The Cardiac cycle

Question 1

In summary, what is the cardiac cycle?

Answer 1

A series of events required to generate one single heartbeat

Question 2

What is responsible for the cardiac cycle?

Answer 2

The cardiac conduction system (The electrical pathways through the heart)

Question 3

What must happen in order for blood to move successfully through the heart?

Answer 3

Coordination must occur between the valves opening and closing and the contraction of the chambers of the heart

Question 4

What is the cause of valves opening and closing?

Answer 4

Contractions

Question 5

What state is the heart in at the start of the cardiac cycle?

Answer 5

All the chambers are relaxed and all valves are closed

Question 6

Contraction, also known as…

Answer 6

Systole

Question 7

Relaxation, also known as…

Answer 7

Diastole

Question 8

When blood fills the atria what does the change in pressure do?

Answer 8

Pushes the AV valve open

Question 9

Where is the right atria filled from?

Answer 9

The superior and inferior vena cava

Question 10

Where is the left atria filled from?

Answer 10

The pulmonary veins

Question 11

In order for an atrial chamber to be filled, what must be true?

Answer 11

The chambers must be relaxed

Question 12

Why does blood flow into the ventricles?

Answer 12

To equalise the pressure between the atrium and ventricle

Question 13

When does blood stop flowing from the atrium into the ventricle?

Answer 13

When around 70% of the blood volume from the atria is in the ventricles

Question 14

What causes the remaining 30% of blood to flow from the atria into the ventricles?

Answer 14

The atria begin to contract

Once all blood is in the ventricles, the atria relax

Question 15

What happens when the ventricles contract?

Answer 15

The AV nodes close

Question 16

What does this drop in pressure in the atria cause?

Answer 16

A vacuum that pulls the flaps of the AV valves closed

Question 17

What effect do papillary muscles have on the AV valves?

Answer 17

When the papillary muscles within the walls contract, they pull on the chordae tendineae to ensure that the valves stay closed
Therefore preventing back flow

Question 18

As ventricular systole increases due to increase pressure inside the ventricles, what happens?

Answer 18

Semi-lunar valves are pushed open, allowing blood to flow through the aorta and pulmonary arteries

Question 19

What happens when the ventricles relax?

Answer 19

Pressure within the ventricles decreases

Semi-lunar valves are pulled shut

Question 20

Movement of blood through the heart is a result of?

Answer 20

Changes in pressure apposed to contractions

Question 21

What must always be balanced for the cardiac cycle to work correctly?

Answer 21

The output of the atria and the ventricles

Question 22

What is a normal heart rate, i.e number of cardiac cycles per minute in the average adult?

Answer 22

60 to 100

Question 23

To summarise, the cardiac cycle consists of…

Answer 23

Atrial systole
Ventricular systole
Complete cardiac diastole

Question 24

Cardiac diastole occurs when…

Answer 24

All chambers are relaxed and blood flows into the heart

Question 25

Atrial systole / ventricular diastole occurs when…

Answer 25

The atria contracts pushing the blood into the ventricles

Question 26

Atrial diastole / ventricular systole occurs when…

Answer 26

After the atria relax, the ventricles contract, pushing blood out of the heart

Question 27

Describe the positioning of the inferior and superior vena cava?

Answer 27

Off centre, right side of the heart and body

Question 28

Describe the positioning of the aorta?

Answer 28

Left ventricle of the heart, extends upwards into the heart

Question 29

Describe the positioning of the carotid arteries?

Answer 29

Located on each side of the neck (supplies brain, face etc…)

Question 30

Describe the positioning of the pulmonary arteries?

Answer 30

Divides the heart into two branches towards the lungs

Question 31

Describe the positioning of the pulmonary veins?

Answer 31

Two located at each lung that drain into the left atrium

Question 32

Describe the positioning of the femoral artery?

Answer 32

Thigh, supplies blood to the lower limbs

Question 33

Describe the positioning of the renal arteries/veins?

Answer 33

The left interior side of the abdominal aorta, supplies the kidneys

Question 34

Describe the positioning of the coronary arteries?

Answer 34

Above the aortic valve, subdivide and cover the surface of the heart

Question 35

Describe the positioning of the circle of willis?

Answer 35

Joining area of several arteries at the inferior side of the brain. Branch into smaller arteries that supply blood to over 80% of the cerebrum.