Neurons Flashcards
What is the cell body called and what is contained in it?
Soma
The nucleus (chromosomes)
Where are the dendrites and what is their role?
They extend from the cell body
They carry electrical impulses from other neurons towards the cell body.
Where are axons and what is their role?
This is an extension of the neuron
Carries the electrical impulses away from the cell body
What covers axons in neurons and what is the role of this covering ?
Covered by a myelin sheath, a fatty substance.
It insulates heat and increases the speed at which electrical impulses propagate (travel along axon)
What are nodes of Ranvier in neurons?
Gaps between myelin sheaths
What occurs in neurons? (regarding action potentials)
Action potentials (nerve impulses) travel down the axon and “jump” from node to node. (Seeds up transmission of information along axon)
At the other side of the axon terminal, the impulses diffuse across a synapse and transmit to another neuron.
What are neurons function?
they transmit and receive info from other cells, i.e sensory cells for smell / taste
how many neurons are there in the spinal cord?
approx. 1 billion
What do the sensory neurons do?
Tells brain what info is available from inside the body and external environments. They process info from all 5 senses
What do relay neurons do?
They carry messages from one part of the CNS to other areas. They often connect sensory / motor neurons in the spinal column as part of a reflex action.
What do motor neurons do?
Carry signals from CNS to organs, glands and muscles.
What is the structure of the sensory neuron?
Cell body is set away from axon. Axon may be before / after the cell body ( to speed up movement of information through the NS)
What is the function of the sensory neuron?
Conducts impulse to spinal cord + brain. Involved in turning the sensory information into NS action potentials.
What is the structure of the relay neuron (interneuron)?
Cell body is in middle. Relay neurons tend to be quite small, to the point they don’t need myelin sheaths to speed action potential up. They are found within brain, spinal cord + retina.
What is the function of the relay neuron (interneuron) ?
They interconnect sensory neurons with appropriate motor neurons. They ‘relay’ the information from one type of neuron to another.
What is the structure of the motor neuron?
Cell body is at one end. Motor neuron axons can be very long, up to 1metre.
They are covered in myelin sheaths throughout.
What is the function of the motor neuron?
Conduct information from brain to a muscle / gland (effector). They are involved in both conscious movement (e.g movement) + unconscious movement (e.g stomach)
Summarise a reflex arc.
These exist to prevent humans from danger
The responses are very fast, so the relay neuron is situated in the spine to save time.
What is the process to a reflex arc? (3 steps)
- Pain information is detected by sensory neuron.
- Info is transmitted to a relay neuron
-The info is then automatically passed to a motor neuron to make muscles / glands (effectors) counteract the threat.
