The Nervous Impulse

What are the 4 stages of the nervous impulse?

What happens in the neurone during resting potential?

What happens to the potential difference of the cell membrane during resting potential?

Complete the sentences:
The Na⁺/K⁺ pumps move Na⁺ out of the neurone, but the membrane isn't _____________ to Na⁺ ions, so they cannot __________ back in. This creates a Na⁺ _________________ gradient.

What happens in the neurone during an action potential?

What happens to the potential difference of the cell membrane during an action potential?

What happens in the neurone during repolarisation?

What happens to the potential difference of the cell membrane during repolarisation?

What happens in the neurone during hyperpolarisation?

What happens to the potential difference of the cell membrane during hyperpolarisation?

Describe the graph showing a nerve impulse travelling through a neurone

What is the refractory period?

The refractory period acts as a time delay between one action potential and the next. This makes sure that action potentials.....

Complete the sentences:
When an action potential happens, some of the Na⁺ ions that enter the neurone diffuse __________. This causes Na⁺ ion channels in the next region to _______ and Na⁺ diffuses into that part. This establishes a _________ __________ and initiates a wave of _________________ to travel along the neurone.

TRUE OR FALSE:
The wave of depolarisation moves away from the parts of the membrane in the refractory period

TRUE OR FALSE:
A bigger stimulus causes a bigger action potential

What does it mean by the "all-or-nothing" nature of action potentials?

TRUE OR FALSE:
Once the threshold is reached, an action potential will always fire with the same change in voltage, no matter how big the stimulus is

What are the 3 factors that affect the speed of conduction of action potentials?

In the peripheral nervous system, what is the myelin sheath of neurones made up of?

Complete the sentences:
Some neurones have a ________ ________ (an electrical conductor). In the peripheral nervous system, the myelin sheath is made of a type of cell called a ____________ _____, which is wrapped around the axon (and/or __________). Between the Schwann cells are the ______ ___ ________ where Na⁺ channels are concentrated.

In a myelinated neurone, the speed of conduction is faster than in a non-myelinated neurone. Why?

How does axon diameter affect the speed of conduction?

How does temperature affect the speed of conduction?

TRUE OR FALSE:
When the temperature gets too high, the speed of conduction decreases