Cells of the Nervous System: The Neuron

Question 1

What are the 2 major cell types within the nervous system?

Answer 1

Neurons and Neuroglia

Question 2

What are neurons?

Answer 2

Neurons are the basic units of the brain

Question 3

What is the main function of neurons?

Answer 3

To send electrical signals over short and long distances in the body, and they are electrically and chemically excitable.

Question 4

What is the function of the neuron dependent on?

Answer 4

The structure of the neuron

Question 5

What does the typical neuron consist of? (5)

Answer 5

dendrites, cell body, axon (including axon hillock), and presynaptic terminal.

Question 6

What is the estimated number of neurons in an adult human brain?

Answer 6

Close to 86 billion neurons

Question 7

Compared to how the rest of the body, what is the percentage of neurons?

Answer 7

About 0.2%

Question 8

What are some unique characteristics of the neuron? (4)

Answer 8

1. Neurons are electroactive
2. Neurons are specialized for rapid communication
   3.Neurons are “forever” cells
3. Neurons can change

Question 9

What does being electroactive mean?

Answer 9

They are charged cells that can change their charge

Question 10

Why can Neurons change?

Answer 10

Because of the plasticity of the brain.

Question 11

Describe how dendrites look.

Answer 11

They are processes that branch out in a tree-like fashion from the cell body.

Question 12

What is the main target for incoming signals received from other cells.

Answer 12

Dendrites

Question 13

What are the small protrusions along the branches of the dendrites?

Answer 13

Dendritic Spines

Question 14

True or False: Many cells lack spines

Answer 14

True. However, they are still capable of permanently changing.

Question 15

What is thought to underlie the reason that we can learn new facts or maintain memories about our childhood over a long period of time?

Answer 15

Dendritic plasticity

Question 16

Where does the information that arrives through the dendrites of a neuron eventually filter into?

Answer 16

The cell body or the soma of the neuron

Question 17

What is the main output extension of the neuron?

Answer 17

The axon

Question 18

Where are is the axon hillock located?

Answer 18

Where the cell body transitions into the axon

Question 19

What is it called when several axons bundle and travel together?

Answer 19

Nerves

Question 20

What is the electrical signal an axon transmits called?

Answer 20

Action potential

Question 21

Where is the largest axon in the body located?

Answer 21

In the sciatic nerve that runs from the posterior end of the spinal cord down the leg to control the muscles of the big toe.

Question 22

Where is the action potential transmitted from?

Answer 22

The axon hillock

Question 23

How is a neurotransmitter released?

Answer 23

The axon releases the action potential from the axon hillock to the presynaptic terminal where the electrical signal will result in the release of a neurotransmitter to communicate with the next cell.

Question 24

What is the myelin sheaths?

Answer 24

A fatty substance the wraps around portions of the axon and increases action potential speed.

Question 25

What are the breaks between the myelin segments called?

Answer 25

Nodes of Ranvier