Cardiac Cycle

Question 1

How big is the heart, and where is it located?

Answer 1

The heart is a muscular organ located
between the lungs in the centre of the chest
(thorax), and is about the size of a fist.

Question 2

When does a fetus’s heart start beating?

Answer 2

In foetuses, the heart begins beating about
5–6 weeks after conception

Question 3

What is the heart made up of?

Answer 3

The heart mainly consists of cardiac muscle tissue,
which like smooth muscle (but not skeletal muscle),
contracts involuntarily.

Question 4

How does the structure of the cardiac muscles help with its perpose?

Answer 4

Cardiac muscle is made up of
cells that are connected by
cytoplasmic bridges. This enables
electrical impulses to pass
through the tissue.

It contains large numbers of
mitochondria (for energy production)
and myoglobin molecules. Myoglobin is
the primary oxygen-carrying pigment in
muscles and allows for more oxygen to
be used by the heart.

Question 5

Name ALL the components in the heart. (16)

Answer 5

Left Atrium
Left Ventricle
Right Atrium
Right Ventricle
Septum
Aorta
Pulmonary artery
Pulmonary Vein
Vena cava
Bicuspid Valve
Tricuspid Valve
Aortic Valve
Pulmonary Valve
Tendinous Chords
Papillary muscles
Pericardium

Question 6

Describe one fun Cardiac cycle.

Answer 6

The vena cava pumps deoxygenated blood from the body to the right atrium. The blood from the upper body comes from the superior vena cava, and the lower comes from the inferior vena cava. The blood is then pumped into the right ventricle via the contraction of the atrium by atrial systole, passing through the Tricuspid valve. Then the blood is pumped through the Pulmonary artery by the contraction of the Right ventricle through the Pulmonary valve by Ventricular Systole. The blood then becomes oxygenated as it comes back from the lungs. The Pulmonary vein then pumps the blood into the left atrium, which is then pumped into the left ventricle through the bicuspid valve by atrial systole. The left ventricle then pumps the blood into the aorta by ventricular systole, passing the Aortic valve then the blood is pumped to the rest of the body and comes back to the Vena cava to complete another cycle

Question 7

What does the Left atrium do?

Answer 7

receives blood from the lungs via the pulmonary vein and
pumps it into the left ventricle)

Question 8

What does the Left ventricle do?

Answer 8

pumps oxygenated blood to the body via the aorta

Question 9

What does the Right atrium do?

Answer 9

receives deoxygenated blood from the body via the vena
cavae and pumps it into the right ventricle. Blood from the upper body is
received via the superior vena cava and blood from the lower body enters
via the inferior vena cava.

Question 10

What does the Right ventricle do?

Answer 10

pumps deoxygenated blood to the lungs via the
pulmonary artery

Question 11

What does the bicuspid Atrioventricular valve do?

Answer 11

The bicuspid AV or mitral AV valve prevents blood from flowing from the
left ventricle into the left atrium during ventricular contraction. It has
two flaps (cusps).

Question 12

What does the tricuspid Atrioventricular valve do?

Answer 12

The tricuspid AV valve prevents blood flowing from the right ventricle
into the right atrium during ventricular contraction. It has three flaps.

Question 13

What does the aortic Semilunar valve do?

Answer 13

The aortic SL valve prevents blood from flowing back into the left
ventricle during diastole. It has three half-moon-shaped flaps (cusps).

Question 14

What does the pulmonary Semilunar valve do?

Answer 14

The pulmonary SL valve prevents blood from flowing back into the right
ventricle during diastole. It has three half-moon-shaped flaps (cusps)

Question 15

What does the Septum do?

Answer 15

– the septum is a thick muscular wall that divides the
heart into the left and right halves. It prevents mixing of
oxygenated and deoxygenated blood

Question 16

What do the Papillary muscles do?

Answer 16

– these muscles are attached to tendinous
chords and contract to prevent the AV valves from opening in the
wrong direction. This prevents backflow into the atria.

Question 17

What do the Tendinous chords do?

Answer 17

attach to the valves and prevent them from
turning inside out due to the back pressure of blood pushing
against them.

Question 18

What does the Pericardium do?

Answer 18

is a tough sac surrounding the heart, comprised of
two pericardial membranes. They protect the heart and
lubricate it with pericardial fluid, reducing friction

Question 19

What are the 3 [hases that take place when the heart pumps?

Answer 19

 Diastole
 Atrial systole
 Ventricular systole

Question 20

What happens during Atrial Systole?

Answer 20

The atria are filled with blood from the vena cavae and
pulmonary vein & contract.

Blood passes through the AV valves into the ventricles filling
them with blood.

The atrioventricular valves (tricuspid and bicuspid) are open.
The semi lunar valves (aortic and pulmonary) are closed.

Question 21

What happens during Ventricular Systole?

Answer 21

The ventricles contract, forcing blood through the semilunar valves
into the aorta & pulmonary artery. As the ventricles start to contract,
all valves of the heart are closed for a fraction of a second.

The force of contraction closes the AV valves, stopping blood from
returing to the atria.

The atrioventricular valves (tricuspid and bicuspid) are closed.
The semi lunar valves (aortic and pulmonary) are open

Question 22

What happens during Diastole?

Answer 22

The ventricles relax. The pressure drops and the SL valves close.
The atria start to fill with blood and as the pressure in the atria
increases, blood starts to trickle into the ventricles

Question 23

What do we use to measure blood pressure?

Answer 23

Blood pressure can be measured using a sphygmomanometer a pressure gauge attached to a
cuff.

Question 24

In what units is blood pressure measured?

Answer 24

Measurements are in mm Hg.