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