Functions of the nervous system The nervous system is responsible for: - sensory perception -...
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Transcript of Functions of the nervous system The nervous system is responsible for: - sensory perception -...
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