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In a normally functioning heart, the SA (sinoatrial) node is the pacemaker of the heart, but if it is nonfunctional then the AV (atrioventricular) node would take over. If it isn't working either then the Bundle of His can trigger contractions, and if it isn't working the Perkinje fibers can trigger contractions. Each progressive one has a slower intrinsic heart rate.
What else can I help you with?
What effect does hypocalcemia have on the cardiac action potential?
Hypocalcemia can lead to a prolongation of the cardiac action potential due to reduced calcium influx. This can result in an increased risk of arrhythmias, as well as potential impairment of cardiac muscle contractility.
Why is the cardiac action potential longer?
The reason why cardiac muscle has a longer action potential is to extend the absolute refractory period to prevent another action potential. If too many action potentials stimulate the cardiac muscle it can get into tetanus which keeps the heart continuously contracted without relaxation.
What is automaticity of the heart?
The property that allows any cell in the cardiac muscle to begin an action potential, or a cardiac conduction, leading to cardiac contraction.
What phase of cardiac muscle action potential caused by sodium ions entering cell?
The first phase of a cardiac action potential (or any action potential) involves influx of sodium ions. This phase may be called:The rising phaseThe depolarization phasePhase 0
Action potentials originate at the?
Action potentials are how nerve impulses are transmitted from neuron to neuron. An action potential is formed when a stimulus to the nerve cell causes the membrane to depolarize and open all of its sodium ion channels toward the threshold potential.
Why do you keep the heart from entering tetanus?
The action potential of cardiac muscle is prolonged consisting of the depolarization spike and plateau and a repolarization period. The action potential causes a long refractory period of about 250-400 milliseconds in the heart.
What is the function of the intercalated disc?
Basically, the cardiac action potential travel across them, making it easier for the electrical impulses to move quickely.
In cardiac muscle the fast depolarization phase of action potential is the result of?
increased membrane permeability to sodium ions
Allow spread of action potential between cardiac fibers?
Visceral Muscle Tissue or Visceral Smooth Tissue is a cardiac muscle. Its gap junctions allows actions that is likely to disseminate from one cell to another.
What is relative refactory period?
The relative refractory period is the phase of the cardiac action potential during which a stronger-than-usual stimulus is required to elicit another action potential. It occurs immediately following the absolute refractory period and allows for the heart muscle to be able to respond to a second, stronger stimulus after the initial action potential.
Where do most action potentials originate?
Action potentials most commonly originate in the axon hillock of a neuron, which is located near the cell body. This region has a high density of voltage-gated ion channels that are responsible for generating and propagating the action potential down the axon.
The plateau portion of the action potential in contractile cardiac muscle cells is due to?
The plateau portion of the action potential in contractile cardiac muscle cells is due to the balance between calcium influx and potassium efflux. This balance helps to maintain prolonged depolarization, allowing for sustained contraction of the heart muscle.
