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    THE CARDIOSVASCULAR

    SYSTEM

    Suhartini drg., M.Biotech

    Physiology-Biomedic Department

    Dentistry Faculty of Jember University

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    The Cardiovascular System

    consists of the heart plus all the blood

    vessels

    transports blood to all parts of the body in

    two 'circulations':

    pulmonary

    systemic

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    The Functions of Circulatory system

    1. Transport of nutrients, wastes, essentialgases

    2. Buffers body pH

    3. Transports hormones

    4. Assists in temperature regulation

    5. Urine formation

    6. Assists in response to infections

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    Circulation Reviewed

    Blood Vessels "closedcirculation"

    Arteriesfrom heart

    Capillaries cell exchange

    Veins to heart

    Heart "four chambered"

    Right atrium & ventricle

    Pulmonary circuit

    Left atrium & ventricle

    Systemic circuit

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    Overview

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    Sirculation & Distribution of

    Blood in the Body Organs

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    The Blood Vessels

    The cardiovascular system has three typesof blood vessels:

    1. Arteries (and arterioles) carry blood

    away from the heart2. Capillaries where nutrient and gas

    exchange occur

    3.Veins (and venules) carry blood towardthe heart.

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    BLOOD VESSELS & CIRCULATION

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    Arteries and arterioles take blood awayfrom the heart.

    The largest artery is the aorta.

    The middle layer of an artery wallconsists ofsmooth muscle that can

    constrict to regulate blood flow and

    blood pressure.Arterioles can constrict or dilate,

    changing blood pressure.

    The Arteries

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    Venulesdrain blood from capillaries,

    then join to form veins that take bloodto the heart.

    Veins have much less smooth muscle

    and connective tissue than arteries.Veins often have valves that prevent

    the backward flow of blood whenclosed.

    Veins carry about 70% of the bodysblood and act as a reservoirduringhemorrhage.

    The Veins

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    The Capillaries

    Capillaries have walls only one cellthick to allow exchange of gases and

    nutrients with tissue fluid.

    Capillary beds are present in all regionsof the body but not all capillary beds

    are open at the same time.

    Contraction of a sphincter musclecloses off a bed and blood can flow

    through an arteriovenous shunt that

    bypasses the capillary bed.12lect/ST1/cardio

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    The Capillaries

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    Make Up of Blood Vessels: Capillaries

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    Capillary exchange

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    Osmotic Pressure in Capillaries

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    The heart

    The heart is a cone-shaped,muscular organ located

    between the lungs behind

    the sternum.

    The heart muscle forms themyocardium, with tightly

    interconnect cells of

    cardiac muscle tissue.

    The pericardium is the

    outer membranous sac

    with lubricating fluid.

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    The heart has four

    chambers: two upper,

    thin-walled atria, and

    two lower, thick-walledventricles.

    The septum is a wall

    dividing the right and

    left sides. The tricuspid valve on

    the right and the

    bicuspid valve on the

    left; both valves arereenforced by chordae

    tendinae attached to

    muscular projections

    within the ventricles.18lect/ST1/cardio

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    Passage of Blood Through the Heart

    Blood follows this sequencethrough the heart: superior and

    inferior vena cava right

    atrium tricuspid valve

    right ventricle pulmonary

    semilunarvalve pulmonarytrunk and arteries to the lungs

    pulmonary veins leaving the

    lungs left atrium bicuspid

    valve left ventricle aorticsemilunarvalve aorta to

    the body.

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    CARDIAC OUTPUT

    volume of blood pumped by each ventricle

    CO = HR (heart rate) (x/mnt) x SV (stroke

    volume) (mL/beat) Heart rate is the number of heart beats per

    minute; normally it is about 70 beat/ minute

    Stroke volume is the volume of blood pumpedby each ventricle per beat; normally it is about

    70 ml/ beat

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    Regulation Stroke Volume

    Intrinsic control:End-diastolic volume (ventricle relax) = stroke volume

    Mechanism : strength of contractionEnd-diastolic volume(the volume of blood in the heart just before the ventricles beginto contract) is called the Frank-Starling law of the heart:

    end-diastolic volume = stretching of of cardiac muscle =strength of contraction = stroke volume

    Extrinsic control:Sympathetic stimulation strength of contraction of cardiac

    muscleMechanism : sympathetic stimulation release of

    norepinephrine increased permeability of muscle cellmembranes to calcium calcium diffuses in more cross-bridges are activated stronger contraction

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    Regulators of the Heart:

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    The Heartbeat

    Each heartbeat is called a cardiac cycle.

    When the heart beats, the two atriacontract together, then the twoventricles contract; then the whole heart

    relaxes.Systole is the contraction of heart

    chambers; diastole is their relaxation.

    The heart sounds, lub-dup, are due tothe closing of the atrioventricularvalves, followed by the closing of thesemilunar valves.

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    Intrinsic Control of Heartbeat

    The SA (sinoatrial) node, orpacemaker,initiates the heartbeat and causes the atria tocontract on average every 0.85 seconds.

    The AV (atrioventricular) node conveys thestimulus and initiates contraction of theventricles.

    The signal for the ventricles to contracttravels from the AV node through theatrioventricular bundle (His) to the smallerPurkinje fibers.

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    Conduction system of the heart

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    The Hearts Electrical System

    Most of the muscle cells in theheart are contractile cells.

    The autorhythmic cells arelocated in these areas:

    Sinoatrial (SA), or sinus,

    nodeAtrioventricular (AV) node

    Atrioventricular (AV) bundle(also sometimes called thebundle of His)

    Right & left bundlebranches

    Purkinje fibers

    Various automatic cells havedifferent 'rhythms':

    SA node 60 - 100 per minute(usually 70 - 80 per minute)

    AV node & AV bundle 40 - 60

    per minute Bundle branches & Purkinje

    fibers - 20 - 40 per minute

    the SA node is commonlyreferred to as the

    PACEMAKER.

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    http://free.ed.gov/resource.cfm?resource_id=1877http://free.ed.gov/resource.cfm?resource_id=1877
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    Extrinsic Control of Heartbeat

    A cardiac control centerin the medullaoblongata speeds up or slows down theheart rate by way of the autonomic nervoussystem branches: parasympathetic system

    (slows heart rate) and the sympatheticsystem (increases heart rate).

    Hormones epinephrine and norepinephrine(simpt) from the adrenal medulla also

    stimulate faster heart rate.

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    The Electrocardiogram

    An electrocardiogram (ECG) is a recordingof the electrical changes that occur in the

    myocardium during a cardiac cycle.

    Atrial depolarization creates the P wave,ventricle depolarization creates the QRS

    wave, and repolarization of the ventricles

    produces the T wave.

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    Electrocardiogram

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    Blood Flow

    The beating of the heart is necessary tohomeostasis because it creates

    pressure that propels blood in arteries

    and the arterioles.Arterioles lead to the capillaries where

    nutrient and gas exchange with tissue

    fluid takes place.

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    Blood Flow: Pressure Changes

    Flows down a pressuregradient

    Highest at the heart,decreases overdistance

    Hydrostatic (reallyhydraulic) pressure in

    vesselsDecreases 90% from

    aorta to vena cava

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    Some Physic of Fluid Movement:

    Blood Flow

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    Mean Arterial Pressure (MAP)

    MAP = Cardiac Output X Total Peripheral Resistance

    Factors effecting MAP are: total peripheral resistance (TPA)

    TPA refers to the sum total of vascular resistance to the flow ofblood in the systemic circulation.

    Because of their small radii, arterioles provide the greatestresistance to blood flow in the arterial system

    TPAMAP

    cardiac output

    blood volume

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    Baroreceptor Reflexes in Short-term

    Regulation of MAP

    Blood pressure is contolled by

    baroreceptor reflexesBlood Pressure

    BPThe cardiovascular control center

    (CCC) responds by decreasing

    sympathetic input and increasing

    parasympathetic input to the heart.

    The CCC sympathetic input to the bloodvessels vasodilation

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    Regulators of the Heart:

    Reflex Baroreceptors

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    Blood Volume in Long Term

    Regulation of MAP Chemical controls

    Act directly on muscle (tunic media) or interact with neural

    Epinephrine - BP

    Nicotinevasoconstriction (BP)

    Alcoholvasodilation (BP)

    Histaminevasodilation (BP)

    Antidiuretic hormone (ADH)(volume BP)

    Kidneys control long term BP Regulate blood volume

    Renin/angiotensin II mechanism (vasoconstriction)

    Temperature Cold vasoconstriction

    Heat vasodilation

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    Summary of Factors that Effect Mean

    Arterial Pressure

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    Summary of Factors that Effect Blood

    Flow during Exercise

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    Blood Pressure Measurement

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    The Average of Blood Pressure BLOOD PRESSURE

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    Cardinal symptoms of Cardiac Disease

    chest pain

    neck and/or UE pain and discomfort

    cool clammy skin

    palpitation

    dyspnea

    syncope

    fatigue

    cough

    cyanosis

    edema

    claudication

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    EDEMA

    1. Reduced concentration of plasma proteins. Factor that reduce plasma proteins include: Kidney disease can result in the loss of plasma proteins

    in the urine.

    Liver disease can decrease the synthesis of plasmaproteins.

    A protein-deficient diet will decrease plasma proteins. Severe burns result in a loss of plasma proteins

    (albumin) at the burn site

    2. Increased capillary permeability

    3. Increase in venous pressure Left heart failure

    Standing still

    4. Blocked Lymphatics.

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    Risk FactorsNon Modifiable

    age

    male sex

    family history

    Race

    Modifiable physical inactivity

    cigarette smoking hypertension

    elevated serumcholesterol levels

    Contributing Factors obesity

    diabetes

    response to stress

    personality

    most at risk personality:

    hostility associated withanger

    4 known triggersvigorous exercise or exertion

    exposure to cold or windpsychological or emotional

    stress

    eating a big meal

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    Cardiovascular Disorders

    Cardiovascular disease (CVD) is theleading cause of death in Western

    countries.

    Modern research efforts have improveddiagnosis, treatment, and prevention.

    Major cardiovascular disorders include

    atherosclerosis, stroke, heart attack,aneurysm, and hypertension.

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    Ath l i

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    Atherosclerosis

    Atherosclerosis is due to a build-up of fatty

    material (plaque), mainly cholesterol, under the

    inner lining of arteries.

    The plaque can cause a thrombus (blood clot) to

    form. The thrombus can dislodge as an embolus and

    lead to thromboembolism.

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    Stroke, Heart Attack, and Aneurysm

    A cerebrovascular accident, orstroke,

    results when an embolus lodges in a

    cerebral blood vessel or a cerebral blood

    vessel bursts; a portion of the brain diesdue to lack of oxygen.

    A myocardial infarction, orheart attack,

    occurs when a portion of heart muscledies due to lack of oxygen.

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    Partial blockage of a coronary artery

    causes angina pectoris, or chest pain.

    An aneurysm is a ballooning of a blood

    vessel, usually in the abdominal aorta or

    arteries leading to the brain.

    Death results if the aneurysm is in a large

    vessel and the vessel bursts.

    Atherosclerosis and hypertension weaken

    blood vessels over time, increasing the

    risk of aneurysm.

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    C B O ti

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    Coronary Bypass Operations

    A coronary bypass operation involvesremoving a segment of another blood

    vessel and replacing a clogged

    coronary artery.It may be possible to replace this

    surgery with gene therapy that

    stimulates new blood vessels to growwhere the heart needs more blood flow.

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    Coronary bypass operation

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    Coronary bypass operation

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    Clearing Clogged Arteries

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    Clearing Clogged Arteries

    Angioplasty uses a long tube threadedthrough an arm or leg vessel to thepoint where the coronary artery isblocked; inflating the tube forces the

    vessel open.Small metal stents are expanded inside

    the artery to keep it open.

    Stents are coated with heparin toprevent blood clotting and withchemicals to prevent arterial closing.

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    Angioplasty

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    Heart Transplants and Artificial Hearts

    Heart transplants are routinely performed butimmunosuppressive drugs must be takenthereafter.

    There is a shortage of human organ donors.

    Work is currently underway to improve self-contained artificial hearts, and muscle celltransplants may someday be useful.

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    H t i

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    Hypertension

    About 20% of Americans suffer fromhypertension (high blood pressure).

    Hypertension is present when systolicpressure is 140 or greater or diastolic

    pressure is 100 or greater; diastolic pressureis emphasized when medical treatment isconsidered.

    A genetic predisposition for hypertensionoccurs in those who have a gene that codesforangiotensinogen, a powerfulvasoconstrictor.

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    Variety of causes/ risk factors of hypertension

    are known

    - sedentary lifestyle- smoking

    - obesity

    - diet (excess sodium; cholesterol;

    calories in general)- stress

    - arteriosclerosis

    - genetic factors

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    THANKYOU