Neurons and Synaptic Transmission

• What percentage of neurons are located in the brain?

  Over 80%
• How do neurons transmit messages?

  Through electrical and chemical transmission
• What are the three main types of neurons?

  Relay, sensory, and motor neurons
• What is the function of sensory neurons?

  Carry messages to the central nervous system
• What do relay neurons connect?

  Sensory neurons to motor neurons
• What is the role of motor neurons?

  Connect central nervous system to effectors
• What happens when you touch something hot?

  Pain receptors are stimulated
• What is the structure of a neuron?

  Cell body, dendrites, axon, terminal buttons
• What does the cell body of a neuron contain?

  Nucleus with genetic material
• What are dendrites responsible for?

  Carrying impulses towards the cell body
• What is the function of the axon?

  Carries impulses away from the cell body
• What is the myelin sheath?

  Fatty layer that protects the axon
• What happens if the myelin sheath is continuous?

  It slows down the electrical impulse
• What are the nodes of Ranvier?

  Gaps in the myelin sheath
• How do nodes of Ranvier affect impulse transmission?

  They speed up the transmission
• What are terminal buttons?

  Communicate with the next neuron
• What is a synapse?

  Gap separating two neurons
• What is electrical transmission in neurons?

  Neurons in a resting state are negatively charged
• What occurs during an action potential?

  The inside of the neuron becomes positively charged
• What triggers the release of neurotransmitters?

  Arrival of an electrical impulse at the presynaptic terminal
• What do neurotransmitters do?

  Diffuse across the synapse
• What happens to neurotransmitters after they transmit a message?

  They are reabsorbed into the presynaptic neuron
• What is the specific function of acetylcholine?

  Causes muscle contraction
• What are the two effects neurotransmitters can have on a neuron?

  Excitation and inhibition effects
• What effect does serotonin have on neighboring neurons?

  Causes inhibition, making them negatively charged
• What effect does adrenaline have on neighboring neurons?

  Causes excitation, making them positively charged
• What is the fight-or-flight response related to?

  Release of adrenaline in the body