Structure and function of neurons

What are the 3 types of neurons?

1)Sensory neuron (afferent)

2)Relay neuron

3)Motor neuron (efferent)

Sensory neuron

Structure:

• Long dendrites

• Short axons

• Unipolar - only transmit information

Function:

• Afferent nerve cell that carries sensory impulses from the sense organs to the CNS

Relay neuron

Structure:

• Short dendrites

• Short axons

• Multipolar - sends and receives information from many sources

• Found in the CNS

Function:

• connect with and act between other neurons (sensory + motor)

• Only found in the CNS

• Involved in analysis of sensation, what it means and decide how to respond to it

Motor neurons

Structure:

• Short dendrites

• Long axons

• Multipolar - sends and receives information from many sources

Function:

• Efferent nerve cell that transmits nerve impulses from the CNS to the muscles and glands

Structural features of neurons

What are neurons and what are they composed of?

• Neurons are cells which exist within the nervous system

• Neurons are the building blocks of communication within the body and are essential to everyday survival

• Neurons send electrical and chemical messages around the body to sense organs, glands and other organs

  • This information is then directed to the central nervous system (CNS)

• A neuron is composed of:

  • The cell body contains a nucleus (where the DNA of the neuron is stored)

  • Dendrites (like tree branches) which carry the electrical charges from one neuron to the next

  • The axon which carries the electrical charge down the length of the neuron and is covered in a protective fatty myelin sheath

  • The myelin sheath has gaps in it called Nodes of Ranvier which speed up the message’s transmission

  • Terminal knobs are found at the end of the neuron; they communicate across the synaptic cleft to the next neuron