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Double circulationDouble circulation

The circulatory system is made up of:

1. heart

- pumps blood around the body

2. blood vessels

- network of tubes to carry blood around the body

3. blood

- a liquid that transports materials around the body

vein

heart

artery

Video on Circulatory System

Head

Lungs

Double circulation:

Blood passes through the heart twice in one complete

circulation.

Systemic circulation

from heart to rest of body and back again

Pulmonary circulationfrom heart to lungs and back again

+

Other parts of body

VIDEO

II

lungs

left atriumright

atrium

left ventricle

right ventricle

digestive system

rest of body

Pulmonary artery

Pulmonary vein

Aorta (artery)

Vena cava (vein)

Deoxygenated blood at low

pressure

Oxygenated blood

Deoxygenated blood

Oxygenated blood at

higher pressure

ORGAN

Blood Vessels

HEART

Artery

Vein

Capillaries

arteries branch into network of

capillaries, which lie close to the

cells

food and oxygen pass from the

blood into the cells

carbon dioxide and other waste

substances pass from the cells into

the capillaries

capillaries join together to form the

veins which carry blood back towards

the heart

The HeartThe Heart

Chest x-ray

sternum

lung

right atrium left atrium

right ventricle

left ventricle

apex

The HeartThe Heart

The heart has 4 chambers:

2 smaller, upper chambers

(one atrium, two atria)

2 larger, lower chambers

(one ventricle, two ventricles)

Human Heart

4

5

6 7

8

9

External structure of heart

vena cava

aorta

pulmonary artery

pulmonary vein

left atrium

left ventricle

right atrium

vena cava

right ventricle

Aorta

Pulmonary vein

Left atrium

Bicuspid valve

Left ventricle

Pulmonary artery

Semi-lunar valve

Right atrium

Tricuspid valve

Chordae tendinae

Right ventricle

Vena Cava

The HeartThe Heart

vena cava (vein)vena cava (vein)

right atriumright atrium

right ventricleright ventricle left ventricleleft ventricle

musclemuscle

left atriumleft atrium

aorta (artery)aorta (artery)

pulmonaryartery

pulmonaryarteryDeoxygenated

blood from the body

Deoxygenated blood from the

body

to the lungsto the lungs

Oxygenated blood from the lungs

Oxygenated blood from the lungs

to the rest of the body again

to the rest of the body again

pulmonaryvein

pulmonaryvein

septumseptum

right atriumright atrium

right ventricleright ventricle left ventricleleft ventricle

musclemuscle

left atriumleft atrium

The HeartThe HeartPulmonary artery

Pulmonary vein

Aorta (artery)

Vena cava (vein)

1

2

3

4

5

6

7

8

9

Why is the left side of the heart thicker than the right?

The left ventricle is more muscular so that it can contract forcefully, to send oxygenated blood quickly to the rest of the body.

The less muscular right ventricular walls contract less forcefully. Blood is pumped out to the lungs at a lower blood pressure so as to allow time for exchange of gases at the lungs

Arteries, veins and capillariesArteries, veins and capillaries

Watch Video on Blood vessels

Intro to blood vessels

http://www.youtube.com/watch?v=CjNKbL_-cwA&feature=related

Structure of blood vessels

http://www.youtube.com/watch?feature=endscreen&v=3ffSxq9iyB8&NR=1

ArteriesArteries

Thick & elastic muscular walls enables the vessel to withstand the immense pressure of blood as it is forced out of the heart.

Dilation & constriction of vessel is brought about by contraction & relaxation of muscles in the vessel wall.

Semi-lunar valves on our hands

http://www.youtube.com/watch?v=d5DGVLTLPg0

Heart valvesHeart valves

Semi-lunar valves in pulmonary artery and Semi-lunar valves in pulmonary artery and aorta.aorta.

Bicuspid valve (left side of heart, between Bicuspid valve (left side of heart, between left atrium and left ventricle)left atrium and left ventricle)

TTrricuspid valve (icuspid valve (rright side of heart, ight side of heart, between right atrium and right ventricle)between right atrium and right ventricle)

Differences betweenDifferences between ArteriesArteriesCarry blood away

from heart to limbs & organs of body

Carry red oxygenated blood

Thick and elastic muscular walls

VeinsVeinsReturn blood

from tissues back to the heart

Carry bluish-red deoxygenated blood

Walls are thinner, with less elastic & muscular tissue

Differences betweenDifferences between ArteriesArteriesFairly wide lumenBlood flows

through fast, in spurts

Blood is under great pressure in these vessels

VeinsVeinsHave wider lumenBlood flows

slowly & smoothly

Blood pressure is low & steady

Differences betweenDifferences between ArteriesArteries Internal valves are

absent

Elasticity allows stretching & recoiling of vessel wall, help to push blood along

VeinsVeinsHave internal

valves along their length to prevent backflow of blood

Movement of blood is assisted by action of skeletal muscles in the body.

Characteristics ofCharacteristics of CAPILLARIECAPILLARIESS

Microscopic blood vessels found between cells of almost all tissues

Walls are made up of only a single layer of greatly flattened cells

Wall of vessel is partially permeable

Characteristics ofCharacteristics of CAPILLARIECAPILLARIESS

Dense network of fine vessels

Connects two types of vessels together

Function: Site of exchange of substances between blood and tissue cells

•Blood plasma and some dissolved food substances are forced out of the capillary walls by diffusion into the tissue fluid, to the body cells

•Blood flow is slow, to enable exchange of substances to occur

blood capillary

carbon dioxide diffuse from the cell into the blood

oxygen diffuse from the blood into the cell

Exchange of substances between cells and blood

O2

CO2

Body cells

Partially permeable membrane

Describe how is the blood capillary adapted for its function

1 cell thick capillary wall enables substances to be exchanged quickly (faster rate of diffusion) as the distance between body cells and blood is shorter.

Network of branching capillaries increases surface area for exchange of substances

Size of lumen is that of a red blood cell. Rate of blood flow is slow, giving more time for exchange of substances between blood and tissue cells.

Coronary Heart DiseaseCoronary Heart Disease

Coronary Heart Disease

During a heart attack, blood flow to a particular part of the heart may be completely blocked

Due to blocked blood flow, that region of heart muscles are deprived of oxygen and nutrients

The heart muscles are damaged and dead.

Causes of Coronary Heart Disease

Diet rich in cholesterolEmotional stressSmoking

Treatment of Coronary Heart Disease

Angioplasty (ballooning)Coronary Heart Bypass Grafting

Angioplasty (Ballooning)Angioplasty (Ballooning)

Watch Video

Coronary Bypass

Watch Video (CABG)

Hole in the HeartHole in the Heart

What are the consequences of a hole in the heart?

The oxygenated blood on the left side of the heart will be mixed with the deoxygenated blood on the right side of the heart. Blood pumped out of the heart to the rest of the body through the aorta is not fully oxygenated. Thus less oxygen transported to other parts of the body.

As blood from left ventricle is pumped into the right side of the heart, this will cause an increased pressure, resulting in enlargement of right side of heart, overworking the heart.