Neurons

Where are neurons located and what is their function?

In the human nervous system, majority are in the brain. Transmit signals electrically and chemically, provide the nervous system with communication

What is the structure of neurons?

Vary in size but all have the same structure. Consists of a cell body, dendrites and an axon

Cell body

Includes a nucleus, contains genetic material of the cell. Control centre of the neuron

Dendrites

Branchlike structures at the beginning of a neuron. Receives chemical messages from neighbouring neurons, turn into electrical signals in the cell body

Axon

Carries the electrical signals away from the cell body down the neuron. Covered in a fatty layer of myelin sheath that protects the axon

Myelin sheath

Not a structure. Segmented by gaps called nodes of Ranvier. Speeds up the transmission of the impulse, forces impulses to go across the gaps along the axon

Axon terminals

At the end of an axon, communicate with dendrites of other neurons, across the synapse

What are the three types of neurons?

Motor, sensory and relay

What is the function of a sensory neuron?

Carry messages from the PNS to the CNS. Have long dendrites and short axons

Where is a sensory neuron located?

In receptors (eyes, ears, tongue, skin) and carry nerve impulses to the spinal cord and brain

How does a sensory neuron function?

Nerve impulses reach the brain then are translated into sensations. Not all sensory neurons reach the brain, some neurons stop at the spinal cord to allow quick reflexes

What is the function of a relay neuron?

Connect the sensory neurons to the motor neurons or other relay neurons. Have short dendrites and axons

Where is a relay neuron located?

Found in the brain and spinal cord

How does a relay neuron function?

Allow sensory and motor neurons to communicate in the brain and spinal cord

What is the function of a motor neuron?

Connect the CNS to effectors (muscles and glands). Have short dendrites and long axons

Where is a motor neuron located?

In the CNS and control muscles movements

How does a motor neuron function?

Motor neurons become stimulated, they release neurotransmitters that bind to the receptors on the muscles. This triggers a response, leads to movement