Nervous system physiology

Question 1

Axonal transport

Answer 1

-Orthograde/anterograde transport (driven by Kinesin): from cell body to axon terminals. (requires two molecular motors “dynein and kinesin”).
has both fast (400mm/day) and slow (10mm/day) axonal transport.

-Retrograde transport (driven by Dynein): nerve ending to cell body. 200mm/day.

Question 2

Resting membrane potential

Answer 2

-A neuron at rest is negatively charged on the inside with RMP=-70mV
-The RMP is caused by difference in the concentrations of ions inside and outside the cell.
-At the resting potential all voltage gated Na+ and K+ channels are closed and the Na+/K+ ATPase pumps K+ in and Na+ out.
-Intracellular and extracellular K+ are the prime determinants of the resting membrane potential
-Both K+ and Na+ contribute to the RMP
RMP is closer to the potassium equilibrium potential than that of sodium, because the resting membrane is more permeable to potassium.
-Increasing extracellular K+ reduced RMP (meaning it renders it closer to zero closer to depolarization)