Heart ValvesHeart Valves

• Atrioventricular valvesAtrioventricular valves– Tricuspid and BicuspidTricuspid and Bicuspid– Prevent backflow into the atria Prevent backflow into the atria

when ventricles are contractingwhen ventricles are contracting

• Semilunar valvesSemilunar valves– Pulmonary and Aortic semilunar Pulmonary and Aortic semilunar

valvesvalves– Prevent backflow into the Prevent backflow into the

ventricles when they are relaxingventricles when they are relaxing

Mechanisms to aid in Mechanisms to aid in return of blood to heartreturn of blood to heart

• One way ValvesOne way Valves– Open to allow blood through then Open to allow blood through then

close to prevent backflowclose to prevent backflow

• Skeletal muscle contractionsSkeletal muscle contractions– Help to pump blood through by Help to pump blood through by

constricting veins and squeezing constricting veins and squeezing bloodblood

• BreathingBreathing– Help to pump blood through by Help to pump blood through by

constricting veins and squeezing bloodconstricting veins and squeezing blood

Problems with blood Problems with blood returnreturn

• FaintingFainting– Standing still too long without moving; Standing still too long without moving;

particularly your lower bodyparticularly your lower body– less blood circulating because of less blood circulating because of

accumulation in veins; already have low accumulation in veins; already have low blood pressureblood pressure

• Varicose veinsVaricose veins– stretching of veins caused by accumulation stretching of veins caused by accumulation

of blood; of blood; – weak valves (allowed pooling of blood), weak valves (allowed pooling of blood),

standing too muchstanding too much

• Light headedness from liftingLight headedness from lifting– improper breathingimproper breathing

Heart soundsHeart sounds• Heart valves closing during each Heart valves closing during each

heartbeat create stereotypical sound heartbeat create stereotypical sound “lub-dup”“lub-dup”

• ““LUB”LUB” = two atroventricular valves = two atroventricular valves close during ventricular contractionclose during ventricular contraction

• ““DUP”DUP” = two semilunar valves close = two semilunar valves close during ventricular relaxationduring ventricular relaxation

Heartbeat conductionHeartbeat conduction

• Myogenic:Myogenic:– The ability of the heart to contract The ability of the heart to contract

is a property of the heart muscle is a property of the heart muscle itself; it is not dependent on the itself; it is not dependent on the body's nervous systembody's nervous system

• But brain does control the rateBut brain does control the rate

HeartbeatHeartbeat

Time (in Time (in seconds)seconds)

AtriaAtria VentriclesVentricles

0.150.15 SystoleSystole DiastoleDiastole

0.300.30 DiastoleDiastole SystoleSystole

0.400.40 DiastoleDiastole DiastoleDiastole

Conduction of heartbeat = 0.85 sec

Electrical and Contractile Electrical and Contractile Sequence of the Heart Sequence of the Heart

BeatBeat • SA node fires, initiating an impulse that rapidly SA node fires, initiating an impulse that rapidly

travels across the atriatravels across the atria

• Atria contract almost simultaneously (as a unit) Atria contract almost simultaneously (as a unit) forcing blood across the valves and into the forcing blood across the valves and into the ventriclesventricles

• Signal passes on to the septum separating right Signal passes on to the septum separating right and left halves of the heart : Atrioventricular and left halves of the heart : Atrioventricular nodenode

• AV node delays conduction of impulses from the AV node delays conduction of impulses from the atria to the ventricle (to ensure complete atrial atria to the ventricle (to ensure complete atrial contraction before ventricles begin contraction)contraction before ventricles begin contraction)

• AV node transfers signal to rapid conduction AV node transfers signal to rapid conduction pathway called the bundle of His pathway called the bundle of His

• Bundle branches divide into right and left Bundle branches divide into right and left halves going to right and left ventricles halves going to right and left ventricles respectivelyrespectively

• Bundle of His accelerates the impulse and Bundle of His accelerates the impulse and passes it down the interventricular septum to passes it down the interventricular septum to the Purkinje fibersthe Purkinje fibers

• Purkinje fibers carry the impulse deep into the Purkinje fibers carry the impulse deep into the ventricular myocardial wallsventricular myocardial walls

• Ventricles contract simultaneously (as a unit), Ventricles contract simultaneously (as a unit), forcing the AV valves shut, and pumping the forcing the AV valves shut, and pumping the blood into the aorta on the left and the blood into the aorta on the left and the pulmonary arteries on the rightpulmonary arteries on the right

Extrinsic control of Extrinsic control of heartbeatheartbeat

• Nervous Control of HeartbeatNervous Control of Heartbeat– Cardiac center Cardiac center in medulla oblongata can in medulla oblongata can

alter heartbeat through autonomic alter heartbeat through autonomic nervous systemnervous system

– ParasympatheticParasympathetic systemsystem promotes promotes normal responses including slowing normal responses including slowing down heartbeatdown heartbeat

– Sympathetic systemSympathetic system promotes stress promotes stress responses including speeding up responses including speeding up heartbeatheartbeat

– Need for oxygen, increase in blood Need for oxygen, increase in blood pressure, etc. may activate systemspressure, etc. may activate systems

Hormones in heartbeatHormones in heartbeat• Chemical messengers (hormones) Chemical messengers (hormones)

called catecholamines, which called catecholamines, which consist of adrenaline (epinephrine) consist of adrenaline (epinephrine) and noradrenaline (norepinephrine) and noradrenaline (norepinephrine) help to speed up heart ratehelp to speed up heart rate

• Acetylcholine, has the opposite Acetylcholine, has the opposite effect, causing the heart rate to effect, causing the heart rate to slowslow

Heart rate (72 Heart rate (72 beats/min)beats/min)

• Factors: age, gender, exercise, body Factors: age, gender, exercise, body temp.temp.– fetus 140-160 beats per min (FYI)fetus 140-160 beats per min (FYI)– faster in womenfaster in women

• Exercise raises heart rateExercise raises heart rate– increases systemic blood pressure increases systemic blood pressure

and routes more blood to the and routes more blood to the working muscles.working muscles.

– Trained athletes may be as low as Trained athletes may be as low as 40-60 beats per min.40-60 beats per min.

Blood PressureBlood Pressure• The pressure the blood exerts against The pressure the blood exerts against

any unit area of the blood vessel wallsany unit area of the blood vessel walls

• Systolic Systolic (heart contracting) : Less (heart contracting) : Less than 120mm Hgthan 120mm Hg

• DiastolicDiastolic (pressure at the moment (pressure at the moment your heart relaxes to permit blood your heart relaxes to permit blood flow into its chambers) : Less than flow into its chambers) : Less than 80mm Hg80mm Hg

• Normal blood pressure written as Normal blood pressure written as 120/80mmHg120/80mmHg

Measured in the arteries

Sounds of KorotkoffSounds of Korotkoff

• Cuff tightens it cuts off the blood flow Cuff tightens it cuts off the blood flow to your arm. As pressure is released, a to your arm. As pressure is released, a thump is heard (Systolic). thump is heard (Systolic). This is This is what we hear as the “LUB” sound what we hear as the “LUB” sound

• As the cuff is loosened further, the As the cuff is loosened further, the pressure continues to fall and the pressure continues to fall and the lighter thumps are heard as the blood lighter thumps are heard as the blood finds it easy to push pass the cuff. finds it easy to push pass the cuff. Thumping stops (Diastolic). Thumping stops (Diastolic). This is This is what we hear as the “DUP” soundwhat we hear as the “DUP” sound

ECG ECG (Electrocardiogram)(Electrocardiogram)

• Recording of Recording of electrical electrical changes changes during a during a cardiac cyclecardiac cycle

ECGECG

• Normal heartbeatNormal heartbeat – Is the result of an electrical Is the result of an electrical

impulse impulse – Originates in a specialized area Originates in a specialized area

in the wall of the right atrium in the wall of the right atrium called the called the SinoAtrial nodeSinoAtrial node

• SinoAtrial node (a.k.a) SA SinoAtrial node (a.k.a) SA node (a.k.a) Pace Makernode (a.k.a) Pace Maker

ECGECG

• P wave-electrical activity initiated P wave-electrical activity initiated by SA node causing atria to by SA node causing atria to contractcontract

• QRS wave-impulses to stimulate QRS wave-impulses to stimulate ventricle to contractventricle to contract

• T wave- electrical recovery of T wave- electrical recovery of ventriclesventricles

Arrhythmia (Irregular Arrhythmia (Irregular heart beat)heart beat)

• Problems that affect the electrical system of the heart muscle

• Irregularities in initiation or Irregularities in initiation or conduction of impulsesconduction of impulses

• Results in abnormal heart beatResults in abnormal heart beat• Cause the heart to pump less

effectively• Occurs due to

– coronary artery disease, high blood pressure, diabetes, smoking, excessive use of alcohol, drug abuse and stress

Irregular heart beats : Irregular heart beats : Too slowToo slow

• Bradycardia Bradycardia – heart rate slower than 60 beats heart rate slower than 60 beats

per minuteper minute• ResultResult

– low body temp, certain drugs, low body temp, certain drugs, brain edema after head traumabrain edema after head trauma

• In endurance type athletes, heart In endurance type athletes, heart rate can lower and still provide the rate can lower and still provide the same cardiac outputsame cardiac output

Irregular heart beats : Irregular heart beats : Too fastToo fast

• TachycardiaTachycardia – abnormally fast heart rate, over 100 abnormally fast heart rate, over 100

beats per minutebeats per minute• Due toDue to

– stress, elevated body temp, stress, stress, elevated body temp, stress, certain drugs or heart disease. Can certain drugs or heart disease. Can promote fibrillationpromote fibrillation

• Rapid and irregular or out of phase Rapid and irregular or out of phase contractionscontractions

• Defibrillation - strong electrical shockDefibrillation - strong electrical shock

Heart MurmurHeart Murmur

• Small deformity in valve – blood Small deformity in valve – blood passes back into the atria after passes back into the atria after the valves have closedthe valves have closed

• Produces a swishing noiseProduces a swishing noise

• Reduce efficiency of blood flowReduce efficiency of blood flow

• Can hinder person’s ability to Can hinder person’s ability to sustain normal activity levelssustain normal activity levels

Emergency DefibrillationEmergency Defibrillation

• Heart attack Heart attack induces induces ventricular ventricular fibrillationfibrillation

• Regain normal Regain normal rhythmrhythm

• CPR (Cardio-CPR (Cardio-Pulmonary Pulmonary Resuscitation)Resuscitation)