Educator Info: What Goes Around Comes Around
Create a traveling circulatory system to learn how blood flow and nutrient exchange happens throughout the body.
Lesson at a Glance
Students will understand the circulatory system's main function is to transport nutrients and remove waste from cells, tissues and organs in the body.
Illinois Learning Standards
3: A, C; 4: A; 5: C; 6: B; 7: C; 23: A, B
Middle / Junior High
3: A, B, C; 4: A; 5: C; 6: B, C; 23: A, B
The circulatory system, also called the cardiovascular system, contains the heart and blood vessels. Its main function is to circulate, or transport, oxygen, blood, hormones, white blood cells and chemicals to all major organs, cells and tissues in our body.
The circulatory system is also responsible for transporting waste products to the appropriate organs to be sent out through the body's excretory systems - the urinary system and the integumentary system. For example, the kidneys filter waste and excess salt from the blood. This waste product, known as urea, is removed from the body through the urniary system in the form of urine.
The circulatory system works as a two-part system. When the heart contracts, it pushes the blood out into two major loops or cycles. In the systemic loop, the blood circulates into the body's systems, bringing oxygen to all its organs, tissues and cells and collecting carbon dioxide and other waste products. One example of this is in the small intestine, where nutrients from the foods we eat are absorbed. The nutrients then enter our bloodstream and are carried by the red blood cells to the rest of the body.
In the pulmonary loop, the blood circulates to the lungs to release carbon dioxide and pick up new oxygen. Blood travels from the right side of the heart to the lungs where deoxygenated blood is exchanged in the alveoli for oxygenated blood. The blood then returns to the heart, only this time to the left side. The blood first enters the heart through the left atrium then travels to the left ventricle which pumps the blood to all cells, tissues and organs.
You are a red blood cell that has just finished its journey through the body system. Write a travel journal of your trip, describing every step of the journey and what you delivered or collected at each stop.
Scientists have estimated that it takes about 30 seconds for a given portion of blood to complete the entire cycle, from lungs to heart to body, back to the heart and out to the lungs. Given this statistic, how many times would a single blood cell circulate through the body in one hour? In one day?
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