Signaling mechanisms part 2

Question 1

RMP and how it works:

Answer 1

RMP is relative voltage difference between inside and outside of cell when the cell is at rest
-Na+/K+ pumps that remove 3 Na+ ions and allow 2 K+ ion in
-K+ leak channels that allow large amounts of K+ to leave cell
-Na+ leak channels that allow Na+ to enter the cell

Question 2

Depolarizing the membrane:

Answer 2

Change in membrane potential occur when ions move across the membrane

Inward flow of positively charged ions means the membrane potential becomes less negative leading to depolarization

Question 3

Repolarizing the membrane:

Answer 3

Depolarized membrane becomes more negative again as it approaches the resting membrane potential (-70mV)

Question 4

What triggers an action potential?

Answer 4

Any event that opens gated channels including:
-binding of a neurotransmitter
-voltage changes
-deformation of the membrane

Question 5

What happens to membrane potential when Na+ diffuses into the cell?

Answer 5

Membrane potential becomes more positive which is called depolorization and reaches threshold point leading to further explosion

Question 6

What does reaching threshold mean in an action potential?

Answer 6

Reaching threshold causes voltage gated Na+ channels to open

Na+ rapidly diffuses into the cell

Membrane reaches peak at about +30mV

At the peak Na+ channels close and voltage gated K+ channels open

Question 7

Sequence of repolarizing?

Answer 7

Potassium diffuses out of cell which makes inside of cell more negatively charged

Membrane potential reaches -70mV

Question 8

Absolute Refractory Period:

Answer 8

Period after depolarization during which membrane cannot be re-stimulated no matter how strong