Heart Anatomy Slides PDF

Summary

These slides provide an overview of the structure and function of the human heart. They cover topics such as the layers of the heart wall and the conduction system of the heart. The information is intended to be used for educational purposes.

Full Transcript

THE HEART Biology 1203 Unit 2 Laura Solteiro MAIN FUNCTIONS OF THE CARDIOVASCULAR SYSTEM ▪Transportation of nutrients, gases, wastes, hormones ▪Regulation of homeostasis (part of internal environment) ▪Protection of body: contains factors for blood clotting and specialized cells t...

THE HEART Biology 1203 Unit 2 Laura Solteiro MAIN FUNCTIONS OF THE CARDIOVASCULAR SYSTEM ▪Transportation of nutrients, gases, wastes, hormones ▪Regulation of homeostasis (part of internal environment) ▪Protection of body: contains factors for blood clotting and specialized cells to fight off diseases CARDIOVASCULAR SYSTEM What are the components of this system?  Blood  Blood vessels  Heart THE HEART ▪A muscular pump that pumps blood through blood vessels (and throughout entire body) https://www.youtube.com/watch?v=OMqkv5RIPjk Heart beat sound "lub dub" LOCATION AND ORIENTATION OF THE HEART Superior vena cava Arch of aorta SUPERIOR BORDER Pulmonary trunk RIGHT BORDER Right lung Left lung Pleura (cut to Heart reveal lung inside) LEFT BORDER Pericardium (cut) APEX OF HEART Diaphragm INFERIOR SURFACE Anterior view of heart in thoracic cavity LOCATION AND ORIENTATION OF THE HEART Where? In mediastinum ▪Apex: directed anteriorly, inferiorly, and to the left ▪Base: directed posteriorly, superiorly, and to the right ▪Anterior surface is deep to the sternum and ribs ▪Inferior surface rests on the diaphragm ▪Located medial to the lungs 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) LAYERS OF THE PERICARDIUM AND HEART WALL Pulmonary trunk Fibrous pericardium Parietal layer of serous Pericardium pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous Heart pericardium) wall Myocardium Endocardium Heart chamber © 2017 Pearson Education, Inc. LAYERS OF THE HEART WALL Three layers of heart wall 1. Epicardium 2. Myocardium 3. Endocardium 1. Epicardium = visceral layer of serous pericardium LAYERS OF THE HEART WALL 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 LAYERS OF THE HEART WALL 3. Endocardium: innermost layer; is continuous with endothelial lining of blood vessels  Lines heart chambers and covers cardiac skeleton of valves Pulmonary trunk Fibrous pericardium Parietal layer of serous Pericardium pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous Heart pericardium) wall Myocardium Endocardium Heart chamber © 2017 Pearson Education, Inc. ANATOMY OF THE HEART Frontal plane Arch of aorta Ascending aorta Pulmonary trunk Superior vena cava PULMONARY SEMILUNAR Left pulmonary veins VALVE Right pulmonary veins LEFT ATRIUM AORTIC SEMILUNAR VALVE BICUSPID (MITRAL) VALVE RIGHT CHORDAE TENDINEAE ATRIUM LEFT VENTRICLE TRICUSPID VALVE RIGHT VENTRICLE Inferior vena Descending aorta cava Anterior view of frontal section showing internal anatomy ANATOMY OF THE HEART 4 Chambers  Atria: right atrium and left atrium  Ventricles: right ventricle and left ventricle EXTERNAL STRUCTURES Aortic arch Pulmonary trunk Right atrium Left atrium (auricle) Coronary artery Right ventricle Left ventricle INTERNAL STRUCTURES Left ventricle Aortic semilunar valve Right atrium Left atrium Tricuspid valve Bicuspid valve (or right atrioventricular valve) (or left atrioventricular valve, or mitral valve) Right ventricle Chordae tendineae Papillary muscle Septum ANATOMY OF THE HEART 4 Valves – ensure blood flows in 1 direction through heart  Atrio-ventricular valves: found between each atrium and ventricle  Anchored by chordae tendineae to papillary muscle  Tricuspid valve: right side TRY before you BUY  Bicuspid valve = mitral valve: left side  Semilunar valves: found between ventricles and arteries leading out Chordae tendineae Papillary attached to tricuspid muscle  Made of 3 flaps valve flap  Aortic semilunar valve: left side  Pulmonary semilunar valve: right side ANATOMY OF THE HEART Veins and arteries leading to and from heart:  Inferior and superior vena cava: into right atrium  Pulmonary trunk: leaving right ventricle  Pulmonary veins: into left atrium  Aorta: leaving left ventricle Capillary beds of lungs where DOUBLE gas exchange occurs CIRCULATION OF Pulmonary Circuit THE HEART Pulmonary arteries Pulmonary veins ▪Both sides of heart pump blood Venae Aorta and branches at the same time. Look to see the cavae Left difference where blood is atrium pumped to leaving each Left ventricle! 2 different locations Right ventricle atrium Right Heart ▪Pulmonary circuit takes blood ventricle from body and carries it to lungs Systemic Circuit to be oxygenated ▪Systemic circuit takes blood from lungs and carries oxygenated blood to rest of the Capillary beds body Oxygen-rich, of all body CO2-poor blood tissues where gas Oxygen-poor, exchange occurs CO2-rich blood https://www.youtube.com/watch?v=GMBSU-2GK3E 2:20 mins PULMONARY CIRCUIT Deoxygenated blood from body → inferior and superior vena cava → ______________ → tricuspid valve → right ventricle → __________________ → pulmonary trunk → lungs SYSTEMIC CIRCUIT Oxygenated blood from lungs Lungs → pulmonary veins → left atrium → bicuspid valve → ________________ → aortic semilunar valve → aorta → body CORONARY CIRCULATION ▪Coronary arteries take blood from the aorta to the myocardium and other tissues of the heart ▪The majority of coronary veins drain the blood into the posterior coronary sinus and then into the right atrium CONDUCTION SYSTEM OF THE HEART Specialized muscle tissue found in heart, controls the flow of blood through heart Each time the conduction system is activated, a cardiac cycle occurs  i.e., conduction of an electrical impulse through whole heart = one heart beat CONDUCTION SYSTEM OF HEART Intercalated discs anchor cardiac cells together  myocardium behaves as a single unit Heart muscle has fibers that are self excitable  Repeatedly generate action potentials that trigger heart contractions 2 important functions  Act as pacemaker  Form conduction system CONDUCTION SYSTEM OF HEART ▪ The heart’s intrinsic conduction system initiates and distributes impulses throughout the heart ▪ Coordinates contraction of heart muscle CONDUCTION SYSTEM OF HEART Autorhythmic fibers ▪ Cells that can spontaneously generate and conduct action potentials that trigger heart muscle contractions 1.Sinoatrial node (SA node) ▪ cluster of cells in wall of right atrium ▪ begins heart activity that spreads to both atria (pacemaker) ▪ excitation spreads to AV node CONDUCTION SYSTEM OF HEART 2. Atrioventricular node (AV node) ▪ in atrial septum ▪ transmits signal to AV bundle 3. AV bundle (bundle of His) ▪ the connection between atria and ventricles ▪ divides into bundle branches 4. Bundle branches ▪ continues down through septum to Purkinje fibers 5. Purkinje fibers ▪ large diameter fibers that conduct signals quickly from apex upward around both ventricles TIMING OF ATRIAL & VENTRICULAR EXCITATION SA node sets the pace since it is the fastest Acts as a natural pacemaker  SA node sets fundamental rhythm  Nerve impulses from autonomic nervous system and hormones modify timing and strength of each heartbeat In 30 msec excitation spreads through both atria to AV node TIMING OF ATRIAL & VENTRICULAR EXCITATION Excitation spreads through both atria to AV node 100 msec delay at AV node due to smaller diameter fibers allows atria to fully contract filling ventricles TIMING OF ATRIAL & VENTRICULAR EXCITATION In 50 msec excitation spreads through bundle branches and Purkinje fibers, and both ventricles simultaneously Atrial repolarization occurs simultaneous with this Ventricular repolarization completes the cardiac cycle ELECTROCARDIOGRAM Relationship between the Cardiac Cycle and ECG Initially, both the atria and ventricles are relaxed (diastole). The P wave represents depolarization of the atria and is followed by atrial contraction (systole). Atrial systole extends until the QRS complex, at which point, the atria relax. The QRS complex represents depolarization of the ventricles and is followed by ventricular contraction. The T wave represents the repolarization of the ventricles and marks the beginning of ventricular relaxation. MECHANISMS THAT CONTROL HEART RATE Left alone, SA node will maintain a constant heart rate. However, other factors are present that can affect the heart rate Autonomic nervous system Chemical regulation  Hormones  Ion composition Body temperature AUTONOMIC REGULATION OF HEART RATE Originates in cardiovascular center of medulla oblongata Sympathetic input increases heart rate  In SA and AV node: speeds up rate of spontaneous depolarization  In contractile fibers: enhances Ca2+ entry and increases contractility Parasympathetic input decreases heart rate AUTONOMIC REGULATION OF HEART RATE Various receptors bring in information to the cardiovascular center:  Proprioreceptors in muscles, joints, and tendons increase signaling with increased physical activity  Baroreceptors are stretch receptors in the aorta, atria, and other local arteries and veins. Rates of firing represent changes in blood pressure, levels of physical activity, and the relative distribution of blood  Chemoreceptors detect increased metabolic byproducts associated with increased activity, such as carbon dioxide, hydrogen ions, and lactic acid, plus falling oxygen levels, and signal increased or decreased blood flow based on the relative levels of these substances REGULATION OF HEART RATE CONTINUED ▪Hormones: Release of stimulatory epinephrine/adrenaline from adrenal gland leads to an increased heart rate (see unit 1). Thyroid hormone also can increase heart rate for a longer duration ▪Ionic Composition: Levels of ions (calcium, sodium, potassium) in blood can affect transmission of impulses through conduction system ▪Body Temperature: Heart rate increases when body temperature increases, to dissipate heat. Heart rate decreases when body temperature decreases, to prevent cold from being circulated around body

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