Exercise 30 Anatomy of the Heart

1. An anterior view of the heart is shown here. Match each structure listed on the left with the correct letter in the figure.

1. right atrium
2. right ventricle
3. left atrium
4. left ventricle
5. superior vena cava
6. inferior vena cava
7. ascending aorta
8. aortic arch
9. brachiocephalic artery
10. left common carotid artery
11. left subclavian artery
12. pulmonary trunk
13. right pulmonary artery
14. left pulmonary artery
15. ligamentum arteriosum
16. right pulmonary veins
17. left pulmonary veins
18. right coronary artery
19. anterior cardiac vein
20. left coronary artery
21. circumflex artery
22. anterior interventricular artery
23. apex of heart
24. great cardiac vein

2. What is the function of the fluid that fills the pericardial sac?

Fluid in the pericardial sac allows the heart to beat in a relatively frictionless environment, to reduce friction during heart activity

3. Match the terms in the key to the descriptions provided below.

Key:

• a. atria
• b. coronary arteries
• c. coronary sinus
• d. endocardium
• e. epicardium
• f. mediastinum
• g. myocardium
• h. ventricles

1. location of the heart in the thorax – f
2. superior heart chambers – a
3. inferior heart chambers – h
4. visceral pericardium – e
5. “anterooms” of the heart – a
6. equals cardiac muscle – g
7. provide nutrient blood to the heart muscle – b
8. lining of the heart chambers – d
9. actual “pumps” of the heart – h
10. drains blood into the right atrium – c

4. What is the function of the valves found in the heart?

The valves enforce a one-way blood flow blood through the heart

5. What is the role of the chordae tendineae?

Their called heart strings, & anchor the cusps to the ventricular walls

Pulmonary, Systemic, and Cardiac Circulations

6. A simple schematic of a so-called general circulation is shown below. What part of the circulation is missing from this diagram? Pulmonary circulation

Add to the diagram as best you can to make it depict a complete. Systemic arteries Systemic capillaries Systemic veins pulmonary circulation systemic sirculation.

7. Differentiate clearly between the roles of the pulmonary and systemic circulations. Differences include pulmonary circulation is strictly to provide gas exchange in the lungs, whereas the systematic circulation provides the functional blood supply to all body tissues.

8. Complete the following scheme of circulation of a red blood cell in the human body.

Right atrium through the tricuspid valve to the right ventricle , through the pulmonary , to the capillary of the heart, through semilunar beds of the lungs, to the the valve to the pulmonary trunk, to the pulmonary arteries pulmonary veins valve to the , to the left atrium , through the bicuspid aortaleft  ventrical aortic semilunar of the , and valve to the , to the systemic arteries, to the capillary bedstissues, to the systemic veins, to thesuperior vena cava, inferior vena cavacoronary sinus & cardiac veins entering the right atrium of the heart.

9. If the mitral valve does not close properly, which circulation is affected?

pulmonary circulation

10. Why might a thrombus (blood clot) in the anterior descending branch of the left coronary artery cause sudden death?

Microscopic Anatomy of Cardiac Muscle

11. How would you distinguish the structure of cardiac muscle from that of skeletal muscle?

12. Add the following terms to the photograph of cardiac muscle below. a. intercalated disc b. nucleus of cardiac fiber c. striations d. cardiac muscle fiber

Describe the unique anatomical features of cardiac muscle. What role does the unique structure of cardiac muscle play in its function?

Dissection of the Sheep Heart

13. During the sheep heart dissection, you were asked initially to identify the right and left ventricles without cutting into the heart. During this procedure, what differences did you observe between the two chambers?

When you measured thickness of ventricular walls, was the right or left ventricle thicker? Knowing that structure and function are related, how would you say this structural difference reflects the relative functions of these two heart chambers?

14. Semilunar valves prevent backflow into the ; AV valves prevent backflow into the . Using your own observations, explain how the operation of the semilunar valves differs from that of the AV valves.

15. Compare and contrast the structure of the right and left atrioventricular valves.

16. Two remnants of fetal structures are observable in the heart—the ligamentum arteriosum and the fossa ovalis. What were they called in the fetal heart, where was each located, and what common purpose did they serve as functioning fetal structures?

References:

• Whitaker, Robert H. “Anatomy of the heart.” Medicine 42.8 (2014): 406-408.
• Mahadevan, Vishy. “Anatomy of the heart.” Surgery-Oxford International Edition 30.1 (2012): 5-8.
• Wessels, Andy, and David Sedmera. “Developmental anatomy of the heart: a tale of mice and man.” Physiological genomics15.3 (2003): 165-176.
• Mahadevan, Vishy. “Anatomy of the heart.” Surgery-Oxford International Edition 33.2 (2015): 47-51.