DHUBS - TEST 3 - Neurones and Neurontransmitters

Question 1

Name the four parts of the neurone and their function.

Answer 1

Dendrites
Processes on the cell that receive connections from other neurones.

Cell body (soma)
Where the nucleus and most organelles of the cell are located.
Energy production and protein synthesis are most significant metabolic activities.

Axon
A specialised structure to conduct the nerve signal to its target.
Pathway for the nerve impulse from the soma to the opposite end of the neurone.
Axon carries the electrical signal to the axon terminal.

Synapse
The end of the axon that passes the signal to another cell.

Question 2

Describe the phases of action potential

Answer 2

The action potential is the signal that travels down the axon causing the release of the neurotransmitters.

First Phase:
- Membrane potential hits -55 mv
- Voltage gated Na+ channels open:
 Na+ rushes into the cell
 Membrane is depolarised
 Membrane potential reaches +40mV
 Voltage gated Na+ channels close

Second Phase:
- At +30mV voltage gated K+ channels open:
 K+ rush in to restore the membrane charge
 Repolarisation

Phase 3:
- Pushes into hyperpolarisation
 K+ equilibrium is closer to -90mV

Whole process takes about 2 milliseconds

Question 3

List the different channel types and how they function.

Answer 3

Energy Dependent channels:
Channels that depend on energy to move ions through them. For example, the Sodium, Potassium pump is one example. This uses energy from ATP to move 3 sodium ions out of the cell, while moving 2 potassium ions in.

Charge Dependent Channels:
Channels that will only allow certain charged ions through. Some channels may have a positive charge, therefore this will repel positive ions, but attract negative ions and vice versa.

Size Dependent Channels:
Channels that only allow ions of a certain size through.

Ligand Gated Channels:
Some channels will only open for certain events. Ligand gated channels only open when a certain molecule binds to par of the channel.

Mechanically Gated Channels:
Mechanically Gated Channels will open with distortion of the cell membrane. These are common with touch receptors.

Voltage Gated Channels:
Voltage gated channels will open with changes in the electrical charge on the membrane.

Leakage Channels:
Leakage channels will randomly open and close. Due to intrinsic switching, “leaking” ions.

Question 4

Name the neurotransmitters that belong to Amino acid neurotransmitters group.

Answer 4

Glutamate: most common excitatory neurotransmitter.

GABA: most common inhibitory neurotransmitter in the brain.

Glycine: most common inhibitory neurotransmitter in the spinal cord.

Question 5

Name the neurotransmitters that belong to Peptide neurotransmitters group.

Answer 5

Include the opioids like endorphins.

Question 6

Name the neurotransmitters that belong to Monoamine Neurotransmitters group.

Answer 6

Serotonin
Histamine
The catecholamines:
- Dopamine
- Adrenaline
- Nor-adrenaline

Question 7

Name the neurotransmitters that belong to “Other” Neurotransmitters group.

Answer 7

Acetylcholine.

Question 8

Name the roles of each neurotransmitter group.

Answer 8

Amino acid neurotransmitters:
The main inhibitory and excitatory messenger for the nervous system.

Peptide Neurotransmitters:
Important for pain modulation.

Monoamines neurotransmitters:
Involved with activation of the brain, emotion, consciousness and attention.

Other neurotransmitters:
Important for memory and brain activation.