The Heart

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    Created by @alipari1

    mediastinum

    an anatomical region that extends from the sternum to the vertebral column, from the first rib to the diaphragm, and between the lungs

    pericardium

    membrane that surrounds and protects the heart

    fibrous pericardium

    superficial layer of the pericardium composed of tough, inelastic, dense irregular connective tissue - prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum

    serous pericardium

    thinner, more delicate membrane that forms a double layer around the heart

    parietal layer

    outer layer of the serous pericardium

    visceral layer

    inner layer of the serous pericardium (also known as the epicardium)

    pericardial fluid

    reduces friction between the layers of the serous pericardium as the heart moves

    myocardium

    middle layer of the heart responsible for the pumping action of the heart and is composed of cardiac muscle tissue

    endocardium

    inner layer of the heart that provides a smooth lining for the chambers of the heart and covers the valves of the heart

    auricle

    wrinkled pouch like structure on the anterior surface of each atrium - increase the capacity of the atria

    right atrium

    heart chamber that receives deoxygenated blood from three veins: the superior vena cava, inferior vena cava, and coronary sinus

    fossa ovalis

    remnant of the foramen ovale, an opening in the interatrial septum of the fetal heart that normally closes soon after birth

    tricuspid

    valve located between the right atrium and right ventricle - closes to prevent blood from going back into right atrium

    right ventricle

    heart chamber that pumps deoxygenated blood through the pulmonary valve to the pulmonary trunk

    left atrium

    heart chamber that receives oxygenated blood from 4 pulmonary veins

    mitral (bicuspid) valve

    valve located between the left atrium and left ventricle

    left ventricle

    heart chamber that pumps oxygenated blood through the aortic valve to the aorta

    papillary muscles

    cone shaped raised bundles of cardiac muscle within the ventricles that attach to chordae tendoneae then to valve cusps

    ligamentum arteriosum

    remnant of the ductus arterioles, a temporary blood vessel between the pulmonary trunk and aorta

    pulmonary arteries

    blood vessels that move deoxygenated blood towards the lungs

    pulmonary veins

    blood vessels that move oxygenated blood from the lung towards the heart

    pulmonary capillaries

    site of gas exchange in the lungs (oxygen into blood/carbon dioxide out of blood)

    right coronary artery

    blood vessel supplies blood to most of the right side of the heart - divides into posterior interventricular and marginal branches

    left coronary artery

    blood vessel supplies blood to most of the left side of the heart - divides into anterior interventricular and circumflex branches

    coronary sinus

    receives blood from coronary veins and drains into the right atrium

    sinoatrial node

    sets the rhythm of the cardiac conduction system - located in the superior wall of the right atrium

    atrioventricular node

    conducts action potentials from the atria to the bundle of His - provides a delay to give time for the atria to empty their blood into the ventricles

    Purkinje fibers

    rapidly conduct the action potentials from the apex of the heart upward to the remainder of the ventricular myocardium

    P wave

    atrial depolarization on an EKG

    QRS complex

    onset of ventricular depolarization on an EKG

    T wave

    ventricular repolarization on an EKG

    First degree heart block

    arrhythmia - slow conduction through the AV node resulting in a prolonged P-R interval

    Second degree heart block

    arrhythmia - some impulses don't pass through the AV node resulting in a "dropped beat"

    atrial flutter

    arrhythmia - rapid, irregular atrial contractions

    atrial fibrillation

    arrhythmia - lack of atrial depolarization resulting in no clear P waves

    ventricular tachycardia

    arrhythmia - ventricles depolarize at high rates leading to premature ventricular contractions (PVCs)

    ventricular fibrillation

    arrhythmia - disorganized electrical activity in the ventricles leading to "quivering"

    end-diastolic volume (EDV)

    volume in a ventricle prior to ejection

    stroke volume (SV)

    volume of blood ejected from a ventricle during a single cardiac cycle

    end-systolic volume (ESV)

    volume in a ventricle after ejection

    ejection fraction

    percentage of end-diastolic volume ejected (= SV/EDV)

    cardiac output

    volume (in L/min) ejected from a ventricle each minute (= SV X HR)

    medulla oblongata

    location of the cardiovascular control center

    cardiac accelerator nerves

    nerves containing sympathetic neurons that increase heart rate and contractility (force)

    Vagus nerves

    nerves containing parasympathetic neurons that decrease heart rate

    preload

    stretching of the heart resulting in more forceful muscle contraction

    contractility

    strength (force) of muscle contraction

    afterload

    pressure that must be overcome before a semilunar valve can open

    positive inotropic agents

    substances that increase contractility (sympathetic stimulation, Epi/NE, thyroid hormones, calcium)

    negative inotropic agents

    substances that decrease contractility (beta blockers, calcium channel inhibitors)

    positive chronotropic agents

    substances that increase heart rate

    negative chronotropic agents

    substances that decrease heart rate