Chapter 9

Question 1

Resting Membrane Potential for Neurons

Answer 1

-70 mV

Question 2

In the ECF, Na+ has ____ meq/L and K+ has ____ meq/L.

Answer 2

145, 4

Question 3

Leak K+ channels

Answer 3

K+ channels that are opened, moving OUT of the cell. # of leak channels determines RMP

Question 4

Neurons are polarized

Answer 4

(negative on the inside, positive on the outside)

Question 5

Threshold potential for Neuron

Answer 5

-55 mV (voltage is required to open channels)

Question 6

Depolarization

Answer 6

More positive, more toward 0.
Opens Na+ channels

If enough Na+ arrives to the axon hillock to change the voltage to a threshold voltage of -55mV,
Voltage-gated Na+ channels activate and open to allow more Na+ to diffuse into cell,

Question 7

Repolarization

Answer 7

More negative, more toward RMP.

When cell reaches ~0 mV
Voltage-gated K+ channels begin to open, K+ diffuses out of cell,
When cells reaches +35 mV
Voltage-gated Na+ channels close, no more Na+ enters cell,
Voltage-gated K+ channels are fully open – as K+ diffuses out, cell becomes negative again,

Question 8

How does your brain ‘understand’ a smell?

Answer 8

A ‘smell’ is a molecule that dissolves in mucous and binds to a ‘smell’ receptor on the plasma membrane of the dendrites of olfactory neurons.

Coffee-smell molecule (ligand)
Binds on dendriodor receptor in olfactory epithelia (nose)

Question 9

Hyperpolarization

Answer 9

Anything over -80 mV.

Voltage-gated K+ channels stay open longer than voltage-gated Na+ channels
More K+ exits than N+ enters,
The cell becomes more negative than RMP for a short period of time,

Question 10

Slide 18

Answer 10

1. ) Action potential from -70 mv to -55 mV.
2. ) Depolarization: Na+ gates open when Action potential reaches -55 mv, Na+ enters cell, K+ begins to open
3. ) Repolarization: Na+ gates close completely, K+ gates fully open, K+ leaves cell
4. ) Hyperpolarization: Na+ gates closed, K+ gates closing

Question 11

Ligands bind to _____

Answer 11

Receptors