Blood Supply

Question 1

Coronary circulation

Answer 1

1. Blood from the coronary sinus drains into the right atrium > right ventricle -›
   oulmonary arteries - pulmonary veins - left atrium -> left ventricle -> aortic root -> coronary arteries -> coronary sinus.
   ?.coronary vessels
   a) The coronary arteries provide oxygenated blood to the heart.

Question 2

Coronary arteries

Answer 2

• The left coronary artery (LCA) branches into the circumflex artery (LCX) and the left anterior descending artery (LAD).
• The LCX supplies blood to the lateral and posterior walls of the left ventricle.
• The PDA branches off of the LCX 10% of the time. These patients are considered to have a left-dominant circulation.
• The LAD supplies blood to the anterior wall of the left ventricle and the anterior ⅔ of the interventricular septum.
• The right coronary artery (RCA)
  branches into the right marginal arteryand the posterior descending artery (PDA) 80% of the time.

(1) The right marginal artery supplies the right ventricle.
(2) Also supplies the papillary muscles of the right ventricle and the posterior wall of the heart.
(3) The RCA gives rise to the PDA in patients with right-dominant circulation.

Question 3

Systemic and pulmonary circulation

Answer 3

Blood from the vena cava drains into the right atrium -> right ventricle -> pulmonary arteries -> pulmonary veins -> left atrium » left ventricle -> aorta -> systemic circulation (arteries, arterioles,
capillaries, venules, veins) -> vena cava.

Oxygen exchange occurs at the capillaries.

Question 4

What part of the systemic circulation contributes the most to total peripheral resistance?

Answer 4

The arterioles

Question 5

How would an arteriovenous (AV) shunt alter the oxygen content in the tissues?

Answer 5

• In an AV shunt, oxygen bypasses the capillaries and goes directly from the arteries to the veins
• Less oxygen enters the tissues -> ^ oxygen in the veins

Question 6

Dilation of what part of the heart can cause dysphagia?

Answer 6

• The esophagus is directly posterior to the left atrium
• Dilation of the left atrium can compress the esophagus -> dysphagia

Question 7

What vessel in the body contains the most deoxygenated blood?

Answer 7

• The heart is more metabolically active than the peripheral tissues
• it extracts more oxygen from RBCs than the peripheral tissues
• Therefore, the last part of the coronary circulation (the coronary sinus) contains the most deoxygenated blood

Question 8

How would the right ventricle appear on an echocardiogram in a patient with stenosis of the right coronary artery?

Answer 8

• The RCA supplies blood to the posterior aspect of the heart
• Stenosis of the RCA would result in decreased activity of the posterior aspect of the right ventricle

Question 9

How would stenosis of the pulmonary artery alter the pressure in the right ventricle, right atrium, and coronary sinus?

Answer 9

• Stenosis of the pulm. artery -> ^ volume in the right ventricle and right atrium - ^pressure so pressure in CS will also increase