Synaptic Transmission

Question 1

Synaptic Transmission

Answer 1

The process by which neighboring neurons communicate by sending chemical messages across the synapse.

Question 2

Chemical transmission

Question 3

Electrical transmission

Answer 3

• When a neuron is in a resting state the inside of the cell is negatively charged compared to the outside.
• When a neuron is activated by a stimulus the inside of the cell becomes positively charged for a split second causing an action potential to occur.
• This created an electrical impulse that travels down the axon towards the end of the neuron.

Question 4

Excitatory Neurotransmitter

Answer 4

When a neurotransmitter, such as adrenaline, increases the likelihood that the neuron will fire and pass on the electrical impulse. This is called an excitatory postsynaptic potential (EPSP)

Question 5

Inhibitory Neurotransmitter

Answer 5

When a neurotransmitter, such as seretonin , makes the charge of the postsynaptic neuron more negative.
This decreases the likelihood that the neuron will fine and pass on the electrical impulse. This is called an inhibitory postsynaptic potential (IPSP)

Question 6

Summation

Answer 6

Excitatory and inhibitory influences are summed and must reach a certain threshold in order for the action potential of the postsnyaptic neuron to be triggered. If the net effect of the neurotransmitters is inhibitory then the postsynaptic neuron is less likely to fire than if the net effect is excitatory.

Question 7

3 of the main neurotransmitters in the brain

Answer 7

• Dopamine (DA)
• Seretonin (5-HT)
• Adrenaline

Question 8

Process of Synaptic Transmission

Answer 8

1. An action potential (electrical charge) travels down the neurons axon (the pre-synaptic neuron)
2. When it reaches the terminal at the end of the neuron, vesicles release the neurotransmitters they contain.
3. Neurotransmitters (chemical messengers) travel out of the neuron, across the synaptic gap into receptors on the dendrites of the receiving neuron (the post-synaptic neuron)
   4.Here, the chemical message is converted back into an electrical impulse and the process of transmission begins again, from this neuron

Question 9

Reuptake of neurotransmitters

Answer 9

After the messages have been sent, any left over neurotransmitters can be recycled.
The effect of a neurotransmitter is lessened when the message has been received by the postsynaptic neuron and during reuptake

Question 10

Reflex Arc

Answer 10

1. Receptors in the skin - sensory neurons send message to retract hand away from heat.
2. Cross-section of spine - Relay neurons (in spinal cord) connects the sensory neuron to motor neuron so the message can be relayed.
3. Effector (muscle) - Motor neurons (connect to muscle) receives message and contracts muscle to move arm away.