Sheep Heart Dissection Lab

11/12/15

Sheep Heart Dissection Lab

Question 7, 10

Question 12

Questions 5

1. The pericardium is a double membrane sac that secretes fluid to lubricate the heart, as it reduces friction as the heart expands and contracts. The visceral layer is part of the heart wall while the parietal layer attaches to the body.
2. Arteries are much thicker than veins, which we observes as we cut through the pulmonary vein to get to the left atrium. The veins were marginally thinner, almost like paper, and much more elastic than the arteries which consisted of more smooth muscle. 
3.  The auricle is hollow and is visible on the outside of the heart. It is an extension of the atrium, which allows the atrium to hold more blood/ increase the capacity.
4. Externally, the ventricles are not visible at all on the outside of the heart. However, atria, on the other hand, have an extension called auricles, which are ear-like structures on the outside surface of the heart. Surrounding the left side of the heart, there is a thicker layer of myocardium because it requires more force to expel the blood to the entire lower half o the body than it does to push the blood to the lungs. 
5. See picture above
6. The anchoring of the heart valves by the chordate tendinae and the papillary muscle is important to heart function because without these, the valves would not be functional, causing a back flow of blood. The chordate tendinae and the papillary muscle are used to close the valve and without being anchored they wouldn't be able to flex and contract and close the valve.
7. We see the inside of the left atrium, which a hollow cavity. Looking down, we can see the bicuspid valve, which is held to the walls by chordate tendinae and papillary muscles. see pic above
8. The semilunar valves are utilized to prevent the back flow of arterial blood from re-entering the heart as the heart pushes blood out to the lungs and the rest of the body. The pulmonary semilunar valve helps stop any leakage of blood as it is pushed to the lungs while the aortic semilunar valve prevents back flow as blood is pumped to the rest of the body.  
9. a) If there is a defect with the valves on the right side of the heart, the blood would leak back through the valves. Because the blood on the right side of the heart comes from the rest of the body, backflow and gravity would pull the blood back down to the feet and ankles, causing swelling.
   b) If the valve disease existed on the left side, one could expect to see problems with the oxygen exchange in the lungs, as the blood would backflow to the lungs. This would probably affect the rest of the body as well because the blood would not be quite as efficient at providing the rest of the body with oxygen.
10. After we cut the heart into cross sections, we had a clear view of the left atrium to the left ventricle. The bicuspid valve is functional due to the chordate tendinae that hold the valve flaps. From the left ventricle, we found an opening to the aortic semilunar valve. Although we found this opening, it was mostly obscured from our view; however, it possessed a similar structure to the biscuspid. see pic above
11. The left side of the heart contains a thicker myocardium layer due to the extra force need to the push the blood to the rest of the body, as the right side of the body only needs to push the blood to the lungs, a lesser distance in comparison. The right side contains deoxygenated blood from the rest of the body while left side contain oxygenated blood from the lungs. 
12. see picture above