A cold stimulus causes a temperature receptor in the skin of the heel to produce an electrical impulse. Three electrodes record the impulse at different positions along the same sensory neurone.
| electrode | position of electrode | time after the stimulus when the impulse is first detected in s |
|---|---|---|
| R | next to the temperature receptor | 0.002 |
| S | at the cell body | 0.011 |
| T | where the sensory neurone enters the central nervous system | 0.012 |
Explain how these results show the direction in which the electrical impulse travels along the dendron and along the axon.
111 exam-style questions on Edexcel GCSE Biology 2.3 The nervous system and brain, covering 2.3.1 Structures and functions of the brain, 2.3.2 Imaging brain function with scanning, 2.3.3 Limitations in treating nervous system damage, 2.3.4 Neurones and impulse transmission, and 2.3.5 Structure and function of a reflex arc. Each one has a worked solution and a mark scheme showing where the marks go.