Lecture 6: basic physiology of nerve cells

Question 1

What can affect the presynaptic neuron?

Answer 1

Stimuli on the dendrites and cell body (the soma)

Question 2

What area generates the action potential?

Answer 2

The axon hillock

Question 3

What response do dendrites and the cell body (soma) make when affected by stimuli?

Answer 3

Graded responses that alter membrane potential (depolarise or hyperpolarise)

Question 4

At what point is an action potential generated?

Answer 4

If the hillock reaches threshold

Question 5

What potential does excitatory neurons produce?

Answer 5

Excitatory post-synaptic potentials

Question 6

What potential does inhibitory neurons produce?

Answer 6

Inhibitory post-synaptic potentials

Question 7

What type of response can action potentials have?

Answer 7

All or nothing response

Question 8

What are the thin, ribbon-like cells that commonly wrap around axons called?

Answer 8

Schwann cells

Question 9

What is the effect of the layers of myelin that make a shwann cell called?

Answer 9

Myelination

Question 10

What are the gaps between Schwann cells where the axon membrane touches the extracellular fluid called?

Answer 10

Nodes of Ranvier

Question 11

How fast does an AP travel down a myelinated axon?

Answer 11

Approx. 150m/s

Question 12

How fast does an AP travel down an unmyelinated axon?

Answer 12

0.5 to 10 m/s

Question 13

The wider the axon, the ____ the AP

Answer 13

Faster

Question 14

What type of neuron are Aalpha?

Answer 14

Motor neurons/proprioceptors, muscle spindles, golgi, tendon, organs

Question 15

What type of neuron are Abeta?

Answer 15

touch, mechanical touch/pressure

Question 16

What type of neuron are Adelta?

Answer 16

Pain (fast) temp

Question 17

What type of neuron are C?

Answer 17

Pain (slow) temp, itch

Question 18

What happens if myelination breaks down?

Answer 18

Signals no longer work in concert, results in multiple sclerosis

Question 19

What are the two main types of cell-cell propagation?

Answer 19

Electrical synapse, chemical synapse

Question 20

Why do electrical synapses act directly and quickly?

Answer 20

Gap junctions allow AP to continue from one cell to the next

Question 21

What is a limitation of electrical synapses?

Answer 21

Does not allow much variation in the post-synaptic response

Question 22

What molecules are released into the synaptic cleft in chemical synapses?

Answer 22

Neurotransmitters

Question 23

What triggers AP on the postsynaptic neuron after a chemical synapse?

Answer 23

Binding of neurotransmitters to the post synaptic membrane (can also rebind to trigger more)

Question 24

What is the first step of voltage-activated Ca2+ channels when an action potential arrives at the synaptic terminal?

Answer 24

Depolarisation opens the voltage-activated Ca2+ channels

Question 25

What happens when the Ca2+ channels initially open after depolarisation?

Answer 25

[Ca2+] inside is low, so concentration and electrical gradients cause Ca2+ to flow inwards

Question 26

Why are calcium ions important in neurotransmitter translocation?

Answer 26

Ca2+ dependent phosphorylation of v-SNARE proteins

Question 27

What happens to vesicles associated with the docking region of the plasma membrane?

Answer 27

It is then primed through synaptic t-SNARE proteins followed by Ca2_ stimulated fission of vesicle with plasma membrane

Question 28

Where are small neurotransmitters (such as acetylcholine and noradrenaline) synthesised?

Answer 28

Synaptic bulb, then packaged into vesicles

Question 29

Where are large (protein) neurotransmitters synthesised?

Answer 29

In the cell body, transported inside vesicles down axon to synapse

Question 30

What is adrenaline?

Answer 30

Fight or flight neurotransmitter

Question 31

What is noradrenaline?

Answer 31

Concentration neurotransmitter

Question 32

What is dopamine?

Answer 32

Pleasure neurotransmitter

Question 33

What is serotonin?

Answer 33

Mood neurotransmitter

Question 34

What is GABA?

Answer 34

Calming neurotransmitter

Question 35

Criteria for neurotransmitter discovery: the chemical must be produced within a...

Answer 35

Neuron

Question 36

Criteria for neurotransmitter discovery: the chemical must be found within a...

Answer 36

Neuron

Question 37

Criteria for neurotransmitter discovery: when a neuron is stimulated/deploarised, a neuron must...

Answer 37

Release the chemical

Question 38

Criteria for neurotransmitter discovery: when a chemical is released/applied, it must...

Answer 38

Act on a post-synaptic receptor and cause a biological effect

Question 39

Criteria for neurotransmitter discovery: after a chemical is released, it must be able to be

Answer 39

inactivated, either through reuptake or by enzyme that stops the action

Question 40

What type of channels are invovled in producing excitatory post-synaptic potentials?

Answer 40

Glutamate-gated channels

Question 41

How do glutamate-gated channels generate depolaization of the post-synaptic neuron?

Answer 41

Cause a net influx of Na+

Question 42

What channels are involved in producing inhibitory postsynaptic potentials?

Answer 42

GABA and glycine-gated channels

Question 43

How do GABA and glycine-gated channels hyperpolarise the postsynaptic neuron?

Answer 43

Cause an net influx of Cl-