Neurons 1

Question 1

What is the resting membrane potential (RMP)?
What is the range?
How can it be measured?

Answer 1

• The membrane potential in the absence of synaptic and action potentials
• Usually between -50 and -70 mV (-65) / zero outside cell
• Intracellular electrodes, patch-clamp pipettes

Question 2

What is the role of the sensory components?

Answer 2

Monitor environmental and internal events

Question 3

What is the role of integrative components?

Answer 3

Process and store sensory and other info

Question 4

What is the role of motor components?

Answer 4

Generate responses to sensory inputs or voluntary commands

Question 5

What are synaptic inputs?

Where are they received?

Answer 5

• Inputs from other neurons

- Received on the dendritic tree and the soma

Question 6

How are action potentials conducted?

Answer 6

Axon conducts AP AWAY from the SOMA to the tips of the axons where their synaptic boutons/axon terminals communicate with other neurons

Question 7

What is the membrane potential?

What is the range?

Answer 7

• The voltage across the cell membrane (changes in different states of cell activity)
• Between -100 and +50

Question 8

What 2 things can alter the RMP?

Answer 8

1. Dif in conc of Na and K ions inside/outside cell = creates electrochemical gradients driving movement of these ions
2. Dif in permeability (P) of cell membrane to these ions

Question 9

What are the 2 types of ion channels that affect permeability?

Answer 9

1. Non-gated channels (leak) - open at rest

2. Gated channels (voltage/ligand gated) - usually closed at rest

Question 10

In the cell membrane of neurons there are many non-gated channels for K+ and few for Na+, this means…?
How is the rundown of concentration gradients prevented?

Answer 10

• At rest, the ratio of P(K+):P(Na+) = 40:1
• There is a steady diffusion of K out of cell and Na into cell The rundown of conc gradients is prevented by Na/K ATPase/pump)

Question 11

What is the Nernst Equation?
When does it apply?
What affects this?
What info do you need for this equation?

Answer 11

Calculates the ‘equilibrium potential’ for EACH ion that contributes to RMP (diffusion vs electricity)

• Applies when a cell is permeable to ONE ion
• ^temp increases dif, ^ion charge DEcreases dif
• Need to know conc of ion in/outside cell

Question 12

What is the Goldman Equation?

What info do you need for this equation?

Answer 12

Calculates RMP value

- Relative permeability and ion concs

Question 13

What are the typical values of concentration inside and outside the cell for Na and K?

Answer 13

INSIDE: Na=15mM K=100mM
OUTSIDE: Na=150mM K=5mM

Question 14

What is the role of the Na/K ATPase (pump)?

Answer 14

Maintains negative MP

3:2 ratio: 3 Na+ out, 2 K+ in

Question 15

What is the approximate equilibrium potential for K+ and Na+?

Answer 15

K+ = -80mV
Na+ = +60mV

Question 16

Glia cells have leak channels for ONLY…?

Answer 16

K+ (so RMP = K+ equilibrium potential = -80mV)