Topic 3 - NERVOUS SYSTEM I (Neurons Review | Electrical Properties of Cells)

Question 1

Neurons Review

Neurons are ______

• ?

Answer 1

neurons are excitable (responsive to stimuli)

• when stimulated (usually on cell body or dendrites) an electrical impulse may be generated and propagated along the axon = nerve impulse

Question 2

Electrical Properties of Cells due to:

2 things

Answer 2

1. ionic concentration differences across the cell membrane (gradients)
2. permeability of cell membrane to ions

Question 3

Electrical Properties of Cells due to ionic concentration differences across the cell membrane (gradients)

A

Answer 3

• important ions
  
  • Na⁺, K⁺, Cl^-, Ca^{<span>++</span>}
  • Large, negatively charged organic ions (org^-) - are non diffusible proteins

Question 4

Electrical Properties of Cells due to ionic concentration differences across the cell membrane (gradients)

B

Answer 4

[Na+] and [K+] due to and maintained by activity of Na+/K+ - ATPase (pump) in cell membrane

Question 5

Electrical Properties of Cells due to ionic concentration differences across the cell membrane (gradients)

C

Answer 5

calcium concentration due to various transporters in cell and ER membrane

Question 6

Electrical Properties of Cells due to ionic concentration differences across the cell membrane (gradients)

D

Answer 6

-Cl^- repelled by large, negatively charged organic ions (org^-) so is higher outside the cell than inside

Question 7

Electrical Properties of Cells due to ionic concentration differences across the cell membrane (gradients)

E

Answer 7

large, negatively charged organic ions (org^-) stay inside the cell

Question 8

Electrical Properties of Cells due to ionic concentration differences across the cell membrane (gradients)

EVERYTHING (A to E)

Answer 8

• important ions
  
  • Na+, K+, Cl-, Ca++
  • Large, negatively charged organic ions (org-) - are non diffusible proteins
• [Na+] and [K+] due to and maintained by activity of Na+/K+ - ATPase (pump) in cell membrane
• calcium concentration due to various transporters in cell and ER membrane
• -Cl- repelled by large, negatively charged organic ions (org-) so is higher outside the cell than inside
• large, negatively charged organic ions (org-​) stay inside the cell

Question 9

Electrical Properties of Cells due to permeability of cell membrane to ions

• determined by what?
• how many types of ion channels?

Answer 9

1. determined by ion channels - ion diffuse through them down concentration gradient
2. 2 types of ion channels

Question 10

Electrical Properties of Cells due to permeability of cell membrane to ions

what are the 2 types of ion channels?

Answer 10

1. non-gated
2. gated

Question 11

Electrical Properties of Cells due to permeability of cell membrane to ions

ion channel type: non-gated

• what ion is more permeable at rest? why?

Answer 11

• always open
• more K^{+ (potassium)} than Na^{+ (sodium)} therefore, cell membrane is more permeable to K⁺ at rest (no stimulus)
• these channels (Especially K⁺ - more numerous) are important in establishing the resting membrane potential (RMP)

Question 12

Electrical Properties of Cells due to permeability of cell membrane to ions

ion channel type: gated

Answer 12

• NOT involved at rest
• open in response to stimuli

Question 13

Electrical Properties of Cells due to permeability of cell membrane to ions

gated ion channels open in response to stimuli.

name 4 examples

Answer 13

1. membrane voltage changes = voltage gates
2. chemical e.g. binding of hormone or neurotransmitter = chemical gates
3. temperature = thermal gates
4. mechanical deformation = mechanical gates

Question 14

what is important in establishing RMP?

Answer 14

K+