Lecture 5

Question 1

The axon allows for

Answer 1

Conduction

Question 2

APs created in axon hillock will travel down the

Answer 2

Axon to reach the muscle cell

Question 3

How are axons in vertebrate motor neurons?

Answer 3

Long

Question 4

What are the special structures found in axons that allow for AP conduction over long distances?

Answer 4

• Myelin Sheath

- Saltatory Conduction

Question 5

What is Myelin?

Answer 5

Fatty substance that wraps in a spiral pattern around axon

Question 6

Myelin Sheath is secreted by

Answer 6

Schwann cells

Question 7

Myelin Sheath allows for

Answer 7

Faster conduction compared to non-myelinated axons

Question 8

What happens during Saltatory Conduction?

Answer 8

New APs are repeatedly created down the length of the axon at the Nodes of Ranvier

Question 9

Saltatory Conduction prevents the

Answer 9

Continuous movement along myelinated axon

Question 10

Formation of new APs during Saltatory Conduction is formed due to

Answer 10

The voltage-gated K+ and Na+ channels that open when AP arrives in the nodes of ranvier

Question 11

End of axon branches into several terminals which are enlarged at each end to form a

Answer 11

Synapse

Question 12

Where is the electrical signal (or AP) converted into a chemical signal?

Answer 12

At the synapse

Question 13

What happens once electrical signal is converted?

Answer 13

There is a release of a neurotransmitter

Question 14

When the AP reaches the synapse, it causes for

Answer 14

Voltage-gated Calcium channels to open

Question 15

The increase of Ca2+ inside the cell results in

Answer 15

The release of neurotransmitters (or acetylcholine) via exocytosis

Question 16

When acetylcholine is released, it binds to

Answer 16

Specific receptors on the cell membranes of muscles

Question 17

Which animals produce myelin?

Answer 17

Vertebrates

Question 18

What kind of axons do invertebrates have?

Answer 18

Larger diameter axons

Question 19

APs travel fastest along axons with

Answer 19

Large diameters or axons wrapped in myelin

Question 20

Conduction speed along an axon (current) is greatest when

Answer 20

• Voltage is high

- Resistance in low

Question 21

What is the function of the myelin sheath?

Answer 21

It creates regions of high resistance surrounding regions of lower resistance

Question 22

Large diameter axons also reduce resistance since

Answer 22

Less of the axon’s SA is exposed to the cell membrane (preventing the slow down of AP)

Question 23

Squids move via jet propulsion, which requires

Answer 23

Large diameter axons

Question 24

Very large diameter axons function to activate muscles at the

Answer 24

Far end of the squid’s mantle

Question 25

Smallest diameter axons function to activate muscles in the

Answer 25

Squid’s mantle closest to CNS