This phase is also known as the “plateau” phase due to the membrane potential remaining almost constant, as the membrane slowly begins to repolarize. This is due to the near balance of charge moving into and out of the cell.
Why is the plateau phase in cardiac muscle contraction important?
This plateau phase allows for a longer muscle contraction and gives time for the nearby cardiac muscle cells to depolarize. This is important in allowing the heart to contract in a steady, uniform and forceful manner.
What is the purpose of the plateau phase?
Plateau phase: >increases strength of heart’s contraction. >allows more calcium ions to enter cell. > allows heart to relax and ventricles to refill with blood before cardiac muscle cells are stimulated to contract again.
How plateau phase is formed in the heart muscles?
Cardiac muscle action potential. Unlike that of the skeletal muscle cell (see Figure 6), an action potential in the cardiac muscle cell elicits prolonged plateau phase, where a slow influx of Ca2+ into the cell balances the efflux of K+, thereby maintaining a stable membrane potential for ∼175 ms.
What causes the plateau phase of cardiac muscle contraction quizlet?
Cardiac muscle has a prolonged period of slow repolarization called the plateau phase. … Early repolarization of cardiac muscle cells occurs when voltage-gated Na+ ion channels close and voltage-gated K+ ion channels open.
What is the plateau phase?
Plateau follows the excitement or sexual arousal phase, and is characterised by increased heart and respiratory rates, increased sexual pleasure, increased muscle tension, and is followed by orgasm. …
What is responsible for the plateau phase of contractile cardiac action potentials?
The L-type calcium current (ICa–L) is the main charge carrier responsible for maintaining the action potential plateau during phase 2. T-type calcium channels, which activate at potentials more negative than those of the L-type calcium channels, may primarily contribute to pacemaker activity in the heart.
What is the plateau phase maintained by quizlet?
Plateau. The next phase of an action potential is a contractile fiber is the plateau, a period of maintained depolarization. It is due in part to opening of voltage-gated slow CA2+ channels in the sarcolemma.
What is responsible for the plateau continued depolarization of the cardiac muscle cell?
Calcium-Induced Calcium Release
CICR creates a “plateau phase” in which the cell’s charge stays slightly positive (depolarized) briefly before it becomes more negative as it repolarizes due to potassium ion influx. Skeletal muscle, by contrast, repolarizes immediately.