Circulatory System

Functions of Circulatory System Brings oxygen, nutrients, and hormones to cells Fights infection Regulates body temperature

Structures of Circulatory System Heart Blood Blood Vessels: Arteries Capillaries Veins

Heart Location: near center of chest Composed of: muscle (myocardium) 4 chambers: 2 Atria, 2 Ventricles Contracts ~ 72 times a minute Pumps ~ 70 milliliters of blood with each contraction During an average lifetime, the human heart will beat more than 2.5 billion times

Heart Give a tennis ball a good, hard squeeze. You're using about the same amount of force your heart uses to pump blood out to the body. Even at rest, the muscles of the heart work hard--twice as hard as the leg muscles of a person sprinting.

Blood Human body contains 4-6 liters Connective tissue containing dissolved substances and specialized cells 45% cells 55% plasma 90% water 10% gases, salts, nutrients, enzymes, hormones, waste products, and plasma proteins

Blood Functions Collects Regulate body temp Fight infection oxygen from lungs Nutrients from digestive tract Wastes from tissues Regulate body temp Fight infection Form clots to repair damaged vessels

Blood Cells Red (erythrocytes) Most numerous 1 ml of blood = ~ 5 million RBCs Transport oxygen Get color from Hemoglobin (iron-containing protein that binds oxygen) Shaped like disks w/ thick edges Produced from red bone marrow Circulate ~ 120 days before being destroyed in liver & spleen

Blood Cells White (leukocytes) Platelets Less abundant (700 RBC to 1 WBC) “army” of circulatory system Attack foreign substances Platelets Clots blood Repairs damaged vessels

Figure 37-10 Blood Clotting Section 37-2 Break in Capillary Wall Blood vessels injured. Clumping of Platelets Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin.. Clot Forms Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..

Blood Vessels Arteries Large (“super highways”) Carry blood away from the heart Carry O2 rich blood (exception: pulmonary artery)

Blood Vessels Capillaries Smallest (“side streets and alleys”) Exchange of nutrients, oxygen, carbon dioxide, and waste Veins Return blood to heart Muscles help force blood through veins against gravity

Figure 37-5 The Three Types of Blood Vessels Artery Vein Connective tissue Smooth muscle Endothelium Valve Venule Arteriole Capillary

Path of Blood Flow Start in the heart: Leaves heart: Left Atrium (through mitral valve) Left ventricle (through aortic valve) Leaves heart: Aorta Body/Capillaries

Path of Blood Flow Returns to Heart: Leaves Heart: Veins Vena Cava (inferior and Superior) Right atrium (through tricuspid valve) Right ventricle (through pulmonary valve) Leaves Heart: Pulmonary artery (goes to lungs) Through pulmonary veins to left atrium

The Circulatory System Section 37-1 Capillaries of head and arms Capillaries of abdominal organs and legs Inferior vena cava Pulmonary vein Capillaries of right lung Superior vena cava Aorta Pulmonary artery Capillaries of left lung

Word Bank Left Atrium Left Ventricle Right Atrium Right Ventricle Pulmonary Artery Pulmonary Veins Aorta Vena Cava