S. MORRIS 2006

The circulatory system carries blood and dissolved substances (hormones, nutrients, O and waste products) to and from different places in the body. The Heart has the job of pumping these things around the body.

The Heart pumps blood and substances around the body in tubes called blood vessels.

The Heart, the blood and blood vessels together make up the Circulatory System.

What is the circulatory system?

Blood flow pattern :

- left ventricle

- aortic arch

- dorsal aorta

- capillary bed

- posterior vena cava

- right atrium

- right ventricle - lungs

- left atrium

- left ventricle

lungs

head & arms

liver

digestive system

kidneys

legs

pulmonary artery

aorta

pulmonary vein

main vein

Left Right

How does this system work?

Circulatory System

Lungs

Body cells

Our circulatory system is a double circulatory system.

This means it has two parts.

the right side of the system

deals with deoxygenated

blood.

the left side of the system

deals with oxygenated

blood.

What are the 3 types of circulation?

• System – between heart to body systems

• Pulmonary – between heart & lungs• Coronary – between heart & heart

Coronary circulation

Pulmonary circulation

Systemic circulation

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Anatomy of the heart:• A hollow muscular organ lying in the center of

the chest• Divided into left and right sides, each have

upper chamber (atrium) that collects blood and a lower chamber (ventricle) that ejects blood

• Inlet and outlet valves in each ventricle ensure one-way blood flow

The Heart

These are arteries. They carry blood away from the heart.

This is a vein. It brings blood from the body, except the lungs.

Coronary arteries, the hearts own blood supply

The heart has four chambers

2 atria

2 ventricles

now lets look inside the heart

The Heart

Left Ventricle

Left AtriumRight Atrium

Right Ventricle

valve

Vein from Lungs

Artery to Head and BodyArtery to Lungs

Vein from Head and Body

valve

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Heart – Anterior View

Heart – Posterior View

Primary functions of the heart include:

• Oxygen mover for the body

• Collects O2-enriched blood coming from lungs

• Pumps it to entire body

• Helps rid body of waste product (CO2)

• Collects oxygen-depleted blood from the body

• Pumps it to the lungs for re-oxygenation

During each heartbeat, each heart chamber:

• Relaxes as it fills (diastole)

• And then contracts as it pumps blood (systole)

Close up of heart valveHeart sounds are made by the valves

as they open and close

Muscle on the left ventricle is thicker than the right. Left ventricle muscle uses a strong force to

push the blood out the aorta.

Blood flow:• CO2-laden blood from

body flows through the

largest veins (vena

cavae) into right atrium• Right atrium fills• Heart muscle propels

blood into right ventricle

• Right ventricle fills• Heart muscle pumps blood

through pulmonary valve into pulmonary arteries to the lungs

• Blood in lungs absorbs O2 and gives up CO2

• CO2 is exhaled (Respiratory System)

• O2-enriched blood returns to the heart through pulmonary veins into the left atrium

• Left atrium fills

• Blood is pumped into left ventricle

• When left ventricle fills, heart muscle pumps blood through aortic valve into aorta (largest artery in the body)

• O2-enriched blood supplies all of body except lungs

blood from the heart gets around

the body through blood vessels

There are 3 types of blood vessels

a. ARTERY

b. VEIN

c. CAPILLARY

The ARTERY

thick muscle and elastic fibres

Arteries carry blood away from the heart.

the elastic fibres allow the artery to stretch

under pressure

the thick muscle can contract to push the

blood along.

• Arteries:– Strong and flexible– Carry blood away from the heart– Bear the highest blood pressures– Help maintain blood pressure between

beats

• Smaller arteries and arterioles:– Have muscular walls – Adjust their diameter to increase or

decrease blood flow to a particular area

The VEINVeins carry blood towards from the heart.

thin muscle and elastic fibres

veins have valves which act to stop the blood from going in the wrong direction.

body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.

• Thin-walled but generally larger in diameter than arteries,

• Carry same volume of blood, but at a lower speed, and

• Under much less pressure

• Carry blood to the heart

• Receive blood from the capillaries

• Transport waste-rich/ oxygen-poor blood back to the lungs and heart

• Valves are located inside the veins

• Allow blood to move in one direction

The CAPILLARYCapillaries link Arteries with Veins

the wall of a capillaryis only one cell thick

they exchange materials between the blood and other body cells.

The exchange of materials between the blood and the body can only occur through capillaries.

• Tiny, extremely thin-walled

• Act as bridges between arteries and veins

• Allow nutrients to pass from blood to tissues

• Allow waste to pass from tissues into blood

• Drain into venules, which drain into veins, which lead back to the heart

what’s in

red blood cells white blood cells

platelets

plasma

carbon dioxide

digested food

waste (urea)

hormones

oxygen

Blood• Pumped by your heart.

• Travels through thousands of miles of blood vessels

• Carries nutrients, water, oxygen and waste products to and from your body cells.

• Made up of liquids, solids and small amounts of oxygen and carbon dioxide.

Red Blood Cells

contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it.

can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.

a biconcave disc that is round and flat without a nucleus

Red Blood Cells• Red blood cells carry oxygen from the

lungs to all the cells of the body.

• Takes carbon dioxide and transports it back to the lungs

• About 5,000,000 Red Blood Cells in ONE drop of blood.

White Blood Cells

there are many different types and all contain a big nucleus.

the two main ones are the lymphocytes and the macrophages.

some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them.

other lymphocytes make antitoxins to break down poisons.

macrophages ‘eat’ and digest micro-organisms .

White Blood Cells• White blood cells protect the body from

germs

• Attack and destroy germs when they enter the body

PlateletsPlatelets are bits of cell broken off larger cells.

Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.

Plasma

A straw-coloured liquid that carries the cells and the platelets which help blood clot.

• carbon dioxide

• glucose

• amino acids

• proteins

• minerals

• vitamins

• hormones

• waste materials like urea.

It also contains useful things like;

SUMMARYcopy and complete the following;

Arteries take blood ______ from the heart. The walls of an artery

are made up of thick _________ walls and elastic fibres. Veins

carry blood ________ the heart and also have valves. The

_________ link arteries and veins, and have a one cell thick wall.

Blood is made up of four main things ______, the liquid part of the

blood; Red Blood Cells to carry ______; White Blood cells to protect

the body from disease and _________ to help blood clot.

away

platelets

towards

capillaries

plasma

oxygen

muscular