3.4 Flashcards
What are neuron’s?
Cells which make up the nervous system are
called neurons. They transmit information
through electrical impulses.
• They are made up of a nucleus, cell
membrane and cytoplasm like all other animal
cells. However, they are specialised for their function
Impulse conduction
Nerve impulses only travel in one direction
along a neuron.
Fibres that conduct impulses towards the cell
body are called dendrites & dendrons
Fibres that conduct impulses away from the
cell body are called axon
3 Types of Neuron
Inter Neuron Sensory Neuron Motor Neuron
What is The Myelin Sheath
• Axons have myelin sheaths around them. This is a
fatty covering which protects the nerve and insulates it.
What is myelination?
When you are born, myelin sheaths are not fully
developed. The process of myelination continues
from birth to adolescence. This means that as a baby or toddler, you are not as rapid or
coordinated as an adult.
What disease most commonly destroys the myelin sheath
MS
What are glial cells ?
• Glial cells are cells which sit around or beside
neurons.
• They have 2 main roles:
– Physical support of neurons
– Production of myelin sheath
How can electrical impulses pass through a synapse?
a chemical called a neurotransmitter must be used
How do neurotransmitters work?
• Neurotransmitters are stored in vesicles (small
pockets) on the end of each axon at each
presynaptic neuron.
• They are released into the synaptic cleft when
a nerve impulse arrives at the end of the axon.
• They diffuse across the synaptic cleft and bind
to receptors on the dendrite of the post synaptic neuron
What happens if the neurotransmitter left in the cleft.
there would be
continuous stimulation and the system could not respond to new signals
How are Neurotransmitters removed?
Neurotransmitters are removed in 2 ways:
– Enzyme degradation:
• Acetylcholine is a neurotransmitter which is broken
down by an enzyme after it’s been used.
– Re-uptake:
• Nor-adrenaline is a neurotransmitter that is reabsorbed by the pre synaptic membrane
What are Endorphins?
• Endorphins are
neurotransmitters that stimulate neurons
involved in reducing the intensity of pain.
When do the Production of endorphins increase?
following
severe injury, prolonged continuous exercise,
stress and eating certain foods.
What is Dopamine?
Dopamine is a neurotransmitter which induces
(gives) feelings of pleasure and reinforces
particular behaviour by activating a reward
pathway in the brain.
What is the reward pathway
• The reward pathway has neurons which respond
to dopamine.
• The reward pathway activates when people do
things that are beneficial to them, e.g. eating when hungry.
