a cell. (our body ignores the antigens of cells it considers ‘self)
Outline T cells
- T Cells develop from stem cells in the bone marrow, and are then matured in the thymus
- Mature T Cells will be programmed to recognise only one type of antigen, and will react to no other
- Once a T Cell encounters its programmed antigen, it is activated and it divides into 4 Specialised T Cells. This process takes 1-2 weeks to find and recognise an antigen for the first time
What are the four types of T cells?
- Killer
- Helper
- Suppressor
- Memory
What is the function of Killer T cells?
Killer T Cells attach to any cell carrying the target antigen and release poison which kill the cell
What is the function of Suppressor T cells?
These are the ‘brakes’ and suppress or stop the immune response once the invader has been completely destroyed
What is the function of Helper T cells?
Helper T Cells communicate with the B Cells to create an antibody that will in future kill the antigen
What is the function of Memory T cells?
These T Cells live long after the threat is gone, and will remember the antigen and how to kill it, meaning a new invasion will be destroyed quickly (less than 2 weeks).
What are B cells?
- B Cells develop and grow in the bone marrow.
- They are not active like T Cells and spend most of their time in lymphoid tissue.
- Once a Helper T Cell has communicated with a B Cell, it divides into two cell types, creating a massive antibody factory
What are the two types of B cells?
- plasma
- memory
What is the function of plasma B cells?
Secrete huge numbers of antibodies into the blood which target the specific antigen.
They float around in the blood seeking out the target antigen and binds to them (tags it) so that the Killer T Cells can come and find it and kill it.
What is the function of memory B cells?
These cells live long in the body after the initial episode and remember the antibody needed to be made to kill the antigen.
How can we acquire immunity?
- vacines
- breast milk
- through placenta as a baby
