Label Diagram #1 (Pg. 664)

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1 Chapter 18 The Cardiovascular System 18.1 Heart Anatomy The Pulmonary and Systemic Circuits Oxygen rich vs. Oxygen Poor Heart is a transport system consisting of two side-by-side pumps Right side receives oxygen-poor blood (dull red) from tissues Pumps blood to lungs to get rid of CO2, pick up O2, via pulmonary circuit (the blood vessels carrying blood to lungs: pulmo=lungs ) Left side receives oxygenated blood (bright red) from lungs Pumps blood to body tissues via systemic circuit (blood vessels and body tissues) Receiving and Pumping Chambers Receiving chambers of heart Right atrium Receives deoxygenated blood returning from systemic circuit (body) Left atrium Receives oxygenated blood returning from pulmonary circuit (lungs) Pumping chambers of heart Right ventricle Pumps blood through pulmonary circuit Left ventricle Pumps blood through systemic circuit Label Diagram #1 (Pg. 664) Size, Location, and Orientation of Heart Approximately the size of a fist Weighs less than 1 pound Location In mediastinum between second rib and fifth intercostal space On superior surface of diaphragm Two-thirds of heart to left of mid-sternal line Anterior to vertebral column, posterior to sternum Base (top)-posterior surface, leans toward right shoulder Apex (bottom)-points toward left hip Apical impulse palpated between fifth and sixth ribs, just below left nipple Label Diagram #2 & #3 (Pg. 665) A# Coverings of the Heart Pericardium: double-walled sac that surrounds heart; made up of two layers 1. Superficial fibrous pericardium: functions to protect, anchor heart to surrounding structures, and prevent overfilling 2. Deep two-layered serous pericardium Parietal layer lines internal surface of fibrous pericardium Visceral layer (epicardium) on external surface of heart Two layers separated by fluid-filled pericardial cavity (decreases friction) 2016 Pearson Education, Inc. 1

2 Pericardium Fibrous Serous Label Diagram #4 (Pg. 666) Parietal & Visceral (epicardium) Clinical Homeostatic Imbalance 18.1 Pericarditis Inflammation of pericardium Roughens membrane surfaces, causing pericardial friction rub (creaking sound) heard with stethoscope Cardiac tamponade Excess fluid that leaks into pericardial space Can compress heart s pumping ability Treatment: fluid is drawn out of cavity (usually with syringe) Layers of the Heart Wall Three layers of heart wall 1. Epicardium: visceral layer of serous pericardium (interchangeable) 2. Myocardium: circular or spiral bundles of contractile cardiac muscle cells Cardiac skeleton: crisscrossing, interlacing layer of connective tissue Anchors cardiac muscle fibers Supports great vessels and valves Limits spread of action potentials to specific paths 3. Endocardium: innermost layer; is continuous with endothelial lining of blood vessels Lines heart chambers and covers cardiac skeleton of valves Chambers and Associated Great Vessels Internal features Four chambers: 2 receiving (atrias) and 2 pumping (ventricles) chambers Two superior atria (right and a left) Two inferior ventricles (right and a left) Interatrial septum: separates atria (collecting areas) Atria: the receiving chambers Small, thin-walled chambers; contribute little to propulsion of blood Right atrium: receives deoxygenated blood from body Three veins empty into right atrium: Superior vena cava: returns blood from body regions above the diaphragm Inferior vena cava: returns blood from body regions below the diaphragm Coronary sinus: returns blood from coronary veins 2016 Pearson Education, Inc. 2

3 Left atrium: receives oxygenated blood from lungs Four pulmonary veins return blood from lungs Ventricles: the pumping/discharging chambers Thicker and more massive than atrias Right ventricle: opens into pulmonary trunk Blood taken to lungs only for gas exchange Left ventricle: opens into aorta (largest artery in our bod) Thicker wall than the right ventricle because it pumps to entire body 18.2 Heart Valves Ensures a one-way flow of blood through heart (leaky valves are no Bueno!) Open and close in response to pressure changes Two major types of valves: 1. Atrioventricular (AV) valves located between atria and ventricles (tricuspid and bicuspid/mitral) Prevents backflow Right AV valve = tricuspid (3 cusps) Left AV valve = bicuspid/mitral (2 cusps) AV valves are limp when heart is at rest/relaxed When ventricles contract papillary muscles contract prevent valves from opening into atria by pulling chordae tendineae Chordae tendineae- heart strings strong connective tissue attaching cusps to papillary muscles protruding from ventricular walls 2. Semilunar (SL) valves located between ventricles and major arteries (pulmonary and aortic) Prevents backflow from major arteries back into ventricles Pulmonary semilunar valve: between right ventricle and pulmonary trunk Aortic semilunar valve: located between left ventricle and aorta Opens and closes in response to pressure changes Each valve consists of three cusps that roughly resemble a half moon Clinical Homeostatic Imbalance 18.2 Two conditions severely weaken heart: Incompetent valve Blood backflows so heart repumps same blood over and over Valvular stenosis Stiff flaps that constrict opening Heart needs to exert more force to pump blood Defective valve can be replaced with mechanical, animal, or cadaver valve Label Diagram #5 (Pg. 670) 2016 Pearson Education, Inc. 3

4 18.3 Pathway of Blood Through Heart Right side of the heart Superior vena cava (SVC), inferior vena cava (IVC) Right atrium Tricuspid valve Right ventricle Pulmonary semilunar valve Pulmonary arteries Lungs Left side of the heart Four pulmonary veins Left atrium Mitral valve Left ventricle Aortic semilunar valve Aorta Systemic circulation Label Diagram #6 (Pg. 674) Let s learn how to trace the blood through the heart!!! Here are some valuable TIPS: 1. There are 14 steps!!! The lungs are the halfway point! Step 7 2. All the blood returning to the heart is DEoxygenated (d) until after it enters the lungs. Then while in the blood it gets Oxygenated (o) and then every step AFTER the lungs has what type of blood? oxygenated 3. Blood always returns to the heart on the RIGHT side! The right side is the RIGHT side. 4. The blood will enter the heart through the VENA CAVA: Super Vena Cava (SVC) if the blood is returning from ABOVE the heart (brain) Inferior Vena Cava (IVC) if the blood is returning from BELOW the heart (feet/legs) 5. Once the blood enters through a vena cava, it has to enter into a RECEIVING chamber Hint: Remember what side of the heart we are on 6. The third step is a valve. Which valve means three? TRIcuspid 7. Sequence begins with the first valve on each side: VALVE VENTRICLE VALVE 8. So step 4 should be the RIGHT ventricle. Hint: What side of the heart are still on? 9. Next valve a semilunar valve (pulmonary or aortic). Since pulmonary means lungs and we are on our way to the lungs, this is the next valve. 10. Pulmonary sandwich time: Pulmonary Arteries Lungs Pulmonary Veins 11. Now we are on the LEFT SIDE and the left side will RECEIVE the blood in the LEFT atrium. 12. Looking back on tip 6, what happened here after the blood moved on from the right atrium? You are right!! It entered an AV valve. So now it s time for the other AV valve: BICUSPID/MITRAL 13. What is the sequence with the first valve on each side? VALVE VENTRICLE VALVE 14. So, what step is next? LEFT VENTRICLE 15. Then which is the only valve left? Aortic Valve. 16. Then the final step is the largest artery in the body called the AORTA, which makes sense considering the valve that came right before it. 17. Then the systemic pathway (out to the body) 2016 Pearson Education, Inc. 4

5 LET s PRACTICE because this is SO FUN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Directions: Now using these tips above, trace the blood by placing the step number and type of blood (d=deoxygenated or o=oxygenated). The blood is returning from the brain. Place an X on the step you will not use during this pathway based on where the blood is returning from. pulmonary valve mitral valve lungs right atrium right ventricle left atrium tricuspid valve left ventricle systemic pathway aorta aortic valve superior vena cava (SVC) pulmonary veins pulmonary arteries inferior vena cava (IVC) This time, try and do it without looking: The blood is coming from the feet. Put an X on the line of the unused part. Remember to number each step and put the type of blood in lowercase letters. (d)=deoxygenated (o) oxygenated pulmonary valve bicuspid/mitral valve systemic pathway lungs pulmonary arteries right ventricle left atrium tricuspid valve left ventricle aorta aortic valve inferior vena cava (IVC) right atrium pulmonary veins superior vena cava (SVC) 2016 Pearson Education, Inc. 5

6 Generating Electricity: Cardiac Conduction System Five structures comprise the Cardiac Conduction System: 1. Sinoatrial Node (SA node) also called the pacemaker: A small knot of caridac muscle-like tissue located on the back wall of the right atrium, near where the SVC enters the heart. The SA node s cells initiate the electrical impulse that generates the heartbeat. 2. Arterioventricular Node (AV node): A similar small mass of tissue located in the right atrium but near the septum that divides the right and left atria from the ventricles. Its function is to relay the impulses it receives from the SA node to the next part of the conduction system. 3. Atrioventricular Bundle (AV bundle): A bundle of fibers that extends from the AV node into the interventricular septum (which divides the heart into right and left sides). The AV bundle transmits cardiac impulses. 4. Left and Right Bundle Branches: Where the septum widens, the AV bundle splits into the right and left bundle branches, each extending down under the endocaridum and then up along the the outside of the ventricles. These bundles carry cardiac impulses. 5. Purkinje Fibers: At the ends of the AV bundle branches are the Purkinje fibers, which deliver the impulse to the myocardial cells, causing the ventricles to contract. The Sequence of Events: Here s how the cardiac cycle goes Depolarization: beginning of the electrical event (spontaneously)-rising phase of action potential 1. The electrical impulse is initated in the SA node. The right and left atria contract simulataneously, pumping blood into the right and left ventricles. 2. The impulse passes to the AV node, which sends it to the AV bundle. In the meantime, the right and left atria relax. 3. The impulse passes into the right and left bundle branhces and ultimately into the Purkinje fibers, causing the right ventricle to contract and to pump its deoxygenated blood into the pulmonary arteries and the lungs. Simultaneously, the left ventricle contracts, pumping oxygenated blood to the aorta. Repolarization: end of electrical event-falling phase of action potential 4. The ventricles relax while the atria begin contracting, and the cycle starts all over again Pearson Education, Inc. 6

7 Electrocardiogram (EKG): record of heart activity The hearts electrical signals can be measured and recorded digitally to produce an image called an Electrocardiogram (ECG or EKG). *cannot measure blood pressure *cannot measure muscle contraction An EKG can identify: 1. abnormal heart rates or rhythms 2. abnormal conduction pathways 3. hypertrophy or atrophy of areas of the heart 4. approximate location of damaged cardiac muscle Three major waves of electic signals appear on the EKG: each showing a different part of the heartbeat. 1. P wave: movement of depolarization wave from the SA node through atria. Approximately.1s after the P wave begins, the atria contract. 2. QRS complex: results from ventricular depolarization preceding ventricular contraction. Average duration of the QRS complex is 0.08s. 3. T wave: caused by ventricular repolarization lasting about 0.16s. Repolarization is slower than depolarization so the T wave is more spread out and has a lower amplitude (height) than the QRS complex. Label Diagram #7 (Pg. 684) > Label each wave and write the steps Normal and abnormal EKG/ECG tracings 2016 Pearson Education, Inc. 7

8 Heart Sounds: (lub dup) 1. 1 st heart sound lub -occurs as AV valves close (tricuspid and mitral/bicuspid) -ventrical pressure rises above atrial pressure -loud and long pitch 2. 2 nd heart sound dup -closure of semilunar valves (pulmonary and aortic) 3. Possible to auscultate (listening to the sounds with a stethoscope) the four valves 1. Aortic valve = 2nd intercostals space at right sterna margin 2. Pulmonary valve = 2nd intercostals space at left sterna margin 3. Mitral valve = 5th intercostals space in line with middle of clavicle 4. Tricuspid valve = right sternal margin of intercostals space a. Ventricular systole occurs btwn. 1st & 2nd heart sounds b. Ventricular diastole occurs btwn. 2nd heart sound & 1st of next beat lasts longer than diastole more time in between heart sounds Label: Use this words to label the events of the Cardiac Cycle: -R repolarization of ventrical -Q -R -S -T T wave -P P wave -D depolarization of atria -Atrial systole (contraction) -Atrial diastole (relaxation) -Ventrical systole =(QRS) -Ventrical diastole 2016 Pearson Education, Inc. 8

9 Homeostatic Imbalances: Cardiac Disorders: 1. Arrhythmia/Dysrhythmia -Definition: Disorder of your heart rate or rhythm *Beating too fast = Tachycardia (100 bpm or faster) *Beating too slow = Bradycardia (50 bpm or slower) -Causes: *Caffiene *Vigorous exercise *Emotional stress -Treatment: *Implantation of a medical device called a pacemaker 2. Myocardial Infarction - heart attack -Definition: Irreversible damage of myocardial tissue caused by a blockage of blood flow to the myocardium. -Causes: *Occlusion (blockage) of a coronary artery *Occulsion might be from a blood clot (coronary thrombosis) Vascular Disorders: 3. Hypertension high blood pressure also can be called the SILENT KILLER -Definition: blood is pushing too hard on the walls off the arteries because cardiac output is high or because the arteries have lost the ability to flex in response to the pulse-wave *Reduced blood flow to organs = Ischemia *Sudden pain as blood squeezes through arteries = Angina *Clot dislodged from the artery wall = Embolus (can be fatal) *Narrowing and stiffening of the arteries due to arterial plaque = Atherosclerosis 4. Stroke -Definition: damage to the brain caused by reduced blood flow (ischemia) or bleeding (hemorragia) -Causes: Bleeding may be caused by a ruptured vessel from atherosclerosis in the arteries that supplies the brain-internal arteries and cerebral arteries *Ruptured vessel of the brain = Aneurysm You ve 2016 Pearson concluded Education, the Inc. Cardiovascular System Notes! Whoop 9