Communication in the Nervous System

Question 1

What types of cells make up the nervous system?

Answer 1

• nerve cells (neurons)

- glial cells (glia)

Question 2

Define: Neurons

Answer 2

• the brain’s communication
• they transmit information throughout the nervous system
• held in place by glia

Question 3

Define: Glial Cells

Answer 3

• provide nutrients, insulation, and protection to neurons

- make up 90% of the brain’s cells

Question 4

A neuron has 3 main parts:

Answer 4

• dendrites
• cell body
• axon

Question 5

Define: Dendrite

Answer 5

• receives messages from other nerve cells
• transmits messages toward the cell body
• does preliminary processing of messages

Question 6

Define: Cell Body

Answer 6

• contains biochemical machinery keeping the neuron alive

- depending on inputs from other neurons, it with transmit (fire) a message to other neurons

Question 7

Define: Axon

Answer 7

• transmits messages away from the cell body

- divide into branches called axon terminals

Question 8

Define: Myelin Sheath

Answer 8

-fatty material that surrounds axons

Question 9

What are the constrictions in the myelin sheath that divide it into sausage-like segments?

Answer 9

Nodes

Question 10

What are 2 purposes of the Myelin Sheath?

Answer 10

• prevent adjacent cell signals from interfering with eachother
• speeds up conduction of neural impulses

Question 11

In the PNS, axons and dendrites are collected together into bundles called:

Answer 11

nerves

Question 12

Most nerves enter or leave __________

Answer 12

the spinal cord

Question 13

What is the process of producing new neurons from immature stem cells?

Answer 13

Neurogenesis

Question 14

Define: Stem Cells

Answer 14

• immature cells that renew themselves and have the potential to develop into mature cells
• stem cells from early embryos can develop into any cell type

Question 15

Why are embryonic stem cells more useful than stem cells from adults?

Answer 15

-because adult stem cells are limited and harder to keep alive

Question 16

Neurons do not directly touch eachother. They are separated by…

Answer 16

the synaptic cleft

Question 17

Define: Synaptic Cleft

Answer 17

-where the axon terminal nearly touches the dendrite or the cell body of another neuron

Question 18

What is a Synapse?

Answer 18

-the axon terminal, cleft, and the covering membrane of the receiving dendrite

Question 19

How do neurons communicate?

Answer 19

• they speak an electrical and chemical language

- Action Potential is the term of the electrical impulse that initiates message exchange

Question 20

How does the Action Potential travel through:

• mylenated axons
• non-mylenated axons

Answer 20

mylenated axons
-action potentials “hop” from one node to the next

Non
-the impulse will travel down the axon like a fuse on a firecracker

Question 21

How is a myelin sheath beneficial in regards to action potential?

Answer 21

nerve impulses travel faster

Question 22

When does a neurotransmitter get released?

Answer 22

-when a received nerve impulse reaches the axon terminals, synaptic vesicles open and release neurotransmitter chemicals (AKA at the synapse)

Question 23

Define: Synaptic Vesicles

Answer 23

• tiny sacs at the tip of the axon terminal

- in charge of releasing neurotransmitter molecules

Question 24

What does a neurotransmitter do?

Answer 24

-alters activity of a receiving neuron

Question 25

Once released, where do neurotransmitter molecules go?

Answer 25

-they diffuse across the synaptic cleft and bind with receptor sites

Question 26

Define: Receptor Sites

Answer 26

• in the membrane of the receiving dendrites

- a lock that needs a key

Question 27

When neurotransmitter binds to a receptor site, the ultimate effect is either…

Answer 27

-excitatory (+) voltage shift
or
-inhibitory (-) voltage shift

Question 28

Why is inhibition in the nervous system extremely important?

Answer 28

without it, we could not sleep or coordinate out movements

Question 29

Define: Plasticity

Answer 29

-the brain’s ability to adapt and change in response to experience, by reorganizing and growing new neural connections
(vividly demonstrated in people who have recovered from brain damage, strokes)