IntroductionThe circulatory (or

cardiovascular) system is the transport system of the body and has four major functions:

1.Transportation of O2 and CO2

2.Transportation of wastes and nutrients

3.Transportation of hormones

4.Maintain body temperature.

Structure of the Circulatory SystemA circulatory system

consists of three parts:1.A fluid in which

materials are transported (i.e. blood)

2.A system of vessels to transport the fluid all over the body (i.e. arteries and veins)

3.A pump (i.e. heart)

Interesting FactsNo cell in your body is

more than two cells away from a blood vessel.

There are 96 000 km of blood vessels in your body to sustain your 100 trillion cells.

Your heart beats around 72 times a minute and in your lifetime it will pump enough blood to fill two ocean tankers!

Two Systems in OneThe left and right side of

your heart do different functions.

The right side of your heart pumps blood to the lungs to exchange CO2 for O2 in the pulmonary circuit.

The left side of your heart pumps oxygen rich blood around your body in the systemic circuit.

Blood moving through the heart is the cardiac circuit.

Lungs

Heart StructureThe wall separating the

left and right sides of your heart is known as the septum.

Each side has a thin walled atrium to collect blood above a more muscular ventricle that pumps blood.

Between the different regions of the heart are valves to ensure blood only flows in one direction.

Heart SoundsThe heart beat is

actually controlled within the heart itself by two bundles of nerves.

The sinoatrial (SA) node acts as a pacemaker causing the atria to contract while the atrioventricular (AV) node ensures the ventricles contract a moment later.

Lub-dubThe sound we hear is

caused by the closing of the heart valves.

The “lub” is from the shutting of the valves between the atria and ventricles when blood is moved from the top to the bottom of the heart.

The “dub” is the closing of the valves between the ventricles and the arteries that leave the heart.

Blood VesselsArteries carry blood

away from the heart and have thicker walls to withstand the greater pressure of blood.

Veins take blood back to the heart and have valves to ensure one way blood flow.

Capillaries are the junction of arteries and veins where gases and nutrients are exchanged with body cells.

Artery (from heart)

Vein (to heart)

Tracing the Path Blood Takes around the Body

Homework1) What are the four functions of a circulatory

system?2) What are the three main parts to a

circulatory system?3) What are two differences between an

Atrium and a Ventricle?4) Using three different points of criteria,

compare arteries, veins and capillaries.