DISEDIAKAN OLEH:

WEE SOO LEE

wslee@psa.edu.my

Introduction • The blood circulatory system is a continuous system which

circulates blood throughout the body.

• Consist of

– HEART – centre of the blood circulatory system, collect blood and pumps the blood through the circulatory system to all parts of the body

– BLOOD VESSELS – composed of many branches, they transport blood from the heart to all parts of the body and then return the blood to the heart. Total length is about 97,000km.

– 3 types of blood vessels

• ARTERIES – Transport blood away from the heart (high pressure) – oxygeneted

• CAPILARIES – minute blood vessels( normally under the skin)

• VEINS – transport blood to the heart (low pressure) - deoxygenated

Circulatory System

• Pulmonary Circulation

- This is the flow of the Blood from the heart

to the lungs and back to the heart again

• Systemic Circulation

- This is the flow of Blood through all the

tissues in the body except Heart and Lung

• Cardiac Circulation

- This is the movement of blood through the

tissues of the heart

The sequence of blood flow through the heart,

arteries, arterioles, capillaries, venules, veins, then

back to the heart

ARTERY

– Arteries are blood vessels that carry blood away

from the heart.

– All arteries, with the exception of the pulmonary

carry oxygenated blood.

– Aorta (the largest artery, carries blood out of the

heart)

– This branch into smaller Arterioles and then

connect to the capillaries

– They are thick and made of three layers

Artery

CAPILLARIES

• Capillaries are the smallest of a body's

blood vessels and are part of the

microcirculation

• These microvesselsconnect arterioles and

venules.

• Enable the exchange of water, o2 , co2 and

many other nutrient and waste chemical

substances between blood and

surrounding tissues

Capillary

• They are very thin , one cell wide

• Here the gaseous exchange takes place

• Liver, spleen and bone marrow have sinusoids instead of capillaries

VEINS

• Veins are blood vessels that carry blood

toward the heart.

• Most veins carry deoxygenated blood from

the tissues back to the heart; exceptions

are the pulmonary veins

• They differ from arteries in structure and

function

Vein

• They are thick and made of three layers

• Veins contain one way valve

• As they contain little oxygen they appear blue.

The structural differences between different types of

blood vessels. More information about this also

follows in the next section.

Major Arteries and Veins

BLOOD PRESURE

Pressure exerted by the Blood on

the Walls of the Arteries

Types of Blood Pressure

1) Arterial Blood Pressure

2) Pulmonary Artery Blood Pressure

3) Central Venous Pressure

Arterial Blood Pressure

• Systolic Pressure - The maximum pressure exerted by the blood on the

walls of the Artery when the Ventricles contract.

- Normal Range 100 to 140 mmHg

• Diastolic Pressure - The minimum pressure exerted by the blood on the

Artery wall when the Ventricles relax.

- Normal Range 60 to 90 mmHg

AHA Recommended Values

Normal blood pressure : 120 / 80 mm hg

• Mean Airway Pressure

- The average pressure exerted by the Blood on the

Artery during the complete cycle of Ventricles

contracting and relaxing.

- Normal Range 100 mmHg

Calculation of MAP :

• MAP =1/3 Pulse Pressure + Diastolic Pressure

• Pulse Pressure = Systolic - Diastolic

CARDIAC OUTPUT

• The volume of blood ejected per minute

from the left ventricle into aorta is called

the cardiac output ( CO )

• In a resting adult, stroke volume averages

70 ml and heart rate is about 75 beats per

minute.

• Cardiac Output = stroke volume X

heart beat (bpm)

Regulation of Blood Flow

• Blood Flow through Vessels is effected by

Pressure and Resistance Blood flow is directly proportional to pressure and

inversely proportional to resistance.

If the pressure in a vessel increases then the blood flow

will increase.

If the resistance in a vessel increases then the blood

flow will decrease.

• The relationships between factors that

effect blood flow are described by

Poiseuille's Law, which states:

• Of all of the factors that effect blood flow, the

radius of the blood vessel is the most potent.

• Blood flow is proportional to the 4th power of

vessel radius.

• This means that if the radius of a blood vessel

doubles (by vasodilation) then the flow will

increase 16 fold.

• If the radius of a vessel is reduce in half (by

vasoconstriction), then the blood flow will be

reduced 16 fold.

• Because small changes in vessel radius make

very large changes in blood flow.

• The body controls blood flow

to specific areas of the body

by controlling the radius of

arterioles.

Blood Flow vs Artery Radius

How blood pressure and blood flow

are regulated?

• A person suffers arteriosclerosis, where plaque is

accumulate in and clogging the arteries.

• As the more plaque accumulates in the blood vessels,

the flow of blood faces more and more resistance.

• In order to maintain an adequate flow of blood, the heart

must pump "harder," and therefore the blood that leaves

the heart is forced out with greater pressure.

Factors that Affect Blood

Pressure

• Blood pressure is affected by several factors:

- peripheral resistance

- vessel elasticity

- blood volume

- cardiac output

Peripheral Resistance

• Blood cells and plasma encounter resistance

when they contact blood vessel walls.

• If resistance increases, then more pressure is

needed to keep blood moving.

• Three main sources of peripheral resistance:

1. blood vessel diameter

2. blood viscosity

3. total vessel length

• Resistance in the blood vessels is effected

by three parameters:

1)Length of the vessel. The longer the vessel the

greater the resistance.

2) Viscosity of the blood. The greater the viscosity

the greater the resistance.

3) Radius of the vessel. The smaller the radius the

greater the resistance.

Heart location

• The heart has four separate chambers.

• Atrium- receives and collects the blood

coming to the heart.

• Ventricle- pumps blood away from the

heart through powerful, rhythmic

contractions.

• Human heart is two pumps in one

• The right side receives oxygen-poor

blood from the various regions of the

body and delivers it to the lungs. In the

lungs, oxygen is absorbed in the blood.

• The left side of the heart receives the

oxygen-rich blood from the lungs and

delivers it to the rest of the body.

• Right-Hand Side of the Heart

The right side of the heart receives

de-oxygenated blood from the body tissues

(from the upper and lower-body via the Superior

Vena Cava and the Inferior Vena Cava) into the

right atrium.

This de-oxygenated blood passes through the

tricuspid valve into the right ventricle.

This blood is then pumped under higher pressure

from the right ventricle to the lungs via the

pulmonary artery

• Left-Hand Side of the Heart

The left-hand side of the heart

receives oxygenated blood from

the lungs (via the pulmonary veins) into the left

atrium.

This oxygenated blood then passes through the

bicuspid valve into the left ventricle.

It is then pumped to the aorta under greater

pressure This higher pressure ensures that the

oxygenated blood leaving the heart via the aorta

is delivered to other parts of the body via blood

vessels (incl. arteries, arterioles, and capillaries).

Conduction System

Of The heart

• SA node which functions as the pacemaker of the heart .

• It initiates the contraction of the heart.

• It also sets the rhythm for concentration of the heart.

• It produces action potentials at a faster rate than others

areas of the heart.

• The action potential of the SA node acts as a stimulus to

adjacent areas of the heart.

• When action potentials originate in an area of the heart

other than SA node, the result is called an ectopic beat

1) SA node,

2) Atrioventricular node (AV ),

3) Atrioventricular bundle,

4) Right and left bundle

branches

5) Purkinje fibers

•All the cells have the ability to

produce spontaneous action

potentials but at a lower rate

than in the SA node.

1. Action potential originate in

the SA node and travel

across the wall of the

atrium from SA node to AV

node.

2. Action potential pass

through the AV node and

along the AV bundle which

extends from the AV node

into the interventricular

septum.

3. AV bundle divides into right

and left bundle branches

and action potential

descend to the apex of

each ventricles.

4. Action potentials are

carried by the purkinje

fibers from the bundle

branches to the ventricular

walls.

TUTORIAL

• http://www.wisc-

online.com/objects/ViewObject.aspx?ID=A

P12704

Online Quiz

http://highered.mcgraw-

hill.com/sites/0072495855/student_view0/chapter22

/animation__conducting_system_of_the_heart.html

http://highered.mcgraw-

hill.com/olcweb/cgi/pluginpop.cgi?it=swf::800::800::/

sites/dl/free/0073378119/601387/cardiaccycle.swf::

The%20Cardiac%20Cycle

HEART ACTIVITY ECG Wave Shows Heart Activity

Heart Activity = ECG Wave

CARDIAC CYCLE

• A single cardiac cycle includes all the events associated

with one heartbeat.

• In normal cardiac cycle, 2 atria contract while 2

ventricles relax; then 2 ventricles contract while 2 atria

relax.

• Systole refer to contraction ; diastole refer to relax.

• At rest, the volume of blood ejected from each ventricles

during ventricular systole is about 70 mL.

• At rest, each cardiac cycle lasts about 0.8 sec

CARDIAC CYCLE

HEART SOUND

• A stethoscope was originally developed to listen to the

sounds of lungs and heart.

• First heart sound can represent lubb and second heart

sound represent dubb

• The lubb heart sound has a lower pitch than the dubb.

• Lubb – at the beginning of ventricular systole and results

from closure of the AV valves.

• Dubb – at the beginning of ventricular diastole and

results from closure of the semilunar valves.

• Abnormally heart sound called murmurs are usually a

result of faulty valves such as incompetent valve close

tightly and blood leaks.

Problems of Blood Pressure

Hypertension

• High blood pressure

• 140 mmHg systolic,

90 mm Hg diastolic

• Cause cerebral

hemorrhage, coronary

infarction, hemorrhage

of renal blood vessel

and poor vision from

burst blood vessels in

retina

Hypotension

• Low blood pressure

• 90 mmHg systolic, 60

mmHg diastolic

• Cause dizziness and

fainting or indicate serious

heart, or neurological

disorders or shock ( not

enough O2 and nutrients

to cellular metabolic)