Nervous Control: Basics: Ms H

Question 1

What is the CELL BODY of a NEURONE?

Answer 1

Contains the nucleus and organelles like mitochondria

Question 2

What are the DENDRITES in a NEURONE?

Answer 2

Threads of cytoplasm leading TOWARDS the cell body

Question 3

What are the AXONS in a NEURONE?

Answer 3

A single fibre that carries NERVE IMPULSES away from the CELL BODY

Question 4

What is the PLASMA MEMBRANE in a NEURONE?

Answer 4

Surrounds the whole cell

Question 5

What is the MYELIN SHEATH in a NEURONE?

Answer 5

Electrical insulator of the AXON to increase the speed of nerve impulses

Question 6

What are the SCHWANN CELLS in a NEURONE?

Answer 6

Forms the MYELIN SHEATH

Question 7

What are the NODES OF RANVIER in a NEURONE?

Answer 7

Small spaces between Schwann cells / BARE plasma membrane

Question 8

What is the RESTING POTENTIAL of a NEURONE?

Answer 8

• The POTENTIAL DIFFERNCE across the AXON MEMBRANE
  -When it is NOT being STIMULATED

Question 9

What does the SODIUM - POTASSIUM PUMP allow?

Answer 9

• Allows Na+, K+ to pass in and out of the AXON
• 2Na+ in, 3K+ out

Question 10

What does the VOLTAGE GATED Na+ CHANNEL ALLOW?

Answer 10

• Allows Na+ to pass in and out of AXON
• When VOLTAGE CHANGES

Question 11

What does the VOLTAGE GATED K+ CHANNEL ALLOW?

Answer 11

• Allows K+ to pass in and out of AXON
  -When VOLTAGE CHANGES

Question 12

Is the OUTSIDE of the AXON more (+)VE or (-)VE?

Answer 12

• More (+)VE
• Thus making the inside more (-)VE

Question 13

How does Na+, K+ move in and out of the SODIUM - POTASSIUM PUMP?

Answer 13

• Via ACTIVE TRANSPORT
• As it utilises ATP

Question 14

How do IONS move in and out the VOLTAGE GATED Na+ & K+ CHANNELS?

Answer 14

• Facilitated Diffusion

Question 15

How is the ELECTROCHEMICAL GRADIENT created across the AXON MEMBRANES?

Answer 15

• The SODIUM - POTASSIUM PUMP pumps 3Na+ OUT of the membrane
• And 2K+ INTO the membrane of the AXON

Question 16

What is the RESTING POTENTIAL CHARGE?

Answer 16

-70mv

Question 17

Where are the NODES OF RANVIER located?

Answer 17

In between the GAPS of the AXONS

Question 18

What is meant by REFRACTORY PERIOD?

Answer 18

• Time period after an ACTION POTENTIAL
• When it is IMPOSSIBLE for a further ACTION POTENTIAL to be generated

Question 19

What are VOLATAGE GATED CHANNELS?

Answer 19

• Channels in AXON MEMBRANE which CHANGES SHAPE
• Depending on the VOLTAGE across the MEMBRANE

Question 20

What is meant by REPOLARISATION?

Answer 20

• When the RESTING POTENTIAL is restored
• Back to -65mv, the AXON is described as this

Question 21

What is meant by HYPERPOLARISATION?

Answer 21

• When the INSIDE of the AXON is more (-)VE
• Relative to the outside, than usual

Question 22

What is meant by DEPOLARISATION?

Answer 22

• Conditions used to describe the part of AXON MEMB
• When the INSIDE has a (+)VE of around +40mv
  -Whilst ACTION POTENTIAL IS HAPPENING

Question 23

What are the 6 STAGES that can occur when the NEURONE is STIMULATED?

Answer 23

• Resting Potential
• Weak/Strong Stimuli
• Threshold/Depolarisation
• Repolarisation
• Hyperpolarisation
• (Refractory Period)

Question 24

What is meant by REFRACTORY PERIOD?

Answer 24

• A period shortly after HYPERPOLARISATION
• In which no further ACTION POTENTIALS can be GENERATED
• Rendering the NEURONE CELL MEMB. to be EXCITED TEMPORARILY

Question 25

At which points are the VG-K+ CHANNELS OPEN & CLOSED?

Answer 25

• Resting Potential - Open
• Stimuli - Open
• Depolarisation - Closed
• Repolarisation - Open
• Hyperpolarisation - Open