Lesson 10 - Heart

Question 1

What is the heart?

Answer 1

Organ that moves blood around the body. In some animal groups, it is no more than a simple muscular tubes.

Question 2

Mammal hearts?

Answer 2

Complex. Four chambered muscular ‘bag’ found in the chest, enclosed by ribs and sternum.

Question 3

Human heart?

Answer 3

Heart consists of two pumps, joined and working together.
- Deoxygenated blood flows through the right side of the heart and is pumped to the lungs
-Oxygenated blood returns to left side of the heart and is pumped to body tissues.
The blood from the two sides of the heart does not mix.

Question 4

What type of muscle is the heart made up of?

Answer 4

Cardiac muscle

Question 5

What does cardiac muscle do?

Answer 5

Contracts and relaxes in a regular rhythm. It does not get fatigued or need to rest like skeletal muscles.

Question 6

Which arteries provide cardiac muscle with oxygenated blood?

Answer 6

Coronary arteries

Question 7

What prevents the heart over-distending (swelling) with blood?

Answer 7

Surrounded by inelastic pericardial membranes.

Question 8

Heart structure:
Features of the aortic arch?

Answer 8

• Aorta
• Carotid arteries

Question 9

Heart structure:
Features of the aorta?

Answer 9

• Aortic arch
• Descending aorta

Question 10

Heart structure:
Cardiac vein –> external or internal structure?

Answer 10

External structure

Question 11

Heart structure:
What is apart of the external structure?

Answer 11

• Aortic arch
• Vena Cava
• Right atrium
• Right coronary artery
• Right ventricle
• Descending aorta
• Cardiac vein
• Left ventricle
• Left coronary artery
• Pulmonary veins
• Pulmonary artery

Question 12

Heart structure:
Valve between right atrium and ventricle?

Answer 12

Tricuspid valve
(Right atrioventricular valve)

Question 13

Atria to ventricle blood passes: Right

Answer 13

• Thin muscular walls
• As blood flows in, slight pressure builds up until the tricuspid valve opens to let blood pass into the right ventricle.
• When both the atrium and valve are filled with blood the atrium contracts, forcing all the blood into the right ventricle and stretching the ventricle walls.
• As the right ventricle contracts, the tricuspid valve closes to prevent backflow.

Question 14

Role of the tendinous cords?

Answer 14

Make sure valves are not turned inside out by the pressures exerted when the ventricle contracts fully.

Question 15

Movement of blood from the right ventricle to the lungs?

Answer 15

• Right ventricle contracts fully and pumps deoxygenated blood through semilunar valves into the pulmonary artery, which transports blood to the capillary beds in the lungs.

Question 16

Semilunar valves?

Answer 16

Prevent backflow of blood into the right ventricle of the heart.

Question 17

Pulmonary vein –>

Answer 17

left atrium

Question 18

What happens when pressure of blood in the left atrium increases?

Answer 18

The bicuspid valve opens.
The left ventricle fills with blood.

Question 19

What happens when both the left atrium and ventricle are filled with blood?

Answer 19

Atrium contracts, forcing all the blood into the left ventricle.

Question 20

Left ventricle –> body

Answer 20

• Left ventricle contracts
• Oxygenated blood pumped through the semilunar valves and to the aorta, back into the body. Semilunar valves close to prevent backflow.
• As the ventricle contracts the bicuspid valve closes and prevent backflow.

Question 21

Where is the muscular wall thicker?

Answer 21

Left side of the heart

Question 22

Why does the left side have a thicker muscular wall?

Answer 22

Lungs closer and smaller than the rest of the body. Right side has to pump blood short distance compared to the left side.
Right side also only has to overcome resistance of pulmonary circulation.
Left side has to produce sufficient force to overcome resistance of aorta, arterial systems of body, and move blood under pressure to all extremities of body.

Question 23

Septum:

Answer 23

Inner dividing wall of heart which prevents the mixing of oxygenated and deoxygenated blood.

Question 24

Timings of heart contractions:

Answer 24

Fill and empty at the same time.

Question 25

Cardiac cycle lasts … in humans?

Answer 25

0.8 seconds

Question 26

Diastole:

Answer 26

The heart relaxes.
- Atria and ventricles fill with blood.
- Volume and pressure of blood in the heart increases as heart fills, pressure in arteries at minimum.

Question 27

Systole:

Answer 27

• Atria contract, closely followed by the ventricles.
• Pressure inside the heart increases dramatically and is forced out into the arteries.
• Volume and pressure of blood in heart is low after systole. Blood pressure in arteries is at a maximum.

Question 28

Atrial systole:

Answer 28

Contraction of the atrium

Question 29

Ventricular systole:

Answer 29

Ventricles contract