Heart Dissection

         Every now and then, we receive the remarkable opportunity of observing the marvels of biology not from a textbook, but in person. The heart is a remarkably adamant organ which takes its job to the extreme by providing an around-the-clock pump for the body's circulatory system. Here are just some of the observations made on this beloved organ:

1) Compare the structure of the atria and ventricles - how are they different?  Why is that?

 Perhaps the most distinguishing feature for the atria were their relatively diminutive size when compared to the more muscular and rigid ventricles. Almost sac-like in appearance, the atria were spongy in texture and were flexible and 'inflatable.'They seemed almost detached from the heart structure, and almost looked like flaps serving no apparent structure. The atria need to be flexible in order to expand when blood rushes through them. They must have sufficient capacity to store the blood, and then must then be able to deliver it to the ventricles. The ventricles are much more muscular (left one being more so) in order to squeeze blood at a high velocity. The left ventricle in specific must be powerful enough to squeeze blood to the entire body, whereas its rightward companion need only to deliver the blood to the lungs.

2) Did you notice a difference between the veins and arteries entering and leaving the heart?  How is their structure different?

 The arteries leaving the heart were very thick and more rigid than the veins entering it. The walls for the arteries were much more thicker, and the diameter was narrower in order to increase pressure and velocity - without the walls giving in. The roles however switch when it comes to the pulmonary system, as the veins and arteries are essentially switched.

3) Describe the valves that you found in the heart - what are their functions?

The tricuspid atrioventricular valve allowing blood from the right atriam to enter the right ventricle was similar to the bicuspid atrioventricular valve between the left atrium and the left ventricle. The valves were narrow and guided the blood to the ventricles. They had thin strings (Chordae Tendinae) attached to prevent inversion. Their purpose is to control the amount of blood entering the ventricles, without inverting and allowing blood back into the atrium. The semilunar valves prior to the pulmonary trunk and the aorta were cresecent-shaped and were fairly concealed and tucked away. They purpose is again to control the output of blood without and straying and flowing backwards.

4) What surprised you about dissecting the heart?  Why?

I was most surprised over how large the blood vessels are in actuality. Seeing them in a textbook gives them an elusive nature of being concealed, and far too small to be easily manipulated. However, I soon found my entire finger sliding through one of these vessels (the aorta), with dare I say surprising ease. For some reason I was under the illusion that such a vital vessel would be much more fragile, almost delicate in sense. To my surprise, the vessel was able to sustain the abuse delivered to it through many a prodding and poking. Amazing.