Circulatory System
Objectives:
1. Students will explain how circulatory system work in the body.
2. Students will explore how exercise affects pulse speed.
3. Students will produce a picture of circulatory system.
Engage
Explains: Today you will work to identify the function of the circulatory system by exploring how the heart works.
Show circulatory video:
Ask students what they learned from the video.
Explore
Teach the students how to make "pulse-o-meter".
Push a small wooden kitchen match into the clay. This is our “pulse-o-meter.”
Distribute a ball of clay and a small wooden kitchen match to each student. Instruct students to roll out a small amount of clay into the size of a dime.
Say:
Place the clay on your wrist. Move the “pulse-o-meter” around until you find the spot with the strongest beat. The match should twitch with each pulse beat.
The students will count the number of their pulse in 15 seconds. Explain to students that one’s pulse is the force felt in an artery of the heart contracting in your chest.
Divide the class into 2 groups. One group will do jumping jack while the other group do jogging in place. Ask the students to count their pulse in 15 seconds after the activity.
Explain
After completing the activity, instruct students to answer the following questions:
What is the relationship between physical activity and pulse rate? The amount of physical activity causes the pulse rate to go up. Which activity caused their pulse rate to increase the most? The activity that was the most vigorous.
Why do you think activity caused the heart to pump faster? The muscles need more oxygen, signaling the heart to pump faster.
Explain that the circulatory system is made up of the vessels and the muscles that control the flow of blood through the body. The main parts of the system are the heart, arteries, arterioles, veins, venules, and capillaries. The capillaries connect the venules and the arterioles. The capillaries are only one cell thick. This thin layer allows molecules of oxygen, water, and lipids to pass through and enter the tissues. Waste products such as carbon dioxide and urea can pass back into the blood to be carried away for removal from the body.
As blood begins to circulate, it leaves the heart from the left ventricle and goes into the aorta. The aorta is the largest artery in the body. The blood leaving the aorta is full of oxygen. The oxygen rich blood travels throughout the body in arteries which break into smallest arterioles.
On its way back to the heart, the blood travels through a system of veins and venules. As it reaches the lungs, the carbon dioxide (a waste product) is removed from the blood and is replaced with fresh oxygen that has been inhaled through the lungs. Hemoglobin is a protein in red blood cells that carries oxygen. Without hemoglobin, the oxygen would not be carried in the blood and would have no way to get to the cells.
A rule of thumb is that arteries take blood away from the heart and the veins bring blood back to the heart.
There are four cavities, or open spaces, inside the heart that fill with blood. The two upper cavities are the atria and the two lower cavities are the ventricles.
Produce a picture of circulatory system on the board while explaining.
Elaborate
Students will draw the picture of circulatory system and take notes about how blood circulate and carries O2 and CO2. They will also take notes about heart structure, veins and arteries.
Evaluate and Summary
Check students' journal for the notes.