Section 12.1 Your Cardiovascular System Objectives Describe the main functions of the cardiovascular system. Trace the pathway of blood through the heart. Identify three types of blood vessels and the four components of blood.

Myth Blood is blue in color when it is not carrying oxygen. Fact Blood is bright red when it is carrying oxygen and dark red when it is not. Veins appear blue in some people because of the way light reflects from their skin. What other knowledge about the cardiovascular system do you hope to gain from this chapter?

Functions of the Cardiovascular System • Your cardiovascular system, or the circulatory system, consists of your heart, blood vessels, and blood. The main functions of the cardiovascular system include delivering materials to cells carrying wastes away In addition, blood contains cells that fight disease.

Delivering Materials Your heart continually pumps the blood in your blood vessels throughout your body. Many substances that your body needs dissolve in the blood.

Removing Wastes Your cardiovascular system transports wastes from your cells. Your blood picks up carbon dioxide and transports it to the lungs, where it is exhaled.

Fighting Disease Your blood contains cells that attack microorganisms that cause disease. It also contains substances that seal cuts.

The Heart • Think of your cardiovascular system as a network of blood vessels with two major loops. The first loop leads from your heart to your lungs. The second loop circles through to the rest of your body. Each time the heart beats, strong cardiac muscles push blood through the blood vessels.

Structure of the Heart Each side of the heart has two chambers: an upper chamber called an atrium (plural, atria) and a lower chamber, or ventricle. The atria receive blood entering the heart. Blood flows from the atria to the ventricles, which pump blood out of the heart.

The Heart The aorta carries blood from the left ventricle to the body. Major vessel from upper body to heart 5 Vessel from heart to lungs 1 Vessels from lung to heart Vessels from lung to heart 6 2 Right Atrium The right atrium receives blood from the body that is low in oxygen and high in carbon dioxide. Left Atrium Oxygen-rich blood is carried from the lungs to the left atrium. 3 7 8 4 Left Ventricle The left ventricle pumps oxygen-rich blood from the heart. 9 Right Ventricle The right ventricle pumps oxygen-poor blood to the lungs.

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Your Heartbeat The action of the heart has two main phases. In the first phase, the heart relaxes and the atria fill with blood. In the second phase, the heart contracts and pumps blood. The rate at which your heart muscles contract is regulated by the pacemaker, a small group of cells in the wall of the right atrium. Average heart rate varies from one person to the next and from one situation to the next.

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Blood Vessels Your heart pumps blood through an extensive network of blood vessels. The three main types of blood vessels in your body are arteries capillaries veins

Blood Vessels Artery Artery Cross Section Layer of cells Smooth muscle Connective tissue

Arteries Blood vessels that carry blood away from the heart are called arteries. Most arteries carry oxygen-rich blood. The largest artery in the body is the aorta (ay AWR tuh). Arteries have thick walls that are both strong and flexible.

Capillaries Branching from the smallest arteries are capillaries, the smallest blood vessels in your body. As blood flows through the capillaries, oxygen and dissolved nutrients diffuse through the capillary walls and into your body’s cells. Capillaries are involved in temperature regulation.

Veins From the capillaries, blood flows into small blood vessels that join together to form veins. Veins are large, thin-walled blood vessels that carry blood to the heart.

Blood Vessels Capillary Vein Vein Cross Section Layer of cells Smooth muscle Capillary Cross Section Connective tissue Single layer of cells

Measuring Blood Pressure Blood pressure is the force with which blood pushes against the walls of your blood vessels. Normal Blood Pressure A blood pressure reading is considered normal if it falls within the range of 90/60 to 119/79. Low Blood Pressure Blood pressure lower than 90/60 is considered to be low blood pressure. High Blood Pressure A person whose blood pressure is consistently 140/90 or greater has high blood pressure, or hypertension.

Blood • The average adult has about 4 to 6 quarts of blood circulating through his or her blood vessels. The four components of blood are plasma red blood cells white blood cells platelets

Plasma The liquid component of the blood is called plasma. This straw-colored liquid makes up about 55 percent of the blood. Plasma is mostly water, with substances such as nutrients, hormones, and salts dissolved in it.

Red Blood Cells The cells that carry oxygen from the lungs to all the parts of your body are red blood cells. Red blood cells contain hemoglobin, which is an iron-containing substance to which oxygen binds.

White Blood Cells White blood cells help protect you against diseases and foreign substances. Some white blood cells make chemicals that help your body resist diseases such as cancer. Others destroy invading microorganisms by surrounding and consuming them.

Platelets Platelets (PLAYT lits) are cell fragments that play an important role in the blood clotting process. When you get a cut, platelets stick to the edges of the cut and release proteins called clotting factors.

Blood Types A person’s blood type is determined by the proteins present on the surface of the red blood cells. Depending on which proteins are present, a person’s blood type can be type A, B, AB, or O. A second blood type is determined by the presence or absence of the Rh factor protein.

Transfusions After an injury, surgery, or some illnesses, a person may require a blood transfusion. During a transfusion, blood from a donor is transferred to the patient’s bloodstream.

Transfusions

Vocabulary atrium An upper chamber of the heart that receives blood from the rest of the body. ventricle A lower chamber of the heart that pumps blood out of the heart. pacemaker A small group of cells in the wall of the right atrium that controls the rate at which the heart muscles contract. artery A thick-walled blood vessel that carries blood away from the heart. capillary The smallest type of blood vessel in the body.

Vocabulary vein A large, thin-walled blood vessel that carries blood to the heart. blood pressure The force with which blood pushes against the walls of blood vessels. hypertension Blood pressure that is consistently 140/90 or greater. plasma A liquid that makes up about 55 percent of the blood. red blood cell A hemoglobin-containing cell that carries oxygen from the lungs to other parts of the body.

Vocabulary white blood cell A cell that helps protect the body from diseases and foreign substances. platelet A cell fragment that plays an important role in the blood clotting process.

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End of Section 12.1 Click on this slide to end this presentation.