Outline the functions of sensory receptor cells in the mammalian nervous system.
Fig. 8.1 illustrates how the potential difference (p.d.) across the membrane of a receptor cell changes over time. The membrane was stimulated at time A and again at time B using stimuli of different strengths.
State which of the letters C, D and E on Fig. 8.1 match each of these events. You may use each of the letters C, D or E once, more than once, or not at all. • The $\text{Na}^+ / \text{K}^+$ pump is working • The voltage-gated $\text{Na}^+$ channels are open • The voltage-gated $\text{K}^+$ channels are open
Explain why stimulus A did not lead to an action potential being formed but stimulus B did.
Describe the significance of the refractory period in the transmission of action potentials.
Describe how action potentials are transmitted along a myelinated axon.