Biopsy 2

Question 1

Differences between motor neuron vs sensory neuron

• location of cell body?
• info is collected from where to where?

Answer 1

Motor:

• cell body at top/beginning
• down from the brain to muscles/other cells

Sensory:

• cell body is half-way/in the middle of the neuron
• from body to the brain

Question 2

How is information carried from one neuron to another?

Answer 2

info is collected from dendrites —> carried as an electrical impulse along the axon to the terminal —> turn into chemical impulse to cross synaptic gap
- info is processed in the cell body in the beginning (motor) / half-way (sensory)

Question 3

Match:

axon, cell bodies, Grey matter, White matter

Answer 3

Grey matter = cell bodies

White matter = axon

Question 4

What are the use of the ion channels and pumps in the membranes?

Answer 4

control the movement of ions in and out of the cell

Question 5

Types of ion channels

Answer 5

• resting
• voltage gated
• ligand gated
• mechanically gated

Question 6

Movement of ions across neuronal membrane can cause ___ ?

Answer 6

electrical signals = action potential

Question 7

Types of ions in intracellular and extracellular fluid?

Answer 7

• Sodium ion (Na+)
• Potassium ion (K+)
• Chloride (Cl-)
• Large negative ions (A-)

Question 8

What forces determine the movement of ions into and out of the cells?

Answer 8

• Concentration

- Electrical (+/-)

Question 9

Describe the Na+ & K+ channels at rest.

Answer 9

Na+ channels are closed

K+ channels are opened

Question 10

Which side have more Na+? Intracellular or Extracellular fluid?

Answer 10

Extracellular

Question 11

Describe K+ during resting membrane potential.

Answer 11

• K+ enters the cell through K+ channel and Na/K pump as the electrical force is more negative inside the cell
• K+ is also moved out of the cell through K+ channel due to a smaller K+ conc. gradient outside
• 2 forces are in equilibrium (-90mv)

Question 12

At rest, is it more positive or negative outide a neuron?

Answer 12

Positive

Question 13

Why are neurons negatively charged at rest?

In terms of Na+/K+ pumps

Answer 13

• Na/K pumps constantly pumping 3 Na+ out and 2 K+ into the cell
• so higher K+ conc. inside & higher Na+ conc. outside

Question 14

Resting membrane potential in __?__mV?

Answer 14

-65 mV

more negative inside

Question 15

Why is an action potential being generated?

Answer 15

• neuron is stimulated excitatory —> resting potential becomes action potential
• movement of ions into and out of cells —> changes in electrical activity

Question 16

How is an action potential being generated?

Answer 16

Post-synaptic potentials are summed up —> if it‘s excitatory —> depolarise membrane at axon hillock to threshold level —> net change above threshold (-50mV) —> action potential is generated and travel down the axon

Question 17

What happen to Sodium & Na+ channel when a cell is stimulated to above threshold?
Name this process.

Answer 17

• Na+ channel open
  —> Na+ enters into the cell through Na+ channel down its conc. gradient and electrical force(negatively charged inside) —> cell becomes positive
• Depolarisation

Question 18

Describe Repolarisation.

Answer 18

Due to positively charged inside:

• Na+ channels closed
• K+ moves out of the cell to the negative outside (electrical force) and down its conc. gradient

Question 19

What has happened lead to resting from Hyperpolarisaton?

Answer 19

• voltage-gated K+ channel shut

- K+ diffuses normally in its ‘resting open’ channel

Question 20

Name the fatty substance that cover axon and the cell that produce it.

Answer 20

Myelin

Schwann cells

Question 21

What‘s the purpose of being myelinated?

Answer 21

conduct action potential faster by saltatory conduction

Question 22

Action potential is an _______ event.

Answer 22

All or Nothing

Question 23

What is refractory period?

Answer 23

The time when membrane cannot be depolarised, and when action potential cannot be generated until preceding potential has finished

Question 24

What determine the strength of stimulus?

Answer 24

• increased firing rate

Question 25

How is action potential travel from one neuron to another?

Answer 25

action potential reaches presynaptic terminal —> voltage-gated ion channel (on presynaptic terminal) open —> Ca2+ enters presynaptic membrane —> chemical signals/neurotransmitters move near to the cell membrane and fuse with Ca2+ —> releasing its content(=neurotransmitters) into the synapses —> log on to ion channels in post-synaptic membrane

Question 26

What happen during epilepsy?

Answer 26

Balance between inhibition and excitation breaks down

Question 27

What happens when neuron becomes too active?

Answer 27

Uncontrollable electrical activity = seizures

Question 28

What is important for a nervous system to work properly?

- interms of pre-synaptic potentials

Answer 28

Correct balance of excitatory (EPSP) and inhibitory (IPSP) signals