The upstroke li mb of the action potential in SA node cells in the cardiac muscle is inresponse to:A. Opening of voltage gated Na+ channels.B. Opening of Transient Ca 2 + channels.C. Opening of Longer lasting Ca 2+ channels.D. Opening of voltage gated K+ channels.E. Opening of voltage gated Na+ channels

Which of the following helps create the refractory period for action potentials frequency in muscle and nerve cells?Group of answer choicesclosed activation gate on voltage gated sodium channelslag for restoration of resting membrane potential by sodium-potassium pumpinability to reach threshold potential for the cellclosed inactivation gate on voltage gated sodium channelsclosed gates on voltage gated potassium channels

00. Which phase(s) of the action potential accounts for thegeneration and propagation of impulses by the heart withoutexternal stimulation?CABAll

During these stages of an action potential, identify whether the voltage-gated sodium (Na+) channels are open or closed:RepolarisationAnswer 1 Question 13DepolarisationAnswer 2 Question 13RestAnswer 3 Question 13Hyperpolarisation

The upstroke of the action potential (ie: its rising phase) is largely due to voltage activated Na channels opening, which cause depolarisation, which open more voltage activated Na channels, causing more depolarisation etc (ie: “positive feedback”). Which of the following mechanisms contributes to terminating the upstroke?  Na channels inactivate when depolarised for more than a few hundred µs   the sodium ion concentration inside the cell becomes too high to allow any more sodium ions to enter   activation of voltage-dependent chloride channels   opening of voltage dependent calcium channels   voltage-activated Na channels are only opened between threshold potential and 0mV – above this they are inhibited

Movement of Na+ ions into a nerve cell during the upstroke of an action potential is an example of of the following transport mechanismSelect one:a. Simple diffusionb. Primary active transportc. Co-transportd. Facilitated diffusione. Counter-transportClear my choice