biopsych

• What is the nervous system?


  a specialised network of nerve cells in the human body, our primary internal communication system
• What are the two functions of the nervous system?


  - To collect, process and respond to information in the environment.

  
  

  - To co-ordinate the working of different organs and cells in the body.
• What is the nervous system divided into?


  central nervous system and peripheral nervous system
• What is the role of the CNS?


  processes, interprets, stores information; issues orders to muscles, glands, organs
• What is the CNS made up of?


  brain and spinal cord
• Function of the brain


  provides conscious awareness and is involved in all psychological processes
• Function of the spinal chord


  - transfers messages to and from the brain and the rest of the body

  
  

  - also responsible for simple reflex actions that do not involve the brain
• What is the role of the PNS?


  Transmits messages via neurons to and from the CNS
• What is the PNS made up of?


  somatic nervous system and autonomic nervous system
• Function of the somatic nervous system


  transmits sensory information to the central nervous system and carries out its motor commands (muscles)
• What is the somatic nervous system made up of?


  - Sensory receptors that carry information to the spinal cord and brain

  
  

  - motor pathways that allow the brain to control movement
• function of autonomic nervous system


  plays an important role in homeostasis, which maintains internal processes like body temperature, heart rate and blood pressure
• What is the autonomic nervous system made up of?


  sympathetic nervous system and parasympathetic nervous system
• What is the role of the sympathetic nervous system?


  - impulses travel from the sympathetic nervous system to organs in the body to help us prepare for action when we are faced with a dangerous situation
• Examples of body reactions to a dangerous situation

  - heart rate, blood pressure and breathing rate increase

  
  

  - less important functions like digestion, salivation and the desire to urinate are suppressed
• What is the role of the parasympathetic nervous system?


  rest and digest - the body relaxes and returns to the 'normal' resting rate
• Examples of rest and digest (parasympathetic)


  - heart rate, breathing rate and blood pressure decrease

  
  

  - any actions that were previously slowed down during a fight or flight reaction are started again (e.g digestion)
• What are the three types of neurons?


  sensory, motor, relay
• What do sensory neurons do?


  - They carry impulses from sensory receptors to the CNS via the PNS

  - they have long dendrites and short axons.
• What do relay neurons do?


  connect sensory neurons to motor neurons in order to communicate with each other
• What do motor neurons do?


  - They carry impulses from the CNS to effectors (muscles)

  - they have short dendrites and long axons.
• Terminal button/axon terminal/ presynaptic terminals


  They communicate with the next neuron in the chain across the synapse
• Myelin sheath


  - a fatty layer that protects the axon and speeds up electrical transmission of the action potential
• Axon


  - this carries action potentials away from the cell body down the length of the neuron
• Cell body


  The is the control centre of the neuron
• Nucleus


  contains the genetic material of the cell
• Dendrites


  These carry nerve impulses from neighbouring neurons or sensory receptors to the cell body
• Nodes of Ranvier


  gaps in the myelin sheath that speed up the transmission took of the action potential
• What are neurons?


  cells of the nervous system that process and transmit messages through electrical and chemical signals
• What are the electrical impulses that neurons move to and from the CNS called?


  action potentials
• When a neuron is in a resting state, what charge is the inside of the cell?


  negative
• How does an action potential occur?


  When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur
• What is the tiny gap between neurons called?

  synapse
• Process of synaptic transmission


  1. When the action potential reaches the presynaptic terminal, it triggers the synaptic vesicles to release neurotransmitters into the synaptic gap.

  
  

  2. The neurotransmitters diffuse across the synaptic gap between the pre and post-synaptic cells.

  
  

  3. The neurotransmitters bind to the post-synaptic receptor sites on the membrane of the post-synaptic neuron's dendrite.

  
  

  4. This stimulation of the post-synaptic receptors converts the chemical message back to an electrical impulse and the process of transmission begins again in the post-synaptic neuron.

  
  

  5. The effects are terminated by a process called reuptake. The neurotransmitters are taken up by the pre-synaptic neuron where they are again stored in synaptic vesicles ready for later release
• What are the two types of neurotransmitters?


  excitatory and inhibitory
• What happens if the neuron is excitatory?


  - this causes the excitation of the post synaptic membrane (depolarisation), and so the post synaptic neuron is more likely to fire an electrical impulse
• What happens if the neurotransmitter is inhibitory?


  - this causes the inhibition of the post synaptic membrane (hyperpolarisation), and so the post synaptic neuron is less likely to fire an electrical impulse
• What happens if the net effect on the post synaptic neuron is inhibitory?


  the neuron will be less likely to fire
• What happens if the net effect on the post synaptic neuron is excitatory?


  the neuron will be more likely to fire
• Summation


  the excitatory and inhibitory influences are summed