I will introduce the circulatory system as an organ that has the main function of delivering blood: that is, moving blood throughout the body. I will ask the students to brainstorm other delivery systems that they know in our world. I will amaze the students by setting the classroom timer for one minute/ sixty seconds. All the students will remain still and quiet during that minute. At the end of the minute, I will tell the students that blood was just circulated throughout their whole body. The students will be informed that it takes a little less than a minute for their blood to circulate throughout their whole body.4 The body consists of five liters of blood and in that minute, when we are sitting still, our body circulated one liter of our five liters of blood throughout the body. To demonstrate this concretely, I will display five liters of water with red food coloring. The students will pour all five liters of red water into a clear bucket. This bucket will demonstrate how much blood is in their body.
The blood consists of water and three types of blood cells carried around in yellow liquid called blood plasma. The three types of blood cells are red blood cells, white blood cells, and platelets.5 The students will view illustrations of each type of blood cell and create their own illustrations in their journals.
: plasma, red blood cells, white blood cell, platelets
I will explain to the students that the blood flows throughout the body through a network of tubes called blood vessels. The main types of blood vessels in the body are arteries, veins, and capillaries. Arteries carry blood away from the heart. Veins carry blood toward the heart.6 Capillaries are the smallest vessels between the arteries and veins, where the exchange of oxygen and nutrients occurs.
: blood vessel, arteries, veins, capillaries
I will place an enlarged illustration of the heart on the board and explain that the heart is what pumps the blood throughout the body. It is located in the middle of the chest, slightly tilted to the left. It weighs about ten ounces. The heart pumps blood by constantly contracting (squeezing) and relaxing (releasing).7 This will be demonstrated by squeezing and releasing a sand filled small red balloon. I will then go on to tell them the basic structure of the heart and functions of the heart using the illustration. The heart has two pumps that are called the left and right ventricles. The right ventricle pumps blood to the lungs and the left ventricle pumps blood throughout the rest of the body to every cell. When listening to a heartbeat the sound is often described as lub-dub lub-dub. The first sound (lub) is caused by the acceleration and deceleration of blood and a vibration of the heart at the time of the closure of the first set of valves. The second heart sound (dub) is caused by the same acceleration and deceleration of blood and vibrations at the time of closure of the second set of valves. Your heart, blood vessels, and blood work together to supply each cell with food and oxygen, and carries away waste. The heart, blood, and blood vessels make up the circulatory system. After the basic explanation of the functions of the heart the students will participate in listening to a human heart beat on the website: http://www.fi.edu/biosci/monitor/heartbeat.html. The students will identify the closing of the valves through the "lub, dub" sounds made. The students will then follow the path of blood flow through the heart using a coloring handout that can be downloaded and printed from the website: www.childrenheartinstitute.org
: heart, ventricle, cell
I will explain to the students that when blood is pumped out from the heart it rushes through the blood vessels, pressing on their walls as it passes by. Blood pressure depends on the amount of blood in the system. I will demonstrate the action of blood pressure to the student by flowing different amounts of red water (blood) through a malleable tube, like varies sized drinking straws. The students will observe the difference in the tube's shape based on increasing and decreasing the red water supply. The average blood pressure for an individual should or close to 120 over 80. I will tap prior knowledge by asking the students, "Has anyone here ever gone to the doctor's office or a hospital? Has anyone here ever had a cuff placed on their arm and tightened at the doctor's office or the hospital?" Well, if yes then you have had you blood pressure taken. Blood pressure is measured by numbers. The top number (120) is called systolic pressure. The systolic pressure is the blood pressure when the heart is contracting. The bottom number (80) is called diastole pressure. The diastole pressure is the pressure of the blood when the heart is relaxing.
: pulse, systolic, diastolic
Healthy Heart Rate
I will ask the students to take their own pulse by placing two fingers on their opposite wrist and press down gently. The students will participate in taking their own pulse twice, the first time they will be at rest. The second time will be after a quick spurt of exercise such as running in place. We will then compare how the heartbeats differed for each activity. We would then talk about being active keeps are heart healthy. The students will then pair up with a partner and the pair will take each others pulse after different activities. Physical activities can influence a heart health by making the heart stronger. I will then go on to explain that there are average healthy pulse rates that are based on the age of a person. Create a classroom chart of age and target and average heart rates. Target and average heart rate information provided by
Target Heart Rates