Regional Circulation - Coronary

Question 1

The coronary circulation covers…

Answer 1

…the circulation of blood in the blood vessels that supply the heart muscle (myocardium)

Question 2

The left coronary artery supplies the…

Answer 2

Left atrium
Left ventricle
Anterior part of interventricular septum

Question 3

The right coronary artery supplies the…

Answer 3

Right atrium
Right ventricle
Posterior part of interventricular septum

Question 4

Two coronary arteries arise from what side of the heart?

Answer 4

The left side of the heart, at the beginning of the aorta. They are the left and right coronary arteries

Question 5

What are the branches of the left coronary artery?

Answer 5

The circumflex artery

The left anterior descending artery

Question 6

What are the branches of the right coronary artery?

Answer 6

• Atrial ventricular nodal branch
• Right marginal artery
• Posterior descending artery

Question 7

There are no anastomoses between the left and right coronary arteries. True or false?

Answer 7

False. There are small anastomotic connections between the 2 coronaries, but they are not sufficient to supply the cardiac muscle with blood

Question 8

What percentage of cardiac output is coronary blood flow?

Answer 8

5%

Question 9

Coronary blood flow at rest in humans is…

Answer 9

250 ml/min

Question 10

The right coronary artery has a greater flow in

Answer 10

50% of population

Question 11

The left coronary artery has a greater flow in

Answer 11

20% of the population

Question 12

Blood flow in the left and right coronary arteries are equal. True or false?

Answer 12

In 30% of the population, yes. It varies from one person to the other.

Question 13

What are the venous systems in the cardiac muscle?

Answer 13

Superficial and Deep

Question 14

The superficial venous system of the cardiac muscle is comprised of…

Answer 14

The coronary sinus and the anterior cardiac vein

Question 15

The veins in the superficial venous system of the cardiac muscle drain…

Answer 15

…mainly left ventricle and open into the right atrium

Question 16

The deep venous system of the cardiac muscle is comprised of…

Answer 16

…thebesian veins

Question 17

The veins in the deep venous system of the cardiac muscle drain…

Answer 17

…small amount of the coronary venous blood directly into all chambers of the heart.

Question 18

What influences the amount of blood flow to the myocardium?

Answer 18

Myocardial demand for oxygen.

Question 19

Phasic changes in the right ventricle is relatively less than that of the left ventricle. True or false? Why?

Answer 19

True. Because the force of contraction of the right ventricle is far less than that of the left ventricle

Question 20

When is myoglobin loaded with oxygen?

Answer 20

Diastole

Question 21

LThe lowest CBF occurs during…

Answer 21

…the isometric contraction phase

Question 22

Does the CBF drop during systole? Why?

Answer 22

It does, due to strong compression of the subendocardial vessels that enter the myocardium as a result of high ventricular pressure

Question 23

What is the effect of the compression of subendocardial coronary vessels during systole?

Answer 23

Momentary retrograde flow which further inhibits perfusion of myocardium

Question 24

Changes in CBF during systole

Answer 24

• CBF drops

- High ventricular pressure

Question 25

The highest CBF occurs during...

Answer 25

...isometric relaxation phase

Question 26

Effect of low coronary perfusion pressures on the endocardium

Answer 26

It makes it more susceptible to ischemia because of extravascular compression

Question 27

Tachycardia lengthens coronary filling time during diastole. True or false?

Answer 27

False, it shortens it.

Question 28

Where is the venous oxygen content higher? Coronary or others?

Answer 28

Others

Question 29

Where is the oxygen consumption higher? Coronary or others?

Answer 29

Coronary vessels

Question 30

Where is the oxygen extraction higher? Coronary or others?

Answer 30

Coronary vessels

Question 31

Where is the venous oxygen reserve higher? Coronary or others?

Answer 31

Others

Question 32

Intrinsic mechanism for regulation of CBF

Answer 32

Oxygen demand or need

Question 33

Extrinsic mechanism for regulation of CBF

Answer 33

Chemical Nervous Mechanical

Question 34

The heart has a very low basal oxygen consumption. True or false? What’s the value?

Answer 34

False. It’s high. 8-10 ml O2/min/100g).

Question 35

Active hyperaemia occurs in the heart during...

Answer 35

...exercise

Question 36

What occurs if the coronaries are temporarily occluded?

Answer 36

Reactive hyperaemia, leading to increase of the CBF about 3-4 folds

Question 37

Mention two coronary vasodilators

Answer 37

Adenosine | Nitric oxide

Question 38

Sympathetic activation of the heart results in...

Answer 38

coronary vasodilation and increased coronary flow due to increased metabolic activity

Question 39

Increased venous return causes CBF to...

Answer 39

...rise

Question 40

Effect of venous return on CBF is called...

Answer 40

Anrep’s reflex

Question 41

Describe the gastrocoronary reflex

Answer 41

Distension of the stomach with heavy meal produces reflex coronary VC and decreased CBF

Question 42

Mechanical factors that affect coronary blood flow

Answer 42

- Phases of cardiac cycle - Heart rate - Mechanical occlusion of coronary artery

Question 43

Effect of the heart rate on coronary blood flow

Answer 43

It is inversely proportional. The higher the heart rate, the shorter the coronary blood flow by shortening of the diastolic period. Otherwise, diastole is prolonged.