The Structure and Function of Neurons
Neurons (nerve cells) are the basic building blocks of the nervous system. They process
and transmit messages through both electrical and chemical signals.
There are 100 billion neurons in the human nervous system and 80% are located in the
brain.
They provide the nervous system with its primary means of communication.
There are 3 types:
- Sensory
- Relay
- Motor
Dendrites: Branch-like structures that extend from the cell body. They receive signals
from other neighbouring neurons or from sensory receptors and carry the nerve impulses
towards the cell body
Cell body (soma): Includes a nucleus, which contains the genetic material of the cell (the
chromosomal DNA)
Axon: A long fibre that carries nerve impulses away from the cell body down the length of
the neuron in the form of an electrical signal (known as an action potential)
Myelin sheath: Most axons are covered in a fatty layer that protects the axon and speeds
up electrical transmission of the impulse
Axon terminal: Present at the end of the axon and contains neurotransmitters within the
synaptic vesicles. Makes synaptic connections with other cells/neurons
, Sensory neurons
- Sensory neurons are found in sensory receptors such as the eyes, ears, tongue
and skin, and carry nerve impulses towards the spinal cord and brain
- They are responsible for converting external stimuli from the organism’s
environment into internal electrical impulses
- When these nerve impulses reach the brain, they are translated into ‘sensations’,
such as vision, hearing, taste and touch
- However, not all sensory neurons reach the brain, as some neurons stop at the
spinal cord, allowing for quick reflex actions
- They have long dendrites and short axons
- Direction of travel: sensory receptors -> CNS
Neurons (nerve cells) are the basic building blocks of the nervous system. They process
and transmit messages through both electrical and chemical signals.
There are 100 billion neurons in the human nervous system and 80% are located in the
brain.
They provide the nervous system with its primary means of communication.
There are 3 types:
- Sensory
- Relay
- Motor
Dendrites: Branch-like structures that extend from the cell body. They receive signals
from other neighbouring neurons or from sensory receptors and carry the nerve impulses
towards the cell body
Cell body (soma): Includes a nucleus, which contains the genetic material of the cell (the
chromosomal DNA)
Axon: A long fibre that carries nerve impulses away from the cell body down the length of
the neuron in the form of an electrical signal (known as an action potential)
Myelin sheath: Most axons are covered in a fatty layer that protects the axon and speeds
up electrical transmission of the impulse
Axon terminal: Present at the end of the axon and contains neurotransmitters within the
synaptic vesicles. Makes synaptic connections with other cells/neurons
, Sensory neurons
- Sensory neurons are found in sensory receptors such as the eyes, ears, tongue
and skin, and carry nerve impulses towards the spinal cord and brain
- They are responsible for converting external stimuli from the organism’s
environment into internal electrical impulses
- When these nerve impulses reach the brain, they are translated into ‘sensations’,
such as vision, hearing, taste and touch
- However, not all sensory neurons reach the brain, as some neurons stop at the
spinal cord, allowing for quick reflex actions
- They have long dendrites and short axons
- Direction of travel: sensory receptors -> CNS
