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The Circulatory SystemChapter 15

The Cardiorespiratory SystemIncludes function of the heart, blood vessels, circulation, and gas exchange, between the blood and atmosphere.Heart pumps blood through the body through pathways (arteries, veins, and capillaries)Blood is enriched with oxygen when it passes through the lungsAs oxygen enters the bloodstream, carbon dioxide leaves it (respiration)The Circulatory SystemCourse taken by blood through the arteries, capillaries, and veins & back to heartUses blood to transport dissolved materials throughout bodyOxygen, carbon dioxide, nutrients, wastePicks up waste products of cell metabolism & takes to lungs and kidneys (to be expelled from body)The HeartTwo major circulationsEach has its own pumpBoth pumps are incorporated into the heartLocationMiddle of chest, behind sternum, within ribcagePericardial cavityAbove diaphragmStructure Primarily a shell with four chambers inside

Blood FlowTwo sides of heart are anatomically and functionally separate pumping unitsRight side pumps blood through pulmonary circulationLeft side pumps blood through systemic circulation

Heart FactsAdult human heart approx size of closed fistAbout 5 inches long and 3 inches wideWeighs just less than 1 poundBeats about 100,000 times each dayPump about 8,000 gallons of blood through 12,000 miles of vessels each dayContracts and relaxes 70-80 bpmStructure of HeartFour cavitiesAtriaForm curved top of heartVentricles Meet at bottom of heart to form pointed base Points toward left side of chest

Structure of HeartLeft SideRight SideOne ventricleOne atriumMitral valveconnects left atrium to left ventricle

One ventricleOne atriumTricuspid valveconnects right atrium to right ventricle

Wall, septum, separates right and left sides

valves that prevent blood that flows out of the heart from flowing back in. This system of valves keeps blood moving throught the heart in one direction, like traffic on a one-way street. The one-way flow increases the pumping efficiency of the heart. The valves are so important to heart function that surgeons often attempt to repair or replace a damaged valve.8

Aortahearts main artery carries blood away from heart to bodys cellsPulmonary arteryartery that connects heart to lungsTwo largest veins:Superior vena cavaInferior vena cavaTwo largest veins carry blood inot hearCalled vena cava b/c they are the hearts veins9CirculationAs heart contracts, it pushes blood though chambers and into the vesselsNerves connected to the heart regulate the speed of contractionsGreater the activity, faster the heart will pump; faster heart pumps, more oxygen and nutrient are carried throughout body

Heart MusclePericardiumEpicardiumMyocardiumEndocardium

BloodOnly tissue that flows throughout bodyCarries oxygen & nutrients to all parts of body and transports waste products back to lungs, kidneys, and liver for disposalEssential part of immune systemCrucial for fluid and temperature balanceHydraulic fluid for certain functionsHighway for hormonal messagesComposed of plasma and billions of cells

PlasmaThe yellowish, liquid part of bloodRiver in which blood cells travelMakes up 55% of total volumeCarries blood cells + Nutrients (sugars, amino acids, fats, salts, minerals)Waste products (CO2, lactic acid, urea)AntibodiesClotting proteins (called clotting factors)Chemical messengers (hormones)Proteins that help maintain bodys fluid balanceBloodRBCs & HemoglobinRed Blood Cells (erythrocytes)Highly specialized cells that have been stripped of everything, including nucleusMajor job: transporting oxygenPercentage of RBCs in total blood volume called hematocritHemoglobinSpecial red-colored molecule that fills RBCsPicks up oxygen in areas where O2 is abundant and releases O2 in tissues where O2 concentration lowest

BloodWhite Blood Cells5 distinct kindsNeutrophils, monocytes, lymphocytes, eosinophils, basophilsAble to change according to need and situation in bodyCan leave blood stream , sliding out through vessel walls & attacking invaders at site of infections

BloodPlatelets Fragments of much larger cell (megakaryocyte) which stays in bone marrow after it differentiates and matures from stem cellPlatelets leave bone marrow & circulate throughout the bodyWhen stimulated by substance from damaged tissue, platelets release substance to help clot blood

16Blood VesselsHollow tubes running throughout the body5 typesArteriesArteriolesVeinsVenulesCapillariesProvide 2 measurements:PulseBlood pressure

ArteriesBlood vessels that carry blood from the heart to organs & cellsMuscular walls that allow them to dilate or constrictArterioles: very small arteriesLargest artery=aortaRuns from chest into abdomen Receives blood directly from left ventricle

VeinsBlood vessels that carry blood back to heartThinner wallContain numerous one-way valves (keep blood moving toward heart)Deep veins in LE surrounded by large muscle groups; compress the deep veins when muscles contractContractions in extremities helps propel blood toward heart; increase venous return

Veins Largest vein=superior & inferior vena cavaBring blood from upper and lower body into right atriumVenules: smallest veins

CapillariesTiny, microscopic blood vessels that connect arteries to veinsResponsible for transferring oxygen and nutrients to cellsWall so thin that O2 passes from arterial blood through them into cells in organs/tissuesWaste products (CO2) pass into capillaries to be carried back by veins to heart/lungs

Coronary ArteriesThe hearts own system of blood vesselsLocated around heart muscle to provide blood and oxygen to all parts of heart

Two primary coronary arteries branch off into smaller vesselsRight coronary artery: feeds right atrium & ventricle and bottom of left ventricleLeft main coronary artery: supplies blood to rest of heartLeft anterior descendingCircumflex

Hearts Conduction SystemHearts electrical systemConsisting of specialized cells within heart muscle that carry an electrical signalRegulates pumping of heart

Blood PressureHeart pumps blood into arteries; surge of blood filling vessels creates pressure against vessel wallsPressure measured by 2 numbers:Systolic: highest pressure in heartCorrelates to ventricular ctxAverage 120 mm/HgDiastolic: lowest pressure in heartRelates to ventricular ctxAverage 80 mm/HgPulse pressure: difference between diastolic and systolic pressures

PulseRhythmical beating of heartCreated by alternating expansion and contraction of artery as blood flows through7 areas where pulse can be felt

Brachial arteryCommon carotid arteryFemoral arteryDorsalis pedis arteryPopliteal arteryRadial arteryTemporal arteryTarget Heart RatePercentage of the maximum heart rate that is safe to reach during exerciseAHA recommends 50-75% for average healthy personCalculated 220-ageTHR is sliding scale that decreases with ageTool for measuring cardiovascular exerciseMaintain THR for 15-30 min daily health benefits

Flow of Blood through HeartSuperior/inferior vena cavaRight atriumTricuspid valveRight ventricleSemi-lunar valvePulmonary artery Lungs http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html 1. The right atrium receives deoxygentated blood from the systemic circuit (the body ) through the vena cavae (superior and inferior).

2. Blood flows from the right atrium through the right AV valve ( right atrioventricular valve or tricuspid valve) into the right ventricle.

3. When the right ventricle contracts it pumps blood through the pulmonary semi-lunar valve to enter the pulmonary trunk which starts the pulmonary circuit.valves that prevent blood that flows out of the heart from flowing back in. This system of valves keeps blood moving throught the heart in one direction, like traffic on a one-way street. The one-way flow increases the pumping efficiency of the heart. The valves are so important to heart function that surgeons often attempt to repair or replace a damaged valve.4. Pulmonary trunk divides into left and right pulmonary arteries. Pulmonary arteries divide smaller and smaller until they deliver blood to gas exchange sites of lungs (alveoli).

5. Once blood is oxygentated it flows back to the heart through the right and left pulmonary veins.

6. Right and left pulmonary veins deliver blood to the left atrium.

7. Blood flows from the left atrium through the left AV valve (aka Mitral or Bicuspid valve) into the left ventricle.

8. Blood is pumped by the strong left ventricle through the aortic semi-lunar valve into the ascending aorta.

9. Blood flows through the aortic arch into the descending aorta. 28Flow of Blood through HeartBack to heart via pulmonary veinLeft atriumBicuspid valveLeft ventricleSemi-lunar valveAortaOrgans in the body

1. The right atrium receives deoxygentated blood from the systemic circuit (the body ) through the vena cavae (superior and inferior).

2. Blood flows from the right atrium through the right AV valve ( right atrioventricular valve or tricuspid valve) into the right ventricle.

3. When the right ventricle contracts it pumps blood through the pulmonary semi-lunar valve to enter the pulmonary trunk which starts the pulmonary circuit.

4. Pulmonary trunk divides into left and right pulmonary arteries. Pulmonary arteries divide smaller and smaller until they deliver blood to gas exchange sites of lungs (alveoli).

5. Once blood is oxygentated it flows back to the heart through the right and left pulmonary veins.

6. Right and left pulmonary veins deliver blood to the left atrium.

7. Blood flows from the left atrium through the left AV valve (aka Mitral or Bicuspid valve) into the left ventricle.

8. Blood is pumped by the strong left ventricle through the aortic semi-lunar valve into the ascending aorta.

9. Blood flows through the aortic arch into the descending aorta. 29Flow of Blood through Heart

Heart Anatomy

Can you label the heart?