33.1 The Circulatory System
What are the functions of the circulatory system?- How does the heart pump blood through the body?
- What are three types of blood vessels?
myocardium • atrium • ventricle • valve • pulmonary circulation • systemic circulation • pacemaker • artery • capillary • vein
Preview Visuals Before you read, look at Figure 33–3. Make a list of questions about the illustration. As you read, write down the answers.
VISUAL ANALOGY
A CITY'S TRANSPORTATION SYSTEM
FIGURE 33–1 The human circulatory system is like the highways and streets of a large city. Use Analogies Compare the needs of a person living in a large city with the needs of a cell in the body.
THINK ABOUT IT “I was about 47 when I collapsed one day at work. There are 22 minutes out of my life that I don't remember. I had gone into cardiac arrest.” These are the words of a man who survived a heart attack. Fortunately he received prompt treatment and had successful heart surgery. He continued to live a fairly normal life. He even ran the Boston Marathon! But more than one-third of the 1.2 million Americans who suffer a heart attack each year die. This grim evidence shows that the heart and the circulatory system it powers are vital to life. Why is that so?
Functions of the Circulatory System
What are the functions of the circulatory system?
Some animals have so few cells that all of their cells are in direct contact with the environment. Diffusion and active transport across cell membranes supply the cells with oxygen and nutrients and remove waste products. The human body, however, contains millions of cells that are not in direct contact with the external environment. Because of this, humans need a circulatory system. The circulatory system transports oxygen, nutrients, and other substances throughout the body, and removes wastes from tissues.
People who live in large cities face a set of problems like those of the body's cells. City dwellers need food and goods that are produced elsewhere, and they need to get rid of their garbage and other wastes. People need to move around within the city. How are these needs met? By the city's transportation system—a network of streets, highways, and subway or train lines that deliver goods to the city and remove wastes from it. The human body's major transportation system is a closed circulatory system made up of a heart, blood vessels, and blood.
Table of Contents
- Formulas and Equations
- Applying Formulas and Equations
- Mean, Median, and Mode
- Estimation
- Using Measurements in Calculations
- Effects of Measurement Errors
- Accuracy
- Precision
- Comparing Accuracy and Precision
- Significant Figures
- Calculating With Significant Figures
- Scientific Notation
- Calculating With Scientific Notation
- Dimensional Analysis
- Applying Dimensional Analysis