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1. It contracts sending oxygen-rich blood tissues and oxygen-poor blood to the lungs.
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2. The nervous system controls heart beat and tissue known as the pacemaker also controls heart beat.
C. Blood Flow
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1. Blood returning to the heart from all parts of the body enters the right auricle.
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2. This aurisle contracts, squeezing the blood through the tricuspid valve into the right ventricle. (The valve prevents the blood from flowing backwards.)
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3. This blood is a dull red color for it has come from the body tissues and it contains CO2. Thus the blood must be sent to the lungs to get rid of the CO2.
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4. The right ventricle pushes this blood into special arteries known as the “pulmonary arteries”. These arteries carry the blood to the lungs.
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5. In the lungs, the blood picks up oxygen and gets rid of carbon dioxide. The blood is now bright red, rich with oxygen and is ready to be sent back to the heart through the pulmonary veins.
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6. From these veins, the blood enters the left side of the heart into the top chamber known as the left auricle.
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7. The left auricle squeezes the blood through the mitral valve and into the left ventricle.
8. The left ventricle pushed the blood out of the heart through the largest artery in the body, the aorta. It branches into smaller arteries which branch throughout the body.
To me, this part of the unit can get complicated. There is an abundance of words and terms, and the order in which the blood flows through the heart is hard to learn for the students cannot see this process work in front of them. We must supplement this with activities that can make the student visualize the order.
Lesson I Learning the Parts
Having posters or diagrams of the heart pinned up somewhere in the classroom is a good start in learning the main parts of the heart. Having students draw diagrams or make a nice colored poster of the heart and its parts is also a good project or homework assignment. The student is drawing and coloring but at the same time learning where parts are located.
Lesson II
I still believe however, that students want to see the real thing. An excellent lab for the students would be to work on and compare a calves’ heart with a fetal pig, frog and chicken heart. Students can actually see the different sizes and shapes of each heart. They can feel and touch and observe the coronary arteries, the outside muscles, the aorta, pulmonary vein and artery and feel the weights of the hearts without opening up the heart. Students can be asked to identify the outside part of the first. You can open up each heart and compare and identify the chambers, septum and the valves. You can discuss the differences between each animal’s heart. I think you would be surprised at the reaction of your students just to be able to see real hearts.
lesson III
I would make this a two day lab. You can put your hearts in a cold place over night and use them again the next day to show how the blood flows.
But first, I would have the students use their heart posters that they made for homework to do a simple activity. On a piece of scrappaper they can draw several blue arrows with their pens. Have them cut the arrows out and paste them on their heart poster according to the correct flow of this bluish-red blood. They must be placed so that the flow is in one direction and passes through every correct part of the right side of the heart. Next, have them draw red arrows to show the oxygen-rich blood. These arrows can also be pasted on the left side of the heart in correct order. (To avoid cutting and pasting they can just draw the arrows in; however, mistakes can lead to a messy paper)
Once they have completed the above activity then they can use their knowledge on a real heart. The students can take a piece of coil or rope about one foot long and apply it to the calves’ heart. The rope can be placed carefully through each heart. This again strengthens and supports their understanding of how blood flows through the heart. V. Diseases of the
Heart and
Blood
Concept
The four diseases, Atherosclerosis, Hypertension, Stroke and Heart Attack (Myocardial Infarction are the main causes of death in the United States. They all have common risk factors in getting the disease.