The Nervous System and The Brain

• Receptors


  Structures that detect stimuli and carry out responses
• Effectors


  Structures that carry out responses to stimuli, such as muscles or glands
• Nervous system


  The system of receptors, nerves, and the brain and spinal cord that coordinates the body's responses
• Parts of the nervous system


  • The Central nervous system (CNS) consists of the brain and spinal cord
  • The CNS connects to the Peripheral nervous system
• Neurone


  An elongated cell consisting of a cell body, long and thin axon, and dendrites that transmits electrical impulses
• Motor neurone


  A neurone that transmits messages from the brain and spinal cord to the muscles and glands
• Synapse


  The gap between two neurones across which impulses pass, involving the release of neurotransmitters
• Transmission of impulses across a synapse

  1. Arrival of impulse triggers release of neurotransmitters

  2. Neurotransmitters diffuse across synapse and bind to receptors on next neurone
• Impulses can only travel in one direction across a synapse
• Reflex arc


  The pathway of a reflex action, where impulses are passed from one part of the nervous system to the next without going through the brain, instead they synapse in the spinal cord. This allows reflex actions to occur more quickly
• The pupil reflex is an exception to the general pattern of reflex arcs, as it involves the brain
• Cerebral cortex


  The highly folded outer layer of the brain responsible for consciousness, intelligence, memory, and language
• Motor cortex


  The region of the brain mapped by Penfield that is responsible for controlling voluntary movements
• fMRI


  A brain imaging technique that shows active areas of the brain while a task is carried out
• Diagram of what a synapse is and looks like

  
• Diagram showing what happens when the presynaptic neurone releases neurotransmitters

  
• Diagram of continuing the electrical impulse

  
• How do the neurotransmitters travel across the gap between the pre-synaptic neurone and the post synaptic neurone?

  Diffusion
• A reflex arc works by activating the spinal motor neurons without the delay of routing messages through the brain
• Reflexes are rapid, automatic and involuntary responses to stimuli that do not involve the brain.
• At the synapse, the sensory neuron releases chemicals called neurotransmitters into the synaptic cleft which diffuse across the gap and bind to receptors on the dendrites of the interneuron.
• The sensory neuron carries an action potential along its axon towards the central nervous system (CNS) where it meets with other neurons at a synapse.
• The sensory receptor detects the change in temperature or pressure from the environment (stimulus).
• Sensory Homunculus


  A diagram showing the relative sizes of different body parts based on the surface area of the surface area of the sensory cortex that receives nerve impulses from them

  
• Ways we determine brain function:

  • Brain injuries
  • Stimulating parts of the brain
  • MRI or fMRI (brain imaging)