The Heart

General InformationGeneral Information

The heart is the The heart is the Pump of the Pump of the Cardiovascular Cardiovascular systemsystem

Located behind the Located behind the sternum, between sternum, between the lungsthe lungs Slightly shifted to Slightly shifted to

the left side of the the left side of the chestchest

Apex: Points Apex: Points downwarddownward

Base: (Top) Where Base: (Top) Where all major vessels all major vessels leave the heart.leave the heart.

Size: About the size Size: About the size of your fistof your fist

APEX

BASE

PericardiumPericardium

Membrane surrounding the heartMembrane surrounding the heart Two Parts:Two Parts:

Fibrous Pericardium: Connects directly to Fibrous Pericardium: Connects directly to heartheart

Dense connective tissue for protectionDense connective tissue for protection Serous Pericardium: Lines the inner Serous Pericardium: Lines the inner

surface of the pericardial sacsurface of the pericardial sac Pericardial Cavity: Lies between the two Pericardial Cavity: Lies between the two

pericardial layerspericardial layers Filled with pericardial fluid: Reduces friction Filled with pericardial fluid: Reduces friction

between membranes during heart beatsbetween membranes during heart beats

Heart AnatomyHeart Anatomy

Two Atria:Two Atria: Right and left atrium are receiving Right and left atrium are receiving

chamberschambers Two Ventricles:Two Ventricles:

Right and left ventricles are pumping Right and left ventricles are pumping chamberschambers

Coronary Sulcus:Coronary Sulcus: Deep groove that separates atria from Deep groove that separates atria from

ventriclesventricles

Major VesselsMajor Vessels

Superior Vena Superior Vena Cava: Returns Cava: Returns blood from above blood from above the heart to the rt. the heart to the rt. AtriumAtrium

Inferior Vena Cava: Inferior Vena Cava: Returns blood from Returns blood from below the heart to below the heart to the rt. Atrium.the rt. Atrium.

Major VesselsMajor Vessels

Pulmonary Artery: Delivers Oxygen Pulmonary Artery: Delivers Oxygen deficient blood to the lungs, from the deficient blood to the lungs, from the rt. Ventriclert. Ventricle

Pulmonary Veins: Delivers oxygen rich Pulmonary Veins: Delivers oxygen rich blood to the left atrium from the lungsblood to the left atrium from the lungs

Ascending Aorta: All oxygen rich Ascending Aorta: All oxygen rich blood being pumped from the left blood being pumped from the left ventricle to the systemic circulation ventricle to the systemic circulation Branches into many other major arteriesBranches into many other major arteries

Heart ValvesHeart Valves

Atrioventricular Valves (cuspid valves):Atrioventricular Valves (cuspid valves): Between atria and ventriclesBetween atria and ventricles Rt. AV valve: Tricuspid valve (3 flaps)Rt. AV valve: Tricuspid valve (3 flaps) Lt. AV valve: Bicuspid valve (2 flaps)Lt. AV valve: Bicuspid valve (2 flaps) Cordae Tendinae: tendon like cords Cordae Tendinae: tendon like cords

attached to valves that control blood attached to valves that control blood passagepassage

Valves open an close based on pressure Valves open an close based on pressure differencesdifferences

When pressure within the ventricles increase, When pressure within the ventricles increase, valves closevalves close

Heart ValvesHeart Valves

Semilunar Valves:Semilunar Valves: Prevent the backflow of ejected bloodPrevent the backflow of ejected blood Pulmonary Semilunar Valve: Between rt. Pulmonary Semilunar Valve: Between rt.

Ventricle and pulmonary arteryVentricle and pulmonary artery Aortic Semilunar Valve: Between left Aortic Semilunar Valve: Between left

ventricle and ascending aortaventricle and ascending aorta

Heart WallHeart Wall

3 Layers3 Layers Epicardium: Very thin outer surface of Epicardium: Very thin outer surface of

the heartthe heart Myocardium: Muscular wall of the heartMyocardium: Muscular wall of the heart

Cardiac muscle: InvoluntaryCardiac muscle: Involuntary Endocardium: Inner surface of the heartEndocardium: Inner surface of the heart

In direct contact with bloodIn direct contact with blood

Cardiac Blood SupplyCardiac Blood Supply

Coronary Circulation (Huge blood Coronary Circulation (Huge blood demand)demand) Lt. And rt. Coronary arteries: arise from Lt. And rt. Coronary arteries: arise from

ascending aortaascending aorta All coronary venous return empties into All coronary venous return empties into

the coronary sinus and empties directly the coronary sinus and empties directly into the rt. Atriuminto the rt. Atrium

Angina Pectoris: Chest pain due to Angina Pectoris: Chest pain due to ischemia (lack of oxygen supply)ischemia (lack of oxygen supply)

Myocardial Infarction (MI)/Heart Attack: Myocardial Infarction (MI)/Heart Attack: death of tissuedeath of tissue

The HeartbeatThe Heartbeat

Conducting System:Conducting System: Heart is Heart is selfself activating activating The heart has specialized cells that initiate The heart has specialized cells that initiate

and transmit impulses throughout the and transmit impulses throughout the heart’s muscular tissue (myocardium)heart’s muscular tissue (myocardium)

Sinoatrial Valve (SA): in the wall of the right Sinoatrial Valve (SA): in the wall of the right atriumatrium

Sets the rhythm/pace of the heartSets the rhythm/pace of the heart Atrioventricular Node (AV): between atria and Atrioventricular Node (AV): between atria and

ventriclesventricles AV bundles, Bundle Branches, and purkinje fibers AV bundles, Bundle Branches, and purkinje fibers

transmit these impulses throughout the hearttransmit these impulses throughout the heart

The HeartbeatThe Heartbeat

Conducting Pathway:Conducting Pathway:1.1. SV NodeSV Node

2.2. AV NodeAV Node

3.3. AV bundlesAV bundles

4.4. Bundle BranchesBundle Branches

5.5. Purkinje FibersPurkinje Fibers

Heartbeat CycleHeartbeat Cycle

Systole: ContractionSystole: Contraction Diastole: RelaxationDiastole: Relaxation Pathway of Blood PropulsionPathway of Blood Propulsion

1.1. Atrial systole (blood pumped to Atrial systole (blood pumped to ventricles) and ventricular diastole ventricles) and ventricular diastole (receive atrial blood) occur at the same (receive atrial blood) occur at the same timetime

2.2. Ventricular systole (pumps blood out of Ventricular systole (pumps blood out of heart) and atrial diastole (receives blood heart) and atrial diastole (receives blood from body and lungs) occur at the same from body and lungs) occur at the same timetime

Heart MurmurHeart Murmur

Valves do not close properly and Valves do not close properly and blood gets pushed back through blood gets pushed back through valvesvalves Can occur at any valveCan occur at any valve Usually occurs due to faulty cordae Usually occurs due to faulty cordae

tendinae or papillary musclestendinae or papillary muscles

Heartbeat DynamicsHeartbeat Dynamics

Heart rate (beats/minute) ~ 75 Heart rate (beats/minute) ~ 75 times/min.times/min.

Blood Pressure: Pressure exerted on Blood Pressure: Pressure exerted on vessel wallsvessel walls Read by a sphygnomometer as soundsRead by a sphygnomometer as sounds Measures left ventricle diastole and systoleMeasures left ventricle diastole and systole

Read systole/diastoleRead systole/diastole Avg. adult male ~ 120/80Avg. adult male ~ 120/80 Avg. adult female ~ 110/70Avg. adult female ~ 110/70 What happens if part of the vessels are What happens if part of the vessels are

blocked??? (i.e. atherosclerosis)blocked??? (i.e. atherosclerosis)

ElectrocardiogramElectrocardiogram

(ECG)/(EKG): Measures electrical (ECG)/(EKG): Measures electrical events within the heartevents within the heart P wave: Atrial depolarizationP wave: Atrial depolarization QRS wave: Ventricle depolarization QRS wave: Ventricle depolarization

(masks atrial repolarization)(masks atrial repolarization) T wave: Ventricle repolarizationT wave: Ventricle repolarization

Heart SoundsHeart Sounds

Recorded using a stethoscopeRecorded using a stethoscope 11stst sound: Lubb sound: Lubb

Caused by the closing of the Atrioventricular Caused by the closing of the Atrioventricular valves as the ventricles contractvalves as the ventricles contract

22ndnd sound: Dubb sound: Dubb Caused by the closing of the Semilunar Caused by the closing of the Semilunar

Valve as the ventricles relaxValve as the ventricles relax Murmur: Caused by the swirling and Murmur: Caused by the swirling and

gurgling of blood as it is forced back gurgling of blood as it is forced back through valvesthrough valves

Cardiac OutputCardiac Output

Cardiac Output = (Stroke volume) X (Heart Cardiac Output = (Stroke volume) X (Heart rate)rate) CO = 75 bpm X 80 ml/beatCO = 75 bpm X 80 ml/beat CO = 6000 ml/min or 6.0 Liters/minuteCO = 6000 ml/min or 6.0 Liters/minute

Cardiac output is altered by either heart Cardiac output is altered by either heart rate or stroke volumerate or stroke volume Elite athletes actually have slower heart rates Elite athletes actually have slower heart rates

but increased stroke volumesbut increased stroke volumes Both are altered by autonomic nervous system Both are altered by autonomic nervous system

and chemicals within the bodyand chemicals within the body