The Nervous System

  • Specialised network of cells and our primary communication system.
  • Two main functions; Collect,process and respond to information and the environment, and to co-ordinate the working of differenet organs and cells in the body.
  • Divided into the Central Nervous System (CNS) and Peripheral Nervous System (PNS)

Structure and functions of CNS

  • Made up of the brain and spinal cord, the brain being the centre of all conscious awareness
  • Spinal cord is an extension of the brain, responsible for reflex actions
  • Passes messages to and from the brain and connects nerves to the PNS

Structure and functions of PNS

  • Transmits messages via millions of neurons to and from the nervous system
  • Subdivided into the ; autonomic nervous sytem and the somatic nervous system
  • ANS- governs vital functions in the body such as breathing, heart rate, digestion 
  • SNS- controls muscle movement and receives info from sensory receptors.
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The Endocrine System

  • works alongside the nervous system to control vital functions in the body through actions of hormones
  • Works much more slower than the nervous system but has powerful effects.


  • Organs in the body that produce hormones
  • major endocrine gland is the pituitary gland, known as the 'master gland', located in the brain.


  • Secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone

Endocrine system and the ANS work together

  • Sympathetic state; increase HR, increase BR, dilated pupils, inhibits digestion etc
  • Parasympathetic state; Decrease HR, decrease BR, constricts pupils, stimulates digestion.
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Structure and function of neurons

There are three types of neurons;

  • Motor neurons- connect the CNS to effectors (muscles and glands). They have short dendrites and long axons
  • Sensory neurons- Carry messages from the PNS to the CNS. They have long dendrites and short axons
  • Relay neurons- Connect sensory neurons to motor or other relay neurons. They have short dendrites and short axons.

Structure of Neurons

  • Cell body (soma)- Includes a nucleus which contains the genetic makeup of the cell
  • Dendrites- branch-like structures that protrude from the cell body. Carry nerve impulses
  • Axon- carries electrical impulse away from the cellbody down the length of the neuron
  • Myelin Sheath- Covers the axon to protect it
  • Nodes of Ranvier- Gaps in the axon that speed up the transmission of the impulse
  • Terminal button- end of axon, to communicate with the next neuron, across the synapse.
  • When a neuron is at resting state- inside is negative, when activated it is positive.
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Synaptic Transmission

Synapse- A tiny gap which separates each neuron

Chemical Transmission

  • Signals within neurons are transmitted electrically
  • Signals between neurons are transmitted chemically across the synapse
  • When the electrical impulse reaches the end of the neuron it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles
  • Once the neurotransmitter crosses the gap it is taken up by the post-synaptic receptor
  • The chemical message is coverted back into an electrical impulse and the process of electrical transmission begins


  • Chemicals which diffuse across the synapse to the next neuron

Excitation and Inhibition- e.g adrenaline is excitatory and serotonin is inhibitory.

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Localisation of the brain

19th century- holistic theory (all parts of the brain were involved in processing thought and action)

Localisation- specific areas of the brain were later linked with specific psychological functions

Brain is divided into two halves, left and right hemispheres. Left side of the body is controlled by the right hemisphere, the right side of the body by the left hemisphere.

Out layer of the brain- cerebral cortex, covers the inner parts of the brain,highly developed.

Cortex divided into four lobes- Motor, Somatosensory, Visual and Auditory

Broca's area- left frontal lobe, damage to this are results in slow, laborious speech

Wernickes area- Back of temporal lobe, produce fluent but meaningless speech when damaged

Strength- Brain scan evidence to support; Peterson et al used brain scans to show Broca's and Wernickes area

Stregnth- Neruological evidence- Surgically removing or destroying areas of the brain to control aspects of behaviour

Strength- support from case studies- Phineas Gage, who received serious brain damage in an accident

Limitation-Contradictory research- Lashley, suggests higher cognitive functions are not localised but distributed more holistic

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