Defence Flashcards
Is the second line of defence specific or non specific?
Non specific
The 5 stages of phagocytosis are…
- Bacteria is attracted to the membrane of the phagocyte
- The phagocyte will ENGULF the bacteria
- Lysosomes will form and make their way to the phagosome containing the bacteria
- lysosomes fuse with the phagosome
- bacteria is killed and digested by enzymes
What are macrophages?
Make proteins to
- Punch holes into the bacteria so that they die
- Proteins stick to outside to make them more appealing for phagocytes to engulf
Weaknesses of the second line of defence
- Can’t deal completely with any one particular micro-organism (some pathogens nearly always survive this attack)
- It cannot remember past infections
What are lymphocytes?
3rd Line of defence
B and T cells
1. B cells= BONE marrow HUMORAL RESPONSE
2. T cells= THYMUS gland, involved in CELL MEDIATED RESPONSE
Do different T cells have different receptors?
Yes- when an antigen invades the macrophages engulf and present it to the lymphocytes
What are the 4 groups of specialised T cells?
- Killer T cells
- Helper T cells
- Suppressor T cells
- Memory cells
Killer T cells?
Combine with antigens on the surface of invading cell and release chemicals which can either kill or stimulate other lymphocytes to become active
Helper T cells?
Co-operate with B cells in antibody production also activate macrophages and encourage inflammation
Suppressor T cells
Keep immune system in check so that once the antigens have been dealt with the system is switched off
Memory cells
Remain after the pathogens have been killed to stop re-infection
What does a B cell do if it comes across a complimentary shaped antigen?
It will form a clone that contains mostly plasma cells for immediate use and some memory cells
