Please enable JavaScript.

Coggle requires JavaScript to display documents.

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

- - - - four chambers:
        
        Atria
        
        two upper chambers (they receive blood).
        
        right
        
        Receives blood returning from systemic circuit
        
        – Three veins empty into right atrium:
        
        § Superior vena cava: returns blood from body regions above the diaphragm
        
        § Inferior vena cava: returns blood from body regions below the diaphragm
        
        § Coronary sinus: returns blood from coronary veins
        
        left
        
        Receives blood returning from pulmonary circuit
        
        § Four pulmonary veins return blood from lungs
        
        – Interatrial septum: separates atria
        
        Fossa ovalis: remnant of foramen ovale of fetal heart
        
        Ventricles
        
        the two lower chambers (they discharge blood)
        
        right
        
        Pumps blood through pulmonary circuit
        
        left
        
        Pumps blood through systemic circuit
        
        – Interventricular septum: separates ventricles
        
        – Trabeculae carneae: irregular ridges of muscle on ventricular walls
        
        – Papillary muscles: project into ventricular cavity
        
        chordae tendineae that are attached to heart valves
        
        Right side receives oxygen-poor blood from tissues
        § Pumps blood to lungs to get rid of CO2, pick up O2, via pulmonary circuit
        
        Left side receives oxygenated blood from lungs
        § Pumps blood to body tissues via systemic circuit
        
        Two major types of valves
        
        – Atrioventricular valves located between atria and ventricles
        
        prevent backflow into atria when ventricles contract
        
        Tricuspid valve (right AV valve):
        
        made up of three cusps and lies between right
        atria and ventricle
        
        Mitral valve
        
        made up of two cusps and lies between left atria and ventricle
        
        Chordae tendineae:
        
        anchor cusps of AV valves to papillary muscles that function to:
        
        The Function of the Atrioventricular (AV) Valves (AV valves open; atrial pressure greater than ventricular pressure)
        
        1 Blood returning to the heart fills atria, pressing against the AV valves. The increased pressure forces AV valves open.
        
        3 Atriacontract,forcing additional blood into ventricles.
        
        2 Asventriclesfill,AVvalve flaps hang limply into ventricles.
        
        The Function of the Atrioventricular (AV) Valves ( AV valves closed; atrial pressure less than ventricular pressure)
        
        Ventriclescontract,forcing blood against AV valve cusps.
        
        2 AVvalvesclose
        
        3 Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria.
        
        – Semilunar valves located between ventricles and major arteries
        
        • Two semilunar (SL) valves prevent backflow from major arteries back into ventricles
        
        Open and close in response to pressure changes
        
        – Aortic semilunar valve: located between left ventricle and aorta
        
        – Pulmonary semilunar valve: located between right ventricle and pulmonary trunk
        
        – Each valve consists of three cusps that roughly resemble a half moon
        
        The Function of the Semilunar (SL) Valves
        
        Semilunar valves closed
        
        As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close.
      - location
        
        mediastinum
        
        Base (posterior surface) leans toward right shoulder
        
        • Apex points toward left hip
        
        • Apical impulse palpated between fifth and sixth ribs, just below left nipple
      - The wall of the heart consists of three layers of tissue:
        
        Epicardium
        
        protective layer mostly made of connective tissue.
        
        Myocardium
        
        the muscles of the heart.
        
        Endocardium
        
        lines the inside of the heart and protects the valves and chambers.
        
        These layers are covered in a thin protective coating called the pericardium.
        
        § Parietal layer lines internal surface of fibrous pericardium
        
        § Visceral layer (epicardium) on external surface of heart
      - Surface features
        
        Coronary sulcus (atrioventricular groove)
        
        Encircles junction of atria and ventricles
        
        Coronary circulation
        
        – Functional blood supply to heart muscle itself
        
        – Shortest circulation in body
        
        – Delivered when heart is relaxed
        
        – Left ventricle receives most of coronary blood supply
        
        • Coronary arteries
        
        ARTERY
        
        Both left and right coronary arteries arise from base of aorta and supply arterial
        
        blood to heart
        
        – Both encircle heart in coronary sulcus
        
        – Branching of coronary arteries varies among individuals
        
        – Arteries contain many anastomoses (junctions)
        
        § Provide additional routes for blood delivery
        
        § Cannot compensate for coronary artery occlusion
        
        – Heart receives 1/20th of body’s blood supply
        
        Right coronary artery
        
        1 more item...
        
        Left coronary artery
        
        1 more item...
        
        Coronary veins
        
        collect blood from capillary beds
        
        Coronary sinus empties into right atrium; formed by merging cardiac veins
        
        4 more items...
        
        – Anterior interventricular sulcus
        
        § Anterior position of interventricular septum
        
        – Posterior interventricular sulcus
        
        § Landmark on posteroinferior surface
      - Pathway of Blood Through Heart
        
        Right side of the heart
        
        Lungs
        
        – Pulmonary arteries →
        
        – Pulmonary trunk →
        
        – Pulmonary semilunar valve →
        
        1 more item...
        
        • Left side of the heart
        
        – Systemic circulation
        
        – Aorta →
        
        – Aortic semilunar valve →
        
        – Left ventricle →
        
        1 more item...
      - Cardiac Muscle Fibers
        
        Cardiac muscle cells
        
        striated, short, branched, fat, interconnected
        
        How Does the Physiology of Skeletal and Cardiac Muscle Differ?
        
        Some cardiac muscle cells are self-excitable
        
        § Two kinds of myocytes
        
        – Contractile cells: responsible for contraction
        
        – Pacemaker cells: noncontractile cells that spontaneously depolarize
        
        • Initiatedepolarizationofentireheart
        
        • Donotneednervoussystemstimulation,incontrasttoskeletal
        
        muscle fibers
        
        Heart contracts as a unit
        
        § All cardiomyocytes contract as unit (functional syncytium), or none contract § Contraction of all cardiac myocytes ensures effective pumping action
        
        § Skeletal muscles contract independently
        
        – The heart relies almost exclusively on aerobic respiration
        
        Cardiac muscle has more mitochondria than skeletal muscle so has greater
        dependence on oxygen
        
        – Cannot function without oxygen
        
        § Skeletal muscle can go through fermentation when oxygen not present
        
        § Both types of tissues can use other fuel sources
        
        Cardiac is more adaptable to other fuels, including lactic acid, but must have oxygen
        
        Influx of Ca2+ from extracellular fluid triggers Ca2+ release from SR
        
        § Depolarization opens slow Ca2+ channels in sarcolemma, allowing Ca2+ to
        
        enter cell
        
        § Extracellular Ca2+ then causes SR to release its intracellular Ca2+
        
        § Skeletal muscles do not use extracellular Ca2+
      - A normal heartbeat has two sounds
        
        a lub
        
        a dub
        
        These sounds are caused by the closing of valves inside your heart. If there are problems in your heart, there may be additional or abnormal sounds
        
        – First sound is closing of AV valves at beginning of ventricular systole
        
        – Second sound is closing of SL valves at beginning of ventricular diastole
        
        – Pause between lub-dups indicates heart relaxation
        
        Areas of the Thoracic Surface Where the Sounds of Individual Valves are Heard Most Clearly
        
        Aortic valve sounds heard in 2nd intercostal space at right sternal margin
        
        Pulmonary valve
        sounds heard in 2nd intercostal space at left sternal margin
        
        Mitral valve sounds heard over heart apex (in 5th intercostal space) in line with middle of clavicle
        
        Tricuspid valve sounds typically heard in right sternal margin of 5th intercostal space
      - Mechanical Events of Heart
        
        Systole: period of heart contraction
        
        • Cardiac cycle: blood flow through heart during one complete heartbeat
        
        • Diastole: period of heart relaxation
      - Regulation of Pumping
        
        Cardiac output
        
        amount of blood pumped out by each ventricle in 1 minute – Equals heart rate (HR) times stroke volume (SV)
        
        Imbalance
        
        • Congestive heart failure (CHF)
        
        Progressive condition; CO is so low that blood circulation is inadequate to meet
        tissue needs
        
        Reflects weakened myocardium caused by:
        
        Coronary atherosclerosis: clogged arteries caused by fat buildup; impairs oxygen delivery to cardiac cells
        
        1 more item...
        
        Persistent high blood pressure
        
        aortic pressure >90 mmHg causes
        myocardium to exert more force
        
        Multiple myocardial infarcts:
        
        heart becomes weak as contractile cells are replaced with scar tissue
        
        Dilated cardiomyopathy (DCM)
        
        ventricles stretch and become flabby, and myocardium deteriorates
        
        – Drug toxicity or chronic inflammation may play a role
        
        – Either side of heart can be affected:
        
        Left-sided failure results in pulmonary congestion
        
        1 more item...
        
        § Right-sided failure results in peripheral congestion
        
        1 more item...
        
        – Failure of either side ultimately weakens other side
        
        2 more items...
        
        Stroke volume
        
        volume of blood pumped out by one ventricle with each beat – Correlates with force of contraction
        
        At rest:
        
        CO(ml/min) = HR (75beats/min)SV (70ml/beat) = 5.25 L / min
        
        Mathematically: SV = EDV - ESV
        
        Three main factors that affect SV:
        
        – Preload
        
        degree of stretch of heart muscle
        
        venous return
        —amount of blood returning to heart
        
        Slow heartbeat and exercise increase venous return
        § Increased venous return distends (stretches) ventricles and increases contraction force
        
        – Contractility
        
        – Contractile strength at given muscle length
        
        § Independent of muscle stretch and EDV
        
        – Increased contractility lowers ESV; caused by:
        
        Sympathetic epinephrine release stimulates increased Ca2+ influx, leading to more cross bridge formations
        
        – Decreased by negative inotropic agents
        
        – Decreased by negative inotropic agents
        
        – Afterload
        
        back pressure exerted by arterial blood
        
        – Aortic pressure is around 80 mm Hg
        
        – Pulmonary trunk pressure is around 10 mm Hg
        
        Cardiac reserve:
        
        difference between resting and maximal CO
        
        Regulation of stroke volume
        – Regulation of heart rates
      - Regulation of Heart Rate
        
        • Heart rate can be regulated by:
        
        – Autonomic nervous system
        
        – Chemicals
        
        Hormones
        
        Epinephrine from adrenal medulla increases heart rate and contractility § Thyroxine increases heart rate; enhances effects of norepinephrine and
        epinephrine
        
        Ions
        
        3 more items...
        
        – Other factors
        
        Age
        
        § Fetus has fastest HR; declines with age – Gender
        
        § Females have faster HR than males – Exercise
        
        § Increases HR
        
        § Trained atheles can have slow HR – Body temperature
        
        § HR increases with increased body temperature
        
        Hypocalcemia: depresses heart
        
        • Hypercalcemia: increases HR and contractility
        
        • Hyperkalemia: alters electrical activity, which can lead to heart block and cardiac arrest
        
        • Hypokalemia: results in feeble heartbeat; arrhythmias
- - - - The fluid buildup strains the right side of the heartleading to right heart failure
        
        When blood and fluid back up into your lungs
        
        it can cause a condition known as pulmonary edema.
  - - - Heart murmur
      - Fluid buildup in the lungs
      - Irregular heart rhythms (arrhythmias)
- - - - When the kidneys are not working well, your hormone system, which regulates blood pressure,
        
        has to work harder to increase blood supply to the kidneys. When this happens, your heart has to pump harder, which can lead to heart disease.
      - Heart disease is the most common cause of death for people on dialysis.
  - - - You breathe in air from the world around you. In the lungs, the oxygen passes into the bloodstream and attaches to a protein called haemoglobin in the red blood cells.
      - This oxygenated blood returns to the heart where it is then pumped through the blood vessels around the organs and tissues of the body.
      - The cells use the oxygen and release carbon dioxide, which is transported in the blood back to the heart.
      - The heart pumps this deoxygenated blood to the lungs.
      - The carbon dioxide passes through the thin walls to be released when you breathe out, ready for the whole process to start again.
    - - Without rapid treatment, part of the heart muscle can die, making the heart less effective at pumping blood and increasing the risk of breathlessness and heart failure.
  - - - is activated and the imbalance of the activity of the SNS and vagal activity interaction occurs.
        
        abnormal activation of the SNS leads to further worsening of heart failure.
    - - increased cardiac contractility
      - reduced venous capacitance
      - including heart-rate acceleration
      - peripheral vasoconstriction