Cardiovascular System Heart Study Guide PDF PDF

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Chapter 19--Cardiovascular System: Heart summary/study guide . A&P II. Spring 2019. MCC....

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SPRING 2019

ANATOMY AND PHYSIOLOGY II CARDIOVASCULAR SYSTEM: HEART AMY LYNN GAGLIANO MONROE COMMUNITY COLLEGE Professor Christopher Wendtland

A&P II—Cardiovascular System: Heart

Cardiovascular System • • • •

The cardiovascular system is comprised of both the heart and blood vessels The cardiovascular system transports blood to capillaries in the body to allow for exchange of substances All regions of the body that have a circulation must be adequately perfused If the heart does not pump adequate blood, or if a blood vessel becomes blocked for some reason, there may be a decrease in perfusion

❖ Perfusion—delivery of blood per unit time per mass of tissue • Infarction may result if the heart does not pump and adequate amount of blood

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The cardiovascular system is a closed circuit The three main types of blood vessels are arteries, veins, and capillaries o Artery—carries blood away from the heart STUDY TIP: A = arteries ‘away’ o Vein—carries blood to the heart o Capillaries—exchange with systemic cells and with air sacs in the lungs

Heart •

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The heart is a four-chambered organ that consists of two pumps, great vessels, and valves o The heart has two chambers in the superior portion known as the atria o The heart has two champers in the inferior portion known as ventricles o The heart has four valves that separate the chambers and great vessels ▪ Valves allow for onedirectional flow o The heart can v physiologically divided into two sides ▪ Left ▪ Right The heart is located within the thorax, specifically the mediastinum of the thorax The apex is inferior, posterior, and juts to the left The base is superior and posterior Pericardium—double layered sac that surrounds the heart

Materials developed by Amy Lynn Gagliano [email protected]

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A&P II—Cardiovascular System: Heart

Pericardial sac—anchors the heart within the mediastinum ▪ Fibrous pericardium— outer layer of fibrous connective tissue ▪ Serous pericardium— innermost serous layer • Parietal pericardium— closes to the fibrous pericardium, it is the outer layer attached to the fibrous pericardium • Visceral pericardium— closest to the heart; associated with the wall of the heart a.k.a the epicardium Pericardial cavity--In between the serous pericardium and parietal pericardium is a space which carries a small amount of serous fluid to help reduce friction as the heart is contracting and the membranes are gliding across each other Epicardium—the wall of the heart made of muscle o Epicardium—synonymous with the visceral pericardium, it is the most superficial o Myocardium—thick muscular layer o Endocardium—innermost layer Right side—pulmonary circuit Left side—systemic circuit o Left ventricular wall is much thicker to allow enough force to pump blood throughout the entire body o

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Materials developed by Amy Lynn Gagliano [email protected]

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Features of the Heart •

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Coronary sulcus (atrioventricular sulcus)—wraps around the heart; space between atria and ventricles; seen on both the anterior and posterior surfaces Interventricular sulcus—between the right and left ventricles on anterior and posterior surfaces Anterior surface of the heart shows the right atrium, right ventricle, and part of the left ventricle, specifically the auricle Posterior surface of the heart shows the left atrium, most of the left ventricle, and a part of the right ventricle

Coronary Arteries and Veins •

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The coronary arteries are the arteries of coronary circulation, which transports blood into and out of the cardiac muscle. They are mainly composed of the left and right coronary arteries, each of which give off branches The left coronary artery arises from the aorta above the left cusp of the aortic valve. It feeds blood to the left side of the heart. It branches into two and sometimes a third artery. The right coronary artery originates from above the right cusp of the aortic valve. It travels down the right coronary sulcus. The coronary sinus is a collection of veins joined to form a large vessel that collects blood from the myocardium (heart muscle). It delivers the less oxygenated blood to the right atrium, as do the superior and inferior vena cavae. The coronary sinus receives blood mainly form the small, middle, great, and oblique cardiac veins. It also receives blood from the left marginal vein and left posterior ventricular vein

Blood Flow

Body → Superior Vena Cava → Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonary Valve → Pulmonary Artery → Lung → Pulmonary Vein → Mitral Valve → Left Ventricle → Aortic Valve → Aorta → Body

1.) Deoxygenated blood enters the IVC and SVC from the body and brain respectively, which goes to the lungs for oxygenation 2.) Oxygenated blood returns to the heart via the PV for systemic circulation to the body 3.) The aorta pumps the now oxygenated blood to the body 4.) Arteries carry blood away from the heart 5.) Veins carry blood to the heart

Heart Muscle Cell •

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Sarcomere is the functional unit from Z disc to Z disc Myofibrils are “long tubes” that make up the myofilaments o Short, branching type of muscle tissue Intercalated disks are present with electrical synapses o Impulses go from one intercalated disk to another

Conducting System • • •

The heart has its own “internal wiring” Sinoatrial node is the “pacemaker” of the heart; electrical impulses begin here o Located in the right atrium The atrioventricular node is located between the right atrium and left ventricle

A&P II—Cardiovascular System: Heart

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Atrioventricular bundles spread into the right and left bundles along the septum of the heart The Purkinje fibers spread along the outside margins The SA and AV nodes are innervated by the parasympathetic division of the autonomic nervous system The myocardia are innervated by the sympathetic nervous system

Path of Electrical Activity SA node → AV node → AV bundle → R/L bundle branches → Purkinje fibers → muscle cells ECG/EKG • Deflections on an EKG represent a depolarizing or repolarizing event • Contraction of the heart to pump blood follows each deflection ➢ P—depolarizing action potential spreads through the two atria; the atria contract ➢ QRS—depolarizing event moves through both ventricles; ventricles contract ➢ T—repolarizing event of both ventricles; the ventricles fill with blood ➢ P—T—one heart beat * The depolarizing event in the ventricles during the QRS complex is so great that it masks the repolarizing of the atria during the same time

External Control of the Heart • • • •

Dual innervation system Sympathetic nervous system controls the cardiac muscle Parasympathetic nervous system controls the electrical impulses There is an antagonistic relationship between the two divisions of the autonomic nervous system when it comes to the heart o The parasympathetic nervous system lowers heart rate o The sympathetic nervous system increases heart rate

Overview of the Cardiac Cycle ❖ Systole—when a chamber of the heart contracts; pressure rises Materials developed by Amy Lynn Gagliano [email protected]

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A&P II—Cardiovascular System: Heart

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Diastole—when a chamber of the heart relaxes; pressure lowers Blood moves one way through the chambers of the heart and out of the heart Blood moves from a region of higher pressure to a region of lower pressure A chamber is systole pushes blood into a chamber in diastole or into a great vessel When the pressure of the blood in a chamber exceeds the pressure in the next chamber, a valve opens (and vice versa) Terminology ❖ End Diastolic Volume (EDV)—volume of blood in ventricle at end of diastole ❖ End Systolic Volume (ESV)—volume of blood in ventricle at end of systole ❖ Stroke Volume (SC)—volume of blood that is circulated per minute (EDV)-(ESV) = SV ❖ Cardiac Output—(HR) * (SV) ❖ Preload—amount of stretch placed on a chamber ❖ Afterload—resistance ❖ Inotropic—force ❖ Chronotropic—time ❖ Isovolumetric contraction—no change in chamber volume ❖ Isovolumetric relaxation—no change in chamber volume ❖ Ejection Fraction—the efficiency of the heart (SV)/(EDV) ❖ Venous return—volume of blood returned to the heart per unit time

The Cardiac Cycle 1.) Atrial contraction and ventricular filling (SYSTOLE) a. Pressure is high; volume is low b. Atria contract; ventricles relax c. Ventricular pressure < atrial pressure and < arterial trunk pressure d. AV valves are open; semilunar valves are closed 2.) Isovolumetric contraction (DIASTOLE) a. Pressure is low; there is no change in volume b. Atria relax; ventricles contract c. Ventricular pressure > atrial pressure but < arterial trunk pressure d. AV valves are closed; semilunar valves are closed 3.) Ventricular ejection a. Pressure is high; volume is low b. Atria relax; ventricles contract c. Ventricular pressure > atrial pressure and > arterial trunk pressure d. AV valves are closed; semilunar valves are open 4.) Isovolumetric relaxation a. Pressure is low; there is no change in volume Materials developed by Amy Lynn Gagliano [email protected]

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A&P II—Cardiovascular System: Heart

b. Atria relax; ventricles relax c. Ventricular pressure > atrial pressure but < arterial trunk pressure d. AV valves are closed; semilunar valves are closed 5.) Atrial relaxation and ventricular filling a. Pressure is high; volume is low b. Atria relax; ventricles relax c. Ventricular pressure < atrial pressure and < arterial trunk pressure d. AV valves are open; semilunar valves are closed

Blood Pressure Blood pressure is controlled by the baroceptor reflex. Blood pressure (BP) is proportional to blood volume (BV) Total peripheral resistance (TPR) can be changed by altering o Vessel length o Vessel radius o Blood viscosity It is easiest to change vessel radius BP = (CO)(TPR) CO = (HR)(SV) • • •

Factors affecting Stroke Volume • Venous return is proportional to stroke volume • Positive inotropic agents increase stroke volume • Negative inotropic agents decrease stroke volume • Afterload is indirectly proportional to stroke volume Factors affecting Cardiac Output • Positive chronotropic agents increase heart rate, which increases cardiac output • Negative chronotropic agents decrease heart rate, which decrease cardiac output • Venous return is proportional to stroke volume which is proportional to cardiac output • Afterload is indirectly proportional to stroke volume which is directly proportional to cardiac output • Positive inotropic agents increase stroke volume which increase cardiac output • Negative inotropic agents decrease stroke volume which decrease cardiac output

Materials developed by Amy Lynn Gagliano [email protected]

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