Functions of the nervous system

• The nervous system is responsible for:

- sensory perception

- cognitive functions

- motor functions

- regulatory functions

Functions of the nervous system

• Collectively, these diverse activities can be grouped into three basic functions:

- sensory input

- integration of information

- motor output

Organisation of the nervous system

• Central nervous system (CNS), brain and spinal cord• Peripheral nervous system (PNS), all nervous tissue

outside the CNS

The brain

The brain

Cells of the nervous system

• Neuron. Principal cell of the nervous system

• Neuronal structure includes:

cell body

dendrites

axon

synaptic terminals

myelin sheath

Cells of the nervous system

• Neuroglia. Support neuronal function• There are various types of neuroglia that differ in their location, morphology and specific functions within the nervous system

Astrocytes

Oligodendrocytes

Microglia

Neurotransmission

• Neurons are electrically excitable. Able to produce actions potential (impulses) in response to stimuli

• This neuronal excitability depends on two basic features of the plasma membrane:

The resting membrane potential

The presence of specific types of ion channels

Neurotransmission

Myelination

• Most axons are surrounded by a lipid covering called myelin sheath

• This electrically insulates the axon and increases the speed of neuronal conduction

Neurotransmission

1. Impulse reaches end of axon.

2. Neurotransmitter is released from presynaptic terminal.

3. Neurotransmitter diffuses across synaptic cleft.

4. Neurotransmitter attaches to receptors on postsynaptic neuron.

5. Action potential is triggered in postsynaptic neuron.

Neurotransmitters

Neurotransmitters can be:

Stimulatory: initiate action potential

e.g. Acetylcholine

Inhibitory: prevent action potential

e.g. GABA, dopamine

Synapses

Sensory systems - pain