CIRCULATORY SYSTEM

WHAT DO YOU NEED TO KNOW?

Circulatory system:

• Brings nutrients and oxygen to cells and removes waste products

• The main processes include circulating blood between heart and lungs,

and circulating blood between the heart and the rest of the body

• The main components include the heart, blood vessels (arteries, veins,

capillaries), blood

• Health issues include high blood pressure, heart attacks, strokes

THE TRANSPORT SYSTEM

WHY DO WE NEED A TRANSPORT SYSTEM?

Nutrients and oxygen need to

be transported to the cells

and waste products like

carbon dioxide need to be

removed from the cells

WHAT FORMS OUR TRANSPORT SYSTEM?

• In man (mammals) the blood circulatory system and lymphatic

system are the means of transport.

• The blood circulatory system in mammals includes the heart and

blood vessels AKA: arteries, veins and capillaries.

• We are classified as having a double circulatory system.

PROCESS 1

Circulating blood from

the heart to the lungs –

the blood that returns to

the heart is rich in

oxygen

Known as PULMONARY

circulation

PROCESS 2

• Circulating blood between

the heart and the rest of the

body. The heart pumps the

oxygen rich blood to every

living cell in the body.

• This is known as systematic

circulation

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THE COMPLETE PROCESS

THE COMPONANTSTHE HEART

• The heart is situated in the middle of the chest or

thorax in a hollow space between the lungs.

• It is protected by the ribs

• The heart is a fist-sized, muscular organ that pumps

blood through the body.

• It is roughly triangular in shape

• It contains _____ chambers, two _______ above and

two _______ below.

THE LEFT SIDE AND THE RIGHT SIDE

• When labelling LEFT and RIGHT

body parts see it as a patient

lying on the operating table – you

are the DOCTOR!

• Hence it appears to be the wrong

way around

Label the diagram of the heart

given to you.

BLOOD VESSELS

ARTERIES

• Arteries carry blood away from the heart to the organs and limbs of the body.

• They have thick elastic walls because arteries must be able to stretch when blood is pumped into them by the heart.

• The blood surges with each heartbeat.

• This pulse can be felt where an artery runs near the surface of the skin or over a bone.

• Arteries divide into thinner vessels, arterioles, These arterioles branch to form a dense network of capillaries in the body organs.

VEINS

• Veins have thinner less elastic walls than arteries.

• They provide a wider passage for blood flow.

• As the blood pressure is very low in veins blood

• could flow backwards. To prevent the blood from flowing backward veins have a system of one way valves that prevent the backflow of blood.

• When the blood flows backwards the valves close to prevent this.

CAPILLARIES

• Capillaries are thinner than a human hair.

• Their walls are only one cell thick, with spaces between the cells so that plasma and white blood cells can pass through.

• Plasma carries dissolved food and oxygen directly to the tissue cells, and carbon-dioxide and other waste products are carried away.

• Blood flow slows down in the capillaries so that this exchange has more time to take place between tissue fluid and the capillary.

• Red blood cells do not leave the capillaries.

• Capillaries join to form wider vessels called venules which then become veins.

COMPARISON

BLOOD

•Our blood is composed of red blood cells,

white blood cells and platelets found in the

blood plasma

•Red blood cells – carry the gases to and from

the cells for gaseous exchange

•White blood cells are useful in fighting

diseases

• Platelets are used for clotting

HEALTH ISSUES

The following are common health issues related

to this system

• High blood pressure

• Heart attacks

• Strokes

(Text book page 23 – copy down the

information on these points)