HIsto 4 resting membrane and action potentials

Question 1

What is the ion concentrations inside vs outside of cells (Na and K)

Answer 1

Na= higher outside of the cell

K= higher inside the cell

Question 2

What is the primary reason for the resting membrane potential?

Answer 2

permeability of the plasma membrane to potassium ions

Question 3

membrane permeability to K⁺,Ca²⁺, Na ⁺

Answer 3

permeable somewhat to K but not as much to Ca or Na

Question 4

K⁺ leak channels

Answer 4

• open all the time
  
  • mostly unregulated passage of ions
• K channels much more common than Na leak channels
• K more likely to leave cell than Na to enter

Question 5

What is the resting membrane potential for Muscle(cardiac/skeletal) , smooth muscle, and neurons?

Answer 5

• M= -80 to -90 mv
• SM= -60 mv
• N= -60 to -70 mv

Question 6

what forces are acting on ions to develop membrane potential?

Answer 6

Diffusion forces- concentration gradient

Electrostatic forces- charge based, opposite attract

charge can develop which can cause no further diffusion

Question 7

What is an electrochemical force?

and equilibrium potential?

Answer 7

• Diffusion forces+ electrical forces

E_ion -membrane potential when electrical and chem forces are equal, no further movement occurs

(NOT MEMBRANE POTENTIAL)

Question 8

Polarization vs depolarazation vs hyperpolarization vs Repolarization

Answer 8

Question 9

What can be different between different cells action potential?

Answer 9

• Deviation from resting membrane potential varies between cell types
• Length of action potential varies between cell types

Question 10

What are the key properties of action potentials?

Answer 10

• All or none response
• propagating or self-reinforcing
• Non-decremental (same action potential it wont differ)

Question 11

Graded potentials?

Answer 11

Question 12

What are the phases of action potentials?

Answer 12

Question 13

Key players in action potentials?

Answer 13

• Na ions
• K ions
• voltage-gated Na channels
• Voltage-gated K channels
• K leak channels (lesser degree)
• *Ca ions are important for many cell types (cardiac)

Question 14

Depolarization (phases of action potential)

Answer 14

• Increase in permeability of membrane to Na+
• Voltage-gated Na channels open RAPIDLY
• after minimal delay channels close automatically

Question 15

Voltage-gated Na channels how they work?

Answer 15

Question 16

what type of feedback loop does a voltage-gated Na channel go through?

Answer 16

Question 17

Repolarization (phases of action potential)

Answer 17

• voltage-gated Na channels are closed
• K leaks out still via K leak channels
• voltage-gated K+ channels SLOWLY open further increasing membrane perm of K

Question 18

Hyperpolarization (phases of action potential)

Answer 18

• voltage-gated K channels stay open too long
• more difficult to stimulated a subsequent action potential
• (refractory period)

Question 19

Types of refractory periods?

Answer 19

Absolute

relative

Question 20

Absolute vs relative refractory period

Answer 20

Question 21

Membrane permeability to ions during stages of action potential?

Answer 21

Question 22

Hypokalemic periodic paralysis

Answer 22

Question 23

What is the equation for nernst at 37 C

Answer 23

61.5/Z (log [Xout]/[Xin])

Question 24

For the nernst equation what creates positive vs negative?

Answer 24

Question 25

What is the difference in permeability across different ions?

Answer 25

Question 26

contribution of K, Na and Na-K ATP in membrane potential

Answer 26

• K= main contributor to resting mem pot
• Na=minimal contribution 5 positive contrib
• Na/K pump=minmal direct 4 neg contrib. contibs to maintain ion concentration gradients

Question 27

K diffusion potential (more or less effects what?)

Answer 27