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Cardiovascular System & Circulation Reading: Chapter #13 A. Heart location -in thoracic cavity A. Heart location -the heart is surrounded by the pericardial sac which has 3 layers: 1) visceral pericardium -next to the heart (inner layer) -also called epicardium 2) parietal pericardium (makes…) -middle layer -serous membrane -lubrication 3) fibrous pericardium -tough outer layer Pericarditis = -inflammation of the pericardium -pericardium begins sticking together -very painful (feels like heart attack) B. HEART STRUCTURE -hollow organ with 4 internal chambers B. STRUCTURE 1) Wall -there are 3 layers to the wall of the heart: a) endocardium -innermost layer -very smooth layer b) myocardium -middle layer (variable thickness) -made of cardiac muscle tissue -has its own blood supply c) epicardium = visceral pericardium (serous membrane) B. STRUCTURE 2) Chambers w/ valves -2 atria on top -2 ventricles below a) Right side: 1) 2) 3) 4) 5) R atrium tricuspid valve chordae tendineae R ventricle (thin) papillary muscles b) Left side of heart: 1) 2) 3) 4) 5) L atrium bicuspid valve chordae tendineae L ventricle (thick) papillary muscles c) Blood flow Superior & Inferior Vena Cavae R atrium R Ventricle (passing tricuspid valve) Pulmonary trunk (passing pulmonary semi-lunar valve) LUNGS (gas exchange) Pulmonary veins (2 L and 2 R) Left atrium Left ventricle (via bicuspid valve) Aorta (via semi-lunar valve) C. BLOOD VESSELS We did this in the blood chapter. D. ROUTES OF BLOOD FLOW 1) Pulmonary Circulation -low O2 blood is pumped out to lungs from the _____ ventricle -via the pulmonary __________ -blood returns to heart via pulmonary ____________(O2 rich) -blood returns to the heart from the lungs via _________________ -newly oxygenated blood enters the _______ __________ 2) Systemic Circulation -oxygenated blood leaves the heart from the ______ ventricle -this blood is pumped out to the body via the _____________ -blood returns to the heart via the vena cavae to the __ ________ 3. Coronary circulation Independent blood vessels supply oxygen & nutrient rich blood to the myocardium. Coronary arteries branch off the aorta. Deoxygenated blood returns to the Right Atrium via cardiac veins. If cardiac veins are blocked: a) Ischemia= small stroke, blocked BV in brain b) Myocardial infarction=heart attack-symptoms? Non-invasive treatments? Invasive treatments? 4. Cerebral Circulation Stroke (CVA)= the brain is deprived of oxygen, there are 4 types. 1. thrombus: blood clot in the brain 2. Embolus: blood clot breaks loose & is carried by blood flow 3. Hemorrhage: great loss of blood 4. Aneurysm: weak spot in an arteryballoons up & may rupture Warning signs of a stroke & risk factors Sudden numbness or weakness ________ Sudden confusion ___________________ Sudden trouble _____________________ Sudden trouble _____________________ Sudden severe _____________________ RISK FACTORS: High BP, _____________ ___________________________________ 5. Fetal Circulation -Does the fetus breathe? What circuit isn’t needed? Foramen Ovale: -hole b/w R & L atrium -most blood by-passes R ventricle & lungs -at birth a flap covers this hole Ductus Arteriosus:-shunt b/w pulmonary artery & aorta -at birth, duct constricts & becomes a ligamentum arteriosus 6. Hepatic Portal Circulation Blood from the capillaries in the intestines travels to the LIVER E. CARDIOVASCULAR PHYSIOLOGY 1) Cardiac cycle (repeated ~ 72 times/min) a) systole = -contraction/emptying phase -pressure goes up -volume goes down b) diastole = -relaxation/filling phase -pressure goes down -volume goes up Ventricular contraction & atrial relaxation Ventricular relaxation & atrial contraction 2) Heart valves and sounds -the heart valves insure one-way flow of blood in the heart -when the valves close, they produce the “lubb-dupp” sound a) AV valves prevent back flow to the atria “lubb” b) Semilunar valves prevent back flow into ventricles “dupp” Auscultation = listening to body sounds Murmur = valve(s) are leaky & blood flows backward Semi-Lunar Valves – superior view Failure of the valves may require surgical valve replacement. 3) Heart Conduction System (ELECTICAL) -the heart has its own electrical conduction system -the heart will keep beating even w/out any nerve connection SA node = -pacemaker (upper R atrium) -where the impulses originates (~72 beats/min) SA node (pacemaker) sends out ~72 beats/min. Impulse travels across atria AV node (atrioventricular) “Bundle of His” (also called the A-V bundle) Left & Right Bundle Branches w/in Interventricular Septum Purkinje Fibers Myocardium Stimulated to Contract If SA node stops working: -AV node takes over -heart rate ~ 60 beats/min. If AV node malfunctions: -much more common -myocardial cells take over -heart rate ~20-30 beats/min. Pacemakers can be inserted to regulate the heart beat. Definitions: Ectopic focus - heart beat originates in a place other than SA node. Arrythmias -irregular heart rate, abnormal rhythm Bradycardia -slow heart rate -rate < 60 beats/min Tachycarda -fast heart rate -rate > 100 beats/min Arrhythmias Normal ECG (70-80 bpm) Tachycardia (>100 bpm) Bradycardia (<60 bpm) 4) ECG (EKG) = electrocardiogram -sensors on skin measure electrical activity in heart (not mechanical) -totally non-invasive Each wave has a meaning: a) P wave = depolarization of atria b) QRS wave = depolarization of ventricles c) T wave = repolarization of ventricles d) atrial repolarization occurs during QRS complex (masked) 4) ECG (EKG) (con’t) e) ECG’s can be used to diagnose heart diseases Sudden heart attack death 5) Cardiac Output (Q) -Amount of blood pumped by the left ventricle/minute. -Varies depending upon need. a) Q = Heart Rate (HR) x Stroke Volume (SV) b) HR = ~72 beats/min -controlled by pacemaker c) SV = volume pumped with each beat = about 70 ml Q= Q= Q= HR x SV 72 beats/min x 70 ml/beat 5040 ml/min (about 5 liters/min) What can cause a change in Q? (Q = HR x SV) 1. ANS (sympathetic & parasympathetic stimulation) 2. Starling’s Law of the Heart -“The heart will pump all of the blood that comes in” -More blood comes into ventricle ventricle contracts harder -So, regular aerobic activity stronger myocardium 6) Blood Flow and Blood Pressure Blood flows from areas of greater pressure to areas of lesser pressure 6) Blood Flow and Blood Pressure (con’t) -Pulse rates = -rate of heart beat -measured by counting pulse waves in major arteries 6) Blood Flow and Blood Pressure (con’t) -Blood Pressure = -strength of pressure waves in arteries -measured indirectly w/ a sphygmomanometer How to use the Sphygmomanometer: Skip for now….we’ll go over this later before the lab. F. CARDIOVASCULAR ABNORMALITIES 1) Hypertension = high blood pressure: a) borderline values are 140 to 150/90 to 100 mmHg b) a “silent” disease c) can damage to vessels, heart, kidneys d) most due to unknown cause e) treatment weight loss, exercise, medication f) NO CURE! Optimal Blood Pressure = 120/80 mmHg Risk factors for developing heart disease Major Risk Factors That Cannot be Changed Heredity Major Risk Factors That Can Be Changed Cigarette Smoking Sex (male) Hypertension Race (African American) Blood Cholesterol (HDL vs LDL) Diabetes Age Obesity Contributing Factors Stress END