Lecture 3- Transmission within neurons

Question 1

What do motor neurons do?

Answer 1

They provide information to the body

Question 2

What do sensory neurons do?

Answer 2

Provide info from the body

Question 3

What do inter neurons do?

Answer 3

Link sensory and motor neurons

Question 4

What do neurons do?

Answer 4

They do all the info processing and transmitting through variety of different neuron types

Question 5

Name the 5 aspects of the structure of a neuron

Answer 5

Soma
Dendrites
Axon
Myelin sheath
Terminal buttons

Question 6

What is the soma?
(neuron structure)

Answer 6

The cell body
-Contains the nucleus

Question 7

What are dendrites?
(neuron structure)

Answer 7

Receive messages
-Tree like structure

Question 8

What is the axon?
(neuron structure)

Answer 8

Carries info (action potential) from soma to terminal buttons

Question 9

What is the Myelin sheath?
(neuron structure)

Answer 9

Wraps around axon

Question 10

What are the terminal buttons?
(neuron structure)

Answer 10

At the end of the axon branches

Question 11

What do Glia (glial cells) include?

Answer 11

Includes Astrocytes, Oligodendrocytes, Microglia

Question 12

What do Glia (Glial cells) do?

Answer 12

Oligodendrocytes produce the myelin sheath that insulates axons.

-Nodes of Ranvier = naked axon

-Cells provide support, waste services, supply of nutrients

Question 13

Describe the transmission within neuron

Answer 13

-An electrical process (all cells have electrical charge, more neg on inside) -This results in a resting potential (store of energy) -Neurons can reverse electrical charge

Question 14

What is the cell membrane?

Answer 14

Membrane- All cells are covered in membrane, 2 layers of phospholipid molecules.

Question 15

What is the ion channel?

Answer 15

Spans the membrane

Question 16

What are the 2 types of ions?

Answer 16

Cations (pos charged)
Anions (neg charged)

Question 17

What does Intercellular fluid contain?

Answer 17

Potassium ions (K+) and anions (A-)

Question 18

What does Extracellular fluid contain?

Answer 18

Sodium (Na+) and chloride (Cl-) ions

Question 19

What is the membrane potential?

Answer 19

The membrane potential is the difference in electrical potential inside and outside the cell.

Question 20

How is the membrane potential balanced?

Answer 20

Diffusion and Electrostatic pressure

Question 21

Describe Organic anions (A-)

Answer 21

-Concentrated inside cell
-Cannot cross the membrane

Question 22

Describe Potassium ions (K+)

Answer 22

-More concentrated inside cell

> Diffusion= Wants to move out
Electrostatic= Attracted to inside

Overall= Forces balance so K+ doesn’t move

Question 23

Describe Chloride ions (Cl-)

Answer 23

-More concentrated outside cell

> Diffusion= Wants to move in >Electrostatic= Repelled from inside

Overall= Forces balance so Cl- doesn’t move

Question 24

Describe Sodium ions (Na+)

Answer 24

-More concentrated outside cell

> Diffusion= Wants to move in >Electrostatic= Attracted to inside

Overall=Both force Na+ into cell

Question 25

How is Na+ kept under control?

Answer 25

-Na+ kept under control by sodium-potassium pumps

Question 26

In resting potential, what is the difference between inside and outside?

Answer 26

Inside= negative Outside= positive

Question 27

What is the resting potential of a neuron?

Answer 27

-70mV

Question 28

Why is maintaining the resting potential important?

Answer 28

It's important so the neuron can respond rapidly to a stimulus.

Question 29

What is an action potential?

Answer 29

An action potential is a reversal in the potential and is how information is sent through an axon. - Also a rapid change in the membrane potential

Question 30

How could you describe an action potential?

Answer 30

Considered an all or none process as either fires or not, they stay the same size throughout transmission.

Question 31

What is depolarisation?

Answer 31

A decrease from normal resting potential (brings membrane closer to 0)

Question 32

What is hyper polarisation?

Answer 32

An increase relative to resting potential (more negative)

Question 33

What is Propagation?

Answer 33

-The action potential is transmitted down an axon via propagation. -The action potential is regenerated at points along axon due to entry of sodium ions at neighbouring point eg dominoes falling

Question 34

What is Saltatory conduction?

Answer 34

-Action potential regenerated along axon at nodes of Ranvier

Question 35

What are the benefits of Saltatory conduction?

Answer 35

Benefits: -Fast conduction -Energy efficient

Question 36

Describe the process of action potential (6 steps)

Answer 36

-Once the threshold of excitation has been reached, the Sodium (Na+) channels open and Na+ enters the cell. -Potassium (K+) channels then open in which K+ begins to leave the cell -Na+ channels the become refractory in which no more Na+ can enter the cell. -K+ continues to leave cell, causing membrane potential to return to resting level. -K+ channels close so Na+ channels reset -Extra K+ outside diffuses away.