Lesson 4

• What are neurons?

  Specialised cells which act as the information processing unit of the brain, responsible for receiving and transmitting information
• What are the three main types of neurons?

  Sensory neurons, relay neurons, and motor neurons
• What are the functions of sensory neurons?

  Carrie electrical signals towards the central nervous system from the peripheral nervous system
• What are the characteristics of sensory neurons?

  Have long dendrites and short axons
• What is another term for electrical signals?

  Nerve impulses
• What is the function of relay neurons?

  Current nerve impulses within the central nervous system, they connect sensor in neurons to motor neurons or connect with other relay neurons
• What are the features of relay neurons?

  They have short dendrites and short axons
• What is the function of motor neurons?

  Carry nerve impulses away from the central nervous system
• What is the name for the muscle or gland at the end of motor neurons?

  Effectors
• What are the features of motor neurons?

  Short dendrites and long axons
• What is another term for the cell body of a neuron?

  Soma
• What does the soma contain?

  A nucleus which contains the genetic material of each neuron
• What is the function of dendrites?

  Receives electrical signals from Neighboring neurons and carries each electrical signal to the cell body
• What is the function of the axon?

  Cars electrical signals away from the cell body and down the length of the neuron
• What is the axon covered in?

  A fatty layer called myelin sheath
• What is another name for nerve endings?

  Terminal buttons
• What is the function of terminal buttons?

  Communicate with the next neuron in the chain across a synapse
• What is a synapse?

  A small gap where two neurons meet
• What process do neurons use to communicate with each other?

  Synaptic transmission
• How are signal within neurons sent?

  Electrically, but an electric impulse cannot directly cross the gap
• How are signals between neurons sent?

  Chemically via neurotransmitters
• What are neurotransmitters?

  Chemicals that are released from synaptic vesicles and scent across the synapse from one neuron to another
• What is the pre synaptic neuron?

  The neuron that transmits the message
• What is the post synaptic neuron?

  The neuron that receives the message
• What is the gap between the two neurons called?

  The synaptic cleft
• When an electrical signal has reached the end of the pre-synaptic neuron it arrives at the terminal button. Here, what can be found and what do they contain?

  Vesicles which contain neurotransmitters
• What does the electrical signal cause the vesicles to release?

  Neurotransmitters which travel across the synaptic cleft to the next neuron in the chain
• What do the transmitters do once they're reach the next neuron?

  Attached to the next neuron at the Post synaptic receptor sites which are located on the dendrites of the next neuron
• At the receptor sites what happens to the chemical message?

  It is turn back into an electrical impulse which sets off again down the neuron
• What happens to the neurotransmitters left in the gap?

  They are broken down by enzymes and/or reabsorbed through the reuptake protein in the pre-synaptic neuron so it can be used again
• What are the two different types/effects of neurotransmitters?

  Excitation and inhibition
• What is excitation?

  Increasing the positive charge of the next neuron, so that it has a higher light behood of an electrical signal firing in the post synaptic neuron
• Which hormone is involved in excitation?

  Adrenaline as a neurotransmitted generally causes excitation
• What is inhibition?

  Increasing the negative charge of the next neuron, so that it has a lower likelihood of an electrical signal firing and the post synaptic neuron
• Which hormone is involved in inhibition?

  Serotonin as a neurotransmitter generally increases the negative charge of the post synaptic neuron
• What is summation?

  The average of excitary and inhibitory neurotransmitters i.e if there are more excitatory signals compared to inhibitory signals
• What is the effect of summation?

  Whether or not an electrical signal will fire