Heat Dissection

1. What is purpose of the pericardium?
1. The pericardium is the membrane enclosing the heart that has an outer fibrous layer and an inner double layer of serous membrane. It gives protection and lubricates the heart.
2. How do arteries differ from veins in their structure?
1. Veins have thinner walls than arteries. Veins are a one way valve and prevent backflow of blood. This is where muscle contractions and blood flow occurs. Viens store the most blood volume in the body and carry blood to the heart from the tissues. Arteries carry blood away from the heart to the tissues. They are elastic and expand when the heart contracts and recoils when the heart relaxes.
3. What function do you think the auricle serves?
1. The auricles are ear shaped pouches located in the atria that collect blood and increase the blood holding capacity.
4. What differences do you observe in the external structures of the atria and ventricles?
1. The ventricles are a lot larger and have much thicker walls than the atria. The atria are superior to the ventricles, which means the atria are the upper chambers and the ventricles are the lower chambers
5. Find and describe the following structures in the heart:
1. Exit from the coronary sinus: A group of veins located in the heart that deliver deoxygenated blood to the right atrium
2. Exit from the inferior vena cava: The inferior vena cava is on the lower right ventricle of the heart and allows blood to enter the right atrium
3. Right atrioventricular valve (tricuspid): The tricuspid valve is located in between the right atrium and ventricle. We noticed there was a big difference between the tricuspid and bicuspid valve because we saw that the tricuspid clearly had 3 chordae tendinae while the bicuspid valve had 2.
6. Draw a picture of the tricuspid valve, including the chordae tendineae and the papillary muscle:

7. Why is the “anchoring” of the heart valves by the chordae tendineae and the papillary muscle important to heart function?
1. Anchoring of the heart valves by the chordae tendineae and the papillary muscles is important because it prevents the valve from moving and pushing blood in the wrong direction.
8. Using pictures/words, describe what the bicuspid valve looks like:

1. Rather than three cusps like in the tricuspid, the bicuspid valve has two cusps complete with chordae tendinae, string like fibers that attach the cusp to the papillary muscles that power the valve.
1. What is the function of the semi-lunar valves?
1. Semilunar valves prevent arterial back flow, meaning they prevent blood from re-entering the heart. There are 2 semilunar valves. The pulmonary valve which is by the left ventricle and the aortic valve, by the aorta.
2. Congestive heart failure is a life-threatening condition
1. If the valve disease occurs on the right side of the heart, it results in swelling in the feet and ankles. Why?
1. Because blood fails to be contained in the right atrium/ventricle and backflows to the body.
2. If the valve disease occurs on the left side of the heart, what complications would you expect to see?
1. There would be swelling of the heart due to the abnormal amount of blood gathering in the heart.
3. Using pictures/words describe what the left ventricle looks like:

1. Entrance to the left/right coronary arteries: The coronary arteries pass from the inside of the heart to the sides and then to the outside, supplying the heart with blood.
2. Left (aortic) semilunar valve (3 cusps): This valve, like the tricuspid, has three cusps. It prevents blood from flowing back into the heart as the oxygenated blood flows through the aorta to the body.
3. Chordae tendinae of the bicuspid valve: These stringy fibers attach the bicuspid valve itself to the papillary muscles, pulling and loosening as the valve closes and opens.
4. Papillary muscle of the bicuspid valve: The papillary muscle provides the muscle power, pulling on the chordae tendinae to open and close the valve.
1. Describe how the left and right sides of the heart differ from each other:
1. The right side of the heart has thinner walls and pumps blood to the body while the left side of the heart has thicker walls due to the aorta and connects blood from the body.
2. Draw and label all structures visible in the interior of the cross-section: