Explain why a change in extracellular Na did not alter the membrane potential in the resting neuron.

Explanation:

A change in extracellular Na did not alter the membrane potential in the resting neuron because the plasma membrane of a neuron is composed of little Na+ leakage channels and it is slightly permeable to few Na, thus lead to reduction in diffusion if Na inside and outside the cells.

the answer is: the „power stroke“ step.

muscle contraction can be divided into a few steps:

1. the release of ach (acetylcholine) in the synaptic cleft, binding of ach for its receptor and consequently opening of the ca channels.

2. the release of ca, binding of ca for the troponin

3. troponin shifting the tropomyosin, which was blocking the active site on the actin

4. myosin heads attaching to actin by breaking down atp to adp+ pi

5.   formation of the ‘cross-bridge’ on the active site of the actin filament by myosin head

6. “power stroke” -the cross bridge pulls actin, which slides over the myosin

9.     7. the release of adp completes the cross-bridge movement and atp attaches to myosin, breaking the actin-myosin cross bridge.

u can get stuck if wrong may u pls give mt the optians

explanation: