THE CIRCULATORY SYSTEMTHE CIRCULATORY SYSTEM

• THE ADULT HUMAN BODY CONTAINS ONLY THE ADULT HUMAN BODY CONTAINS ONLY ABOUT 5 LITRES OF BLOODABOUT 5 LITRES OF BLOOD

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COMPOSITION OF THE COMPOSITION OF THE BLOODBLOOD

BLOOD IS MADE UP OF:BLOOD IS MADE UP OF:

1.1. A LIQUID PART CALLED PLASMAA LIQUID PART CALLED PLASMA

2.2. CELLS THAT ARE SUSPENDED IN THE CELLS THAT ARE SUSPENDED IN THE PLASMAPLASMA

COMPOSITION OF THE COMPOSITION OF THE BLOODBLOODTHE PLASMA IS MADE UP OF:THE PLASMA IS MADE UP OF:

1.1. 90% WATER90% WATER

2.2. There are many substances dissolved in There are many substances dissolved in the water,the water,e.g. Sugar, Protein, Hormones, Enzymes, e.g. Sugar, Protein, Hormones, Enzymes, Minerals etc.Minerals etc.

COMPOSITION OF THE COMPOSITION OF THE BLOODBLOOD

THERE ARE 3 TYPES OF CELLS SUSPENDED THERE ARE 3 TYPES OF CELLS SUSPENDED IN THE PLASMA:IN THE PLASMA:

1.1. RED BLOOD CELLSRED BLOOD CELLS

2.2. WHITE BLOOD CELLSWHITE BLOOD CELLS

3.3. PLATELETSPLATELETS

Functions of the BloodFunctions of the Blood

THE BLOOD HAS THREE MAIN FUNCTIONS:THE BLOOD HAS THREE MAIN FUNCTIONS:

1.1. TRANSPORTTRANSPORT

2.2. FIGHTING INFECTIONFIGHTING INFECTION

3. CLOTTING3. CLOTTING

TRANSPORT:TRANSPORT: The blood carries very many The blood carries very many

substances around the body.substances around the body.

For example:For example:

• Blood carries oxygen from the lungs Blood carries oxygen from the lungs to the cells.to the cells.

• Blood carries carbon dio0xide from Blood carries carbon dio0xide from the cells to the lungs.the cells to the lungs.

• Blood carries digested food products from Blood carries digested food products from the intestines to the cells.the intestines to the cells.

• Blood carries waste from the cells to the Blood carries waste from the cells to the liver and the kidneys.liver and the kidneys.

• Blood carries hormones and enzymes Blood carries hormones and enzymes around the body.around the body.

FIGHTING INFECTION:FIGHTING INFECTION:

• The blood destroys bacteria, and viruses The blood destroys bacteria, and viruses that may infect the body.that may infect the body.

CLOTTING:CLOTTING:

• Sometimes a tear occurs in a blood vessel Sometimes a tear occurs in a blood vessel e.g. when you are cute.g. when you are cut

• Blood will leak outBlood will leak out

• Infection may enterInfection may enter

•It is vital that such tears are repaired It is vital that such tears are repaired quicklyquickly•The blood does this by forming a clot that The blood does this by forming a clot that seals the woundseals the wound

• Another function of the blood is to help Another function of the blood is to help maintain normal body temperature.maintain normal body temperature.

• THIS IS 37THIS IS 37° C° C

• The function of red blood cells is The function of red blood cells is to carry oxygen around the bodyto carry oxygen around the body

Red blood cells

• The function of white blood cells is The function of white blood cells is to fight infectionto fight infection

• Some white blood cells produce substances Some white blood cells produce substances called antibodies that identify and destroy called antibodies that identify and destroy bacteria, virusesbacteria, viruses

• Other white blood cells kill bacteria by Other white blood cells kill bacteria by engulfing them and digesting.engulfing them and digesting.

• The function of the platelets is to help The function of the platelets is to help the blood to clot.the blood to clot.

THE CIRCULATORY SYSTEMTHE CIRCULATORY SYSTEM

• On leaving the heart, the blood passes into On leaving the heart, the blood passes into all of the organs and limbs of the body all of the organs and limbs of the body before being returned to the heart.before being returned to the heart.

The The Circulatory Circulatory SystemSystem

THE HEARTTHE HEART

• The heart is located in the centre of the The heart is located in the centre of the chest, behind the breast bone.chest, behind the breast bone.

• The function of the heart is to pump blood.The function of the heart is to pump blood.

• The heart is made up of muscle called The heart is made up of muscle called cardiac muscle.cardiac muscle.

The Structure of the HeartThe Structure of the Heart

• The heart is divided into two sides, left and The heart is divided into two sides, left and right, separated by a wall of muscle called right, separated by a wall of muscle called the septum.the septum.

• Each side has two chambers.Each side has two chambers.

• The top chambers are called atria.The top chambers are called atria.

• The lower chambers are called ventricles.The lower chambers are called ventricles.

THE HEARTTHE HEART

left atriumleft atrium

left ventricleleft ventricleright ventricleright ventricle

right atriumright atrium

THE FOUR CHAMBERS OF THE HEARTTHE FOUR CHAMBERS OF THE HEART

septum septum

The heart acts as if it were The heart acts as if it were two separate pumps:two separate pumps:

1.1. The right ventricle pumps blood to The right ventricle pumps blood to the lungs.the lungs.

2.2. The left ventricle pumps blood all The left ventricle pumps blood all round the rest of the body.round the rest of the body.

•Since the lungs are very close to Since the lungs are very close to the heart, the right ventricle the heart, the right ventricle doesn`t pump blood very far.doesn`t pump blood very far.

•Since it must pump blood much Since it must pump blood much further, the muscle of the left further, the muscle of the left ventricle is much thicker than of ventricle is much thicker than of the right ventricle. the right ventricle.

BLOOD VESSELS OF BLOOD VESSELS OF THE HEARTTHE HEART

THE HEARTTHE HEART

• The Vena Cava carry deoxygenated The Vena Cava carry deoxygenated blood from all over the body to the blood from all over the body to the right atrium.right atrium.

• The Superior Vena Cava collect The Superior Vena Cava collect deoxygenated from the upper parts of deoxygenated from the upper parts of the body.the body.

• The Inferior Vena Cava collect the The Inferior Vena Cava collect the blood from the lower parts of the blood from the lower parts of the body.body.

•The blood then flows into the The blood then flows into the right ventricle.right ventricle.

• It is then pumped into It is then pumped into pulmonary artery.pulmonary artery.

• The Pulmonary Artery carries deoxygenated The Pulmonary Artery carries deoxygenated blood from the right ventricle to the lungs.blood from the right ventricle to the lungs.

• It divides in two, one to each lung.It divides in two, one to each lung.

• This blood is oxygenated in the lungs.This blood is oxygenated in the lungs.

• The Pulmonary Veins carry oxygenated blood The Pulmonary Veins carry oxygenated blood from the lungs to the left atrium of the heart.from the lungs to the left atrium of the heart.

• There are four pulmonary veins, two from each There are four pulmonary veins, two from each lung.lung.

Pulmonary Circulation

• The left ventricle contracts and pumps The left ventricle contracts and pumps blood out of the heart through the aorta.blood out of the heart through the aorta.

• The aorta is the major artery of the body.The aorta is the major artery of the body.• It carries blood all over the body.It carries blood all over the body.• It collects carbon dioxide.It collects carbon dioxide.• The deoxygenated blood travels back to the The deoxygenated blood travels back to the

right atria through the vena cava.right atria through the vena cava.

Systemic or General Circulation

Blood Flow Through the Blood Flow Through the HeartHeart

BLUE = deoxygenated blood

RED =

oxygenated blood

Superior Vena Cava

Inferior Vena Cava

Pulmonary Veins

AortaPulmonary Artery

Blood Flow Through the Blood Flow Through the HeartHeart

Blood Flow Through the Blood Flow Through the HeartHeart

BLOOD VESSELSBLOOD VESSELS

• The tubes that carry blood are known as The tubes that carry blood are known as blood vessels.blood vessels.

• There are three types:There are three types:

ArteriesArteries

VeinsVeins

CapillariesCapillaries

BLOOD VESSELSBLOOD VESSELS

• Arteries carry blood away from the heart.Arteries carry blood away from the heart.

• Veins carry blood towards the heart.Veins carry blood towards the heart.

• Capillaries connect arteries to veins.Capillaries connect arteries to veins.

THE DIFFERENCES THE DIFFERENCES BETWEEN ARTERIES AND BETWEEN ARTERIES AND VEINSVEINS• The blood in the arteries is under much The blood in the arteries is under much

higher pressure than in veins.higher pressure than in veins.

• This means that the wall of an artery is This means that the wall of an artery is much thicker than that of a vein.much thicker than that of a vein.

• This also means that the passage through This also means that the passage through an artery is much narrower than in a vein.an artery is much narrower than in a vein.

THE DIFFERENCES THE DIFFERENCES BETWEEN ARTERIES AND BETWEEN ARTERIES AND VEINSVEINS

• Arteries do not have valves because the Arteries do not have valves because the blood is under high pressure.blood is under high pressure.

• To prevent low pressure blood flowing To prevent low pressure blood flowing backwards, veins have valves.backwards, veins have valves.

THE DIFFERENCES THE DIFFERENCES BETWEEN ARTERIES AND BETWEEN ARTERIES AND VEINSVEINS

•The blood in arteries is The blood in arteries is oxygenated except for the oxygenated except for the pulmonary artery.pulmonary artery.•The blood in veins is The blood in veins is deoxygenated except for the deoxygenated except for the pulmonary vein.pulmonary vein.

Structure of Arteries

•They are thick-walled tubes. They all have the same basic construction:

•A fibrous outer covering

•A middle layer of muscle and elastic tissue

•An endothelial layer (a single layer of flattened cells)

Structure of Capillaries

•The capillaries are the smallest blood vessels.

•Their walls are one cell thick and porous, thus allowing the passage og gases and nutrients.

Structure of Veins•They have three-layered walls

similar to that of arteries.

•Their walls are much thinner and the lumen is larger.

•They have a fibrous outer coating

•A middle layer of muscle and elastic tissue

•An endothelial layer

•They have valves to prevent the back flow of blood.

THE HEARTBEATTHE HEARTBEAT

•When the heart pumps, a When the heart pumps, a pulse pulse of blood is sent down the of blood is sent down the arteries.arteries.

•This pulse can be felt in several This pulse can be felt in several places, e.g. the wrist, the places, e.g. the wrist, the temples and the neck.temples and the neck.

What is Pulse•The rate at which your heart

pumps blood through your circulatory system.

•When blood is pumped from the left ventricle into the aorta, the aorta swells.

•The elastic wall of the aorta contacts thus forcing the blood to move on.

•This sets up a wave of swelling and contracting which continues along all the elastic tissues.

• It can be felt wherever an artery passes close to the surface of the skin and over a bone.

•Most adults heartbeat is 72 – 80 beats per minute.

•Babies have a beat of 130 times a minute.

Anaemia

• Is a reduction in the bloods ability to carry oxygen.

• It may be caused by : Loss of blood, Lack of iron in the diet,A failure of the bone marrow to

produce the normal level of red blood cells.

THE HEARTBEATTHE HEARTBEAT

•The normal human heartbeat is The normal human heartbeat is seventy beats per minute.seventy beats per minute.

•The normal human adult The normal human adult breathing rate is 16-17 breaths breathing rate is 16-17 breaths per minute.per minute.

THE HEARTBEATTHE HEARTBEAT

• If more oxygen is needed by the If more oxygen is needed by the muscles and the brain the rate of the muscles and the brain the rate of the heartbeat increases.heartbeat increases.

• Extra blood is pumped to these Extra blood is pumped to these organs and so they get extra oxygen.organs and so they get extra oxygen.

• Carbon dioxide is also removed Carbon dioxide is also removed faster.faster.

FACTORS THAT INCREASE THE FACTORS THAT INCREASE THE RATE OF THE HEARTBEAT RATE OF THE HEARTBEAT INCLUDE:INCLUDE:

•EXERCISEEXERCISE

•A FRIGHTA FRIGHT

•SMOKINGSMOKING

•EXCITEMENTEXCITEMENT

•FACTORS THAT FACTORS THAT DECREASE THE RATE OF DECREASE THE RATE OF THE HEARTBEAT THE HEARTBEAT INCLUDE:INCLUDE:

•REST AND SLEEPREST AND SLEEP