Cardiovascular SystemCardiovascular System

Part IPart I

Chapter 11Chapter 11

Anatomy of the HeartAnatomy of the HeartFunction:Function:– Transportation. Uses blood to carry oxygen, nutrients Transportation. Uses blood to carry oxygen, nutrients

and cell wastes. and cell wastes. Size:Size:– Approximately the size of your fistApproximately the size of your fist– Weighs less than one poundWeighs less than one poundLocation:Location:– Within the bony thorax between the lungsWithin the bony thorax between the lungsApex:Apex:– Pointed end which is directed towards the left hip Pointed end which is directed towards the left hip

and rest on the diaphragm.and rest on the diaphragm.Base:Base:– Posterosuperior aspect. Area where the blood vessels Posterosuperior aspect. Area where the blood vessels

of the body emerge. Points towards the right of the body emerge. Points towards the right shoulder and lies under the second rib. shoulder and lies under the second rib.

Coverings and Wall of the HeartCoverings and Wall of the HeartPericardium:Pericardium:– Double sac/Serous membraneDouble sac/Serous membrane

Visceral Pericardium/Epicardium:Visceral Pericardium/Epicardium:– Thin covering of the external surface of the heart Thin covering of the external surface of the heart

composing part of its wallcomposing part of its wall

Parietal Pericardium:Parietal Pericardium:– Loose covering which is reinforced on its superficial Loose covering which is reinforced on its superficial

face by connective tissue. Protects the heart and face by connective tissue. Protects the heart and anchors it to its surrounding structures.anchors it to its surrounding structures.

– Serous Pericardial Membranes: Serous Pericardial Membranes: Produce a slippery lubricating fluid …Produce a slippery lubricating fluid …

– Serous Fluid: Serous Fluid: Allows the heart to beat easily and the pericardial layers to Allows the heart to beat easily and the pericardial layers to slide smoothly across one another.slide smoothly across one another.

Coverings and Wall of the HeartCoverings and Wall of the HeartMyocardium:Myocardium:– Thick bundles of cardiac muscle. This is Thick bundles of cardiac muscle. This is

the layer of the heart which actually the layer of the heart which actually contractscontracts

Endocardium:Endocardium:– Thin sheet of endothelium that lines the Thin sheet of endothelium that lines the

hearts chambershearts chambers– Paricarditis:Paricarditis:

Inflammation of the pericardium resulting in Inflammation of the pericardium resulting in a loss of serous fluid causing the layers to a loss of serous fluid causing the layers to form adhesions which interferes with the form adhesions which interferes with the movement of the heart. movement of the heart.

Chambers and Associated Vessels Chambers and Associated Vessels of the Heartof the Heart

There are 4 chambers within the There are 4 chambers within the heart. Each is lined with heart. Each is lined with endocardium to help blood flow endocardium to help blood flow smoothly through the heart.smoothly through the heart.

Atria:Atria:– 2 of the chambers2 of the chambers

Ventricles:Ventricles:– 2 of the chambers2 of the chambers

Chambers and Associated Vessels Chambers and Associated Vessels of the Heartof the Heart

Superior/Receiving Chambers:Superior/Receiving Chambers:– Composed of the atriaComposed of the atria– Is not important in pumping blood through the heartIs not important in pumping blood through the heart– Blood flows into these atria at a low pressure which Blood flows into these atria at a low pressure which

fills the two ventriclesfills the two ventriclesInferior/discharging Chambers:Inferior/discharging Chambers:– Composed of the ventriclesComposed of the ventricles– In charge of actual pumping of blood through the In charge of actual pumping of blood through the

heart. heart. – They contract to propel blood out of the heart and They contract to propel blood out of the heart and

into circulationinto circulation– Right Ventricle:Right Ventricle:

Forms most of the anterior surface Forms most of the anterior surface – Left Ventricle:Left Ventricle:

Forms the apexForms the apex

Chambers and Associated Vessels Chambers and Associated Vessels of the Heartof the Heart

Interventricular/Interarterial Septum:Interventricular/Interarterial Septum:– Divides the heart longitudinallyDivides the heart longitudinallySuperior and inferior Vena Cavae:Superior and inferior Vena Cavae:– Pump blood out through the pulmonary trunk.Pump blood out through the pulmonary trunk.Pulmonary Trunk:Pulmonary Trunk:– Splits into the right and left pulmonary arteriesSplits into the right and left pulmonary arteriesPulmonary arteries:Pulmonary arteries:– Carry blood to the lungs, pick up oxygen, get rid of Carry blood to the lungs, pick up oxygen, get rid of

CO2.CO2.– Oxygen rich blood is then transported from the lungs Oxygen rich blood is then transported from the lungs

to the left side of the heart through the …to the left side of the heart through the …Pulmonary veins:Pulmonary veins:– Transport blood from the lungs to the left side of the Transport blood from the lungs to the left side of the

heartheart

Chambers and Associated Vessels Chambers and Associated Vessels of the Heartof the Heart

Pulmonary circulation:Pulmonary circulation:– Circulation from the right side of the heart, to the lungs and Circulation from the right side of the heart, to the lungs and

back to the left side of the heart.back to the left side of the heart.– Its only function is to carry the blood to the lungs for gas Its only function is to carry the blood to the lungs for gas

exchange and return it back to the heart.exchange and return it back to the heart.

Aorta:Aorta:– Blood from the left side of the heart is pumped out of the heart Blood from the left side of the heart is pumped out of the heart

and into the aortaand into the aorta– From the aorta all the systemic arteries branch out and supply From the aorta all the systemic arteries branch out and supply

the body tissues with blood.the body tissues with blood.

Systemic Circulation:Systemic Circulation:– Circulation of oxygen poor blood circulating from tissues back Circulation of oxygen poor blood circulating from tissues back

to the right atrium via the systemic veins which empty into the to the right atrium via the systemic veins which empty into the superior or inferior vena cavae moving through the lefts side of superior or inferior vena cavae moving through the lefts side of the heart through the body tissues and back to the right side of the heart through the body tissues and back to the right side of the heart. the heart.

ValvesValves

The heart has 4 valves allowing blood to The heart has 4 valves allowing blood to flow in only one direction through the flow in only one direction through the hearts chambers.hearts chambers.Atrioventricular/AV Valves:Atrioventricular/AV Valves:– Between the atrial and ventricular chambers Between the atrial and ventricular chambers

on each side.on each side.– Prevent back flow into the atria when Prevent back flow into the atria when

ventricles contract.ventricles contract.– Bicuspid/Mitral valve:Bicuspid/Mitral valve:

Left AV Valve consists of two flaps of endocardiumLeft AV Valve consists of two flaps of endocardium

– Tricuspid valve:Tricuspid valve:Right AV valve consists of 3 flaps of endocardiumRight AV valve consists of 3 flaps of endocardium

ValvesValvesChordae Tendinae:Chordae Tendinae:– Tiny white cords which anchor the flaps of the valves Tiny white cords which anchor the flaps of the valves

to the walls of the ventricles.to the walls of the ventricles.– When the heart is relaxed and blood is filling the When the heart is relaxed and blood is filling the

chambers the AV valve flaps hand loose into the chambers the AV valve flaps hand loose into the ventricle and when it contracts they are forced ventricle and when it contracts they are forced upwards keeping the valve open.upwards keeping the valve open.

Semilunar valves:Semilunar valves:– Pulmonary & Aortic Valves: have three flaps which Pulmonary & Aortic Valves: have three flaps which

lift all at once when the valves are closed and when lift all at once when the valves are closed and when the ventricles contract they openthe ventricles contract they open

– As they open and close in response to pressure As they open and close in response to pressure changes they force blood to continually move changes they force blood to continually move through the heart.through the heart.

ValvesValvesIncompetent Valve:Incompetent Valve:– Valve which is not working properly and Valve which is not working properly and

either stays open allowing blood to move either stays open allowing blood to move back and forth continuously or may stay shut back and forth continuously or may stay shut not allowing any blood to move through the not allowing any blood to move through the heart.heart.

Valvular stenosis:Valvular stenosis:– Bacterial infection of the endocardium Bacterial infection of the endocardium

causing the valves to become stiff forcing the causing the valves to become stiff forcing the heart to contract more rigorously in order to heart to contract more rigorously in order to open the valve.open the valve.

Cardiac CirculationCardiac CirculationCoronary Arteries:Coronary Arteries:– Provides blood that oxygenates and nourishes the Provides blood that oxygenates and nourishes the

heart. heart. – Branches from the base of the aorta and encircle the Branches from the base of the aorta and encircle the

heartheart– They are compressed when the ventricles contract They are compressed when the ventricles contract

and fill with blood when they are relaxed.and fill with blood when they are relaxed.

Cardiac Veins:Cardiac Veins:– Drain into the myocardium emptying into an Drain into the myocardium emptying into an

enlarged vessel on the backside of the heart called enlarged vessel on the backside of the heart called the … the …

Coronary sinus:Coronary sinus:– Empties into the right atriumEmpties into the right atrium

Cardiac CirculationCardiac CirculationAngina Pectoris:Angina Pectoris:– Crushing chest pain due to the myocardium Crushing chest pain due to the myocardium

being deprived of oxygenbeing deprived of oxygen– When the heart beats rapidly the When the heart beats rapidly the

myocardium receives inadequate blood myocardium receives inadequate blood supply because of the shortened relaxation supply because of the shortened relaxation periods between heart beatsperiods between heart beats

– If this condition is prolonged heart cells may If this condition is prolonged heart cells may die causing…die causing…

Myocardial infarction:Myocardial infarction:– Heart attack!Heart attack!

Physiology of the HeartPhysiology of the Heart

In one day the heart pushes the body’s 6 In one day the heart pushes the body’s 6 quarts of blood through the blood vessels quarts of blood through the blood vessels over 1,000 times pumping 6,000 quarts in over 1,000 times pumping 6,000 quarts in a day!a day!

Conduction system: Conduction system: – Cardiac muscle cells contract spontaneously Cardiac muscle cells contract spontaneously

and independently of nerve impulses. Muscle and independently of nerve impulses. Muscle cells in different areas of the heart then have cells in different areas of the heart then have different rhythms. different rhythms.

Cardiac Conduction SystemCardiac Conduction SystemNerves of the ANS: act as brakes to accelerate Nerves of the ANS: act as brakes to accelerate or decelerate heart rateor decelerate heart rate

Intrinsic conduction system/Nodal system: Intrinsic conduction system/Nodal system: – Composed of special tissue found only in the heart Composed of special tissue found only in the heart

and is a cross between muscle and nervous tissue.and is a cross between muscle and nervous tissue.– Causes the heart muscle depolarization from the Causes the heart muscle depolarization from the

atria to the ventricles and enforces a contraction rate atria to the ventricles and enforces a contraction rate of 75 bpm on the heart so that it beats as a unit.of 75 bpm on the heart so that it beats as a unit.

– Atrial cells: beat at 60 bpmAtrial cells: beat at 60 bpm– Ventricular cells: beat at 20-40 bpmVentricular cells: beat at 20-40 bpm

Conduction System of the HeartConduction System of the HeartSinoatrial Node (SA node):Sinoatrial Node (SA node):– Crescent shaped tissue located in the right atriumCrescent shaped tissue located in the right atrium– Has the highest rate of depolarizationHas the highest rate of depolarization– It starts each heartbeat and sets the paceIt starts each heartbeat and sets the pace– It is our internal “pacemaker”It is our internal “pacemaker”Atrioventricular Node (AV Node):Atrioventricular Node (AV Node):– Found at the junction of the atria and ventriclesFound at the junction of the atria and ventricles– Impulses from the SA node cause the atria to Impulses from the SA node cause the atria to

contract and is delayed by the AV node and passed contract and is delayed by the AV node and passed quickly to the AV bundlequickly to the AV bundle

– The bundle branches and purkinje fibers contract the The bundle branches and purkinje fibers contract the ventricles causing blood to be pumped out of the ventricles causing blood to be pumped out of the heartheart

Conduction System of the HeartConduction System of the Heart

Atrioventricular (AV) bundle:Atrioventricular (AV) bundle:– Sometimes referred to as the bundle of HISSometimes referred to as the bundle of HIS– Located in the interventricular septumLocated in the interventricular septum

Bundle Branches:Bundle Branches:– Right and left branches off the AV bundleRight and left branches off the AV bundle

Purkinje Fibers:Purkinje Fibers:– Thin fibers spread within the muscle of the Thin fibers spread within the muscle of the

ventricular walls allowing them to contractventricular walls allowing them to contract

Conduction System of the HeartConduction System of the HeartHeart Block:Heart Block:– Damage to the AV node releasing the ventricles from control of Damage to the AV node releasing the ventricles from control of

the SA node and the ventricles begin to beat at their own rate – the SA node and the ventricles begin to beat at their own rate – usually slowerusually slower

Ischemia:Ischemia:– Lack of adequate blood supply to the heart leading to …Lack of adequate blood supply to the heart leading to …

Fibrillation:Fibrillation:– Rapid, uncoordinated shuttering of the heart muscle making the Rapid, uncoordinated shuttering of the heart muscle making the

heart totally useless as a pumpheart totally useless as a pump– Major cause of death from a heart attackMajor cause of death from a heart attack

Tachycardia:Tachycardia:– Rapid heart rate. Over 100 bpm (at rest)Rapid heart rate. Over 100 bpm (at rest)

Bradycardia:Bradycardia:– Heart rate that is slower than normal (below 50 bmp)Heart rate that is slower than normal (below 50 bmp)

Cardiac Cycle and Heart SoundsCardiac Cycle and Heart Sounds

In a healthy heart the atria contract In a healthy heart the atria contract simultaneously and as they relax the simultaneously and as they relax the contraction of the ventricles begins.contraction of the ventricles begins.

Systole:Systole:– Contraction of the ventricles when the heart Contraction of the ventricles when the heart

is pumping bloodis pumping blood

Diastole:Diastole:– Relaxation of the ventricles when the heart Relaxation of the ventricles when the heart

is at restis at rest

Cardiac Cycle and Heart SoundsCardiac Cycle and Heart Sounds

Cardiac Cycle:Cardiac Cycle:– The events of one complete heart beatThe events of one complete heart beat– Occurs in less than 0.8 secondsOccurs in less than 0.8 seconds

1.1. Mid to late DiastoleMid to late Diastole1.1. Heart is completely relaxed, pressure is low, Heart is completely relaxed, pressure is low,

blood flows passively into the atria and into the blood flows passively into the atria and into the ventricles from the pulmonary and systemic ventricles from the pulmonary and systemic circulations.circulations.

2.2. Semilunar valves are closed, AV valves are openSemilunar valves are closed, AV valves are open

3.3. Atria contracts forcing remaining blood into the Atria contracts forcing remaining blood into the ventriclesventricles

Cardiac Cycle and Heart SoundsCardiac Cycle and Heart Sounds2. Ventricular Systole:2. Ventricular Systole:

- Ventricles contract, increase in pressure in - Ventricles contract, increase in pressure in ventricles, AV valves close, when intraventricular ventricles, AV valves close, when intraventricular pressure is greater than the pressure I the large pressure is greater than the pressure I the large arteries the semilunar valves open arteries the semilunar valves open and and blood blood rushes out of the ventriclesrushes out of the ventricles

- Atria are relaxed and begin to fill with - Atria are relaxed and begin to fill with blood.blood.3. Early Diastole:3. Early Diastole:

- Ventricles relax, semilunar valves shut for a - Ventricles relax, semilunar valves shut for a brief brief moment the ventricles are completely closedmoment the ventricles are completely closed

- Interventricular pressure decreases and when it - Interventricular pressure decreases and when it drops below the atrial pressure the AV valves are drops below the atrial pressure the AV valves are forced open and ventricles refill with blood and forced open and ventricles refill with blood and

the the cycle is complete!cycle is complete!

Heart SoundsHeart SoundsDuring each cycle of the heart there are two During each cycle of the heart there are two distinct sounds which can be heard:distinct sounds which can be heard:– The first is the closing of the AV valves and is a The first is the closing of the AV valves and is a

louder and longer soundlouder and longer sound– The second is the closing of the semilunar valves and The second is the closing of the semilunar valves and

the end of systole which is shorter and sharper the end of systole which is shorter and sharper soundingsounding

Murmurs:Murmurs:– Abnormal or unusual heart soundsAbnormal or unusual heart sounds– Common in young childrenCommon in young children– Indicates a valve problem Indicates a valve problem

(closed or narrowed valves)(closed or narrowed valves)

Cardiac Output (CO)Cardiac Output (CO)Defined: the amount of blood pumped out by Defined: the amount of blood pumped out by each side of the heart in 1 minute. The product each side of the heart in 1 minute. The product of heart rate and stroke volume.of heart rate and stroke volume.Stroke volume (SV):Stroke volume (SV):– Volume of blood pumped out by a ventricle with each Volume of blood pumped out by a ventricle with each

heartbeat.heartbeat.– Stroke volume increases as the force of the ventricle Stroke volume increases as the force of the ventricle

contraction increases.contraction increases.– Average is 70 ml/beatAverage is 70 ml/beat– The entire blood supply passes through the body one The entire blood supply passes through the body one

time each minute!time each minute!CO = HR (60-80 bpm) x SV (70 ml/beat)CO = HR (60-80 bpm) x SV (70 ml/beat)CO = 5250 ml/minCO = 5250 ml/min

Regulation of Stroke VolumeRegulation of Stroke Volume

The healthy heart pumps out 60% of the blood The healthy heart pumps out 60% of the blood that enters it – approximately 70 ml with each that enters it – approximately 70 ml with each heartbeat!heartbeat!

Starlings Law of the Heart:Starlings Law of the Heart:– States that the factor controlling SV is how much States that the factor controlling SV is how much

cardiac muscle cells are stretched just before the cardiac muscle cells are stretched just before the contraction. More stretch equals a stronger contraction. More stretch equals a stronger contraction.contraction.

Venous Return:Venous Return:

The amount of blood entering the heart and The amount of blood entering the heart and descending its ventricles keeps the amount pumped descending its ventricles keeps the amount pumped out each side of the heart equal. This creates an out each side of the heart equal. This creates an increase in venous return, increased stroke volume increase in venous return, increased stroke volume and increase of the forcefulness of contraction.and increase of the forcefulness of contraction.

Regulation of Heart RateRegulation of Heart RateBlood volume is decreased causing SV to Blood volume is decreased causing SV to decrease and CO is maintained by increasing decrease and CO is maintained by increasing the HRthe HRHR can be changed by the ANS, various HR can be changed by the ANS, various chemicals and hormoneschemicals and hormonesDuring physical and emotional stress the During physical and emotional stress the nerves of the sympathetic system stimulate nerves of the sympathetic system stimulate the SA and AV nodes to increase HR which the SA and AV nodes to increase HR which leads to an increase in O2 and glucoseleads to an increase in O2 and glucoseThe demand then decreases and the The demand then decreases and the parasympathetic nerves slow and steady the parasympathetic nerves slow and steady the heart giving it a chance to restheart giving it a chance to rest

Irregularities of the HeartIrregularities of the HeartCongestive Heart Failure (CHF):Congestive Heart Failure (CHF):– Heart is “worn out” because of age or hypertension and the Heart is “worn out” because of age or hypertension and the

heart pumps weakly.heart pumps weakly.– Epinephrine: mimics the effects of the sympathetic system and Epinephrine: mimics the effects of the sympathetic system and

increases HRincreases HR– Thyroxin: hormone used to increase HRThyroxin: hormone used to increase HR

Pulmonary congestion:Pulmonary congestion:– The pumping efficiency of the heart is decreased and The pumping efficiency of the heart is decreased and

circulation is inadequate to meet the needs of the tissues. circulation is inadequate to meet the needs of the tissues. – Progressive weakening of the heart due to clogged coronary Progressive weakening of the heart due to clogged coronary

vessels, increased BP or multiple myocardial infarctions causes vessels, increased BP or multiple myocardial infarctions causes one side of the heart to fail (usually the L) and fluid leaks into one side of the heart to fail (usually the L) and fluid leaks into the lungs causing pulmonary congestionthe lungs causing pulmonary congestion

Peripheral congestion:Peripheral congestion:– The right side of the heart fails edemaThe right side of the heart fails edema