Cardiovascular System

Editor's Notes

• #3 (Energy needed to raise 1 L of water by 1oC.)
• #5 Orientation: R and L are the perspective of the heart’s owner as it sits in their chest cavity. All mammals & birds have 4 chambered heart that don’t allow oxygenated and deoxygenated blood to mix. Ectotherms have 1, 2, or 3-chambered heart, don’t need the efficiency of a 4-chambered heart because they don’t need the extra energy for thermoregulation.
• #6 EXPERIMENT 14.1 - Your Own Cardiac Cycle Supplies : A watch with a second hand or (better yet) a stopwatch Introduction - Each person has his or her own cardiac cycle time depending on metabolic rate and other factors. In this experiment, you will determine your own cardiac cycle under different conditions. Procedure : You have probably been sitting down quietly (or at least reasonably quietly) reading this incredibly interesting course. Although you have, most likely, been excited about all of the wonderful things you have been learning, chances are good that you are close to your “resting” cardiac cycle. Thus, I want you to measure that now. To measure your cardiac cycle, place the index finger of your right hand at the inside of your left wrist on the thumb side. Lightly push around the area until you feel a constant beat. That's your pulse. Count the number of times your pulse beats in 30 seconds. When your heart pumps blood into your aorta, the increased pressure in your arteries causes them to expand. That expansion travels through the arteries. When you feel your pulse, you are touching an artery, and the beat that you feel is caused by the artery expanding and contracting in response to the heart pumping blood into the aorta. In the end, then, each beat you feel corresponds to a heartbeat. If you double the number of beats you felt in 30 seconds, that will tell you how many times your heart beats per minute. However, I want you to do something else. Divide 30 by the number of beats you counted. This will give you your cardiac cycle, which essentially tells you how long your heart takes to make one beat. The average person your age has a cardiac cycle of about 0.75, which corresponds to 80 beats per minute. Now, of course, the cardiac cycle you just measured corresponds to your resting cardiac cycle. If your body starts expending lots of energy, the blood must flow more quickly so that the cells in your body can get enough oxygen to make the energy they need. This changes your cardiac cycle. To measure this, do one full minute of vigorous jumping jacks right now. As soon as you are done with the jumping jacks, put your finger back on your wrist and count the beats you feel in your pulse for 30 seconds. Wait for one full minute, sitting quietly, and count your pulse beats again for a period of 30 seconds. Repeat step (F) at least 4 more times. Once you are done, go back and divide 30 by each of the number of pulse beats that you counted. This gives you your cardiac cycle during the time that you rested after completing the jumping jacks.
• #9 http://www.ac-creteil.fr/biotechnologies/doc_biohum-heart3Dinsight.htm
• #10 Lub = “lower” (outer) valves closing
• #11 http://www.sumanasinc.com/webcontent/animations/content/human_heart.html
• #13 Supplies: laminated circulatory system labels, string/yarn, envelopes with oxygen & carbon dioxide cards. Optional: use balls (inflatable beach balls, stuffed soccer balls, big rubber playground balls, etc.) that students toss or hand off to each other as they stand at different body locations. Students in the lungs and capillaries have the job of removing/attaching O2 and CO2. Set labels on floor in order.
• #14 Blood vessels carrying deoxygenated blood appear to be blue, when in fact they are dark red. Even though this is a distortion of color caused by viewing the blood vessels through the skin, the blue color is still used as a means of representing deoxygenated blood. Arteries also have a smooth muscular layer that functions to regulate the flow of blood through the artery. Contraction of the smooth muscle decreases the internal diameter of the vessel in a process called vasoconstriction. Relaxation of the smooth muscle increases the internal diameter in a process called vasodilation. If you took a person's arteries (not including arterioles or capillaries) and laid them all out end to end, you'd have about the same distance as Portland to LA...and back again (2,500 miles)