section 34-1

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Section 34-1

The Circulatory System

Bio 30 NWRC

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Functions of the circulatory system

• The circulatory

system is composed

of the heart and blood

vessels, includingarteries, veins, and

capillaries.

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Blood Vessels

• Arteries

• Arteries are muscular

blood vessels that

carry blood away fromthe heart All arteries,

(with the exception of

the pulmonary and

umbilical arteries),

carry oxygenated

blood.

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Capillaries

• Branch throughout the

body

• Microscopic blood

vessels -capillaries are

very thin and fragile. The

capillaries are actually

only one epithelial cell

thick. They are so thin

that blood cells can onlypass through them in

single file

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Capillaries

• The exchange of oxygenand carbon dioxide takesplace through the thincapillary wall. The redblood cells inside the

capillary release their oxygen which passesthrough the wall and intothe surrounding tissue.The tissue releases its

waste products, likecarbon dioxide, whichpasses through the walland into the red bloodcells.

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Veins

• In the circulatory

system, a vein is a

blood vessel that

carries blood towardthe heart. The

majority of veins in

the body carry low-

oxygen blood fromthe tissues back to

the heart

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The Heart- watch video

• Muscular organ about as

large as your fist

• The heart is the key

organ in the circulatorysystem. As a hollow,

muscular pump, its main

function is to propel blood

throughout the body. Itusually beats from 60 to

100 times per minute

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http://uk.youtube.com/watch?v=D3ZDJgFDdk0&feature=relatedFirefoxHTML\Shell\Open\Command

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The Heart is divided into 4

chambers

Right Ventricle Left Ventricle

Right Atrium Left Atrium

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chambers

Right Atrium Left Atrium

The Atria -The right atrium receives de-oxygenated blood

from the body through the superior vena cava (head and

upper body) and inferior vena cava (legs and lower torso).The left atrium receives oxygenated blood from the lungs

through the pulmonary vein. As the contraction triggered by

the sinoatrial node progresses through the atria, the blood

passes through the mitral valve into the left ventricle.

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chambers

Right Ventricle Left Ventricle

The right ventricle is one of four chambers (two

atria and two ventricles) in the human heart. It

receives de-oxygenated blood from the right atrium

via the tricuspid valve, and pumps it into the

pulmonary artery via the pulmonary valve.

Left ventricle: The left lower chamber of the heart that receives blood from the

left atrium and pumps it out under high pressure through the aorta to the body.

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The chambers

• Right Atrium

• Left atrium

• Left ventricle

• Right ventricle

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Blood flow through the Heart

• Deoxygenated Blood

collects in the right

atrium

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• Blood passes into the

right ventricle through

the tricuspid valve• The ventricle is a

powerful pump which

pushes the

deoxygenated blood

out to the lungs

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pulmonary artery

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• Oxygenated blood

returns to the heart

from the lungs

• Pulmonary veins

return oxygenatedblood from the lungs

to the heart

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• Oxygenated blood

collects in the left

atrium

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aorta and out to body

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Valves of the heart

• The valves of the heart arelocated within the chambers of the heart and are critical to theproper flow of blood throughthe heart. All of the valves,

when functioning normally, actas one-way valves, allowingblood to flow either from onechamber to another, or allowing blood to flow out of the heart, in only one direction.

The valves control the flow of blood through the heart byopening and closing during thecontractions of the heart.

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The “Pacemaker”

• Acting as the heart's naturalpacemaker, the SA node"fires" at regular intervals tocause the heart of beat with arhythm of about 60 to 70 beats

per minute for a healthy,resting heart. The electricalimpulse from the SA nodetriggers a sequence of electrical events in the heart tocontrol the orderly sequence of

muscle contractions that pumpthe blood out of the heart.

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The “Pacemaker”• The sinus rhythm

normally controls bothatrial and ventricular rhythm. Action potentialsgenerated by the SAnode spread throughoutthe atria, depolarizing this

tissue and causing atrialcontraction. The impulsethen travels into theventricles via theatrioventricular node (AV

node). This causes theventricles to contract –the 2 step process makesa complete heartbeat

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Pulse

• a person's pulse is the

throbbing of their arteries

as an effect of the

heartbeat. It can be felt in

any place that allows for an artery to be

compressed against a

bone, such as at the neck

at the wrist ,behind theknee, and on the inside of

the elbow , or near the

ankle joint

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Blood Pressure

• Blood pressure is thepressure of the bloodagainst the walls of thearteries.

• Blood pressure resultsfrom two forces. One iscreated by the heart as itpumps blood into thearteries and through the

circulatory system. Theother is the force of thearteries as they resist theblood flow.

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Blood Pressure

• The higher (systolic)number represents thepressure while the heartcontracts to pump bloodto the body.

• The lower (diastolic)number represents thepressure when the heartrelaxes between beats.

• The systolic pressure is

always stated first.Normal is 120/80although that is variablewith different sources

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Blood Components

• Blood plasma is the

liquid component of

blood, in which the

blood cells aresuspended. It makes

up about 55% of total

blood volume.

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Blood Components

• Red Blood Cells. A

single drop of blood

contains millions of

red blood cells whichare constantly

traveling through your

body delivering

oxygen and removingwaste.

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Blood Components• Platelets :Platelets are

irregularly-shaped,colourless cell fragments that

are present in blood. Their

sticky surface lets them,

along with other substances,form clots to stop bleeding.

The platelets release a

chemical called FIBRIN

which weaves a network of

fibres across a cut andenables healing

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Blood Components• White Blood Cells

• White blood cells or

leukocytes are cells of

the immune system

defending the bodyagainst both infectious

disease and foreign

materials.

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Blood Types

• See Table 34-1 on page 998

• As you know there are 4 possible blood

types: A B O or AB

• There are several possible markers on

your blood cells if you have type A you

have A markers, B you have B markers

• And if you have AB you have both and

neither if you have type O blood

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Blood Types

• The plasma (liquid part of the blood) hasproteins called ANTIBODIES which attackforeign markers and cause the blood to

clump.• TYPE A blood has anti-B proteins

• TYPE B blood has anti-A proteins

• TYPE AB blood has no anti -proteins• TYPE O blood has both anti- A and anti-B

proteins

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Blood Types

• People with blood group 0 are called

"universal donors" (they can safely give

blood to anyone because their blood has

no markers) and people with blood groupAB are called "universal receivers." (they

can receive blood from anyone because

they have no antibodies)

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Blood Types• RH factor Many people

also have a Rh factor

on the red blood cell's

surface. This is also an

antigen and those whohave it are called Rh+.

Those who haven't are

called Rh-.

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Blood Types• A person with Rh- blood

does not have Rhantibodies naturally in theblood plasma (as one canhave A or B antibodies, for instance). But a person with

Rh- blood can develop Rhantibodies in the bloodplasma if he or she receivesblood from a person withRh+ blood, whose Rhantigens can trigger theproduction of Rh antibodies.A person with Rh+ bloodcan receive blood from aperson with Rh- bloodwithout any problems.

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Assessment

• 1. The main function of the circulatory

system is to supply your body cells with O2

and nutrients and also to remove wastes

including CO2

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Assessment

• 2.

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Assessment

• 3. Arteries have a thicker wall than veins

have – veins have valves and arteries do

not

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Assessment

• 3. For every 100 white blood cells there

would be about 50-100,000 red blood cells

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