The Heart PPT Notes - Saladin PDF

The Circulatory System: Heart Slides Prepared By: Justin Wiethop, D.C., MTAA LEARNING OBJECTIVES Define and distinguish between the pulmonary and systemic circuits Describe the general location, size and shape of the heart Describe the pericardial sac that encloses the heart Label the layers to the...

The Circulatory System: Heart Slides Prepared By: Justin Wiethop, D.C., MTAA LEARNING OBJECTIVES Define and distinguish between the pulmonary and systemic circuits Describe the general location, size and shape of the heart Describe the pericardial sac that encloses the heart Label the layers to the heat wall and know their function HOW DOES BLOOD FLOW THROUGH THE BODY? Pulmonary circuit Systemic circuit O2 CO2 Image Source: (Saladin, 2018) THE IMPORTANT ORGAN THE SIZE OF YOUR FIST Mediastinum: the heart and lungs Upside down triangle: apex and base The size of your fist Image Source: (Saladin, 2018) WHAT PROTECTS THE HEART? The Pericardium Parietal pericardium Visceral pericardium Pericardial cavity Pericardial fluid Image Source: (Saladin, 2018) HOW MANY LAYERS TO THE HEART WALL? 3 Layers 1. Epicardium: (aka: visceral pericardium); epithelial cells; adipose tissue 2. Myocardium: cardiac muscle; thickest layer 3. Endocardium: inner layer; simple squamous epithelium; areolar CT Image Source: (Saladin, 2018) CHECKPOINT 1. What is the middle layer of the heart wall? 2. What is the protective tissue surrounding the heart? CHECKPOINT - ANSWERS 1. MYOCARDIUM 2. PERICARDIUM LEARNING OBJECTIVES Identify the four chambers of the heart Label surface markings of the heart Identify and label the AV and semilunar valves Trace blood though the heart Identify the great vessels of the heart WHAT ARE THE FOUR CHAMBERS OF THE HEART? 2 Atria – Atria accept blood 2 Ventricles – Ventricles vacate blood out of heart Image Source: (Saladin, 2018) THE TALE OF HEMOGLOBIN Coronary sulcus: encircles heart; separates atria from ventricles Anterior interventricular sulcus Posterior interventricular sulcus Image Source: (Saladin, 2018) WHAT ARE VALVES? Prevent backflow of blood Like closing a door 2 types in the heart 1. AV valves 2. Semilunar valves Image Source: (Saladin, 2018) AV VALVES: VALVES BETWEEN THE ATRIUM AND VENTRICLES Tricuspid valve – “If you tri you will be right” Bicuspid valve – aka Mitral valve; found on the left Image Source: (Saladin, 2018) The Valves 3 Figure 19.8a Aortic Valve Figure 19.8b b: Biophoto Associates/Science Source AV VALVES: VALVES BETWEEN THE ATRIUM AND VENTRICLES Chordae Tendineae– prevents eversion of the valve Papillary muscle – pulls the strings Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 1. Superior vena cava, Inferior vena cava, and Coronary sinus (No O2) 1 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 2. Blood enters right atrium 1 2 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 3. Right atrium contracts and sends blood through the Tricuspid valve 1 2 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 3. After passing through the Tricuspid valve the blood enters the Right ventricle 1 2 3 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 4. Right ventricle contracts and sends blood through the Pulmonary valve into the Pulmonary trunk 1 4 2 3 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 5. Pulmonary trunk sends blood though the pulmonary arteries into the lungs to gain O2 1 5 4 2 3 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 6. Lungs sends blood (O2) though the pulmonary veins into the left atrium 1 5 4 2 6 3 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 7. Left atrium contracts and sends blood through bicuspid valve into left ventricle 1 5 4 2 3 6 7 Image Source: (Saladin, 2018) HOW DOES BOOD FLOW THROUGH THE HEART? 8. Aorta send oxygenated blood out to the body 1 5 8 4 2 3 6 7 Image Source: (Saladin, 2018) Blood Flow Through the Chambers 3 Figure 19.9 HOW DOES BOOD FLOW THROUGH THE HEART? Blood though the heart rap Image Source: Youtube CHECKPOINT 1. Blood flows from the right ventricle through what valve? 2. What heart artery contains nonoxygenated blood? CHECKPOINT - ANSWERS 1. PULMONARY VALVE 2. PULMONARY ARTERY (TRUNK, RIGHT, and LEFT) WHEN DO VALVES OPEN AND CLOSE? Systole Diastole Image Source: (Saladin, 2018) DOES THE HEART USE BLOOD? Arterial supply to the heart (Coronary Circulation) Left coronary artery o Anterior interventricular branch o Circumflex branch ▪ Left marginal branch Right coronary artery o Right marginal branch o Posterior interventricular branch Image Source: (Saladin, 2018) DOES THE HEART USE BLOOD? Venous drainage of the heart Great cardiac vein Posterior interventricular vein Left marginal vein Coronary sinus Image Source: (Saladin, 2018) LEARNING OBJECTIVES Describe the structure and function of cardiac muscle Describe the significance of intercalated discs Label the electroconductive system of the heart HOW DO CARDIAC MUSCLES DIFFER FROM OTHER MUSCLES Short Fat Branched Uninucleate Striated Autorhythmic Involuntary Intercalated discs Image Source: (Saladin, 2018) WHAT ARE INTERCALATED DISCS Contain gap junctions Lack electrical conduction Direct the current Image Source: (Saladin, 2018) HOW TO MAKE YOUR HEART BEAT Electrical conduction system Image Source: (Saladin, 2018) TO SPEED UP OR SLOW DOWN, THAT IS THE QUESTION Vagus nerve (CN X) Parasympathetic Less speeds up More slows down Image Source: (Saladin, 2018) CHECKPOINT 1. Which nerve slows down the heart? 2. What is the pacemaker also known as? CHECKPOINT - ANSWERS 1. VEGUS NERVE (CN X) 2. SA NODE HOW DOES A HEART BEAT CHEMICALLY? Sinus rhythm Pacemaker potential Image Source: (Saladin, 2018) HOW TO MAP ACTION POTENTIAL WITH THE HEART CONDUCTION Action potential of a ventricular cardiocyte Image Source: (Saladin, 2018) HOW DO WE SEE A HEART BEAT CLINICALLY? P wave QRS Complex T wave P wave = SA Node has fired and caused the atrium to depolarize P-Q Interval = Ventricular filling QRS Complex = Ventricular depolarization S-T Segment = Ventricular emptying T wave = Ventricular repolarization Image Source: (Saladin, 2018) WHAT IS HAPPENING TO THE HEART DURING AN ECG? Relationship of ECG to electrical activity and contraction of the myocardium Image Source: (Saladin, 2018) Cardiac Arrhythmias 5 Atrial fibrillation—chaotic depolarizations that do not stimulate ventricles; common in elderly and alcoholics Heart block—failure of any part of the cardiac conduction system to conduct signals, usually result of disease or degeneration of conduction system Premature ventricular contraction—ventricular ectopic focus with extra beat; may result from stress, lack of sleep or stimulants Cardiac Arrhythmias 2 Figure 19.17 a, b Cardiac Arrhythmias 4 Figure 19.17 c, d, e LEARNING OBJECTIVES Describe blood pressure and how it relates to changes in the heart Explain what causes heartbeat sounds Describe one cardiac cycle Relate the cardiac cycle to the volume of blood exiting and entering the heart Blood Flow, Heart Sounds, and the Cardiac Cycle Cardiac cycle—one complete contraction and relaxation of all four chambers of the heart Questions to consider: How does pressure affect blood flow? How are heart sounds produced? Principles of Pressure and Flow 1 Two main variables govern fluid movement: pressure causes flow and resistance opposes it Fluid will only flow if there is a pressure gradient (pressure difference) Fluid flows from high-pressure point to low-pressure point Pressure measured in mm Hg with a manometer (sphygmomanometer for BP) WHAT IS BLOOD PRESSURE? Amount of blood in the blood vessel at a given time Measured with a sphygmomanometer Flow = Pressure/ Resistance WHAT IS RESISTANCE? Factors that affect resistance: 1. Blood vessel length 2. Blood vessel diameter 3. Blood viscosity Image Source: (Saladin, 2018) WHAT CAUSES HEART SOUNDS? Lubb (S1) – AV Valves Dubb (S2) – SL Valves Image Source: (Saladin, 2018) Phases of the Cardiac Cycle 1 Ventricular filling (during diastole) Isovolumetric contraction (during systole) Ventricular ejection (during systole) Isovolumetric relaxation (during diastole) Phases of the Cardiac Cycle 2 Ventricular filling Ventricles expand and their pressure drops below that of the atria AV valves open and blood flows into the ventricles Phases of the Cardiac Cycle 3 Isovolumetric contraction Atria repolarize, relax and remain in diastole for rest of cardiac cycle Ventricles depolarize, causing QRS complex, and begin to contract “Isovolumetric” because although ventricles contract, they do not eject blood Pressures in aorta and pulmonary trunk are still greater than those in the ventricles Cardiomyocytes exert force, but with all four valves closed, the blood cannot go anywhere Phases of the Cardiac Cycle 4 Ventricular ejection Begins when ventricular pressure exceeds arterial pressure and semilunar valves open T wave of ECG occurs late in this phase Stroke volume (SV) is about 70 mL Ejection fraction is about 54% of EDV (130 mL) 60 mL remaining blood is end-systolic volume (ESV) = EDV − SV Phases of the Cardiac Cycle 5 Isovolumetric relaxation T wave ends and ventricles begin to expand Blood from aorta and pulmonary trunk briefly flows backward filling cusps and closing semilunar valves Heart sound S2 occurs “Isovolumetric” because semilunar valves are closed and AV valves have not yet opened Ventricles are therefore taking in no blood When AV valves open, ventricular filling begins again PHASES OF THE HEART LIKE PHASES OF THE MOON Ventricular filling Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Image Source: (Saladin, 2018) THE HEART NEEDS TO PUMP OUT THE SAME AMOUNT THAT CAME IN The necessity of balanced ventricular output Image Source: (Saladin, 2018) CHECKPOINT 1. What are the three factors of resistance? 2. What causes the lubb sound? CHECKPOINT 1. BV LENGTH, BV DIAMETER, BLOOD VISCOSITY 2. CLOSING OF THE AV VALVES LEARNING OBJECTIVES Define cardiac output and explain it’s importance Describe the effects of exercise on cardiac output Autonomic Innervation of the Heart 2 Sympathetic nerves increase heart rate and contraction strength Sympathetic pathway to heart originates in the lower cervical to upper thoracic segments of the spinal cord Parasympathetic nerves slow heart rate Pathway begins with nuclei of the vagus nerves in the medulla oblongata Fibers of vagus nerve lead to the SA node Autonomic Innervation of the Heart 4 Figure 19.22 WHAT EFFECTS HOW MUCH BLOOD COMES OUT OF THE HEART? Cardiac Output (CO) = Heart Rate x Stroke Volume Stroke Volume = EDV - ESV Heart Rate 2 Tachycardia—resting adult heart rate above 100 bpm Stress, anxiety, drugs, heart disease, or fever Loss of blood or damage to myocardium Bradycardia—resting adult heart rate of less than 60 bpm In sleep, low body temperature, and endurance-trained athletes Positive chronotropic agents—factors that raise the heart rate Negative chronotropic agents—factors that lower the heart rate Chronotropic Effects of the Autonomic Nervous System 5 Without influence from cardiac centers, the heart has an intrinsic firing rate of 100 bpm Vagal tone—holds down the heart rate to 70 to 80 bpm at rest Steady background firing rate of the vagus nerves WHAT EFFECTS HOW MUCH BLOOD COMES OUT OF THE HEART? Heart rate: beats per minute ▪ Controlled by: 1. Autonomic nervous system 2. Exercise 3. Chemoreceptors Image Source: (Saladin, 2018) WHAT EFFECTS HOW MUCH BLOOD COMES OUT OF THE HEART? Stroke volume: amount of blood exiting left ventricle ▪ Effected by: 1. Preload 2. Contractility 3. Afterload Image Source: (Saladin, 2018) Preload 1 Preload—the amount of tension in ventricular myocardium immediately before it begins to contract Increased preload causes increased force of contraction Exercise increases venous return and stretches myocardium Cardiomyocytes generate more tension during contraction Increased cardiac output matches increased venous return Contractility 1 Contractility refers to how hard the myocardium contracts for a given preload Positive inotropic agents increase contractility Catecholamines increase calcium levels Hypercalcemia can cause strong, prolonged contractions and even cardiac arrest in systole Digitalis raises intracellular calcium levels and contraction strength Afterload 1 Afterload—sum of all forces opposing ejection of blood from ventricle Largest part of afterload is blood pressure in aorta and pulmonary trunk Opposes the opening of semilunar valves Limits stroke volume Hypertension increases afterload and opposes ventricular ejection Summary of Factors Affecting Cardiac Output Access the text alternative for slide images. Figure 19.23 HOW DOES EXERCISE EFFECT CARDIAC OUTPUT? Proprioceptors signal the brain Brain increases heart rate Increased heart rate increases cardiac output Increased cardiac output means more O2 for cells Sustained exercise can cause ventricular hypertrophy Image Source: (Saladin, 2018) CHECKPOINT 1. Cardiac output equals what? 2. Exercise does what to cardiac output? CHECKPOINT 1. HR x SV 2. Increases WORKS CITED S. (2012, July 22). Circulatory System Rap (Pump it Up!). Retrieved October 03, 2017, from https://www.youtube.com/ watch?v=KSbbDnbSEyM Saladin, K. (2018). Anatomy & Physiology: The Unity of Form and Function(8th ed.). New York, NY: McGraw-Hill.