L1: Introduction

Question 1

Why do we need a cardiovascular system?

Answer 1

• All living cells are metabolically active- use O2 and produce CO2
• Single cells or small organisms can get O2 and nutrients directly from the envrioment via diffusion
• Larger organisms need a system for getting nutrients and O2 close to the cells for diffusion to happen

Question 2

What allows diffusion to take place in larger organisms?

Answer 2

Capillaries are specifically designed.
One endothelial cell thick surrounded by thin layer of basal lamina.
Lipid soluble molecules diffuse across the membrane, water soluble molecules diffuse between the cells.

Question 3

What is the purpose of the CVS?

Answer 3

• Take O2 and nutrients to the capillaries where diffusion can take place
• CO2 and waste products diffuse into the blood at the capillaries
• Deoxygenated blood leaving tissue is pumped via the heart to the lungs where it is oxygenated
• Alveoli have a rich blood supply
• Capillaries are the most important site for diffusion

Question 4

Why does the heart need a blood supply?

Answer 4

Left ventricle contains oxygenated bloods, however the distance of cells from O2 and nutrients is too far for diffusion.

Question 5

What is the name of the arteries that supply the heart?

Answer 5

The Coronary Arteries; right and left coronary arteries arise from the aortic sinuses. (small opening behind the left and right flap of the aortic valve).

Question 6

What are the branches of the left coronary artery?

Answer 6

The LCA branches to give the left anterior descending (LAD) artery (or left interventricular artery) (left anterior surface of the heart) and the circumflex artery (onto the posterior surface of the heart)

Question 7

What does the right coronary artery become?

Answer 7

RCA out of right side of the aorta, supplies the right side of the heart and becomes the marginal artery which runs along the border of the inferior surface of the heart.

Question 8

What are the name of veins? Where do they drain?

Answer 8

The cardiac veins. Drain into the coronary sinus into the right atrium.
Greater cardiac veins, middle cardiac veins, Small cardiac veins, anterior cardiac veins and oblique vein of left atrium

Question 9

What happens if the coronary arteries get blocked?

Answer 9

Myocardial infarction.
Cells are starved of oxygen and begin to die.
Few end arteries (anastomoses- joining of arteries) in the heart.
Prone to atheroma (narrowing due to atheromatous plaque formation)

Question 10

Where does the heart sit?

Answer 10

Middle mediastinium

Question 11

What covers the heart?

Answer 11

Layer of epicardial fat which has the coronary arteries embedded.
Then the visceral pericardium (epicardium) which is the inner serous layer.
Pericardical cavity filled with pericardial fluid (excess fluid squishes the heart preventing it from relaxing properly)
Outer parietal pericardium which is the outer serous layer.

Question 12

Where is the transverse pericardial sinus and oblique sinus?

Answer 12

Transverse pericardial sinus –> under the pulmonary trunk, arch of aorta, and superior vena cava.
Oblique sinus –> Posterior surface of the heart it is a blind ended sac.