neurons and synaptic transmission

Question 1

Describe synaptic transmission

Answer 1

1. In order for signals to be sent between neurons, action potentials need to be converted from electrical
   signals into chemical signals, via synaptic transmission
2. Inside a neuron, the electrical impulse/action potentials reach the end of the presynaptic neuron, to the
   terminal buttons.
3. This triggers the synaptic vesicles to release neurotransmitters into the synapse [so the signal is now
   chemical].
4. Neurotransmitters diffuse across the synaptic cleft and bind to receptors in the in postsynaptic neuron
   [signal now converted back into electrical].
5. Neurotransmitters either have an excitatory or inhibitory effect, resulting in the neuron becoming more
   positively charged or more negatively charged.
6. Through the process of summation, this may result in depolarisation, making the post synaptic neuron
   more likely to fire an action potential again.

Question 2

What is a neuron

Answer 2

Specialised cells that transfer information throughout the body

Question 3

Describe a motor neuron (efferent neuron)

Answer 3

Conducting away from CNS to organs:
short dendrites and long axons.
Relays messages from the brain or spinal cord to the muscles and organs
Connect CNS to effectors like muscles/glands.

Question 4

Describe relay neuron (interneuron)

Answer 4

Short dendrites and short axons.
Relays message/connects messages from sensory neuron to motor neuron.
Make up the brain and spinal cord neural cells.

Question 5

Describe sensory neuron

Answer 5

Conducting inwards towards CNS:
Long dendrites + short axons
Bring in sensory information from outside world to brain. Relays messages from receptors to the brain or spinal cord.
Connects sensory neuron to motor neuron

Question 6

What are dendrites

Answer 6

Branch-like structures
- Receives information from other neurons and carries the nerve impulse to the cell body

Question 7

What are axons

Answer 7

Long slender structure
• Carries nerve impulse (action potential) away from cell body towards axon terminals.
• Surrounded by myelin sheath (except for relay neurons) to help impulses travel faster.

Question 8

What are axon terminals

Answer 8

• Contains neurotransmitters
• Connects the neuron to other neurons using synaptic transmission.

Question 9

What is the cell body

Answer 9

‘control centre of neuron
-Has a nucleus which contains genetic material of cell

Question 10

What is the nodes of fancier

Answer 10

Areas of gaps in myelin sheath
• It re-charges the action potential (like a turbo boost) to help impulses travel faster.

Question 11

Describe the reflex arc

Answer 11

1. Sense organs/receptors in the PNS detects a stimulus (change in temperature)
2. Sensory neuron sends electrical impulses from PNS to a relay neuron in brain/CNS
3. Relay neurons connect sensory neurons to motor neurons.
   Involved in analysis of the sensation, what it means, deciding about how to respond to it.
4. Motor neuron sends electrical impulses to an effector.
5. Effector produces a response (muscle contracts to move hand away).