How do depolarization and repolarization relate to muscle contraction and relaxation?

How do depolarization and repolarization relate to muscle contraction and relaxation?

Explain how depolarization and repolarization occur. How do these relate to muscle contraction and relaxation? Depolarization is caused by a flood of ions (sodium and potassium) across the cell membrane and drives the cells, therefore cardiac muscle tissues, to contract.

What is cardiac cycle and its stages?

The atria and ventricles alternately contract in each cardiac cycle. The pressures in the chambers change greatly over the course of the cardiac cycle. The cardiac cycle is essentially split into two phases, systole (the contraction phase) and diastole (the relaxation phase).

What are the 5 stages of the cardiac cycle?

5 Phases of the Cardiac Cycle

• Atrial Systole.
• Early Ventricular Systole.
• Ventricular Systole.
• Early Ventricular Diastole.
• Late Ventricular Diastole.

What is the duration of one cardiac cycle?

about 0.8 seconds

What is the shortest stage of the cardiac cycle?

Maximum Ejection Phase

When both ventricles relax and fill this is the?

diastole

What phase of the cardiac cycle is the heart in when the P wave begins?

atrial depolarization

How many valves are closed in this phase?

5. Bicuspid and Tricuspid valves are closed in this phase to prevent backflow of blood into atria.

What percentage of cardiac output is atrial kick?

(approximately 20%)

Is the atrial kick essential for life?

Atrial kick is a significant part of the cardiac cycle as it is necessary to maximize left ventricular end-diastolic volume. Health care professionals must be able to recognize the loss of the atrial kick.

What does loss of atrial kick mean?

Definition. Atrial fibrillation and loss of “atrial kick” leads to a decrease in stroke volume due to decreased in left ventricular end-diastolic volume (preload). This effect is especially severe in diastolic dysfunction, impaired contraction, or in mitral stenosis.

What part of the cardiac cycle is missing in atrial fibrillation?

Atrial fibrillation occurs when the P wave is missing and represents irregular, rapid, and inefficient atrial contraction, but is generally not fatal on its own.

What are the 3 stages of the cardiac cycle?

The cardiac cycle has 3 stages:

• Atrial and Ventricular diastole (chambers are relaxed and filling with blood)
• Atrial systole (atria contract and remaining blood is pushed into ventricles)
• Ventricular systole (ventricles contract and push blood out through aorta and pulmonary artery)