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Chapter 11 The Cardiovascular System Biology 112 Tri-County Technical College Pendleton, SC

Chapter 11 The Cardiovascular System

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Chapter 11 The Cardiovascular System. Biology 112 Tri-County Technical College Pendleton, SC. Functions of CV System. Major function is transportation - PowerPoint PPT Presentation

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Page 1: Chapter 11 The Cardiovascular System

Chapter 11 The Cardiovascular System

Biology 112Tri-County Technical College

Pendleton, SC

Page 2: Chapter 11 The Cardiovascular System

Functions of CV System Major function is transportation Using blood as transport vehicle, system

carries oxygen, nutrients, cell wastes, hormones, and many other substances vital to homeostasis to and from cells

The force to move blood around the body provided by beating heart

Heart located in body thorax flanked by lungs

Page 3: Chapter 11 The Cardiovascular System

Have a heart… More pointed apex pointed toward

left hip & rests on diaphragm Broader posterosuperior aspect, or

base from which great vessels of body merge, points toward right shoulder and lies beneath the second rib

Page 4: Chapter 11 The Cardiovascular System

Location of Heart, Visual

Page 5: Chapter 11 The Cardiovascular System

Coverings of the Heart Enclosed by double sac of serous membane

(pericardium) Thin visceral pericardium (epicardium)

hugs external surface of heart and is part of heart wall

Epicardium continuous at heart base with loosely applied parietal pericardium

Serous fluid (slippery lubricating) produced by serous pericardial membranes

Allows heart to beat almost frictionless environment as pericardial layers slide across each other

Page 6: Chapter 11 The Cardiovascular System

Walls of the Heart Epicardium, Myocardium, Endocardium Epicardium is thin visceral pericardium Myocardium (middle layer) is composed of

thick bundles of cardiac muscle twisted & whorled into ringlike arrangement Myocardium that actually CONTRACTS

Endocardium (innermost) is thin, glistening sheet of endothelium that lines chambers Continuous with lining of blood vessels entering

and leaving heart

Page 7: Chapter 11 The Cardiovascular System

Heart Chambers Four hollow chambers or cavities Two atria and two ventricles—all lined with

endocardium Superior atria primarily receiving chambers Inferior, thick-walled ventricles discharging

chambers (actual pumps of heart Septum dividing heart longitudinally referred

to as interatrical and interventricular septum

Page 8: Chapter 11 The Cardiovascular System

Gross Anatomy of Heart

Page 9: Chapter 11 The Cardiovascular System

Great Vessels of the Heart Superior and inferior vena cavaright

atria Right ventriclepulmonary truckright

and left pulmonary arterieslungs O2 rich blood from lungs to heart4

pulmonary veins (pulmonary circuit)left atrialeft ventricleaortasystemic arteriesbody tissues (systemic circuit)

Page 10: Chapter 11 The Cardiovascular System

Circulation Visual

Page 11: Chapter 11 The Cardiovascular System

Heart Valves Four valves whose general function is to

prevent backflow of blood Atrioventricular (AV) valves between atrial

and ventricular chambers on each side Left AV valve (bicuspid/mitral) has 2 cusps

(flaps) & prevents backflow into left artium Right AV valve (bicuspid) has 3 cusps &

prevents backflow into right atrium Pulmonary semilunar valve—right

ventricle Aortic semilunar valve—left ventricle

Page 12: Chapter 11 The Cardiovascular System

Heart Valves Visual

Page 13: Chapter 11 The Cardiovascular System

Blood Flow From body into right atrium via vena

cava Right atriumright ventricle via tricuspid Right ventriclelungs via pulmonary

semilunar valve and pulmonary arteries Lungsleft atrium via pulmonary veins Left atriumleft ventricle via bicuspid Left ventriclebody via aortic semilunar

valve and aorta

Page 14: Chapter 11 The Cardiovascular System

Cardiac Circulation Blood in heart does NOT nourish myocardium Right and left coronary arteries responsible Branch from base of aorta, encircle heart in

atrioventricular groove Anterior interventricular & circumflex arteries

on left and posterior interventricular and marginal arteries on right compressed when ventricles contracting and fill when ventricle relax

Myocardium drained by several cardiac veins Empty into coronary sinus (enlarged vessel on

backside of heart Coronary sinus empties into right atrim

Page 15: Chapter 11 The Cardiovascular System

Some Key Terms Pericarditis-inflammation of pericardium often

from decrease in amount of serious fluid Pericardial layers bind and stick to each other Forms painful adhesions interfering with heart

movements Valvular Stenosis-valve flaps become stiff

(repeated bacterial infection of endocardium) Forces heart to beat more vigorously than normal Workload increases, heart weakens, and may fail

Page 16: Chapter 11 The Cardiovascular System

Key Terms, cont. Myocardial infarction (heart attack

or coronary)-myocardial cells NOT receiving adequate blood supply

Ischemic heart cells begin to die

Page 17: Chapter 11 The Cardiovascular System

Impulse Conduction 2 types of controlling systems regulate Nerves of ANS and intrinsic

conduction system (nodal system) ANS acts like “brakes” or “accelerator”

depending on which division is activated Intrinsic system composed of special

tissue found no where else in body Cross between nervous & muscle tissue Causes depolarization in only ONE direction-

from atria to ventricles

Page 18: Chapter 11 The Cardiovascular System

Impulse, cont. Nodal system composed of sinoatrial (SA)

node (right atrium); atrioventricular (AV) node(junction of atria & ventricles); AV bundles (bundle of His); Right and Left bundle branches (interventricular septum); and Purkinje fibers (within muscle of ventricular wall)

SA (Pacemaker) fires Impulse spreads through atria to AV node

Atria contract

Page 19: Chapter 11 The Cardiovascular System

Impulse, III

AV node delays impulse preventing simultaneous atria/ventricle contraction allows complete emptying of atria

Impulse conducted to AV bundle, bundle branches, and Purkinje fibers Ventricles contract

Heart beats to internal rhythm but body can speed it up or slow it down

Vagus nerve <; Sympathetic fibers >

Page 20: Chapter 11 The Cardiovascular System

Impulse Conduction, Visual

Page 21: Chapter 11 The Cardiovascular System

Heart Block UNC, depolarization waves reach

ventricles only through AV node Damage to AV node can

partially/totally release ventricles from control of SA node

Ventricles begin to beat at their own rate (which is much slower) some or all the time

This condition is called heart block

Page 22: Chapter 11 The Cardiovascular System

Three Key Terms Ischemia is lack of adequate blood supply to

heart muscle May lead to fibrillation (rapid, uncoordinated

shuddering of hear muscle) which makes heart useless as pump and major cause of death from heart attacks

Often followed by arrest Bradycardia is heart rate substantially slower

than normal (less than 60 beats per minute) Tachycardia is rapid heartbeat (over 100

beats per minute) May progress to fibrillation

Page 23: Chapter 11 The Cardiovascular System

Cardiac Cycle Refers to events of ONE heartbeat Average is 75 beats per minute so

cycle normally about 0.8 seconds Systole means heart contraction Diastole means heart relaxation Atria are in systole at same time

and ventricles are in systole at the same time

Page 24: Chapter 11 The Cardiovascular System

Cardiac Cycle, Visual

Page 25: Chapter 11 The Cardiovascular System

Heart Sounds Lub-Dup First sound (lub) = closing of AV valves Second sound (dup) caused by closing of

semilunar valves at end of systole Lub sound longer and louder; Dup tends to

be short and sharp Abnormal/unusual sounds called murmurs

Caused by turbulance of blood flow Fairly common in children/elderly people

Page 26: Chapter 11 The Cardiovascular System

Sounds, cont. Murmurs may indicate valve problem If valve does NOT close tightly

(incompetent), swishing will be heard as blood flows back through partially “open” valve

Distinct sounds also heard when blood flows turbulently through “stenosed” (narrowed) valves

Page 27: Chapter 11 The Cardiovascular System

Cardiac Output CO is amount of blood pumped out

by each side of heart Actually each ventricle in ONE minute

Stroke volume is volume of blood pumped out by each ventricle with each heartbeat SV >s as force of ventricular

contraction >s CO is PRODUCT of heart rate (HR)

x stroke volume (SV); CO=HR x SV

Page 28: Chapter 11 The Cardiovascular System

Output, cont. 75 beats/min x stroke volume of 70

ml/beat equals 5250 ml/min Normal blood volume = ~5000 ml, entire

blood supply passes through heart once each minute

SV regulated by many factors > volume or speed of venous return >s SV &

force of contraction < volume or speed of venous return <s SV &

force of contraction

Page 29: Chapter 11 The Cardiovascular System

Output, cont. “Starlings law of the heart: more heart

muscle is stretched, the stronger contraction

Critical factor “stretching” heart muscle is venous return

Insures volume of blood going out equals volume of blood coming in (vice-versa)

REGULATION of heart rate dependent of many factors

Page 30: Chapter 11 The Cardiovascular System

Output and Regulation, cont.

Heart rate can be changed temporarily by autonomic nerves

Sympathetic nerves stimulate SA and AV nodes and heart muscle itself to > rate

Parasympathetic nerves (vagus) slow and steady heart giving rest time during noncrisis

Epinephrine and thyroxine >s heart rate

Page 31: Chapter 11 The Cardiovascular System

Output & Regulation, cont. Physical factors (age, gender, exercise,

and body temperature) influence heart rate

Hypocalcemia (reduced levels of ionic calcium) depress the heart

Hypercalcemia (> levels of ionic calcium) causes prolonged contraction to point heart may stop entirely

Hypokalemia (reduced levels of ionic potassium causes feeble heart beat and abnormal rhythms appear

heatheart rate and coldheart rate

Page 32: Chapter 11 The Cardiovascular System

Congestive Heart Failure Pumping efficiency depressed so circulation

inadequate to meet tissue needs = congestive heart failure

One side can fail independently of the other Left side fails = Pulmonary congestion occurs

vessels in lungs swells-fluid leaks-pulmonary edema-if untreated, person suffocates

Right side fails = Peripheral congestion occurs blood backs up in systemic circulation-edema most

noticeable in distal body parts (swollen feet, ankles, fingers)

Failure of one side puts strain on other side & eventually whole heart fails

Page 33: Chapter 11 The Cardiovascular System

Electrocardiogram (ECG) Impulses cause electrical currents to pass

through body Can be detected by electrocardiograph Three recognizable waves (P, QRS complex, & T) P wave first and small-depolarization of atria

before they contract QRS complex is large wave-depolarization of

ventricles; precedes their contraction T-wave results repolarization of ventricles Atrial repolarization normally hidden by QRS May reveal heart problems: abnormal waves;

changes in timing; fibrillation

Page 34: Chapter 11 The Cardiovascular System

Arterial Pulse Expansion and recoil of artery occurring

with each ventricle beat creates PULSE Pulse rate = heart rate Averages 70-80 per minute Influenced by activity, postural changes,

emotions May be taken at any artery close to

surface Temporal, carotid, brachial, & radial most

common

Page 35: Chapter 11 The Cardiovascular System

Blood Pressure Points, Visual

Page 36: Chapter 11 The Cardiovascular System

Blood Pressure… Is pressure blood exerts against inner

walls of blood vessels Force that keeps blood circulating USD, understood to mean pressure

within large systemic arteries NEAR heart Pressure highest in large arteries and <s

thru pathway Reaches 0 or negative at vena cava Return dependent on valves in larger

veins, milking activity of skeletal muscles, and pressure changes in thorax

Page 37: Chapter 11 The Cardiovascular System

Auscultatory Method for BP

Systemic arterial BP measured indirectly System uses brachial artery of arm Systolic pressure=pressure at peak of

ventricular contraction Diastolic pressure=pressure when

ventricles are relaxed “Normal” is 120/80 but range is 110-

140/75-80 Varies with age, weight, mood, race,

activity, and posture

Page 38: Chapter 11 The Cardiovascular System

Blood Pressure, Visual

Page 39: Chapter 11 The Cardiovascular System

BP Math…or whatever BP = cardiac output x peripheral

resistance Cardiac output increases, BP increases Peripheral resistance increases; BP

increases Cardiac output decreases; BP

decreases Peripheral resistance decreases; BP

decreases

Page 40: Chapter 11 The Cardiovascular System

Factoring the factors Sympathetic division of ANS

causes vasoconstriction >ing peripheral resistance which >s BP

Parasympathetic division of ANS causes vasodilation <ing peripheral resistance which <s BP

Kidneys help regulate BP by altering blood volume Retain or excrete water Also produce RENIN

Page 41: Chapter 11 The Cardiovascular System

Factors, cont. If BP low, kidney cells release enzyme

renin into blood Renin triggers cascade of reactions that

produce Angiotensin II which is potent vasoconstrictor

Vasoconstriction raises BP AT II stimulates adrenal cortex to

release Aldosterone (hormone that >s sodium ion reabsorption by kidneys

Water follows sodium ions thus blood volume and BP both rise

Page 42: Chapter 11 The Cardiovascular System

Enough of factoring, already..

Epinephrine >s heart rate and BP Nicotine >s BP by causing vasoconstriction Alcohol/Histamine < BP by causing

vasodilation Diuretics cause kidneys to excrete more

water which reduces blood volume thereby lowering BP

TOO much salthypertonic blood which absorbs water from tissues increasing blood volume and BP

Page 43: Chapter 11 The Cardiovascular System

The end of factoring…Yeah!!

TOO much fatsexcessive fats in blood

Makes blood more viscous and more difficult to pump

Peripheral resistance is increased which increases the blood pressure

Page 44: Chapter 11 The Cardiovascular System

Hypotension Low BP = systolic < 100 mm Hg Physical conditioning and/or health Orthostatic hypotension = temporary drop

in BP resulting in dizziness upon rising May be slow reacting sympathetic NS and

blood pooling in lower limbs reducing BP and blood delivery to brain

Chronic hypotension may be result of inadequate blood proteins, low viscosity, and/or low pressure

Page 45: Chapter 11 The Cardiovascular System

Hypertension Sustained elevated arterial pressure of

140/90 or higher Heart has to work against increased

resistance and has to work HARDER Myocardium enlarges; when strained

beyond capacity to respond, weakens and becomes flabby

Causes small tears in endothelium of blood vessels that > progress of artherosclerosis

Page 46: Chapter 11 The Cardiovascular System

Hypertension, cont. Most cases (90%+) are primary or

essential which CANNOT be accounted for by any specific organic cause Diet, obesity, heredity, race, stress involved

Treatment for hypertension diuretics vasodilators/beta blockers ACE-inhibitors (inhibit renin) Cardiac inhibitors (calcium channel blockers) Lifestyle changes