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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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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

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