Anatomy of the Heart

Question 1

The heart

Answer 1

• Transport system that moves blood
• Right side = oxygen-poor blood coming from body tissues to the lungs that release CO2 and picks up O2 (pulmonary circuit)
• Left side = receives oxygenated blood from the lungs and pumps it to boy tissues (systemic circuit)

Question 2

Location

Answer 2

• Size of a fist
• Weight 250-300g
• Sits in the mediastinum (space between the lungs) and 2/3 is found left of the midsternal line

Question 3

Pericardium

Answer 3

• The heart is enclosed in a pericardium (double-walled sac)
• Fibrous: The outside wall. Protects the heart, prevents 4th heat from overfilling and anchors it to surrounding structures
• Serous: The inside wall, double-walled connective tissue.
• It has a parietal and visceral layer

Question 4

Serous Pericardium

Answer 4

Parietal layer: lines the inside of the pericardium
Visceral layer: covers the surface of the heart
Pericardial cavity: between parietal and visceral layer which contains a film of shroud fluid lubricating their movements against each other

Question 5

Myocardium

Answer 5

Composed mainly of cardiac muscle and forms the bulk of the heart
- Cardiac Skeleton: a network of connective tissue within the myocardium that supports the heart valves and provides electrical insulation between areas of the heart

Question 6

Endocardium

Answer 6

Epithelial tissue that lines the chambers of the heart and is continuous with the endothelial linings of the vascular system

Question 7

Atria

Answer 7

Receiving chamber of the heart only minimally contracts to propel blood into the ventricles
- Vena cava: veins that return blood from the body into the right atrium
- Coronary sinus: a vein that returns blood from the myocardium
- 4 pulmonary veins enter the left atrium from the lungs

Question 8

Ventricles

Answer 8

• Pump blood out of the heart
• Right: pumps blood into the pulmonary trunk -> pulmonary arteries to take low-pressure blood to the lungs (thinner than left)
• Left: pumps blood into the aorta to carry high pressure blood throughout the body (3-times thicker than right)

Question 9

Septa of the heart

Answer 9

Partitions that separate the heart
- Inter-atrial septum divides the atria
- Inter-ventricular septum divides the ventricles

Question 10

Atrioventricular valves

Answer 10

There are two between the atrial-ventricular junction
- Tricuspid valve is in the right junction and the bicuspid or mitral valve is in the left junction
- Hang loosely into the ventricles when the heart is relaxed
- Ventricles contract and the blood going up pushes the valves to close
- Anchored to the papillary muscle by chordae tendinae to prevent eversion of the valves into the atria

Question 11

AV Valves opening

Answer 11

• Returning blood fills the atria which press against the valves to force them open
• The valve flaps hang loosely into the ventricles and the ventricles fill up
• The atria contract forces more blood into the ventricles

Question 12

AV Valves closing

Answer 12

• The ventricles contract, forcing blood against the cusps of the valves

Question 13

Semilunar valves

Answer 13

• Aortic and pulmonary semilunar valves
• Located at the base of the arteries exiting the heart
• Prevent backflow of blood into the ventricles

Question 14

Semilunar valves opening

Answer 14

• The ventricles contract and the pressure in the ventricles rise
• Blood is pushed against the semilunar valves, forcing them open

Question 15

Semilunar valves closing

Answer 15

• As the ventricles relax, the pressure in there falls
• Blood flows back from the arteries filling the cups of the semilunar valves and they close

Question 16

Blood flow from the body to the lungs

Answer 16

• Right side = pumps blood to the pulmonary circuit (lungs)
• Systemic capillaries => vena cava => right atrium => atrium contracts and tricuspid valve open => right ventricle => ventricle contracts and pulmonary semilunar valves open => pulmonary arteries => lungs

Question 17

Blood flow from. the lungs to the body

Answer 17

• Pulmonary capillaries => pulmonary veins => left atrium => atrium contracts and the bicuspid (mitral) valve opens => left ventricle => ventricle contracts and aortic semilunar valves open => aorta => body

Question 18

Coronary circulation

Answer 18

• There is no nourishment to the heart from the blood passing through the chambers
• A series of coronary circulation/vessels exist to supply blood to the heart itself

Question 19

Myocardial infarction

Answer 19

• Heart attack
• Blockage of blood flow to the coronary blood vessels
• Cardiac muscles don’t regenerate (no mitosis), any damage from temporary lack of O2 = fibrosis (scarring) and a permanent reduction in heart function