bio-psychology

• Sensory neurons carry messages from the peripheral to the central nervous system and have long dendrites and short axons.
• Relay neurons connect sensory and motor neurons and have short dendrites and short axons.
• Motor neurons connect the central nervous system to effectors such as muscles and glands, and have short dendrites and long axons.
• Neurons vary in size from millimetre to meter.
• The cell body of a neuron includes a nucleus.
• Branch-like structures called dendrites protrude from the body cell and carry nerve impulses from neighbouring neurons towards the stoma.
• The axons of a neuron carry impulses away from the body cell.
• The axon of a neuron is covered in a fatty layer of myelin sheath which protects the axons and speeds up the electrical transition of impulses.
• The myelin sheath of a neuron is segmented by gaps called nodes of Ranvier, which speed up the transition as impulses jump across the axons.
• At the end of the axons of a neuron are terminal buttons that communicate with the next neuron across a gap known as a synapse.
• Cell bodies of motor neurons may be in the central nervous system but have long axons which are a part of the peripheral nervous system.
• Sensory neurons are located outside the central nervous system in clusters known as ganglia.
• Relay neurons make up 97% of all neurons and are mostly found in the brain and visual system.
• In the resting state of a neuron, the inside of the cell is negatively charged.
• A neuron is activated by a stimulus, causing the inside of the cell to become positively charged for a split second, creating an action potential.
• The action potential created by a neuron travels down the axon towards the end of the neuron.