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.

Why Eating Beets Can Lead To Some Startling Discoveries

              You're just finished your business after almost rupturing your bladder from the wait, and are just about to leave when you notice. Your urine is red! Now before screaming in horror and dialing the nearest hospital, think back on your day and reflect on what you ate. Chances are, you probably had a beet recently.

                
            Known as a phenomena called "Beeturia," excreting red-urine from your urethra can be a tell-tale sign that you may be low on iron. Experts suggest the science behind it relies on "pernicious anemia, which is a chronic condition caused by gastric atrophy which leads to deficient intrinsic factors to process B 12." However, the reasoning behind it isn't that simple. Some evidence points to a genetic problem resulting in being unable to metabolize betalaine - a red pigment. So if you are part of the 14% of people that get a shocker after eating beets, don't feel the need to drop your beet consumption as they are very healthy.

          Iron deficiency, known as anemia, can be compensated by eating a diet rich in dietary iron. Dark leafy vegetables, fish, and eggs are an excellent source of such iron and should be consumed regularly. Beets also carry this iron, along with a host of other 'goodies' such as magnesium, calcium, and folic acid. Beets can cleanse and protect the body through increased production of immune cells and healthy metabolic processes.

So eat up! Just make sure to flush!

http://voices.yahoo.com/sporadic-red-urine-may-beeturia-46741.html


         

Circulation Celebration of Learning

The human body also contains networks of blood vessels. Unless otherwise specified, the vein equivalent of arteries generally share the same name.

Compare the following:

Pulmonary vs. systemic (blood vessels, function, oxygenated vs. deoxygenated)

Arteries vs. veins (structure)

The pulmonary system serves to get deoxygenated blood into the lungs -specifically to the alveoli- where the blood cells can get oxygenated. The pulomanary trunk branches into the pulmonary arteries, which carry deoxygenated blood. After oxygenation, they begin making their way back to the heart, thus being called the pulmonary veins. The systemic system serves to get oxygenated blood throughout the body, with arteries carrying oxygenated blood and veins carrying deoxygenated blood.

Arteries must have thick walls in order to stand through the high pressure of blood that passes through them. They have 3 distinct layers to handle the influx of blood at a high velocity from the aorta. Veins are larger in dimater and are thinner than arteries. They also have valves that allow the blood to move through systematic contractions, and prevent backflow from occuring.

List the structures (specific blood vessels, parts of the heart) that a blood cell would pass by within the circulatory system - moving from the carotid artery all the way back to the aorta.  Include information about where and when the blood is oxygenated and deoxygenated.

Carotid artery (oxygenated) -> Brain (Oxygen arrives) -> Internal Jugular Vein (deoxygenated) -> Superior Vena Cava (deoxygenated) -> Right Atrium (deoxy) -(AV)> Right Ventricle -(Semilunar Valve)> Pulmonary Trunk -> Pulomary Arteries -> Lungs (oxygenated) -> Pulmonary Veins -> Left Atrium -(AV)> Left Ventricle -(SL Valve)> Aorta (oxygenated)

Fetal circulation:  Describe the 3 major modifications of the fetal circulatory system.  What is the purpose of each?

Foramen Ovale : Allows blood to enter the Light Atrium from the Right Atrium through an opening; effectively bypasses the lungs.

Ductus Arteriosis: Allows blood from the Pulomanary Arteries to bypass developing lungs and enter the aorta.

Ductus Venosus: Allows oxygenated blood from the placenta to enter the vena cava and bypass the liver