circulatory system pressure gradients move blood through the heart and vessels. pulmonary...
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cardiac
Circulatory systemPressure gradients move blood through the heart and vessels.
Pulmonary circulation vs. systemic circulation
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headand arms(to pulmonarycircuit)aorta(frompulmonarycircuit)heartother organsdiaphragmliverintestineslegsDouble pump both ventricles pump an equal volume of blood into systemic and pulmonary circuits
Higher resistance through the systemic circuitPressure - force exerted by pumped blood on a vessel wall
Resistance - opposition to blood flow from friction
venacavaRight atriumTricuspid valvevena cavaRight ventricle
Pulmonarysemilunar valveLeft pulmonaryarteryRight pulmonaryarteryRight atriumTricuspid valveRight ventricle
AortaLeft atriumRightpulmonary veinLeft pulmonaryveinBicuspid valveLeft ventricle
AortaLeft pulmonaryveinRightpulmonary veinAortic semilunarvalveLeft atriumLeft ventricle
When pressure is greater behind the valve, it opens.When pressure is greater in front of the valve, it closesValves ensure one-way flow
Leakproofseamssemilunar valve
Right atriumTricuspid valveRight ventriclePapillary muscle contracts with ventricleChordae tendineaeSeptumShape of the AV valves is maintained by chordae tendineaeVentricularVentricular Systole Diastole
Blood pressure variation
Heart myocardiumCardiac muscle fibers are interconnected by intercalated discs.
DesmosomeGap junctionIntercalated discActionpotentialJunctions between cardiac muscle cells
Pacemaker activitySlow depolarizations set off action potentials in a cycle
Pacemaker cellSpontaneous action potential
Action potential spreadto other cellsGap junctionsCardiac muscleSelf-excitable muscles - action potential gradually depolarizes, then repolarizesGap junctionsNo gap junctions between atria and ventricles
Fibrous insulating tissue prevents AP from directly spreading from atria to ventricles
Sinoatrial(SA) nodePurkinjefibersAtrioventricular(AV) nodePacemaker locations:
SA node
AV node
Bundle of His
Purkinje fibersConduction of contractionBundle of His
Problems with heart rateAV node rhythm is slower - bradycardia
Heart block a type of bradycardia. Ventricles pump slowly and out of rhythm of atria Problems with heart rate
Problems with heart rate
Ventricular fibrillation
Atrial fibrillation
PlateauphaseThresholdpotentialAction potential in cardiac muscle
ActionpotentialContractionRefractoryperiodLong refractoryperiod ensures nosummation of twitches
Relaxation of cardiac muscles is requiredElectrocardiogram (ECG or EKG)Currents from electrical activity of heart spread to body tissues and fluidThis electrical activity is detected by electrodes and transformed to waveforms
PRQSTPPRSTTP interval
time (seconds)bradycardiatachycardiaventricularfibrillation
Ventricular and atrial diastoleCardiac cycle25
Atrial contractionCardiac cycle
Isovolumetric ventricular contractionCardiac cycleLubEnd diastolic volumeis in the ventricles
Ventricular ejectionCardiac cycle
Isovolumetric ventricular relaxationCardiac cycleDubEnd systolic volumeis in ventricles
Systolic or diastolic murmurs
Often due to stenosis or regurgitation at a valve (whistle vs. swish)
Normal heart lub-dup
Diastolic mitral stenosislub-dup-whistle
Diastolic aortic regurgitationlub-dup-swish
Systolic aortic stenosislub-whistle-dupSystolic tricuspid regurgitationlub-swish-dup
Diastolic patent ductus arteriosusWhat are heart murmurs?
Extrinsically: conduction speed
contraction strengthSympathetic signals increase stroke volume
Optimal lengthEnd-diastolic volume (EDV) (ml)Normal resting lengthIncreasein SVStroke volume (SV) (ml)B1A1Increasein EDVFrank Starling law(intrinsic increase in stroke volume)Would you expect type 1 or type 2 fibers in heart muscle?Cardiac muscle cells are highly resistant to fatigueMany mitochondria, larger mitochondria, myoglobin, high vascularization.Mitochondria convert lactate pyruvate glucose
Mitochondria
How does the heart regulate its contration?Heart diseaseWhat is a heart attack, what causes it?Why some heart attacks worse than others?
Heart failureDue to: Poor circulation to heart muscle (blockage)High blood pressure makes heart work harder
Insufficient valve
Less bloodleaving39Heart failureContinued sympathetic action can temporarily alleviate heart failure effects on output
Kidney fluid retention thus stroke volume
Stroke volume is so low that blood backs up in blood vessels leading to heart
Failure on left side - blood collects in pulmonary circuit and causes pulmonary edema. Oxygenation decreases.
Response of kidneys to fluid retention is now problematic.Congestive heart failureDue to thickening of heart muscle:To pump against high pressureLeaking or stiffness in heart valves
Due to over-dilation due bc of heart failure (usually pulmonary edema)
What causes an enlarged heart?
Heart attacks, strokes
Blockage due to plaques, embolismsArteriosclerosis
smooth musclepart of plaquevessel wallEndotheliumLipid centerof plaquePlaques in blood vesselsLDLs, inflammation contribute to plaque formationCholesterol carried in the blood:High-density lipoprotein - helps move cholesterol back to liver for removal
Low-density lipoprotein - used by cells, excess LDL infiltrates artery walls
Saturated fats and trans fats raise LDLs and are atherogenic
Free radicals oxidize LDLs and make them more likely to attach to plaques
blockagegraftedarteriesCoronary bypass