neuronal communication

Describe two differences between the structure of sensory and motor neurones.

sensory neurons have dendron, motor neurons don’t

motor neurons have longer axons

motor neurons have more dendrites

Multiple sclerosis (MS) is a disease that causes the loss of myelin around motor neurones.

Explain why the speed of nerve impulses is slower in people diagnosed with MS.

saltatory conduction cannot occur

there are fewer/no nodes of Ranvier so nervous impulses cannot jump between nodes

depolarisation must take place along the whole length of the axon

Which event starts depolarisation?

sodium ion channels open

Which event starts repolarisation?

potassium ion channels open

Sodium and potassium ions can only cross the cell membrane through proteins.

Explain why.

cannot pass through the phospholipid bilayer because they are water soluble

OR

because they are not lipid soluble

OR

because they are hydrophilic