Neurons and Synaptic Transmission

Question 1

What are the structures and functions of neurons?

Answer 1

• there are 100 billion neurons in the human body, ,making up 80% of the human body
• neurons transmit signals electrically and chemically, providing the nervous system with a means of communication

Question 2

What are the three types of neurons?

Answer 2

• sensory neurons
• motor neurons
• relay neurons

Question 3

What are the features and fuctions of a sensory neuron

Answer 3

• sensory neurons carry messages from the peripheral nervous system to the central nervous system
• They have long dendrites and short axons

Question 4

What is the function and structures of motor neurons

Answer 4

• the motor neuron connects the CNS to our muscles and glands
• They have short dendrites and long axons

Question 5

What is the structure and function of relay neurons?

Answer 5

• the relay neurons connect the sensory neurons to the motor or other relay neurons
• They have short dendrites and short axons

Question 6

What are the features that every neuron has?

Answer 6

• The cell body
• Dendrites
• Axons
• Myelin sheath
• Nodes of ranvier
• Terminal buttons

Question 7

What are the functions of each feature of neurons?

Answer 7

• The cell body = includes a nucleus which contains the genetic material of a cell
• Dendrites = Branch - like structures that protrude from the cell body and carry nerve impulses from neighbouring neurons towards the cell body of other neurons
• Axon = Part of the neuron that carries impulses away from the cell body down the length of a neuron
• Myelin sheath = a fatty layer that protects the axon and speeds up electrical transmission
• Nodes of ranvier = segments on the myelin sheath which speed up transmission
• Terminal buttons = the ends of the axon and they communicate with the next neuron across the synapse

Question 8

How are electrical impulses generated?

Answer 8

• when a neuron is in its resting state, the inside of the neuron is negatively charged compared to the outside
• when a neuron is activated by a stimulus, the inside becomes positively charged for a second and this causes action potential to occur
• this creates an electrical impulse that travels down the axon, toward the end of a neuron

Question 9

What is synaptic transmission?

Answer 9

• the process in which neighbouring neurons communicate with each other by sending chemical messengers (neurotransmitters) across a synapse

Question 10

How are signals transmitted within neurons compared to across a synapse?

Answer 10

within neurons = electrical
across a synapse = chemical

Question 11

Draw a diagram based on synaptic transmission

Answer 11

• axon = part at the top
• synaptic vesicle = empty sacs that carry neurotransmitters in the axon
• neurotransmitters = chemical messengers
• synapse = gap
• post synaptic receptor sites = receptor sites that nuerotransmitters bind to
  dendrite = end of other neuron

Question 12

What is the process of synaptic transmission?

Answer 12

1. When an electrical impulse reaches the end of the postsynaptic neuron, neurotransmitters are released
2. neurotransmitters the chemically diffuse across the synapse
3. once across the gap, neurotransmitters bind to the post receptor sites on the postsynaptic neuron
   4.then the chemical message is converted back into an electrical impulse

Question 13

What does inhibition do?

Answer 13

• neurotransmitters such as serotonin which results in the recieving neuron becoming more negatively charged and less likely to fire

Question 14

what do excitatory neurotransmitters do?

Answer 14

• an excitatory neurotransmitters makes a recieving neuron more positive, which makes a neuron more likely to fire

Question 15

What is summation?

Answer 15

• whether a postsynaptic neuron fires is based on summation
• if net summation is inhibitory, it is less likely to fire and if it is excitatory, it is more likely to fire