The Cardiovascular The Cardiovascular SystemSystem

Chapter Chapter #13#13

Human Heart

13.1 Introduction13.1 Introduction

• The heart pump 7,000 liters of blood/day.The heart pump 7,000 liters of blood/day.• Pumps 2.5 billion times in an average life Pumps 2.5 billion times in an average life

span.span.• The heart, arteries, veins, capillaries, and The heart, arteries, veins, capillaries, and

blood make up the cardiovascular system.blood make up the cardiovascular system.• The main job of the cardiovascular system The main job of the cardiovascular system

is to deliver oxygen and nutrients to all is to deliver oxygen and nutrients to all body cells and remove waste from all cells.body cells and remove waste from all cells.

• Without fresh OWithout fresh O2 2 and removing waste death and removing waste death would be quick.would be quick.

13.2 Structure of the 13.2 Structure of the HeartHeart

• The heart is a hollow, cone-shaped, muscular The heart is a hollow, cone-shaped, muscular pump located within the thoracic cavity and pump located within the thoracic cavity and resting on the diaphragm. The upper most of resting on the diaphragm. The upper most of the heart is the the heart is the BASE. BASE. The pointy end is theThe pointy end is the Apex.Apex.

• An average heart is about the size of your An average heart is about the size of your fist.fist.

• The base of the heart lies beneath your 2The base of the heart lies beneath your 2ndnd rib.rib.

• Pericardium is the covering of the heart.Pericardium is the covering of the heart.• Pericardial cavity contains a small volume of Pericardial cavity contains a small volume of

fluid that reduces friction the pericardium fluid that reduces friction the pericardium and the heart itself.and the heart itself.

13.2 Continued…13.2 Continued…• The wall of the heart is made of 3 The wall of the heart is made of 3

layers:layers:1.1. The The outer pericardiumouter pericardium which protects which protects

the heart by reducing friction.the heart by reducing friction.2.2. The The thickestthickest middle myocardium middle myocardium

consist mostly of muscle and pumps consist mostly of muscle and pumps blood out of the heart.blood out of the heart.

3.3. The The inner endocardiuminner endocardium consists of consists of epithelium and connective tissue that epithelium and connective tissue that contains many elastic and collagenous contains many elastic and collagenous fibers. The endocardium is continuous fibers. The endocardium is continuous with the inner linings of blood vessels with the inner linings of blood vessels attached to the heart.attached to the heart.

13.2 Heart Chambers 13.2 Heart Chambers and Valvesand Valves

• The heart is divided into 4 chambers.The heart is divided into 4 chambers.• The upper chambers are the The upper chambers are the atriaatria. .

Atria have thin walls and receive Atria have thin walls and receive blood returning to the heart. blood returning to the heart.

• The lower chambers are the The lower chambers are the ventriclesventricles. Ventricles receive blood . Ventricles receive blood from the atria and contract to force from the atria and contract to force blood out of the heart into arteries.blood out of the heart into arteries.

Tricuspid

Bicuspid valve

• The The septumseptum separates the atrium and separates the atrium and ventricle on the right side from the left ventricle on the right side from the left side. The blood from the two sides side. The blood from the two sides NEVER NEVER mixes.mixes.

• An atrioventricular valve, the An atrioventricular valve, the tricuspidtricuspid on the RIGHT side and the on the RIGHT side and the bicuspid bicuspid (Mitral)(Mitral) on the LEFT side ensure on the LEFT side ensure one-one-way blood flowway blood flow from atria to ventricle. from atria to ventricle.

• TricuspidTricuspid has 3 cusps allows blood to has 3 cusps allows blood to move from the right atrium into the right move from the right atrium into the right ventricle.ventricle.

• VeinsVeins carry blood to the heart. carry blood to the heart.• ArteriesArteries carry blood away from the carry blood away from the

heart. A-away.heart. A-away.• The right atrium receives blood from The right atrium receives blood from

two large veins and 1 small.two large veins and 1 small.

1.1. Superior vena cavaSuperior vena cava

2.2. Inferior vena cavaInferior vena cava

3.3. (Small) Coronary sinus drains blood (Small) Coronary sinus drains blood into the right atrium from the into the right atrium from the myocardium.myocardium.

• Strong, fibrous strings called Strong, fibrous strings called chordae tendineaechordae tendineae attach to the attach to the cusps of the tricuspid valve on the cusps of the tricuspid valve on the ventricular side. They keep the cusps ventricular side. They keep the cusps from swinging back into the atrium.from swinging back into the atrium.

• The right ventricle has a thinner The right ventricle has a thinner muscular wall than the left ventricle. muscular wall than the left ventricle.

• The The right chamberright chamber pumps blood a pumps blood a short distance to the short distance to the lungslungs. .

• The The left ventricleleft ventricle pumps blood to all pumps blood to all other parts of the other parts of the bodybody..

ValvesValves

• The bicuspid and tricuspid valves The bicuspid and tricuspid valves are called are called atrioventricular valves atrioventricular valves because they are between atria and because they are between atria and ventricles. ventricles.

• The pulmonary and aortic valves are The pulmonary and aortic valves are called called semilunarsemilunar because of the half- because of the half-moon shapes of their cusps.moon shapes of their cusps.

Skeleton of the HeartSkeleton of the Heart

• Rings of dense connective tissue Rings of dense connective tissue surround the pulmonary trunk and aorta surround the pulmonary trunk and aorta and dense masses of connective tissue and dense masses of connective tissue make up the Skeleton of the Heart. make up the Skeleton of the Heart.

• These rings provide firm attachments These rings provide firm attachments for heart valves and for muscle fibers. for heart valves and for muscle fibers.

• They prevent the outlets of the atria and They prevent the outlets of the atria and ventricles from dilating during ventricles from dilating during contraction. contraction.

Path of BloodPath of Blood• Vena cava Vena cava (Largest vein in the body)(Largest vein in the body)• Right atrium Right atrium (Right side deoxygenated blood)(Right side deoxygenated blood)• Tricuspid valueTricuspid value• Right ventricleRight ventricle• Pulmonary arteryPulmonary artery• Right and left lung Right and left lung (Picks up O(Picks up O2 2 & drops off & drops off

COCO22))• Pulmonary veinPulmonary vein• Left atrium Left atrium (Left side oxygenated blood)(Left side oxygenated blood)• Bicuspid valueBicuspid value• Left ventricleLeft ventricle• Aorta Aorta (Largest artery in the body)(Largest artery in the body)• To all body cellsTo all body cells

Blood Supply to the Blood Supply to the HeartHeart

• Coronary vessels carry blood to and Coronary vessels carry blood to and from the heart itself.from the heart itself.

• Heart attack is the death of a Heart attack is the death of a section of heart muscle.section of heart muscle.

Heart ActionsHeart Actions

• SystoleSystole atria contract and ventricles atria contract and ventricles relaxed.relaxed.

• DiastoleDiastole atria relaxed and ventricles atria relaxed and ventricles contract.contract.

• Both atria contract while both Both atria contract while both ventricles relax and them both ventricles relax and them both ventricles contract as both atria ventricles contract as both atria relax.relax.

Heart SoundsHeart Sounds• A heartbeat heard through a A heartbeat heard through a stethoscopestethoscope

sounds like lubb-dupp.sounds like lubb-dupp.• The sound is caused by the The sound is caused by the closing of valves.closing of valves.• LubbLubb when bicuspid and tricuspid valves when bicuspid and tricuspid valves

close.close.• DuppDupp when semilunar valves close. when semilunar valves close.• A A heart murmurheart murmur blood flowing backward blood flowing backward

through the heart when valves are not through the heart when valves are not closing tightly. closing tightly.

• Lubb-dupp-swish would signal a problem Lubb-dupp-swish would signal a problem with the semilunar valve. with the semilunar valve.

• Lubb-swish-dupp= problem with bicuspid Lubb-swish-dupp= problem with bicuspid and/or tricuspid valve.and/or tricuspid valve.

Cardiac Muscle FibersCardiac Muscle Fibers

• Cardiac muscle fibers function much Cardiac muscle fibers function much like those of skeletal muscles. The like those of skeletal muscles. The heart pumps as one unit.heart pumps as one unit.

• Functional syncytiumFunctional syncytium is a mass of is a mass of merged cells that function as a unit.merged cells that function as a unit.

• Sinoatrial nodeSinoatrial node (S-A node) is a small, (S-A node) is a small, elongated mass of specialized elongated mass of specialized cardiac muscle tissue just beneath cardiac muscle tissue just beneath the epicardium in the right atrium.the epicardium in the right atrium.

• S-A nodeS-A node are the cells that initiate are the cells that initiate the stimulus for contraction of the the stimulus for contraction of the heart muscle.heart muscle.

• Electrocardiogram (ECG)is the recording Electrocardiogram (ECG)is the recording of the electrical charges that occur in the of the electrical charges that occur in the myocardium during a cardiac cycle.myocardium during a cardiac cycle.

• Blood volume of changes to Blood volume of changes to accommodate cellular requirements. accommodate cellular requirements. Example during strenous exercise, Example during strenous exercise, skeletal muscles require more blood.skeletal muscles require more blood.

• The cardiac control center is in the The cardiac control center is in the brains medulla oblongata.brains medulla oblongata.

• The ions that influence the heart the most The ions that influence the heart the most are are potassium (Kpotassium (K++) and Calcium (Ca) and Calcium (Ca+2+2).).

• Excess potassium ionsExcess potassium ions (hyperkalemia) (hyperkalemia) decrease the rate and force of decrease the rate and force of contractions.contractions.

• Low potassium ions Low potassium ions (hypokalemia)(hypokalemia) the the heart may develop a potentially life-heart may develop a potentially life-threatening abnormal rhythm threatening abnormal rhythm (arrhythmia).(arrhythmia).

• Excess calcium ionsExcess calcium ions (hypercalcemia) (hypercalcemia) increase heart actions, posing the danger increase heart actions, posing the danger that the heart will contract for a prolonged that the heart will contract for a prolonged time.time.

• Low calcium ions (hypocalcemia) Low calcium ions (hypocalcemia) depresses heart action.depresses heart action.

13.4 Blood Vessels13.4 Blood Vessels• ArteriesArteries

1.1. They carry blood They carry blood awayaway from the heart from the heart

2.2. They carry blood under They carry blood under high pressurehigh pressure

3.3. They are They are roundround in shape in shape

4.4. They have They have thick, muscular wallsthick, muscular walls Arterioles Arterioles are arteries that have divide are arteries that have divide

and divide into progressively thinner and divide into progressively thinner tubes.tubes.

VasoconstrictionVasoconstriction when arteries when arteries contract.contract.

VasodilationVasodilation when arteries dilate. when arteries dilate.

VeinsVeins

• VeinsVeins

1.1. They carry blood They carry blood to the heartto the heart

2.2. They carry blood under They carry blood under low low pressurepressure

3.3. They are They are flat in shapeflat in shape and have and have little musclelittle muscle

4.4. They have many They have many one-way valvesone-way valves to to keep blood flowing in one direction.keep blood flowing in one direction.

96 000 96 000 kilometers kilometers

of blood of blood vessels in vessels in the human the human body. 2 ½ body. 2 ½

times times around the around the

earth.earth.

13.5 Blood Pressure13.5 Blood Pressure• Blood pressureBlood pressure is the force of blood is the force of blood

exerts against the inner walls of exerts against the inner walls of blood vessels.blood vessels.

• Blood pressure is most commonly Blood pressure is most commonly refers to pressure in arteries.refers to pressure in arteries.

• Pulse Pulse is the force of blood through is the force of blood through an artery.an artery.

• Blood pressure is recorded as a Blood pressure is recorded as a fraction. Systolic over diastolic.fraction. Systolic over diastolic.

• Systolic pressureSystolic pressure is the maximum is the maximum pressure during ventricular pressure during ventricular contraction.contraction.

• Diastolic pressureDiastolic pressure is the lowest is the lowest pressure that remains in the arteries pressure that remains in the arteries before the next contraction before the next contraction (ventricular relaxation).(ventricular relaxation).

Heart ActionHeart Action

• Stroke VolumeStroke Volume the volume of blood the volume of blood discharged from the left ventricle with discharged from the left ventricle with each contraction.each contraction.

• Cardiac outputCardiac output the volume discharged the volume discharged from the left ventricle per minute. Can be from the left ventricle per minute. Can be calculated by multiplying the stroke calculated by multiplying the stroke volume by the beats per minute.volume by the beats per minute.

• Blood volume equals the sum of the Blood volume equals the sum of the formed elements and plasma volumes in formed elements and plasma volumes in the vascular system. (It is usually about 5 the vascular system. (It is usually about 5 liters for adults)liters for adults)

• Peripheral resistancePeripheral resistance is the friction is the friction between the blood and the walls of between the blood and the walls of blood vessels.blood vessels.

• Blood viscosityBlood viscosity is the ease with which a is the ease with which a fluid flows. The greater the viscosity, fluid flows. The greater the viscosity, the greater the viscosity.the greater the viscosity.

• Starling’s law of the heartStarling’s law of the heart is the is the relationship between fiber length ( due relationship between fiber length ( due to the stretching of the cardiac muscle to the stretching of the cardiac muscle cell just before contraction) and the cell just before contraction) and the force of contraction. Sooooo the more force of contraction. Sooooo the more blood that enters the heart the stronger blood that enters the heart the stronger in contracts. This ensures that the in contracts. This ensures that the volume of blood discharged from the volume of blood discharged from the heart is = to the volume entering its heart is = to the volume entering its chambers.chambers.

HypertensionHypertension

• High blood pressureHigh blood pressure• One of the more common diseases of One of the more common diseases of

the cardiovascular system. the cardiovascular system. • Hypertension can be caused by kidney Hypertension can be caused by kidney

disease, high sodium intake, obesity, disease, high sodium intake, obesity, psychological stress, and psychological stress, and arteriosclerosis. arteriosclerosis.

• ArteriosclerosisArteriosclerosis decreases the elasticity decreases the elasticity of arterial walls and narrows openings of arterial walls and narrows openings increases blood pressure.increases blood pressure.

Hypertension Cont….Hypertension Cont….

• If hypertension is left untreated it can If hypertension is left untreated it can cause cause atherosclerosisatherosclerosis or plaque or plaque accumulation in arteries that can lead to accumulation in arteries that can lead to a stroke.a stroke.

• PlaquePlaque are deposits of fatty materials on are deposits of fatty materials on the inside of the arterial walls.the inside of the arterial walls.

• Hypertension can be treated with regular Hypertension can be treated with regular exercise, controlling body weight, exercise, controlling body weight, reducing stress, and limiting sodium in reducing stress, and limiting sodium in the diet.the diet.

13.6 Paths of Circulation13.6 Paths of Circulation

• Pulmonary circuitPulmonary circuit consists of vessels consists of vessels that carry blood from the heart to that carry blood from the heart to the lungs and back to the heart.the lungs and back to the heart.

• Systemic circuitSystemic circuit carries blood from carries blood from the heart to all other parts of the the heart to all other parts of the body and back to the heart.body and back to the heart.

Pulmonary CircuitPulmonary Circuit

• Right ventricleRight ventricle• Right and left pulmonary arteriesRight and left pulmonary arteries• Right and left lungsRight and left lungs• Arterioles into the alveoli (gas Arterioles into the alveoli (gas

exchange)exchange)• Pulmonary viensPulmonary viens• Left atriumLeft atrium

Systemic CircuitSystemic Circuit

• Left atriumLeft atrium• Left ventricleLeft ventricle• AortaAorta

• Head and body (deliver OHead and body (deliver O22 and pick and pick up COup CO22))

• VeinsVeins• Right atriumRight atrium

13.7 Arterial System13.7 Arterial System

• Jugular veinsJugular veins drain blood from the drain blood from the face, scalp, and superficial regions face, scalp, and superficial regions of the neck.of the neck.

• Femoral arteryFemoral artery located in the upper located in the upper thigh supply blood to the tissue of thigh supply blood to the tissue of the thigh, skin of the groin and the the thigh, skin of the groin and the lower abdominal wall. lower abdominal wall.