The immune response and memory cells
Introduced| English | Meaning |
|---|---|
| primary response/ˈpraɪməri rɪˈspɒns/ | Macrophage displays antigen → T-helper activates → B-lymphocytes → plasma cells (antibodies) + memory cells. |
| T-helper cell/tiː ˈhelpə sel/ | A T lymphocyte that coordinates immune responses by signalling to other immune cells after recognising an antigen. |
| B-lymphocyte/biː ˈlɪmfəsaɪt/ | B-lymphocyte |
| plasma cell/ˈplæzmə sel/ | An activated B-cell descendant specialised for secreting antibodies. |
| memory cell/ˈmeməri sel/ | A long-lived immune cell that enables a faster or stronger response when the same antigen is encountered again. |
| secondary response/ˈsekəndəri rɪˈspɒns/ | secondary response |
| clonal selection/ˈkləʊnl sɪˈlekʃn/ | clonal selection |
The body fights back
- The first time a new pathogen enters, the response is slow.
- Several cell types work together to destroy it — and to remember it.
- That memory is what makes you immune next time.
The secondary immune response is slower and weaker than the first.
Difficulty 1/5 · 100 coins + a small bonus on first completion today
False. Memory cells from the first exposure react quickly, so the secondary response is faster and stronger. This is the basis of long-term immunity.
The primary response 初次反应
- a macrophage engulfs the pathogen and displays its antigen.
- T-helper cells 辅助性T细胞 recognise that antigen, become active, and switch on other cells.
- matching B-lymphocytes B淋巴细胞 are selected; they divide into plasma cells 浆细胞 (which pour out antibodies) and memory cells 记忆细胞.
- T-killer cells destroy the body's own cells that are infected.
A blood smear: the large stained cells are white blood cells among the red cells.
The primary immune response
Step through the specific response — the antigen is presented, T-helper cells switch on B-cells, and plasma cells pour out antibodies.
T-helper cells in the immune response:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
T-helper cells recognise the presented antigen and activate B-lymphocytes and other cells.
Which cells actually secrete antibodies?
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Selected B-lymphocytes divide into plasma cells (which secrete antibodies) and memory cells.
Put the primary immune response in order.
Difficulty 3/5 · 200 coins + a small bonus on first completion today
Antigen presented → T-helper activated → B-lymphocytes selected → plasma cells make antibodies.
Match each cell to its job in the immune response.
Difficulty 2/5 · 140 coins + a small bonus on first completion today
The macrophage presents, the T-helper switches things on, plasma cells make antibodies, and memory cells wait for next time.
Memory and the secondary response 二次反应
- Memory cells stay in the body for years.
- If the same pathogen returns, they launch a secondary response that is much faster and larger.
- The pathogen is destroyed before it makes you ill — long-term immunity.
The secondary immune response is faster and larger because:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Memory cells made in the primary response respond quickly and strongly when the same pathogen returns.
Long-lived cells that stay behind to give a fast secondary response are ______ cells.
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Memory cells let the body respond before you even feel ill the second time — the basis of immunity.
Clonal selection 克隆选择
- Each lymphocyte has receptors for one specific antigen.
- When that antigen appears, the matching lymphocyte is selected and divides rapidly to make an army of identical cells — clonal selection.
The one lymphocyte whose receptor matches the antigen is selected and cloned into many identical cells
You've got it
- primary response: macrophage displays antigen → T-helper activates → B-lymphocytes → plasma cells (antibodies) + memory cells
- T-killer cells destroy infected body cells
- memory cells persist; the secondary response is faster and larger
- that's long-term immunity — the pathogen is cleared before you fall ill
Write from a faster secondary response
- A person meets a pathogen for the second time.
- Memory cells were made during the first infection.
How does the second response compare with the first?
Memory cells are ready before the second meeting.
Why is the second response faster?
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Memory removes the slow start.