3.2.4- The Structure Of The Heart

Question 1

Describe what the atrio- ventricular valve is.

Answer 1

Valves that are between the atria and ventricles that ensure blood flows in the correct direction.

Question 2

What is the semilunar valve?

Answer 2

Valves that prevent blood from reentering the heart from the arteries.

Question 3

What is cardiac muscle?

Answer 3

Specialised muscle found in the walls of the heart chambers.

Question 4

The mammalian heart is a _______ ________.

Answer 4

Muscular pump.

Question 5

What does the right side f the heart do?

Answer 5

Pumps deoxygenated blood to the lungs to be oxygenated.

Question 6

What does the left side of the heart do?

Answer 6

Pumps oxygenated blood to the rest of the body.

Question 7

On both sides of the heart, how is the blood moved?

Answer 7

By pressure being created to force the blood along the arteries and through the circulatory system.

Question 8

The main part of the heart consists of what?

Answer 8

Dark Red Cardiac Muscle.

Question 9

What are the two main pumping chambers of the heart?

Answer 9

The atria and the ventricles.

Question 10

Explain where the atria and ventricles are in the heart.

Answer 10

The atria are smaller and above the ventricles.

Question 11

Lying over the surface of the heart are the _________ __________.

Answer 11

Coronary arteries.

Question 12

What is the function of the coronary arteries that lie on the heart surface?

Answer 12

They supply oxygenated blood to the heart muscle.

Question 13

Explain the effect restricted arteries can cause.

Answer 13

It can restrict blood flow to the heart and reduce the delivery of oxygen and nutrients like fatty acids and glucose. This can cause angina or heart attack.

Question 14

What is at the top of the heart on its surface?

Answer 14

Tubular blood vessels.

Question 15

What is the function f the tubular blood vessels that lie on top of the heart?

Answer 15

They are veins that carry blood to the atria and carry blood arteries that carry blood away from the heart.

Question 16

What do the atria receive?

Answer 16

The atria receive deoxygenated blood from the body through the vena cava to the right atrium.

Question 17

What delivers deoxygenated blood from the body to the right atrium?

Answer 17

The vena cava.

Question 18

Explain what blood type and how it is delivered to the left atrium.

Answer 18

Oxygenated blood from the lungs is delivered to the left atrium by the pulmonary vein.

Question 19

How is blood carried from the atria to the ventricles?

Answer 19

It flows through the atrio- ventricular valve.

Question 20

How does the heart ensure that oxygen and deoxygenated blood are kept in the separate sides of the heart.

Answer 20

The heart has a wall of muscle called the septum that separates the two ventricles.

Question 21

Attached to valves are ________ _________.

Answer 21

Tendinous cords.

Question 22

What do the tendinous cords attached to valves do?

Answer 22

Prevent the valves from turning inside out when the ventricle walls contract.

Question 23

Explain what happens once deoxygenated blood leaves the right ventricle.

Answer 23

It flows through the pulmonary artery where it leads to the lungs to be oxygenated.

Question 24

Explain what happens once oxygenated blood leaves the left ventricle.

Answer 24

It flows into the aorta where it carries the blood to a number of arteries that supply all parts of the body.

Question 25

Where are semilunar valves found?

Answer 25

At the base of the major arteries where blood leaves the heart on the left heart.

Question 26

What is the function of the semilunar valves?

Answer 26

They prevent blood returning to the heart as the ventricles relax.

Question 27

Explain the sequence of events that describe what happens on the left side of the heart.

Answer 27

Oxygenated blood flows from lungs via the pulmonary vein to the left atrium where it flows through the atrio- ventricular valve to the left ventricle. It then leaves the left ventricle through the aorta were it is carried to a number of main arteries that supply the rest of the body with oxygenated blood.

Question 28

Explain the sequence of events that describe the action of blood and how it moves on the right side of the heart.

Answer 28

Deoxygenated blood brought from the body by the vena cava into the right atrium where it flies down through the atrio- ventricular valve to the relight ventricle. The deoxy blood then leaves the right ventricle by the pulmonary artery that leads it to the lungs to be oxygenated.

Question 29

Why does the cardiac muscle in the walls of the heart contract?

Answer 29

To create pressure in the heart to push the blood.

Question 30

Explain the thickness of the atria and how this is related to its function and the pressure it needs to create.

Answer 30

It has thin walls as the chambers don’t need to create much pressure. It’s function is to receive blood from the veins and push it into the ventricles.

Question 31

Explain the thickness of the left ventricle and how this is related to its function and the pressure it needs to create.

Answer 31

It has walls twice as thick as the right ventricle as sufficient pressure if needed to overcome the resistance of systematic circulation, so the thick walls are needed to create this high pressure.

Question 32

Explain the thickness of the right ventricle and how this is related to its function and the pressure it needs to create.

Answer 32

Thicker than the walls of the atria, thinner than left ventricle. Thickness needed to create enough pressure to pump deoxygenated blood to the lungs Too high pressure isn’t needed as it may damage the alveoli in the lungs and the blood doesn’t need to travel that far.

Question 33

What does cardiac muscle consist of?

Answer 33

Fibres that Branch to produce cross bridges.

Question 34

What two things does the branching fibres that produce cross bridges help with (in cardiac muscle).

Answer 34

To spread the stimulus around the heart and to ensure the muscle can produce a squeezing action rather than a simple reduction in length.

Question 35

There are lots of __________ between the muscle fibres (myofibrils) of cardiac muscle.

Answer 35

Mitochondria

Question 36

Why are there many mitochondria present between the myofibrils of cardiac muscle?

Answer 36

To supply the energy needed for muscle contraction.

Question 37

The muscle cells in cardiac muscle are separated by ________ _______.

Answer 37

Intercalated discs.

Question 38

What is the function of intercalated discs that separate muscle cells in cardiac muscle?

Answer 38

They facilitate synchronised contraction.

Question 39

Each muscle cell in cardiac muscle has a nucleus and is divided into contractile units called __________.

Answer 39

Sacromeres