Neurology and cytology

Question 1

Typical Neuron

Answer 1

• cell body; makes proteins
• dendrites; receives signals
• axons; transmits signals to PSTs
• PSTs; transmit chemical signal
• myelin sheath; insulates, speeds conduction

Question 2

Neuronal circuit

Answer 2

Receptor
Afferent neuron
Interneuron
Efferent neuron
Effector

Question 3

Neuroglial cells

Answer 3

• Oligodendrocytes; form myelin sheath aka Schwann cells
• Astrocytes; protoplasmic (grey matter) or fibrous (white matter) barriers between neurons
• Microglia; cellular clearance after injury

Question 4

The axon terminal

Answer 4

• axon ends in a synapse
• terminal contains vesicles of neurotransmitters
• as nerve impulse travels down the axon vesicles fuse with the presynaptic membrane
• neurotransmitter diffuses across synaptic cleft & interacts with postsynaptic receptor

Question 5

Neurotransmitter examples

Answer 5

Acetylcholine
noradrenaline
dopamine
serotonin

Question 6

Nerve conduction

Answer 6

• Neurons have resting potential
• When threshold potential reached, neuron “fires”
• Signalling is all or nothing
• Increased freq. of APs increases intensity of signal
• Excitatory neurons move resting potential towards threshold
• Inhibitory is opposite

Question 7

Action Potential generation

Answer 7

• Na ions in causes depolarisation
• K ions out causes repolarisation
• hyperpolarisation; goes below resting

Question 8

Refractory period of a neuron

Answer 8

A second stimulus less than 0.001 seconds after the first won’t trigger another impulse, this is the refractory period
- when the membrane is depolarised

Question 9

Synaptic Transmission

Answer 9

1) Uptake of precursors
2) Synthesis of neurotransmitters
3) Storage of transmitter in vesicles
4) Degradation of surplus transmitter
5) Action Potential
6) Influx of calcium ions
7) Release of neurotransmitter
8) Diffusions of NT to postsynaptic membrane
9) Inactivation of transmitter
10) Reuptake of NT

Question 10

Neurotransmitters

Answer 10

Chemicals used for neuronal communication
- Classified as either excitatory (ACh) or inhibitory (GABA)

Question 11

Summation in Action potential generation

Answer 11

Single excitatory postsynaptic potential (EPSP) isn’t enough to bring postsynapse to threshold
- The Postsynaptic response is a result of possibly thousands of synaptic events from many neurons

Question 12

Types of summation in AP generation

Answer 12

• Temporal; high frequency of APs from single presynaptic terminal
• Spatial; activation of multiple presynaptic terminals