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 – 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.
The Heart: Blood Flow Superior/Inferior Vena Cava Right Atrium Tricuspid Valve Right Ventricle Pulmonary Valve Pulmonary Artery Lungs Pulmonary Veins Left Atrium Mitral Valve Left Ventricle Aortic Valve Aorta
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.
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.
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.
The Heart: Heart Rate Varies depending on.. – Activity level – Oxygen need Not directly controlled by nervous system. – Is influenced though
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.