Heart Actions

Heart ActionsCardiac Cycle: One complete heartbeat. The contraction of a heart chamber is called systole and the relaxation of a chamber is called diastole.

Cardiac cycle1 complete sequence of pumpingheart contracts & pumpsheart relaxes & chambers fill

contraction phasesystoleventricles pumps blood out

relaxation phasediastoleatria refill with blood2Heart Sounds - Opening and Closing of Valves, "Lub Dub"

Stethoscope - instrument to listen and measure heart sounds

AVSLAVLub-dub, lub-dubHeart sounds - closing of valvesLubforce blood against closed AV valvessignifies beginning of systole

Dubforce of blood against semilunar valvesclose at the beginning of ventricular diastole

4Heart murmurIrregular heart soundsleaking valve causes hissing sound blood squirts backward through valve

The cusps (flaps) of the bicuspid and tricuspid valves are anchored to the ventricle walls by fibrous cords called chordae tendineae, which attach to the wall by papillary muscles. This prevents the valves from being pushed up into the atria during ventricular systole.

Can you identify these parts?

Right Atrium Right Atrioventricular Valve (Tricuspid Valve) Right Ventricle Left Atrium Left Atrioventricular Valve (Mitral Valve) Left Ventricle

7. Papillary Muscle8.Chordae Tendinae9. Mitral Valve cusps

Blood pressure is the force of blood against the walls of arteries.

Blood pressure is recorded as two numbersthe systolic pressure (as the heart beats) over the diastolic pressure (as the heart relaxes between beats).

pump (peak pressure)_________________fill (minimum pressure)How is this reflected in blood pressure measurements?

chambers fillventriclesfillventriclespumpsystolic________diastolic110________809The cardiac cycle. For an adult human at rest with a pulse of about 75 beats per minute, one complete cardiac cycle takes about 0.8 second. During a relaxation phase (atria and ventricles in diastole), blood returning from the large veins flows into the atria and ventricles. A brief period of atrial systole then forces all remaining blood out of the atria into the ventricles. During the remainder of the cycle, ventricular systole pumps blood into the large arteries. Note that 7/8 of the timeall but 0.1 second of the cardiac cyclethe atria are relaxed and are filling with blood returning via the veins.The average (normal) blood pressure for an adult is 120/80. This number varies by person and it is best if you know what is *normal* for you, so that you (or your doctor) recognize when something is not normal.

We will be doing a lab where you will learn to use a this device and check your own blood pressure.SPHYGMOMANOMETERMeasurement of blood pressure

hypertension =(high blood pressure) if systolic > 150orif diastolic > 9011Factors affecting blood pressure: Average is 120/80 (higher number is the systolic pressure)1. Cardiac Output2. Blood volume (5 liters for avg adult)3. Blood Viscosity4. Peripheral Resistance

Cardiac Output (CO)Volume of blood pumped by each ventricle in one minuteCO = heart rate (HR) x stroke volume (SV)HR = number of beats per minuteSV = volume of blood pumped out by a ventricle with each beatCopyright 2010 Pearson Education, Inc.Cardiac Output (CO)At restCO (ml/min) = HR (75 beats/min) SV (70 ml/beat) = 5.25 L/minMaximal CO is 45 times resting CO in nonathletic peopleMaximal CO may reach 35L/min in trained athletesCardiac reserve: difference between resting and maximal COCopyright 2010 Pearson Education, Inc.

Electrical signalsallows atria to empty completely before ventricles contractstimulates ventricles to contract from bottom to top, driving blood into arteriesheart pumping controlled by electrical impulses signal also transmitted to skin = EKG15Cardiac Conduction

S-A NodeJunctional FibersA-V NodeA-V BundlePerkinje Fibers

Can you identify these parts?

1 Sinoatrial node (Pacemaker)2 Atrioventricular node3 Atrioventricular Bundle (Bundle of His)4 Left & Right Bundle branches5 Bundle Branches (Purkinje Fibers)View the heart animations at McGraw Hill to understand the Cardiac Cycle

Regulation of Cardiac Cyclecontrolled by the cardiac center within the medulla oblongata. The cardiac center signals heart to increase or decrease its rate according to many factors that the brain constantly monitors.

Muscle ActivityBody TemperatureBlood ion levels (potassium & calcium)

Variables in Heart RateIncreased muscle activity = Higher oxygen demands = increase in heart rate

Higher Body temperature = increased heart rate; Lower body temp = lower heart rate

Blood level of certain ions - Potassium High = Lower heart rate; Potassium Low = Higher heart rate

- Calcium high = Higher heart rate; Calcium Low = Lower heart rateECG electrocardiogram a recording of the electrical events (changes) during a cardiac cycle P Wave depolarization of the atria (atrial contraction systole)QRS Complex depolarization of the ventricles (ventricular contraction, systole)T Wave Repolarization of the ventricles

Heart Sounds opening and closing of the valves, flow of blood into and out of the chambers, vibrations in muscleIrregular Heart RatesArrhythmia-irregular heart rate

Tachycardia- rapid heartbeat (>100 BPM)

Bradycardia-slow heartbeat ( < 60 BPM)

Fibrillation = rapid, uncoordinated unsynchronized heart rate. Atria (not serious. Ventricles (deadly)

SADS = (Sudden Arrhythmia Death Syndromes or Sudden Adult Death Syndrome)Routine ECG Screening may help prevent deaths in young people

Interpreting ECGs

An ECG is printed on paper covered with a grid of squares.Notice that five small squares on the paper form a larger square. The width of a single small square on ECG paper represents 0.04 seconds.

A common length of an ECG printout is 6 seconds; this is known as a "six second strip."

Analyze an ECG

Each one of the figures represents an ECG pattern displaying three types of abnormal rhythms. Identify:

ArrhythmiaTachycardiaBradycardia

Defibrillatorcommon treatment for life-threatening cardiacarrhythmia

The device shocks the heart and allows it to re-establish its normal rhythm

The device can also be used to start a heart that has stopped.

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