Biospychology

• Nervous system

  Specialised network of cells in the body
• Main function of the nervous system

  Enable communication between all parts of the body
• Divisions of the nervous system

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
• Central nervous system (CNS)


  • Made up of the brain and spinal cord
• Main areas of the brain

  • Cerebrum
  • Cerebellum
  • Diencephalon
  • Brain stem
• Cerebrum


  • Largest area of the brain
  • Split into two cerebral hemispheres connected by the corpus callosum
  • Each hemisphere divided into four main lobes
• Frontal lobe


  Involved in speech, learning and thought
• Temporal lobe


  Involved in hearing and memory
• Parietal lobe


  Involved in touch and taste
• Occipital lobe


  Involved in vision
• Cerebellum


  • Lies beneath the back of the cerebrum
  • Involved in controlling motor skills and balance
  • Coordinates muscles to allow precise movements
• Diencephalon


  • Lies beneath the cerebrum and on top of the brain stem
  • Contains the thalamus and hypothalamus
• Thalamus


  • Acts as a relay station for nerve impulses coming from sensory receptors
  • Routes them to the appropriate part of the brain where they can be processed
• Hypothalamus


  • Regulates body temperature, hunger and thirst
  • Acts as the link between the nervous system and the endocrine system by controlling the release of hormones from the pituitary gland
• Brain stem


  • Lies at the base of the brain
  • Responsible for regulating involuntary bodily functions such as breathing, heartbeat and digestion
  • Connects the brain to the spinal cord
• Spinal cord

  Relays nerve impulses between the brain and the peripheral nervous system (PNS)
• Peripheral nervous system (PNS)


  • Carries information to and from the CNS
  • Divided into the somatic nervous system (SNS) and the autonomic nervous system (ANS)
• Somatic nervous system (SNS)


  • Governs voluntary actions
  • Sends nerve impulses from sensory receptors to the CNS
  • Sends nerve impulses from the CNS to the skeletal muscles, allowing the CNS to coordinate bodily movement
• Autonomic nervous system (ANS)


  • Governs involuntary bodily functions such as breathing, heartbeat and digestion
  • Divided into the sympathetic nervous system and the parasympathetic nervous system
• Sympathetic nervous system

  Prepares an individual for action when faced with a threat by triggering the fight-or-flight response
• Parasympathetic nervous system


  Relaxes an individual once the threat has passed
• Neurons


  • Specialised cells that transmit electrical impulses (action potentials) to provide the nervous system with its primary means of communication
• Structure of a neuron

  • Dendrites
  • Cell body
  • Axon
• Dendrites


  • Receive impulses from sensory receptors or other neurons
  • Carry impulses towards the cell body
• Cell body


  • The control centre of the neuron
  • Contains a nucleus
• Axon


  • Carries impulses away from the cell body
  • Impulses terminate at the axon terminals
• Types of neuron

  • Sensory neurons
  • Relay neurons
  • Motor neurons
• Sensory neurons

  • Carry impulses from sensory receptors to the CNS
  • Some terminate in the spinal cord, allowing reflex actions to occur quickly
  • Have long dendrites and short axons
  • Dendrites and axon covered in myelin sheath to speed up electrical transmission
• Relay neurons


  • Carry messages from one part of the CNS to another
  • Lie wholly within the CNS
  • Have short dendrites and short axons
• Motor neurons

  • Connect the CNS to effectors
  • Have short dendrites and long axons
  • Axon covered in myelin sheath to speed up electrical transmission
• Synaptic transmission

  • Electrical impulse reaches axon terminal of pre-synaptic neuron, stimulating release of neurotransmitter into synapse
  • Neurotransmitter diffuses across synapse and binds to receptor sites on dendrite of post-synaptic neuron
  • This produces either an excitatory or inhibitory effect on the post-synaptic neuron
• Types of neurotransmitter

  • Excitatory neurotransmitters
  • Inhibitory neurotransmitters
• Excitatory neurotransmitters

  Cause positively charged sodium and potassium ions to flood into the post-synaptic neuron, producing an excitatory post-synaptic potential (EPSP) and making the neuron more likely to fire
• Inhibitory neurotransmitters

  Cause negatively charged chloride ions to flood into the post-synaptic neuron, producing an inhibitory post-synaptic potential (IPSP) and making the neuron less likely to fire
• Summation

  The net result of adding up the excitatory and inhibitory synaptic input, which determines whether or not the post-synaptic neuron fires
• Endocrine system

  • Works alongside the nervous system to control vital functions in the body
  • A network of glands throughout the body that produce and secrete hormones
• Examples of glands

  • Pituitary gland
  • Adrenal glands
• Hormones

  Chemical messengers that travel in the bloodstream and affect only a limited number of target cells that have receptors for that hormone
• Pituitary gland


  • Controlled by the hypothalamus
  • Controls the release of hormones from all other endocrine glands
  • Secretes stimulating hormones in response to releasing hormones from the hypothalamus
• As hormone levels rise


  The hypothalamus shuts down secretion of releasing hormone, the pituitary gland shuts down secretion of stimulating hormone, and the target gland shuts down secretion of its hormone