Introduction to the Human Circulatory System

Overview The circulatory system is made up of the heart and blood vessels. There are three types of blood vessels: arteries, veins, and capillaries.

ARTERIES Blood vessels that carry blood away from the heart are called arteries. They are the thickest blood vessels and they carry blood high in oxygen known as oxygenated blood (oxygen rich blood).

VEINS Blood vessels that carry blood back to the heart are called veins. They have one-way valves which prevent blood from flowing backwards. They carry blood that is high in carbon dioxide known as deoxygenated blood (oxygen poor blood).

CAPILLARIES The smallest blood vessels are capillaries and they connect the arteries and veins. This is where the exchange of nutrients and gases occurs.

A great partnership! Our circulatory system works with our respiratory system to supply our bodies with oxygen and nutrients. Together they are known as the cardiovascular system

How do they help each other? Our circulatory system carries waste products to the respiratory system which gets rid of wastes such as carbon dioxide. Our respiratory system brings in oxygen and our circulatory system delivers the oxygen to all the cells in the body.

The Blood Every time your heart beats, blood is sent through your body. Each day about six litres of blood is constantly circulated through your body. This blood travels through about 96,560 km of blood vessels!

Your Amazing Heart Your heart is a muscular pump that beats from 60 to 100 times per minute, but can beat much faster if it has to. That is about 100,000 beats per day, more than 30 million beats per year!

Cardiovascular Problems Problems with the cardiovascular system are common, but they don’t just affect older people. Many heart problems affect children and teenagers.