L20 Coronary Circulation, Pathology and Effects of Ischemic Heart Disease

Question 1

Which coronary vessels branch from the aorta?

Answer 1

Left and right coronary arteries

Question 2

True or false: The left coronary artery passes posteriorly to the left atrium

Answer 2

False

The left coronary artery passes anterior to the left atrium

Question 3

What are the main branches of the left coronary artery?

Answer 3

Circumflex

Anterior descending

Remember Left Coronary Artery = LCA:

L = left coronary artery
C = circumflex
A = anterior descending

Question 4

Where does the circumflex branch go?

Answer 4

Circumflex runs along the coronary sulcus and supplies the left atrium and ventricle with blood

Question 5

Where does the left anterior descending branch go?

Answer 5

LAD extends along anterior interventricular sulcus and supplies blood to the walls of both ventricles

Question 6

True or false: The right coronary artery extends inferiorly to the right atrium

Answer 6

True

It has small branches that supply the right atrium

Question 7

What are the main branches of the right coronary artery?

Answer 7

Posterior descending

Right marginal

Think! RPM:

R = right coronary artery

P = posterior descending

M = marginal (right)

Question 8

Where does the posterior descending (posterior interventricular) branch go?

Answer 8

Follows posterior interventricular sulcus and supplies walls of both ventricles

Question 9

Where does the right marginal branch go?

Answer 9

Follows the coronary sulcus and supplies the right ventricle

Question 10

Which coronary vessel drains deoxygenated blood from the anterior region of the heart?

Answer 10

Great cardiac vein

Question 11

Which coronary vessel drains deoxygenated blood from the posterior region of the heart?

Answer 11

Middle cardiac vein

Question 12

The great and middle cardiac veins return deoxygenated blood to which common vessel?

Answer 12

Coronary sinus

Question 13

Where does the coronary sinus empty into?

Answer 13

Right atrium

Question 14

What happens in myocardial ischemia?

Answer 14

Partial or full obstruction of a coronary artery causes hypoxia. Lack of O2 means heart cells cannot produce ATP, and this inhibits actin/myosin contraction, Na/K pumps, ATP-gated K channels.

Can induce angina pectoralis

Question 15

True or false: Pain in the neck, chin or left arm could be a symptom of angina pectoralis

Answer 15

True

Question 16

What is a chylomicron?

Answer 16

The largest classification of lipoprotein (100nm-1um)

Question 17

What is the function of apoproteins?

Answer 17

Ligands incorporated to the outer shell of a lipoprotein. They govern how and where the protein is transported.

Question 18

The outer shell of a lipoprotein is made of apoproteins and amphipathic lipids (having hydrophobic and hydrophilic parts).

What amphipathic lipids make up the outer shell of the lipoprotein?

Answer 18

Phospholipid

Cholesterol

Question 19

What molecules make up the core of the lipoproteins?

Answer 19

Triglycerides and cholesterol ester

Question 20

Apoprotein-B100 is present in LDL-C particles. Where does it direct the LDL-C molecules to go?

Answer 20

To cells where cholesterol is used in membrane and steroid synthesis

Question 21

Fill in the gaps: Lipoprotein lipase hydrolyses triglycerides into __1__ fatty acid chains and one __2__ molecule.

Answer 21

1. two

2. monoacylglycerol

Question 22

How does an atheroschlerotic plaque develop?

Answer 22

1. ↑ in LDL lipoproteins. These are removed by macrophages.
2. Macrofages form foam cells, which attach themselves to endothelial wall.
3. Foam cells release cytokines, inducing replication of SMCs of tunica intima and attracting more monocytes
4. Macrophages, SMCs and endothelial cells take up lipoproteins, resulting in atherosclerotic plaque
5. Gaps form in endothelium and platelets attach to exposed collagen - forms clot

Question 23

What are the treatments for hypercholesterolaemia?

Answer 23

• Statins: inhibit HMG-CoA and mevalonate pathway
• Fibrates: ↑ hepatic LDL-C uptake
• Bile acid-binding resins: reduce cholesterol absorption from intestines, stimulate upregulation of LDL receptors to ↑ clearance from the blood. Often cause diarrhoea