Neurons

• What are nerve cells also known as?

  Neurons
• How many neurons are there approximately in the human nervous system?

  About 100 billion
• Where are 80% of neurons located in the human body?

  In the brain
• What is the primary function of neurons in the nervous system?

  To transmit signals electrically and chemically
• What is the general structure of neurons?

  1. Dendrite (receptor) receives a signal
  2. Signal carried towards the cell body (contains the nucleus)
  3. Signal travels along an axon (protected by myelin sheaths) to the axon terminal
  4. Terminal boutons pass the electrical signal to the next neuron
• What is the function of dendrites in neurons?

  To receive signals
• What does the cell body of a neuron contain?

  The nucleus
• What is the role of the axon in a neuron?

  To carry impulses away from the cell body
• What is the function of the myelin sheath?

  To protect the axon and speed up transmission
• What are nodes of Ranvier?

  Segments in the myelin sheath that speed up transmission
• What are terminal buttons in neurons?

  Structures that communicate with the next neuron across a synapse
• What are the three main types of neurons based on their function?

  1. Sensory neurons: Transmit information from senses to the central nervous system
  2. Motor neurons: Transmit information between the central nervous system and organs/muscles
  3. Relay neurons: Connect neurons to other neurons and transmit information within the central nervous system
• What do sensory neurons do?

  Transmit information from the senses to the central nervous system
• What is the role of motor neurons?

  To transmit information between the central nervous system and organs/muscles
• What are relay neurons also known as?

  Interneurons
• What is the function of relay neurons?

  To connect neurons to other neurons and transmit information within the central nervous system
• What do motor neurons transmit information between?

  The central nervous system and the organs and muscles
• What is an example of a function of motor neurons?

  To instruct the adrenals to produce adrenaline
• What do relay neurons connect?

  Neurons to other neurons
• How do relay neurons differ from motor neurons?

  Relay neurons connect neurons to other neurons, while motor neurons connect the central nervous system to organs and muscles
• What is the charge of the inside of a neuron when it is in a resting state?

  Negatively charged
• What happens to the charge of a neuron when it is activated by a stimulus?

  The inside of the cell becomes positively charged
• What occurs when the inside of a neuron becomes positively charged?

  An action potential occurs
• What does the electrical impulse created by an action potential do?

  It travels down the axon towards the end of the neuron
• What enables the signal to pass to the next neuron once it reaches the axon terminal?

  Synaptic transmission
• How do neurons communicate within neural networks?

  • Neurons communicate within groups known as neural networks
  • Each neuron is separated by a gap called a synapse
  • Signals within neurons are transmitted electrically
  • Signals between neurons are transmitted chemically across synapses
• What triggers the release of neurotransmitters from synaptic vesicles?

  The electrical impulse reaching the presynaptic terminal
• What happens to neurotransmitters after they are released into the synapse?

  They diffuse across the synapse as a chemical impulse
• How do neurotransmitters interact with postsynaptic receptor sites?

  They fit the receptor site like a lock and key
• What happens to the neurotransmitter after it reaches the postsynaptic receptor site?

  It is taken up by the receiving neuron
• What are the effects of neurotransmitters on the receiving neuron?

  • Excitation: Increases the likelihood of the neuron firing (e.g., acetylcholine)
  • Inhibition: Decreases the likelihood of the neuron firing (e.g., GABA)
• Which neurotransmitter is known to cause excitation in the postsynaptic neuron?

  Acetylcholine
• What effect does adrenaline have on the postsynaptic neuron?

  It causes excitation by increasing its positive charge
• Which neurotransmitter is associated with inhibition in the receiving neuron?

  GABA
• What is the effect of serotonin on the receiving neuron?

  It causes inhibition, making the neuron less likely to fire
• What is the effect of excitatory neurotransmitters on the next neuron?

  They make it more likely the next neuron will fire.
• What is the role of acetylcholine in neuronal firing?

  It is an excitatory neurotransmitter that increases the likelihood of the neuron firing.
• How do excitatory neurotransmitters influence neuronal activity?

  They increase the likelihood of the neuron firing.
• What is adrenaline classified as?

  Adrenaline is a hormone and a neurotransmitter.
• How does adrenaline affect the post-synaptic neuron?

  It increases the positive charge, making it more likely to fire.