Electrical properties

Question 1

Where is resistance located in the axon?

Answer 1

1. In the fluid INSIDE the axon

2. Across the cell membrane

Question 2

What effect will increasing diameter have on resistance?

Answer 2

Decrease resistance

Question 3

How is resistance decreased across the cell membrane?

Answer 3

Ion channels (allow ions to move freely)

Question 4

Ion channel specific to sensory neurons; Located on dendrites; Channels open or close in response to some sensory stimulus (temp, light, etc.); Cause local potentials

Answer 4

Modality-gated ion channels

Question 5

Ion channels that open in response to neurotransmitter or drug binding; Located on post-synaptic terminal; Cause local potentials

Answer 5

Ligand-gated ion channels

Question 6

Ion channels that open or close in response to changes in the membrane potential; Channels will only let specific ions pass; Located on axons and presynaptic terminals; Important for: action potentials and release of neurotransmitters from the presynaptic terminal

Answer 6

Voltage-gated ion channels

Question 7

The inside of an axon is usually more [negative/positve] compared to the outside. Where are Na, K, Cl, and Ca most located?

Answer 7

Negative; K= inside; Na, Cl, Ca = outside

Question 8

The equilibrium potential is [positive/negative] for Na. The equilibrium potential is [positive/negative] for K. The equilibrium potential is [positive/negative] for Cl.

Answer 8

Positive; Negative; Negative

Question 9

When ion channels open in a resting neuron, which way does sodium move? Potassium? Chloride? Calcium

Answer 9

Na = moves into cell
K = moves out of cell
Cl = moves into cell
Ca = moves into cell

Question 10

Sodium-potassium ATPase pumps __ Na+ ions out and __ K+ ions in.

Answer 10

3; 2

Question 11

Local potentials, or graded potentials, in sensory neurons are called _______ potentials. What type of ion channels are in sensory neurons?

Answer 11

Receptor potentials; Modality-gated

Question 12

Local potentials, or graded potentials, in post-synaptic membranes are called _______ potentials. What type of ion channels are in post-synaptic membranes?

Answer 12

Synaptic; ligand-gated

Question 13

______ refers to the inside of the cell becoming more positive where ______ refers to the inside of the cell becoming more negative

Answer 13

Depolarizing; hyperpolarizing

Question 14

Sequential local potentials can add together on one neuron

Answer 14

Temporal summation

Question 15

Different local potentials that occur at the same time can combine from more than one neuron; The effect can be additive or subtractive

Answer 15

Spatial summation

Question 16

Large, brief depolarization that is repeatedly regenerated along the length of an axon; Actively propagated, so it travels long distances along the axon without a decrease

Answer 16

Action potentials

Question 17

What does a strong stimuli increase in terms of APs?

Answer 17

1. Increases the frequency of action potentials in one neuron
2. Increases the number of neurons that are activated

Question 18

Sodium ion channels quickly open due to ____ and close ____

Answer 18

Voltage; spontaneously

Question 19

Potassium ion channels remain open as long as the membrane is _______ and close who the membrane is _______

Answer 19

Depolarized; hyperpolarized

Question 20

No stimulus, no matter how strong, can produce a second action potential

Answer 20

Absolute refractory period

Question 21

A larger than normal stimulus can produce a second action potential

Answer 21

Relative refractory period

Question 22

What are the roles of a relative refractory period

Answer 22

1. Allows APs to occur at greater frequency (do’t need to wait for another to occur)
2. APs will only go in one direction

Question 23

How can you in increase the speed of APs?

Answer 23

1. Increase membrane resistance (myelination)

2. Decrease resistance inside the neuron (larger axon/dendrite spine diameter)

Question 24

In terms of Na ion channel density, where are they most concentrated? where are they least concentrated?

Answer 24

Nodes of Ranvier; internode region

Increases the speed of AP dramatically

Question 25

In myelinated axons, is the speed of the AP the same throughout the axon?

Answer 25

No, APs slow at the nodal regions where APs are regenerated

Question 26

What will happen to the equilibrium potential for potassium in a hypokalemic patient?

Answer 26

increase (more negative)

Question 27

What will happen to the membrane potential for potassium in a hypokalemic patient?

Answer 27

increase (more positive)

Question 28

Will a neuron become more or less excitable in a patient with hyperkalemia?

Answer 28

more excitable