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What contains myelinated axons?
Myelinated Fibers.
What carries information to the brain to be interpreted?
Sensory Neurones
Are dendrites always myelinated?
No. They are almost never myelinated, but can be.
The speed of nerve impulse transmission through the axon of a sensory neuron will be quickest in?
I'm guessing; "myelinated nerve fibres" contrary to the much slower "non-myelinated nerve fibres"
What is a bundle of neurones?
Synapse
At what speed are nerve impulses conducted in myelinated and unmyelinated neurons?
In thick well insulated (myelinated) neurones the impulse can travel in excess of 100m/s. In unmyelinated neurones the impulse can be conducted at less than 1m/s
White matter of the spinal cord?
it is the substance surrounding the gray matter. It is also composed of myelinated nerve fibers and makes up nerve pathways called tracts.
Why are nerves myelinated?
Some neurons are myelinated so they can carry signals faster.
Does a worm have a myelinated or non-myelinated neuron?
non-myelinated
What are bundles of neurones?
A nerve is a bundle of neurones
What contains myelinated axons?
Myelinated Fibers.
What carries information to the brain to be interpreted?
Sensory Neurones
Are dendrites always myelinated?
No. They are almost never myelinated, but can be.
How many synapses occur in this reflex arc?
there are 2 - one between the sensory and relay neurones; the other between the relay and motor neurones.
What type of neuron's involved in a knee jerk?
sensory neurones motor neurones
The axons of some neurons have an insulating coating called?
This is called myelin or myelin sheath. It's made mainly from fat with a few proteins in it, and is produced by oligodendrocyte cells in the CNS and schwann cells in the peripheral nervous system. It speeds up nerve signalling by allowing action potentials (the electric currents that make up nerve impulses) to skip between the gaps in the myelin (nodes of ranvier). In unmyelinated axons, sodium and potassium channels have to create the voltage differences at every single step along the nerve. (Say for example 100 times per nerve). Myelinated neurones only need to create these voltage differences at the nodes of ranvier (where sodium and potassium ion channels are located on myelinated neurones) Say for example there are 10 nodes of ranvier on a myelinated axon. The unmyelinated axon must create this voltage difference 10 times more frequently than the myelinated axon, hence the nerve impulse travels 10 times faster in a myelinated axon. (Based on the random numbers I used. In real life the numbers may be wildly different, but they still work in this way).
Why does the body have both sensory and motor neurones?
the body has both sensory and motor neurones because the sensory neurones sense what is happening and sends the message along and like a motor the motor neurones pass on the message constantly round and round until it reaches its destination
