About the human heart: 1.0) Explain the variation of membrane potential of cardi
ID: 3519967 • Letter: A
Question
About the human heart:
1.0) Explain the variation of membrane potential of cardion cells and also skeletal muscle cells of the heart, and name the different channels involved in each of the phases.
1.1) Explain the variation of skeletal muscle cell of the heart membrane potential and name the different channels involved in each phase.
1.2) Define the cardiac revolution and describe the various phenomena that accompany it at each stage (eg, at what point in the cardiac revolution are all the valves closed?) Be able to describe what happens during the isovolumetric contraction of the ventricles.
Explanation / Answer
1.0)
The difference in the concentrations of ions on opposite sides of a cellular membrane lead to a voltage called the membrane potential.
The cardaic action potential is a brief change in voltage across the cell membrane of heart cells. It is caused by the movement of charged atoms called ions between inside and the outside of the cells.through proteins called ion channels .
The resting membrane potential of ventricular cells is around -90millivolts.it is more negative inside than the outside.
Action potential begins with the voltage becoming more positive known as depolarization .
There is important physiological differences between the cells that spontaneously generate action potential .
Phase 4 .
in the ventricular myocyte phase 4 occurs when the cell is at rest in a period known as diastole .this phase of more or less constant at roughly-90mV.
PHASE O
This phase consists of rapid positive change in voltage across the cell membrane lasting less than 2ms in ventricular cells and 10/20ms in SAN cells.
Na+ channels increase membrane conductance .
Phase 1.
This phase begins with rapid inactivation of the Na+ channels by inner gate reducing the movement of sodium into the cell .at the same time potassium channels open and close .
Phase 2 .
This phase is also known as the plateau as the membrane potential remain almost constant. Here membrane begins to repolarize
During this phase delayed rectifier potassium channels allow pottaduim to leave cell whilst L type calcium channels allow the movement of calcium into the cell .This calcium is responsible for contraction of heart .
Phase 3
During this phase 3 action potential the L type ca2+ channels close .while as k+ channels remain open as more pottasuim leak channels open .
1.1.
Skeletal muscles are the effector organs of the locomotor system. They are under voluntary control although much of their activity is subconsciously regulated.
Stimulas got physiological skeletal muscle activity is always derived from a nerve impulse.
A skeletal muscle action potential is generated when the motor endplate potential is sufficient to raise the surrounding sarcolemmal potential .