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60-year-old woman with history of obesity and DM II experienced a…

- - - - labored breathing and gurgling sound
  - - - blood leak backward into left atrium
      - left-sided heart failure
      - low blood pressure
- - - - age
      - myocardial infarction: heart attack
        
        by a thrombus or embolus
        
        thrombus forms inside a coronary artery narrowed by atherosclerosis,
        
        coronary artery blocked suddenly or has extremely slow blood flow.
        
        If demand for oxygen greater than supply, heart attack can happen without formation of blood clot
      - Indirect causes
        
        diabetes melllitus type 2
        
        hyperglycemia
        
        pancreas produce even more insulin
        
        resistance to insulin action
        
        glucose can't get into cells normally
        
        obesity
        
        increased levels of fatty acids caused insulin resistance
- - - - gross anatomy
        
        Internal features
        
        4 chambers
        
        2 inferior pumping chambers
        
        right ventricle
        
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        left ventricle
        
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        trabeculae camea
        
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        papillary muscles
        
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        make up most of heart volume
        
        actual pumps of heart
        
        thicker walls than atria
        
        2 superior receiving chambers
        
        right atrium
        
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        left atrium
        
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        small, thin-walled chambers
        
        auricles
        
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        contribute little to propulsion of blood
        
        Interatrial septum
        
        Fossa Ovalis
        
        remnant of foramen ovale oof fetal heart
        
        foramen ovale: bypass some of pulmonary circulation
        
        separates atria
        
        interventricular septum
        
        separates ventricules
        
        3 layers of heart wall
        
        myocardium
        
        circular/ spiral bundles of contrails cardiac muscle cells
        
        cardiac skeleton
        
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        endocardium
        
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        epicardium
        
        visceral pericardium
        
        general :2 side-by-side pumps
        
        piulmonary circuit
        
        receives oxygen-poor blood from tissues
        
        pumps blood to lungs to get rid of CO2 and pick up O2
        
        right side
        
        systemic circuit
        
        recipes oxygenated blood from lungs
        
        pumps blood to body tissues
        
        left side
        
        Surfaces features
        
        anterior interventricular sulcus
        
        anterior atrioventricular artery
        
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        anterior position of interventricular septum
        
        posterior interventricular sulcus
        
        landmark on posteroinferior surface
        
        coronary sulcus
        
        encircles junction of atria and ventricles
        
        atrioventricular groove
      - size and location
        
        size of a fist
        
        located in mediastinum
        
        2/3 of heart to left of midsternal line
        
        base leans toward right shoulder
        
        sits on superior surface of diaphragm
        
        apex points toward left hip
        
        less than 1 pound
      - Coverings of Heart: pericardium
        
        double -layer surrounding heart
        
        superficial fibrous pericardium
        
        protects and anchor heart to surrounding structures
        
        prevent overfilling of heart
        
        deep two-layered serous pericardium
        
        visceral pericardium
        
        epicardium
        
        external surface of heart
        
        pericardial cavity
        
        fluid-filled cavity separating the 2 layers
        
        decreases friction
        
        parietal pericardium
        
        lines internal surface of fibrous pericardium
    - - Right Side: oxygen-poor blood from body tissues back to heart
        
        inferior vena cava
        
        right atrium
        
        tricuspid valve
        
        right ventricle
        
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        coronary sinus
        
        superior vena cava
        
        Left Side: oxygen-rich blood returns to heart from lungs
        
        4 pulmonary veins
        
        left atrium
        
        mitral valve
        
        left ventricle
        
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    - - Heart sounds
        
        lub-dup sound
        
        associated with closing of valves
        
        1st sound: lub
        
        closing of AV valves at beginning of ventricular systole
        
        2nd sound:dup
        
        closing of SL valves at beginning of ventricular diastole
        
        pause between sounds
        
        heart relaxation
        
        0.1 s of pause from AV node
    - - microscopic anatomy
        
        intercalated discs
        
        desmosomes
        
        prevent cells from separating during contraction
        
        hold cells together
        
        gap junctions
        
        allow ions to pass from cell to cell
        
        couple adjacent cells electrically
        
        allow heart to be functional syncytium
        
        connecting junctions between cardiac cells
        
        intercellular space
        
        contains numerous capillaries
        
        connects cardiac muscle to cardiac skeleton
        
        giving cells something to pull against
        
        endomysium
        
        connective tissue layer
        
        cardiac muscle cells
        
        striated, short , branches, fat, interconnected
        
        one central nucleus
        
        numerous large mitochondria
        
        25-35% of cell volume
        
        afford resistance to fatigue
        
        rest of volume: sarcomeres
        
        A Bands
        
        I bands
        
        Z discs
        
        T tubules wider and less numerous
        
        enter cell once at Z disc
        
        sarcoplasmic reticulum simpler
        
        no triads
        
        2 type of myocytes
        
        contractile cells
        
        responsible for contraction
        
        pacemaker cells
        
        spontaneously depolarize
        
        initiate depolarization of entire heart
        
        noncontractile cells : autorhythmic cells
        
        don’t need nervous system stimulation
    - - functional blood supply of heart muscle
        
        coronaries arteries
        
        supply arterial blood to heart
        
        encircle heart in coronary sulcus
        
        arise from aorta
        
        contain main anastomoses
        
        provide additional routes for blood delivery
        
        cannot compensate for coronary artery occlusion
        
        left coronary artery
        
        2 branches
        
        anterior interventricular artery
        
        circumflex artery
        
        supplies
        
        left atrium
        
        posterior wall of left ventricle
        
        anterior ventricular walls
        
        interventricular septum
        
        right coronary artery
        
        supplies
        
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        2 branches
        
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        cardiac veins
        
        great cardiac vein of anterior interventricular sulcus
        
        middle cardiac vein in posterior interventricular sulcus
        
        small cardiac vein for inferior margin
        
        coronary sinus empties into right atrium
        
        collect blood for capillary beds
        
        merge into coronary sinus
        
        several anterior cardiac veins empty directly into right atrium anteriorly
    - - arteries
        
        carry blood away from heart
      - veins
        
        carry blood rewards heart
  - - - open and close in response to pressure changes
      - 2 types
        
        2 atrioventricular valves: AV
        
        hang in ventricles when heart relaxed
        
        allowing filling
        
        tricuspid valve:right AV valve
        
        made up of cusps
        
        between right atria and ventricle
        
        prevent back flow into atria during ventricles contraction
        
        bicuspid (mitral) valve: left AV valve
        
        made up of 2 cusps
        
        between left atria and ventricle
        
        chordae tendineae
        
        anchor cusps of both AV valves to papillary muscles
        
        papillary muscles function
        
        hold valves flaps in closed position during ventricular contraction
        
        prevent flaps from everting back into atria
        
        2 semilunar valves:SL
        
        open and close in response to pressure changes
        
        consisting of 3 cusps resembling half moon
        
        prevent back flow into ventricles from arteries
        
        pulmonary SL valve
        
        between right ventricle and pulmonary trunk
        
        aortic SL valve
        
        between left ventricle and aorta
      - ensure unidirectional blood flow through heart
  - - - extrinsic innervation of heart
        
        autonomic nervous system modify rhythm
        
        cardiac center: medulla oblongata
        
        sympathectic nervous system
        
        cardiaoacceleratory center
        
        accelerator
        
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        parasympathetic nervous system
        
        brakes
        
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        cardioinhibitory center
    - - blood pressure decreases as blood flows from arteries through capillaries and into veins
        
        arterial blood pressure
        
        aortic pressure fluctuates up, down with each heartbeat
        
        pulse pressure
        
        difference between systolic and diastolic pressure
        
        diastolic pressure
        
        aortic pressure drops to lowest during diastole
        
        mean arterial pressure
        
        pressure that propels blood to tissues
        
        diastolic pressure+ (pulse pressure/3)
        
        systolic pressure
        
        aortic pressure peak generated by ventricular contraction
        
        regulated by
        
        total peripheral resistance
        
        blood volume
        
        cardiac output
      - blood pressure
        
        force per unit area exerted on a vessel wall by contained blood
        
        systemic arterial blood pressure in largest arteries near Heart
      - blood flow= cardiac output
      - resistance
        
        opposition to flow
        
        measure of amount of friction blood encounters as it passes through vessels
        
        most friction encountered in peripheral/ systemic circulation
        
        called total peripheral resistance
    - - coordinated heartbeat function of
        
        Intrinsic conduction system
        
        sets basic rhythm
        
        initiate+ distribute impulse to coordinate depolarization and contraction of heart
        
        action potential initiation
        
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        sequence of excitation
        
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        network of non contractile- auorhythmic - cells
        
        presence of gap junctions
      - electrocardiography
        
        electrocardiogram
        
        graphic recording of electrical activity of heart
        
        ECG features
        
        T wave
        
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        P-R interval
        
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        QRS complex
        
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        S-T segment
        
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        P wave
        
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        Q-T interval
        
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        electrocardiograph
        
        instrument that can detect electrical currents generated by heart
      - Heart depolarizes and contract without nervous system
      - rhythm can be altered by autonomic nervous system
      - Action Potential of contractile muscles cells
        
        steps involved
        
        depolarization by Na+
        
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        after 200ms
        
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        depolarization
        
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        action potentials have plateau
        
        Benefit of longer AP and contraction
        
        sustained contraction ensures efficient ejection of blood
        
        longer refractory period prevents titanic contraction
        
        contractile muscle fibers
        
        make up bulk of heart
        
        responsible for pumping action
    - - cardiac cycle
        
        Phases
        
        isovolumetric contraction
        
        ventricles completely close
        
        volume remains constant
        
        ventricles continue to contract
        
        split-second period
        
        all valves closed
        
        atria relax
        
        ventricles begin to contract
        
        rising ventricular pressure causes closing of AV valves
        
        ventricular ejection
        
        pressure in aorta reaches ≈120 mm Hg
        
        semilunar valves forced open
        
        ventricular pressure exceeds pressure in large arteries
        
        ventricular filling
        
        atrial depolarization triggers atrial systole
        
        pushing remaining 20% of blood into ventricle
        
        80% of blood passively flows from atria through open and relaxed AV valves
        
        pressure low
        
        depolarization spreads to ventricles
        
        end diastolic volume; EDV
        
        volume of blood in each ventricle at end of ventricular diastole
        
        ventricle completely relaxed
        
        mid-to-late diastole
        
        isovolumetric relaxation
        
        ventricular pressure drops
        
        causing back flow of blood from aorta and pulmonary trunk
        
        ventricles relax
        
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        triggers closing of SL valves
        
        no valves open
        
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        atria continue to fill during ventricular systole
        
        early diastole
        
        AV valves open
        
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        atrial pressure exceeds ventricular pressure
        
        end systolic volume: ESV
        
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        represents series of pressure and blood volume changes
        
        mechanical events follow electrical events seen on ECG
        
        blood flow through heart during one complete heartbeat
      - systole:period of heart contraction
      - diastole:period of heart relaxation
      - Heartbeat ≈75 times/minute
      - cardiac cycle last 0.8 seconds
        
        atrial systole lasts ≈0.1 second
        
        ventricular systole ≈0.3 seconds
    - - cardiac reserve
        
        gives measure of level of exercise individual can pursue
        
        during exercise
        
        heart rate accelerates
        
        stroke volume increases
        
        capacity to increase cardiac output above rest level
        
        difference between resting and maximal CO
        
        stroke volume: SV
        
        SV= end diastolic volume - end systolic volume
        
        EDV affected by
        
        length of ventricular diastole
        
        venous pressure ≈120ml/beat
        
        amount of blood pumped out by one ventricle each heartbeat
        
        ESV affected by
        
        arterial blood pressure
        
        force of ventricular contraction ≈50ml/ beat
        
        normal SV=120ml-50ml= 70mL/ beat
        
        cardiac output: CO
        
        cardiac output=heart rate x stroke volume
        
        must meet tissues needs
        
        amount of blood pumped out by each ventricle in one minute
        
        average CO = 75 beats/min x 70mL/beat = 5250mL/min
        
        changes if stroke volume or heart rate changes
        
        factors affecting stroke volume—> cardiac output
        
        contractility
        
        negative inotropic agents
        
        electrolytes imbalance
        
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        impair / decrease contractility
        
        drugs
        
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        positive inotropic agents
        
        hormones
        
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        drugs
        
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        substances increasing contractility
        
        high levels of cellular Ca2+
        
        strength of contraction
        
        based on Ca2+ availability
        
        rises more when more Ca2+ enter cytoplasm
        
        afterload
        
        back pressure exerted on aortic and pulmonary valves
        
        pressure that ventricle must overcome to eject blood
        
        back pressure exerted by arterial blood
        
        in hypertension
        
        blood remains in heart after systole
        
        increasing ESV and reducing SV
        
        reduce ventricles ability to eject blood
        
        increased afterload
        
        preload
        
        venous return
        
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        degree of stretch of heart muscle just before contraction
        
        Franck-Sterling Law
        
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        slow heartbeat and exercise increase venous return