Chapter 19.8

Question 1

cardiac cycle

Answer 1

inclusive changes within the heart from the initiation of one heartbeat to the start of the next

Question 2

systole

Answer 2

contraction of a heart chamber

Question 3

diastole

Answer 3

relaxation of a heart chamber

Question 4

pressure changes within chambers

Answer 4

• pressure increases during contraction
• pressure decreases during relaxation

Question 5

ventricular contraction

Answer 5

• ventricles contract, ventricular pressure rises
• one way flow because AV valves are closed
• semilunar valves are opened to allow ejection of blood from ventricle into arterial trunk

Question 6

ventricular relaxation

Answer 6

• ventricles relax, ventricular pressure decreases
• semilunar valves close to prevent back flow of blood
• AV valves open allowing blood to flow from the atrium to the ventricles

Question 7

beginning of cardiac cycle

Answer 7

• four chambers at rest
• blood returns to right atrium through SVC, IVC, and coronary sinus and to the left atrium through the pulmonary veins
• no contraction of atria
• AV valves open
• semilunar valves closed

Question 8

atrial contraction

Answer 8

• initiated by SA node stimulating cardiac muscle cells
• moves remainder of the blood in the atrium to the ventricle

Question 9

ventricular filling

Answer 9

• ventricles now hold maximum blood volume
• end-diastolic-volume (EDV)

Question 10

5 steps in cardiac cycle

Answer 10

atrial contraction + ventricular filling, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, atrial relaxation and ventricular filling

Question 11

isovolumetric contraction

Answer 11

• no change in ventricular blood volume when the ventricles are contracting
• ventricular contraction initiated by Purkinje fibers, pressure within the ventricles increase
• AV valves are forced closed + prevents backflow of blood from ventricles to the atria