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The Circulatory System

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Functions of the Circulatory System Brings blood containing oxygen, nutrients, and hormones to cells Transports CO 2 and other wastes away from cells

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Fights infection Regulates body temperature Helps stabilize pH and ionic concentration of body fluids. Functions

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Circulatory System Components Heart Blood Vessels Arteries Veins Capillaries

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The Heart A muscular pump Moves blood through the body Is suspended in the pericardial sac Composed of four chambers Divided into right and left halves Made up of cardiac muscle cells Aorta Left pulmonary artery Left atrium Left pulmonary veins Left ventricle Superior vena cava Right pulmonary veins Right atrium Right ventricle Inferior vena cava

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Pericardium Protective sac of connective tissue Surrounds the heart Filled with fluid

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Myocardium The muscle of the heart Strong and thick Composed of spontaneously contracting cardiac muscle fibers Can conduct electricity like nerves Its blood supply comes from the coronary arteries Myocardium (heart muscle) shown in red Epicardium (Outer surface of myocardium) Endocardium (Inner surface of myocardium)

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Structures of the Heart Chambers Atria- (2) upper chambers Thin walled Receive blood from veins Send blood to ventricles Ventricles- (2) lower chambers Thick walled Receive blood from atria Pump blood out through arteries Septum Wall that divides heart into right and left halves Septum Pulmonary valve Right atrium Tricuspid valve Right ventricle Left atrium Aortic valve Mitral valve Left ventricle

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Structures of the Heart Valves Prevent backflow of blood Keep blood moving in one direction Located between the chambers Located at the junctions of the artery and chamber Tricuspid valve Pulmonary veins Mitral valve Left atrium Pulmonary valve Aortic valve Right atrium Valves seen from above Chordea tendinea Pulmonary valve

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Structures of the Heart Chordae tendinease Heart strings Cord-like tendons Connect papillary muscles to tricuspid and mitral valves Prevent inversion of valve Papillary muscles Small muscles that anchor the cords Papillary muscle

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aortic valve left common carotid artery left subclavian artery brachiocephalic artery right pulmonary artery septum left pulmonary artery aorta pulmonary trunk left pulmonary veins left atrium (auricle) mitral valve pulmonary valve papillary muscle left ventricle right pulmonary veins superior vena cava right atrium tricuspid valve right ventricle inferior vena cava 2006 Merriam-Webster, Inc. Structures of the Heart 6 11 10 14 1 9 8 7 5 3 4 2 17 12 16 13 15

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Cardiac Cycle Refers to all of the events from the beginning of one heart beat to the beginning of the next heart beat When cardiac muscle contracts it does so as a single unit, creating a heart beat One heartbeat - a cardiac cycle - consists of two parts called systole and diastole

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Cardiac Cycle Diastole is the period of time when the heart relaxes after contraction Oxygenated blood from the lungs fills the left atrium Deoxygenated blood from other parts of the body fills the right atrium. At the end of the diastole, the atria contract, starting the Systole

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Cardiac Cycle Atrial systole is the contraction of the heart muscle of the left and right atria. Both atria contract at the same time, sending blood into the corresponding ventricle Ventricular systole is the contraction of the muscles of the left and right ventricles, which contract at the same time. The term systole is synonymous with contraction of a muscle.

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Cardiac Cycle During systole the ventricles contract, forcing the blood into the pulmonary artery to be re-oxygenated in the lungs, and into the aorta for systemic distribution of oxygenated blood

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Two normal heart sounds with each heart beat described as a.. Heart Sounds Lub- sound- due to closure of the atrioventricular valves (mitral and tricuspid) Dub- sound- due to closure of the aortic valve and pulmonary valve

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Cardiac Cycle Heart Rate - count of each heart beat On average, a heart beats 72 times a minute when at rest Usually it is calculated as number of contractions of heart (heart beats) in one minute and expressed as "beats per minute" (bpm). The pulse is the most straightforward way of measuring the heart rate Heart rate is controlled by nervous system Hearse on an emergency

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Cardiac Cycle Resting heart rate can be significantly lower in athletes Sympathetic division increases heart rate Parasympathetic division decreases heart rate Heart rate increases when more food and oxygen are needed by the cells, or when under stress

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Cardiac Cycle An electrocardiogram abbreviated as EKG or ECG is a test that measures the electrical activity of the heartbeat or one cardiac cycle.

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Cardiac Conduction System Why dont the atria and ventricles contract at the same time? Inefficient. Blood would not be moved in one direction, some would flow backwards

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Includes: SA node AV node Bundle of His Purkinje fibers

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Cardiac Conduction System Sinoatrial Node (SA node) Located high on the right atrium. Pacemaker of the heart. Causes the wave of contractions in the atria. Sending blood into the ventricles

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Cardiac Conduction System Atrioventricular Node (AV node) Located in the interatrial septum close to the tricuspid valve Carries the electrical impulse from the SA node to fiber bundles in the ventricles. This causes the ventricles to contract The location of nerve fiber bundles cause the ventricles to contract from the apex (bottom) up squeezing blood up and out

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Pathway of Circulation Oxygen-poor blood draining from the body through veins into the superior and inferior vena cava flows to the right atrium, through the tricuspid valve, and into the right ventricle. As the right ventricle contracts, oxygen-poor blood passes through the pulmonary valve into the pulmonary arteries and on to the lungs to receive oxygen.

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Oxygen-rich blood from the lungs enters the heart through the pulmonary veins, passing into the left atrium. Then through the mitral valve to the left ventricle. Contraction of the left ventricle forces blood through the aortic valve into the aorta. Various arteries branch off from the aorta to supply blood to all parts of the body.

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Arteries branch into smaller and smaller vessels (arterioles) They eventually become capillaries, which supply blood to all body parts Capillaries merge into (venuoles) which join into veins and carry blood back to the heart. Nutrients pass into tissues Waste products filter back Blood pumped out of heart into arteries, which branch into smaller and smaller vessels until blood flows into capillaries Blood returns to the heart through the veins Heart Capillary network

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Pathway of Circulation

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14 9 11 10 8 6 13 12 6 5 4 3 2 1 1 16 15 14 7 And so on It takes about 1 min. for blood to make 1 complete cycle

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Pulmonary Circuit Systemic Circuit Lung Pulmonary vein Aorta Left atrium Left ventricle Pulmonary artery Right atrium Right ventricle Vena cava oxygen-poor blood oxygen-rich blood Cardiovascular Circuits

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Pulmonary Circulation Takes place on the right side of the heart. Pumps blood low in oxygen to the lungs to pick up oxygen and return to heart

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Systemic Circulation Takes place on left side of heart Oxygenated blood is pumped to the body cells thru the aorta and other arteries Blood low in oxygen returns to the heart

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Coronary Circulation Although blood fills the chambers of the heart, the muscle tissue of the heart is so thick that it requires coronary blood vessels to deliver blood deep into the myocardium. The coronary circulation consists of the blood vessels that supply blood to, and remove blood from the heart muscle itself.

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The vessels that supply blood high in oxygen to the myocardium are known as coronary arteries.

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Blood Vessels Form a closed circuit of tubes that carry blood throughout the body Laid end to end, the blood vessels in an average human body will stretch approximately 62,000 miles2.5 times around the earth

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Blood Vessels Have characteristic features Are distinguished by size, tissue layers and direction of blood flow

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Blood Vessels Arteries Receive blood from ventricles Take blood away from the heart Usually carry oxygenated blood Thickest vessel walls Withstand greater blood pressure Are very elastic Connect to capillaries Aorta is the largest artery

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Blood Vessels Veins Transport blood away from capillaries Carry blood toward heart Take blood to atria Have valves Thinner vessel walls with less smooth muscles than arteries Can stretch a great deal Have larger diameters Usually carry de-oxygenated blood Vena cava is the largest vein

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Blood Vessels The contraction of muscles compressing veins helps push blood up through the leg veins back to the heart. The valves allow the blood to flow towards the heart only. Calf muscle relaxed Calf muscle contracts Muscle squeezes veins Veins constrict; blood moves; valves open Veins dialated; blood still; valves closed Valves OPEN Valves CLOSED

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Blood Vessels Capillaries Smallest of blood vessels Only one cell thick (epithelial cell) Connect arteries to veins Bring oxygen and nutrients to cells Removes CO 2, urea, and other wastes from cells Where blood is under low pressure and moving slowly

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A network of capillaries runs close to the cells in every part of the body. The capillaries have very thin walls which allows nutrients to diffuse through into the tissues and waste products to filter back into the capillaries. Arteriole Venule Tissue cells Vein Artery capillaries Capillaries

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CB CB O L M O PO AD R I V SE OS NS E OL FS

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Blood Pressure Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels The pressure of the circulating blood decreases as blood moves through arteries, arterioles, capillaries, venules, and veins

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Blood Pressure Blood pressure is most commonly measured via a sphygmomanometer (blood pressure cuff) It uses the height of a column of mercury to reflect the circulating pressure Average blood pressure for an adult is 120/80

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Blood Pressure Systolic pressure is defined as the maximum pressure in the arteries exerted during ventricular contraction (which occurs near the beginning of the cardiac cycle) Diastolic pressure is the minimum pressure exerted when ventricles relax and fill (at the resting phase or end of the cardiac cycle) Blood pressure readings = S/D

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Blood Pressure Pressure waves move through the blood vessels A person's pulse is the throbbing of their arteries as an effect of the pressure waves (heart beat) Pulse is used to denote the frequency of the heart beat It can be felt at neck, wrist, and other places Pulse is usually measured in beats per minute.. In most people, the pulse is an accurate measure of heart rate.

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Blood Pressure Vasoconstriction is narrowing of a blood vessel. When a blood vessel constricts, the flow of blood is restricted or slowed. Blood pressure will increase Vasodilatation is where blood vessels in the body become wider following relaxation of smooth muscle in vessel wall. This will reduce blood pressure - since there is more room for the blood. and

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Blood The life stream of the body, affecting every cell and system we have. The blood is an accumulation of many different elements, each working in a specific way to keep us alive.

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Blood A circulating connective tissue consisting of several types of cells suspended in a fluid medium known as plasma.

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Functions of blood: Supply oxygen to tissues Supply nutrients such as glucose, amino acids and fatty acids to tissues Removal of wastes such as CO 2, urea and lactic acid from tissues Immunological functions, including circulation of white cells, and detection of foreign material by antibodies

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Functions of blood continued: Messenger functions, including transport of hormones and signaling of tissue Coagulation, part of body's self-repair mechanism Regulation of core body temperature Regulation of body pH and ion concentrations

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What percent of your body is blood? How much blood do we contain? On average 4-6 liters We contain about a pint of blood for every 15 pounds of body weight Composition of Blood: What percent of your blood is cellular? What percent of your blood is plasma? 8% 45% 55%

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Blood What is plasma? A clear, straw colored fluid What percent of plasma is water? Whats in plasma? Dissolved gasses Vitamins Minerals Salts Nutrients Enzymes Hormones Waste products Plasma proteins 90% Buffy coat leukocytes and platelets (