AMA 178 - Anatomy & Physiology/Medical Terminology/Pathology 9 Cardiovascular System

1. AMA 178 - Anatomy & Physiology/Medical Terminology/Pathology 9 Cardiovascular System

2. Function: • Composed of the heart, a powerful muscular pump, and blood vessels that send oxygen and nutrients to all parts of the body via the bloodstream. • Waste products are also eliminated from body tissues via the bloodstream.

3. Structure of the Cardiovascular System: Blood vessels Three types of blood vessels: arteries, veins and capillaries • Arteries: large blood vessels that carry oxygen rich blood away from the heart • Veins: carry deoxygenated blood to the heart from the tissues, and waste products to other systems of the body to be released • Capillaries: delicate, microscopic vessels that carry nutrient rich, oxygenated blood from the arteries to the body cells

6. Blood Circulation: Pulmonary Circulation: • Oxygen poor blood from body tissues enters the right side of the heart via the venae cavae (2 large veins) where it travels into the pulmonary artery (only artery in the body that carries oxygen poor blood); this branches into two sections, one to each lung. • Blood passes into the pulmonary capillaries where it picks up oxygen rich blood and then goes back through the heart to be pumped to all areas of the body.

7. Blood Circulation: Systemic Circulation: • Oxygen rich blood enters the left side of the heart from the pulmonary veins. • Blood is pumped via the aorta (largest artery in the body) to other arteries that branch out to all parts of the body via tissue capillaries near body cells, where nutrients are broken down in the presence of oxygen and energy is released. • This chemical process releases carbon dioxide as a waste product; this is taken back to the lungs and the body releases it via exhalation. • Other wastes are taken by the veins to be eliminated by other systems in the body.

9. Structure of the Cardiovascular System:Heart • Located in the thoracic cavity between the lungs. • Weighs less than a pound and is about the size of a human fist. • It is a pump consisting of four chambers and four valves; its action is controlled by electrical impulses initiating in the cardiac muscle tissue.

10. Anatomy of the Heart: • Atria: upper chambers of the heart • Ventricles: lower chambers of the heart • Superior vena cava: drains deoxygenated blood from the upper portion of the body • Inferior vena cava: carries deoxygenated blood from the lower portion of the body • Tricuspid valve: valve between the right atrium and right ventricle • Pulmonary valve: valve between the right ventricle and the pulmonary artery • Mitral valve: valve between the left atrium and left ventricle • Aortic valve: valve between the left ventricle and the aorta

14. Two Phases of the Heartbeat: • Cardiac cycle: occurs 70-80 times a minute (100,000 times a day). Heart pumps approximately 3 ounces of blood with each contraction (5 quarts a minute) • Diastole: relaxation – ventrical walls relax and blood flows into heart from the venae cavae and pulmonary veins • Systole: contraction – ventrical walls contract pumping blood into the pulmonary artery and aorta to all parts of the body

16. Conduction System of the Heart: Electrical impulse originates in a small region of specialized muscle tissue (SA node) and is sent in waves through the heart causing contraction of ventricals • Sinoatrial node (SA node): pacemaker of the heart; generates current of electricity that causes atria to contract fording blood into the ventricles • Atrioventricular node (AV node): electrical impulse goes here from the SA node and on to the bundles • Bundle of His: bundle of specialized fibers that send impulse to the left and right bundle branches • Left & Right bundle branches: form the conduction myofibers (electrical muscle tissue) that extend through ventricle walls and stimulate them to contract.