The Cardiomyocyte Action Potential [Part 2]: Physiological Events in Cell

The video tutorial explains the action potential in cardiac muscle cells, focusing on the role of gap junctions in facilitating rapid ion movement. It details the physiological events within cardiomyocytes, including the changes in membrane potential and the opening of voltage-gated channels. The tutorial covers the plateau phase, highlighting calcium-induced calcium release from the sarcoplasmic reticulum, and concludes with the repolarization process and the mechanisms for calcium removal to prevent tetany in heart cells.

What is the primary function of gap junctions in cardiac muscle cells?

• To store calcium ions

• To provide structural support

• To generate electrical impulses

• To facilitate rapid ion movement between cells

What happens to the resting membrane potential when positively charged ions enter a cardiomyocyte?

• It becomes more negative

• It becomes more positive

• It remains unchanged

• It fluctuates randomly

Which ion's influx is responsible for the depolarization phase in cardiac muscle cells?

• Potassium

• Chloride

• Calcium

• Sodium

During the plateau phase, what is the relationship between potassium efflux and calcium influx?

• Neither occurs

• They are balanced

• Calcium influx is greater

• Potassium efflux is greater

What triggers the release of more calcium from the sarcoplasmic reticulum during the plateau phase?

• Sodium influx

• Calcium influx

• Potassium efflux

• Mechanical stress

What happens to the calcium channels during the repolarization phase?

• They open wider

• They remain unchanged

• They become inactive

• They close

Why is it important to remove calcium from the sarcoplasm during repolarization?

• To store energy

• To increase contraction strength

• To prevent tetany

• To maintain a positive membrane potential

What is the role of the calcium pump in the sarcoplasmic reticulum during repolarization?

• To move calcium back into the sarcoplasmic reticulum

• To release calcium into the sarcoplasm

• To generate electrical impulses

• To transport calcium out of the cell

What is the final membrane potential after repolarization is complete?

• Positive 30 millivolts

• Negative 70 millivolts

• Negative 90 millivolts

• Zero millivolts

What is the consequence if calcium remains in the sarcoplasm after contraction?

• The heart will relax completely

• The heart will contract more forcefully

• The heart will remain in a contracted state

• The heart will stop contracting