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The Circulatory System

The Circulatory System. Section 33.1. Functions of the Circulatory System. Needed because the body has millions of cells. Transports nutrients, oxygen, wastes, other substances. The Heart: Structure. The heart consists of 4 chambers Numerous valves A muscle (cardiac) Hollow

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The Circulatory System

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  1. The Circulatory System Section 33.1

  2. Functions of the Circulatory System • Needed because the body has millions of cells. • Transports nutrients, oxygen, wastes, other substances.

  3. The Heart: Structure • The heart consists of • 4 chambers • Numerous valves • A muscle (cardiac) • Hollow • Septum separates right from left. • In the walls of the heart, 2 thin layers of connective and epithelial tissue sandwich a muscle called the myocardium. • Myocardium contracts and pumps blood through circulatory system.

  4. The Heart: Structure • Diagram

  5. The Heart: Blood Flow Right Atrium Superior/Inferior Vena Cava Tricuspid Valve Right Ventricle Lungs Pulmonary Valve Pulmonary Veins Pulmonary Artery Left Atrium Left Ventricle Aortic Valve Mitral Valve Aorta

  6. The Heart: Blood Supply • Coronary Arteries give blood to heart’s tissue. • Branch from aorta • Run through heart tissue • Narrow • If blocked, tissue may die=heart attack.

  7. The Heart: Circulation • Pulmonary • Right side of heart pumps to lungs. • Gas exchange occurs • Oxygen rich blood returns to left side of heart. • Systemic • Blood pumped from left side of heart to body. • Cells use oxygen • Oxygen poor blood comes back to right side of heart.

  8. The Heart: Heartbeat • 1. Atria Contract • Starts in right atrium • In a small muscle group, sinoatrial node (SA). • AKA pacemaker. • When SA node fires, electrical impulse spreads and muscle contracts. • 2. Ventricles Contract • Impulse from SA picked up by atrioventricular (AV) node. • Impulse delayed. • AV node produces impulses that spread through ventricles. • They contract.

  9. The Heart: Heart Rate • Varies depending on.. • Activity level • Oxygen need • Not directly controlled by nervous system. • Is influenced though

  10. Blood Vessels: Arteries • Oxygen rich blood to the tissues of the body and usually flow with gravity • Large (superhighways) • Thick walled…highly pressurized • Consist of connective tissue, smooth muscle, endothelium.

  11. Blood Vessels: Capillaries • Smallest vessels • Narrow, blood cells move single file • Thin walls

  12. Blood Vessels: Veins • Blood flows against gravity • Large veins near skeletal muscles, push blood towards heart. • Veins contain valves • Consist of connective tissue, smooth muscle, endothelium.

  13. Blood Pressure • System always under pressure due to arterial walls. • Pressure needed to make blood flow. • Blood pressure regulated by the nervous system, also kidneys.

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