The Nervous System - C6

Question 1

What do these types of receptors respond to?
Chemoreceptors, Mechanoreceptors, Thermoreceptors, Photoreceptors, Baroreceptors, Osmoreceptors, Proprioceptors, Nocirecptors.

Answer 1

Chemical, mechanical, temperature, light, pressure, osmolarity of fluid, sense of position, noxious stimuli

Question 2

What functions do neurons (nerve cells) carry out?

Answer 2

Moving muscles (motor neurons), forming memories and regulating behavior

Question 3

What do dendrites do?

Answer 3

Receive input from other neurons

Question 4

What is the function of the cell body?

Answer 4

Performs cellular functions ( protein production, metabolism)

Question 5

What is the function of the axon?

Answer 5

Carries electrical signals to terminals

Question 6

What is the function of the axon terminal?

Answer 6

Release neurotransmitters into the synapse

Question 7

What is the function of a myelin sheath

Answer 7

Made of Schwann cells wrapped around axon to insulate the electrochemical so it can travel faster (Multiple Sclerosis damages myelin sheath)

Question 8

What are the three types of neurons?

Answer 8

Motor (controlling muscles or glands)
Interneurons (processing and transmitting information coming into central nervous system or initiating actions), sensory neurons (transmit information to enable the senses)

Question 9

What do dendrites do?

Answer 9

Receive input from other neurons

Question 10

What is the function of the axon?

Answer 10

Carries electrical signals to axon terminals

Question 11

What is the function of axon terminals?

Answer 11

To release neurotransmitters

Question 12

What is the myelin sheath?

Answer 12

Made of Schwann cells wrapped around the axon to insulate the electrochemical so it can travel faster

Question 13

What are the three types of neurons?

Answer 13

Sensory (Afferent), Motor (Efferent) and Interneurons

Question 14

What are afferent neurons?

Answer 14

Detectors of change in the internal and external environment

Question 15

What are efferent neurons?

Answer 15

Detectors involved in controlling muscles or glands

Question 16

What are interneurons?

Answer 16

For processing and transmitting information coming into the central nervous system or initiating actions

Question 17

Outline the process of a nerve impulse being created

Answer 17

1. Potassium is inside the cell, and sodium is outside (inside = -, outside = +)
2. If the channel protein for sodium becomes triggered, it will open and sodium floods into the cell and the charge becomes more positive
   (note: if trigger is strong enough, nearby sodium channels open within cell, creating a chain reaction)
3. Then potassium pumps push the potassium ions back into the cell a little too much, making the cell overcompensate, going to around -100 (resting potential is -70)
4. Ion pumps fine tune this process and add back in the right amount of sodium to bring the charge back to resting -70

Question 18

What is the resting potential of a nerve cell?

Answer 18

-70mV

Question 19

Define action potential

Answer 19

How information travels in nervous systems - it is the rapid, brief reversal of membrane potential charges in and outside the cell. It is an all or nothing event.

Question 20

Where does action potential initiate?

Answer 20

At the axon hillcock

Question 21

What does the axon hillcock contain?

Answer 21

A high concentration of voltage gate sodium ion channels

Question 22

What is the action potential threshold?

Answer 22

When voltage gated sodium channels open. A stimulus from a sensory neuron causes target neuron to depolarize. If the threshold of excitation is reached, all of the sodium channels open and the membrane depolarizes. The influx of sodium into the cell through these channels is the beginning of action potential

Question 23

Is potassium or sodium inside a nerve cell in a high concentration before action potential

Answer 23

Potassium

Question 24

Can action potential travel faster in myelinated or unmyelinated neurons? Why?

Answer 24

Myelinated, because the signal can jump between the nodes of Ranvier via saltatory conduction - does not need to be reinitiated constantly, like a non-myelinated sheath does

Question 25

What is a synapse?

Answer 25

Where one nerve cell meets another (the axon terminal of ones meets the dendrites of another)

Question 26

How does an electrical signal travel across a synapse?

Answer 26

The electrical signal is converted into a chemical signal using neurotransmitters, and the chemical signal jumps the gap and is picked up by the neighboring neurons’ dendrites