Lecture 11

Question 1

True or false: dendrites are the principle synaptic input sites

Answer 1

True

Question 2

How do signals or voltage changes Flow

Answer 2

Signals flow from dendrites to soma to axons and finally to synapses and penises

Question 3

Where is information primarily received in a neuron

Answer 3

Information is received primarily by the dendrites and soma but synaptic input can also be found and axons and axon terminal

Question 4

Where is information integrated?

Answer 4

Neuronal soma

Question 5

Where is the decision made for whether an action potential will fire?

Answer 5

The decision is made at the Axon hillock

Question 6

How does the information received translate into finding patterns?

Answer 6

Firing patterns are dependent on ion channels expressed in the axon

Question 7

True or false? Axons act as transmitter’s of information to the axon terminal

Answer 7

True

Question 8

Where does the conversion of an action potential into chemical signal occur?

Answer 8

It occurs in the axon terminal

Question 9

What type of channels are found at the synaptic sites?

Answer 9

Ligand gated channels

Question 10

Where in a neuron are synaptic sites found?

Answer 10

Predominately in the dendrites and the somatic but can also be found in axons

Question 11

Where are Sodium and delayed rectifying potassium channels located

Answer 11

In parts of the neuron that display action potential’s

Question 12

How does a neuron with only fast sodium currents and delayed rectifying potassium current respond to continuous depolarization

Answer 12

And neuron will exhibit repetitive spiking and the rate of firing could be regulated by the presence of an a type potassium current

Question 13

How does the neuron with a slowly accumulating potassium current such as the calcium activated potassium spikes underlying the SAHP respond to continuous depolarization?

Answer 13

This neuron will display spike frequency adaptation

Question 14

True or false? Neurons can also exhibit rhythmic bursting behaviour by exploiting the interplay between depolarizing and hyperpolarizing friends

Answer 14

True

Question 15

What are regenerative signals

Answer 15

Action potential’s all or nothing

Question 16

What are non-regenerative signals?

Answer 16

Sub threshold potential’s or graded potential’s that spread for short distances along Cell membranes

Question 17

How are receptor potentials generated

Answer 17

They are generated during the transduction of sensory stimuli

Question 18

How are post synaptic synaptic potential is generated

Answer 18

They are generated by the opening of an agonist activated channel

Question 19

What does the spread of electrical current depend on

Answer 19

Cell geometry, electrical resistance of aqueous solutions, cell membrane and membrane capacitance

Question 20

True or false? Passive responses decay with distance through an axon but active responses do not

Answer 20

True

Question 21

What are PSP

Answer 21

Post synaptic potential’s

Question 22

What are post synaptic potential is also referred to

Answer 22

Graded potential’s or GP

Question 23

What is a characteristic of an excitatory postsynaptic potential or EPSP

Answer 23

Depolarization

Question 24

What is a characteristic of an inhibitory postsynaptic potential or I PSP

Answer 24

Hyperpolarization

Question 25

What is local current flow?

Answer 25

A wave of deep polarization/hyperpolarization that moves through the cell membrane

Question 26

Why do PSP lose strength as they move through the cell?

Answer 26

Current leak and cytoplasmic resistance

Question 27

True or false? If strong enough and EPSP to fire an action potential at the trigger zone

Answer 27

True

Question 28

True or false? PSPs attenuate

Answer 28

True

Question 29

Where do you PSPs attenuate

Answer 29

Dendritic potentials usually decline in amplitude before reaching the soma

Question 30

What is Spatial Summation?

Answer 30

EPSPs arriving from different dendrites combine

Question 31

What is Temporal Summation?

Answer 31

EPSPs arrive rapidly in succession

Question 32

What is the space constant?

Answer 32

Is determines the spread of voltage changes in space

Question 33

True or false?

The greater the specific membrane resistance and cable radius. The greater the length constant and the less the loss of signal

Answer 33

True

Question 34

True or false?

The greater the resistance of the internal conductor the smaller the length constant and the greater the loss of signal

Answer 34

True

Question 35

Does a signal spread farther in a thick dendrite or thin

Answer 35

Thick dendrite

Question 36

What are Nav channels?

Answer 36

Voltage gated na Channels

Question 37

Is there a high or low density of Nav and Kv channels in dendrites?

Answer 37

Low density of both

Question 38

What allows dendrites to have a boost in signal?

Answer 38

Some have voltage gated channels (na or ca) that boost signal

Question 39

What are characteristics of calcium spikes?

Answer 39

Purkinje cells: Ca dendritic spiked

Ca spikes can propagate into the soma (not down the axon)

Question 40

True or false?

There is a high concentration of Nav at initial segment?

Answer 40

True

Question 41

Where does the EPSP attenuate?

Answer 41

Soma and initial segment

Question 42

Can an EPSP trigger an action potential in the initial segment?

Answer 42

Yes if it is large enough

Question 43

Where is the threshold of excitability along the neuron high? And where is it steep?

Answer 43

In regions where there are few Nav channels. Steep in hillock and initial segment

Question 44

Where is there a high density of Nav Channels?

Answer 44

Initial segment and node of ranvier