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

Fact or Fiction: Blood is blue in color when it is not carrying oxygen. Fiction: 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.

Functions of the Cardiovascular System 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: Glucose (Blood Sugar or Energy) from the digestive system and delivers it to the cells that need it for energy. Waste Removal: Carbon Dioxide from the break down of glucose and is delivered and exhaled in the lungs.

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. Textbook pp 293

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.

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. Average heart rate varies from one person to the next and from one situation to the next.

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- carry blood away from the heart Capillaries- the smallest arteries As blood flows through the capillaries, oxygen and dissolved nutrients diffuse through the capillary walls and into your body’s cells. Veins- large, thin-walled blood vessels that carry blood to the heart

Blood Vessels Artery Artery Cross Section Smooth muscle

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

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.