The nervous system

  • Created by: cieran32
  • Created on: 20-10-18 16:20

Nervous system

The nervous system has two key parts

  • your nervous system is what allows you to respond to changes in your environment 
  • Receptors detect stimuli and effectors bring about a repsonse to a stimulus, effectors include muscle cells and cells found in the glands
  • Receptors communicate with effectors via the nervous and endocrine system or both
  • The Nervous system and Endcorine coordinate the response
  • The nerovus system has two parts the CNS and PNS
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The Cells of the nervous System are called Neurons

  • Neurons transmit information as electrical impulses around the body
  • The cell body has dendrites that recieve and send information from other neurons 
  • This information passes along the Axon in the form of an electrical impulse that ends up at a synaptic knob. The mylein Sheath insulates the axon to speed up nerovus transmission
  • Theres  a small gap before the next neuron called a synapse 
  • neurotransmitters are chemicals that are released from the synaptic knob. They pass across the synapse to pass on the signal to the dendrites of the next neuron 
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Different types of Neurons have different roles

Sensory neurons

  • The nerve cells that transmit electrical impulses from the receptors to the CNS

relay neurons 

  • The nerve cells that transmit electrical impulses between sensory nuerons and motor neurons

motor neurons 

  • The Nerve Cells that transmit electrical impulses from the CNS to effectors 
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A synapse is a junction between a Neuron and the N

A synapse is a junction between a neuron and the next cell 

  • A synapse is the junction between a neuron and another neuron, or between a neuron and an effector cell 
  • The tiny gap between the cells at a synapse is called the synaptic cleft 
  • The presynaptic neuron - the one before the synapse has a swelling called a synaptic knob. This contains synaptic vesicles filled with neurotransmitters.
  • When an electrical impulse reaches the end of a nueron , neurotransmitters are released into the cleft. They are then diffused and spread across the postsynaptic membrane and bind to specific receptors
  • When they bind they might trigger impulses , casue muscle contraction or a hormone to be secreted 
  • As receptors are only on postsynpatic membranes , impuleses are undirectional - only goes one direction 
  • Neurotransmiters are removed from the cleft so the resposne doesn't keep happening - broken down by enzymes 
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Neurotransmitters are Excitatory or inhibatory

Excitatory 

  • neurotransmitters increase the likelihood that an electrical impulse will be triggered

Inhibitory

  • Neurotransmitters decrease the likelihood that an electrical impulse will be triggered in the postsynptic neuron
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Common neurotransmitters

Acetycholine

  • This excitatory neurotransmitter -involved in voluntary movement, memory, learning and sleep. Too much -linked to depression and too little may result in dementia 

Dopamine 

  • Helps with movement attention and learning. Too much linked-schizophrenia , too little depression and parkinson's disease 

Noradrenaline

  •  linked with adrenaline. Associated with 'flight or fight' response. Too much linked to schizophrenia and little in depression
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Common neurotransmitters continued

Serotonin

  • Is involved in emotion, mood, sleeping and eating. Too little is linked to depression

GABA

  • GABA is an inhibitory neurotransmitter. Too little GABA is linked to anxiety disorders. 
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