A&P - Chapter 19 (Part 1)

Question 1

Nerve impulse

Answer 1

A self propagating wave of electrical disturbances that travels along the surface of a neruon’s plasma membrane

Question 2

What is the direction of a neural impulse?

Answer 2

Towards the axon terminals

Question 3

What is the charge on the outside of a membrane?

Answer 3

Slightly positive

Question 4

What is the charge on the inside of a membrane?

Answer 4

Slightly negative

Question 5

Membrane potential

Answer 5

Is the result of difference in an electrical charge across the membrane

Question 6

Potential

Answer 6

Ions of opposite charges the have the potential to move toward one another if they get an opportunity to cross the membrane

Question 7

What is a membrane said to be if it exhibits a membrane potential?

Answer 7

Polarized

Question 8

Resting membrane potential

Answer 8

When a neuron isnt conducting electrical signals

Question 9

During what phase is there slightly more positive ions outside the membrane?

Answer 9

In resting position

Question 10

What do neurons of the plasma membrane contain?

Answer 10

Channels that allow efficient movement of the positive ions across it

Question 11

What are 2 examples of positive ions that can move across the membrane?

Answer 11

1. Na+
   - sodium ions
2. K+
   - potassium ions

Question 12

What are the channels called that move Na and K?

Answer 12

Sodium-potassium pumps

Question 13

What directions do Na and K move through the channels?

Answer 13

In opposite directions

Question 14

What does the movement of Na and K do?

Answer 14

It maintains the electrical difference across the plasma membrane
- slightly positive on the outside

Question 15

Local potentials

Answer 15

A fluctuation in the resting membrane potential in a specific part of the plasma membrane

Question 16

When do local potentials occur?

Answer 16

In response to a stimulus

- excitation

Question 17

What does excitation trigger?

Answer 17

The opening of stimulus gated channels in the plasma membrane

Question 18

What does the opening of the stimulated gates allow?

Answer 18

For more Na+ to enter the neuron

- charge is now more slightly negative on the outside

Question 19

Depolarization

Answer 19

More Na+ entering the neuron means that the size of the membrane potential is reduced

Question 20

What initiates an action potential?

Answer 20

Depolarization

Question 21

Resting potential

Answer 21

The membrane of a resting neuron has a slightly positive charge on the outside and a negative charge on the inside

Question 22

Action potential

Answer 22

A stimulus triggers the opening of the Na+ channels in the plasma membrane of the neuron (starting at the dendrites) allowing Na+ to rush into the neuron (depolarization

Question 23

When do action potentials move faster?

Answer 23

When they are myelinated

Question 24

Nerve impulse

Answer 24

An electrical disturbance of the neurons membrane stimulates Na+ channels in the adjacent section of the membrane to open

Question 25

What does the nerve impulse travel along?

Answer 25

The entire length of the neurons membrane

Question 26

Why do signals travel faster in myelinated neurons?

Answer 26

Because the impulse will jump over it making it faster

- saltatory conduction

Question 27

Do neurons normally touch each other or the effector they act on?

Answer 27

No

Question 28

What is there between neurons and the effector that prevent them from touching?

Answer 28

Synapse

Question 29

What 2 things can synapse be?

Answer 29

1. Electrical

2. Chemical

Question 30

Where do electrical synapse occur?

Answer 30

Where cells joined by gap junctions allow an action potential to simply continue along the postsynaptic membrane

Question 31

Where do chemical synapse occur?

Answer 31

Where presynaptic cells release chemical transmitters across tiny gaps to the post synaptic cells
- possibly inducing an action potential