Cardiac Cycle Look at the graph What does

Quiz Identify the part of the heart indicated by an arrow. There are 10

Answers ● 1 left ventricle ● 2 vena cava ● 3 right atrium ●

Definitions ● Systole = period of contraction. ● Diastole = period of relaxation.

Cardiac cycle ● Contraction of the heart muscle generates pressure changes which result in

Atrial systole ● The heart is full of blood and the ventricles are relaxed

Ventricular systole ● The atria relax. ● The ventricle walls contract, forcing the blood

Ventricular systole ● The pressure of blood opens the semi-lunar valves. ● Blood passes

Diastole ● The ventricles relax ● Pressure in the ventricles falls below that in

● Blood from the vena cava and pulmonary veins enter the atria. ● The

Role of Valves Atrioventricular valves - prevent backflow of blood from ventricles to atria

Cardiac cycle Match the letter on the graph to the following events ● Semi-lunar

Cardiac Output Cardiac output is the volume of blood pumped by one ventricle of

Cardiac Calculations Complete the worksheet questions If you finish, have a go at the

Describing the stages of the cardiac cycle ● Complete the worksheet by describing each

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Cardiac Cycle Look at the graph What does it show?

Heart Structure Quiz!

Quiz Identify the part of the heart indicated by an arrow. There are 10 questions in total.

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Answers ● 1 left ventricle ● 2 vena cava ● 3 right atrium ● 4 pulmonary artery ● 5 aorta ● 6 pulmonary vein ● 7 left atrium ● 8 atrio-ventricular (tricuspid) valve ● 9 semi-lunar (aortic) valve ● 10 right ventricle

Definitions ● Systole = period of contraction. ● Diastole = period of relaxation.

Cardiac cycle ● Contraction of the heart muscle generates pressure changes which result in the orderly movement of blood. ● Blood flows from an area of high pressure to an area of low pressure, unless flow is blocked by a valve. ● Events on the right and left sides of the heart are the same, but pressures are lower on the right.

Atrial systole ● The heart is full of blood and the ventricles are relaxed ● Both the atria contract and blood passes down to the ventricles ● The atrio-ventricular valves open due to blood pressure ● 70% of the blood flows passively down to the ventricles so the atria do not have to contract a great amount.

Ventricular systole ● The atria relax. ● The ventricle walls contract, forcing the blood out ● The pressure of the blood forces the atrioventricular valves to shut (producing the heart sound ‘lub’)

Ventricular systole ● The pressure of blood opens the semi-lunar valves. ● Blood passes into the aorta and pulmonary arteries.

Diastole ● The ventricles relax ● Pressure in the ventricles falls below that in the arteries ● Blood under high pressure in the arteries causes the semi lunar valves to shut. This produces the second heart sound, ‘dub’. ● During diastole, all the muscle in the heart relaxes.

● Blood from the vena cava and pulmonary veins enter the atria. ● The whole cycle starts again.

Role of Valves Atrioventricular valves - prevent backflow of blood from ventricles to atria Semilunar valves - prevent backflow of blood from aorta and pulmonary artery into ventricles Pocket valves - prevent backflow in veins

Cardiac cycle Match the letter on the graph to the following events ● Semi-lunar valves open ● Atrio-ventricular valves close, ● Semi-lunar valves close ● Atrio-ventricular valves open

Cardiac Output Cardiac output is the volume of blood pumped by one ventricle of the heart in one minute. It is usually measured in dm 3 min-1. Cardiac Output = stroke volume x heart rate Heart rate - rate at which heart beats Stroke volume - volume of blood pumped out per beat

Cardiac Calculations Complete the worksheet questions If you finish, have a go at the questions on page 176/177

Describing the stages of the cardiac cycle ● Complete the worksheet by describing each stage in each of the diagrams. ● What is contracting? What is relaxed? ● Are valves open or closed? ● Where is the blood flowing to and from?