The Heart- What Makes You Tick?
The heart is beating every second of our lives and yet we experience very little of how it actually works. This lesson is designed to introduce students to the structure and function of the heart and what happens when it doesn’t work right. If students have already studied the cardiovascular system, this lesson will serve as a review to bring all students to the same level of proficiency.
A fun introductory video: http://www.youtube.com/watch?v=LqhvmUEdOYY
The purpose of the heart is to pump oxygen and nutrient rich blood to all of the cells in the body and carry carbon dioxide and waste products to the lungs, kidneys and other excretory organs for elimination. An important concept:
Students will participate in a variety of situated-learning activities to reinforce characteristics of the heart. They will watch parts of the PBS DVD series “The Mysterious Heart,” use models and dissect sheep hearts, and participate in an activity that explores the importance of valves and one-way blood flow in the circulatory system. Students will engage in a group activity that investigates the physics of flow (a cross-cutting concept) and learn about the electrophysiology of the heart and Sudden Cardiac Arrest (SCA). Finally, students will use a schematic diagram to apply their knowledge of the heart and the flow of blood.
Your Electrical Heart
Your heart beats about 75 times per minute for your entire life. Each heartbeat is triggered by electrical impulses that travel down a special pathway through your heart. These impulses start in the upper atria in an area called the Sinoatrial (SA) Node. Because this cluster of cells determines the rate of the beats, we call it the “Pacemaker” of the heart. From here, the impulse is transferred through the atria, down the wall between the ventricles and then up the outside walls of the ventricles. As this impulse moves through each area of the heart, it initiates the contraction of the muscles around it. The brain can send signals to speed up or slow down your heart rate. Also, exercise, fever and some medications can do the same.
When the heart beats too fast, too slow, or in an uncoordinated fashion, it is called an Arrhythmia. When this happens, the heart cannot effectively pump blood to the rest of the body. This can feel very uncomfortable and may even stop the heart. If the heart stops beating, this is called Cardiac Arrest. If this happens, an electrical shock can be delivered to the person so that their heart starts to beat normally again. An Automated External defibrillator (AED) is a computerized device that will prompt another person so they can use the machine to effectively deliver the electric shock to the affected person. To treat this type of ailment, medication may be prescribed, or a device may be implanted that monitors and regulates the heart rate, such as a Pacemaker or Defibrillator. A procedure may be done that destroys the heart tissue causing the abnormal rhythm. This is called an Ablation.
An Electrocardiogram is a test used to study a person’s electrical activity of their heart. This test will be used to look for arrhythmias. It can also be used to see if a heart attack has taken place. A Heart Attack is when cells in heart tissue die due to the lack of oxygen. This lack of oxygen is caused when the blood supply is cut off in one of the coronary arteries by a blockage. The Coronary Arteries deliver oxygen and nutrients to the cells of the heart. This blockage may be bypassed by a stent or bypass surgery. A Stent is small, lattice shaped tube that is placed inside the blockage to hold the artery open. A Bypass is when another blood vessel from the body is sewed around the blocked area of the blood vessel. If the heart becomes too damaged by heart attacks, the heart will no longer be able to pump the blood to meet the body’s needs. This is called Heart Failure.
*Information retrieved from American Heart Association website, FDA Heart Online website, Fletcher Allen Healthcare website, and Cleveland Clinic website.
The main concepts explored in this lesson are the structure and function of the heart and the path the blood takes as it flows through the heart. The concept of flow (physics) is introduced as a cross-cutting concept. Additionally, the electrophysiology of the heart will be explored in relation to Sudden Cardiac Arrest (SCA).
Student Learning Outcomes
After completing Module 1, students will be able to:
- that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.
- that arise from examining models or a theory, to clarify and/or seek additional information and relationships.
- to clarify and refine a model, an explanation, or an engineering problem.
- Ask questions that can be investigated within the scope of the school laboratory with available resources and, when appropriate, frame a hypothesis based on a model or theory.
- Plan an investigation or test a design (sheep’s heart dissection) individually and collaboratively about the structure and function of the human heart to produce data to serve as evidence as part of building and revising models, supporting explanations of phenomena, or testing solutions to problems.
- Select appropriate tools to collect, record, and analyze data.
- Manipulate variables and collect data about the structure and function of the heart to identify failure points or improve performance relative to criteria for success specific to heart disease, cardiac arrest, and heart failure.
- Apply scientific reasoning, theory, and/or models to link evidence of the structure of the heart to the explanation of its function.
- Develop, revise, and/or use a model based on evidence to illustrate and/or predict the relationships between pressure and resistance to investigate their effects on flow within the cardiovascular system.
- Apply techniques of algebra and functions to represent and solve scientific and engineering problems related to vasoconstriction and vasodilation on the flow of blood to the tissues and organs of the body.
- Critically read scientific literature adapted for classroom use to determine the central ideas or conclusions and/or to obtain scientific and/or technical information to summarize complex evidence, concepts, processes, or information presented in a text by paraphrasing them in simpler but still accurate terms.
- Compare, integrate, and evaluate sources of information presented in different media or formats (e.g., visually, quantitatively) as well as in words in order to address a scientific question or solve a problem.
- Communicate scientific and/or technical information or ideas in multiple formats (including orally, graphically, textually, and mathematically).