Neurons and synaptic transmission

• What are the three types of neurons?

  Sensory, relay, and motor neurons
• What is the primary function of the nervous system?

  To carry messages to and from the brain and spinal cord to other parts of the body
• How many neurons are approximately in the human brain?

  Approximately 100 billion neurons
• What is the role of neurons in the nervous system?

  Neurons specialize in carrying information throughout the body
• What is the definition of a neuron?

  A nerve cell that processes and transmits messages through electrical and chemical signals
• What are the main components of a neuron and their functions?

  • Cell body: Contains the nucleus
  • Axon: Carries the impulse away from the cell body
  • Dendrites: Receive signals from other neurons or sensory receptors
  • Myelin sheath: Insulates the axon and speeds up the impulse
  • Axon terminals: Communicate with the next neuron via synapses
  • Nodes of Ranvier: Help speed up the impulse
• What are the functions of sensory neurons?

  Carry messages from sensory receptors to the Central Nervous System
• Where are sensory receptors located?

  Sensory receptors are found in various locations such as eyes, ears, tongue, and skin
• What happens when sensory neurons convert information from receptors?

  They convert it into neural impulses that the brain translates into sensations
• What is the role of relay neurons?

  They allow sensory and motor neurons to communicate with each other
• Where are relay neurons found?

  In the brain and spinal cord
• What is the function of motor neurons?

  They connect the Central Nervous System to muscles and control muscle contraction
• What happens when motor neurons are stimulated?

  They release neurotransmitters that trigger a response in the muscle
• Describe the process of how neurons communicate.

  1. Dendrites receive information
  2. Information travels to the cell body
  3. Action potential travels down the axon
  4. Action potential reaches the axon terminals
  5. Neurotransmitters are released into the synaptic gap
  6. Neurotransmitters bind to receptors on the postsynaptic neuron
• What is an action potential?

  A brief electrical charge that travels down the axon
• What is the synaptic gap?

  The gap between neurons that the message needs to jump across
• What are synaptic vesicles?

  Sacs at the end of each axon that contain neurotransmitters
• What happens when a neurotransmitter binds to a receptor?

  It produces either an excitatory or inhibitory effect on the postsynaptic neuron
• What is the process of synaptic transmission?

  1. Action potential arrives at the axon terminal
  2. Neurotransmitters are released into the synaptic gap
  3. Neurotransmitters bind to receptors on the postsynaptic neuron
  4. The chemical message is converted back into an electrical signal
• What is reuptake in synaptic transmission?

  When the neurotransmitter is absorbed and stored back in the presynaptic neuron
• How does reuptake affect neurotransmitter effects?

  The quicker the neurotransmitter is re-stored, the shorter the effect on the postsynaptic neuron
• What is the difference between excitatory and inhibitory neurotransmitters?

  Excitatory neurotransmitters increase the likelihood of firing, while inhibitory neurotransmitters decrease it
• What is an Excitatory Post-Synaptic Potential (EPSP)?

  It means the postsynaptic neuron is more likely to fire
• What is an Inhibitory Post-Synaptic Potential (IPSP)?

  It means the postsynaptic neuron is less likely to fire
• What is summation in the context of neuron firing?

  • The overall calculation of EPSPs and IPSPs determines whether the postsynaptic cell fires
  • Example: 5 EPSPs - 2 IPSPs = 3 EPSPs = Excitatory charge
• What are the two ways to increase the strength of EPSPs?

  1. Spatial summation: Large number of EPSPs at many different synapses on one postsynaptic neuron
  2. Temporal summation: Large number of EPSPs generated at one synapse by high-frequency action potentials