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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
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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
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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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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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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