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The Circulatory System. The Circulatory System. Major Function TRANSPORTATION Helps maintain homeostasis within the body Two sub-divisions Cardiovascular system Lymphatic system. The Cardiovascular System. Consists of: Blood Transporting fluid Heart Pumps the blood Carries the blood
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The Circulatory System • Major Function • TRANSPORTATION • Helps maintain homeostasis within the body • Two sub-divisions • Cardiovascular system • Lymphatic system
The Cardiovascular System • Consists of: • Blood • Transporting fluid • Heart • Pumps the blood • Carries the blood • Arteries, veins, capillaries
The Heart • Heart wall has 3 layers • Epicardium, myocardium, endocardium • Made of cardiac muscle • Rich in mitochondria • Four chamber • Two Atria – upper chambers • Pumps blood to the ventricles • Two Ventricles – lower chambers • Left pumps blood to the entire body • Right pumps blood to the lungs
Blood Flow in the Heart • Oxygen-poor blood enter through the superior & inferior venae cavae into the right atrium • Passes down through the tricuspid valve to the right ventricle. • Passes out the pulmonary trunk arteries to the lungs & gas exchange occurs. • Oxygen-rich blood returns via the pulmonary veins & passes into the left atrium. • Flows down through the bicuspid valve or mitral valve to the left ventricle. • Oxygen-rich blood then flows out the aorta to the body tissues.
Physiology of the Heart • Heartbeat & Heart Sounds • Two phases of the heartbeat • Diastole (relaxation) • Occurs when the ventricle walls relax & blood flows into the heart from the venae cavae & pulmonary veins • Tricuspid & mitral valves open; pulmonary & aortic valves close • Systole (contraction) • Walls of right & left ventricles contract; pumping blood into the pulmonary artery & aorta • Tricuspid & mitral valves are closed, preventing backflow
Physiology of the Heart • Closure of the valves is associated with audible sounds • “lubb-dubb” • “Lubb” associated with closure of the tricuspid & mitral valves at the beginning of systole • “Dubb” closure of the aortic & pulmonary valves at the end of systole • Murmur • Abnormal swishing sound • http://www.dundee.ac.uk/medther/Cardiology/audio/normal.wav • http://www.dundee.ac.uk/medther/Cardiology/audio/ms.wav
Physiology of the Heart • Conduction System • Sinoatrial Node (SA Node) • (pacemaker) • Specialized muscle tissue that initiates the heartbeat • Wave of electricity passes to another region of the myocardium (within the interatrial septum) to the Atrioventricular node (AV node) • AV node sends excitation wave to atrioventricular bundle (bundle of His) • Bundle divides into the left bundle branch & right bundle branch
Physiology of the Heart • Electrocardiogram (ECG or EKG) • Record used to detect the electrical changes in the heart muscle
Blood Vessels • Arteries • Large blood vessels that carry blood away from the heart • Lined with connective tissue, muscle, tissue, elastic layer, & endothelium (innermost layer) • Strong to withstand high pressure pumping from the heart • Arterioles • Smaller branches of arteries • Thinner & carry blood to capillaries
Blood Vessels • Capillaries • One endothelial cell thick • Carry nutrient-rich, oxygenated blood from the arteries & arterioles to the body cells • Pick up waste products (i.e. CO2) & flow back to the small venules, which combine to form larger vessels called the veins.
Blood Vessels • Veins • Thinner walls compared with arteries • Take blood toward the heart • Have valves to prevent the backflow of blood
Blood Pressure • Blood moves through our Circulation System because it is under Pressure. • caused by the Contraction of the Heart and by Muscles that surround Blood Vessels. • Blood Pressure is Always highest in the Two Main Arteries that leave the Heart. • Maintained by TWO WAYS: • (1) The Nervous System, which can speed up or slow down the Heart Rate; • (2) The KIDNEYS, which regulate blood pressure by the amount of fluid in our Blood. • When pressure is too high, kidneys remove water from blood, lowering the total amount of fluid in the Circulatory System. • Both High and LOW Blood Pressure can cause our bodies problems.
Blood Pressure • Usually Measured in the Artery Supplying the upper Arm. • Measured by a sphygmomanometer • Systolic Blood Pressure • force of blood recorded during ventricular contraction • Diastolic Blood Pressure • force of blood reordered during ventricular relaxation • Average blood pressure = 120/80 mm Hg
Factors Affecting Blood Pressure • Neural Factors • Renal Factors – Kidneys • Temperature • Chemicals • Diet • Age & Weight • Exercise • Emotional State
Cardiac Disorders • Risk factors of heart disease • High blood pressure, high blood cholesterol, cigarette smoking, obesity, lack of exercise, diabetes mellitus, and genetics. • Immediate Causes of Heart Disease • Inadequate blood supply, anatomical disorders, arrhythmias • CHF – Congestive Heart Failure • Heart cannot meet the body’s oxygen demands
The Lymphatic System • Consists of lymphatic vessels, lymph nodes, & lymph organs. • Supports both Cardiovascular System & the Immune System. • Functions: • Picks up fluid leaked from the blood vessels & returns it to the blood. • Disposes of debris in the lymphatic stream • Houses WBCs involved in immunity
Lymphatic Vessels • Picks up excess tissue fluid called lymph, & returns it to the bloodstream. • Fluid accumulation in tissues can cause edema, which impairs blood-to-tissue exchange • One-way system towards the heart • Lymph capillaries absorb fluid in tissues • Enters the venous system through two large ducts • Right lymphatic duct • Thoracic duct
Lymph Nodes • Removes foreign material from the lymphatic stream by producing lymphocytes (WBCs) that function in immune response. • Act as tiny filters • Contain macrophages that engulf & destroy bacteria • Swollen glands are a result of trapping substances in the nodes.
Other Lymphoid Organs • Spleen • Filters blood & destroys worn-out RBCs & returns the breakdown products to the liver • Thymus • Produces hormones that program lymphocytes (immune system cells) • Tonsils • Masses of lymphoid tissue embedded in mucus • Trap any foreign material entering the throat.
