Tutorial membrane excitability

At resting membrane potential, why does a small amount of sodium leak into the cell instead of out?

at RMP, -70mV n membrane permeability of K+ higher, the concen gradient favors movement of Na+ into the cell. As leak channel always open allowing K+ leaked out, the inside cell is negatively charged relative to the outside, so sodium (+) r attracted to - charged ion inside the cell. Na+/K+ ATPase pump also creates higher concen of Na outside, making it move down the concen gradient into the cell.

Define depolarisation and hyperpolarisation and their relationship to threshold

Depo: from RMP to less - value & moves toward threshold, -55mV. Na+ entry → a depolarising potential. Neuron more likely to fire an all-or-nothing AP

Hyper: from RMP to more - & moves away from threshold. K+ exit & Cl- entry → a hyperpolarising potential. Less likely

The student is conscious when certain neurons in his brain are active—they depolarize and undergo action potentials. Describe the process of depolarization of a neuron to threshold.

• more + charged Na in → neuron depolarise 

• Stimulus creates (strong or not, temporal/spatial) → local/GP → axon hillock → open ligand/mechanically gated Na channels

• Threshold= MP at which the v-g channels open

• MP>threshold → AP

Is it correct when the student assumes that leak potassium channels are different than voltage-gated potassium channels?

Leak K: Always open, ions move freely down their concen gradient. K⁺ leak channels are vital for establishing RMP.
- under resting membrane why hyperpolarization bcs slower closing in voltage gated K so efflux and leak channel always open n excessive K went out

Gated: have a "gate", open or close in response to a specific stimulus.

• V-g K: located in axon of neuron, vital for AP production, normally closed until MP reach threshold, a delayed opening= K+ out of cells by flow down concen grad (repolarise) → MP

What does it mean when the student says that anesthesia “inhibits the neurons?” If the anesthesia causes more potassium leakage, why are the neurons of the student less likely to produce action potentials?

anesthesia alter the MP & inhibit to reach threshold.
Increased leak of K+ down its concen grad → hyperpolarise
RMP more → moves away from -55mV so less likely to fire an AP