Download The Cardiovascular System Work Sheets File - NW 14-19

Work Sheet 4.8 – The Cardiovascular System
This system is the body’s delivery and transport system and is made up of the Heart and the
Blood Vessels.
The heart works tirelessly to pump blood around the body.
There are five types of blood vessels which are arteries, arterioles, veins, venules and
capillaries.
• Arteries – the largest blood vessel in the body which carries oxygenated blood out of
the heart and around the body. They are elastic in order to be able to expand and have
thick walls to prevent them from bursting when blood under high pressure is pumped
into them.
• Arterioles – are very similar and do exactly the same job as arteries but are smaller.
• Veins and venules – carry de-oxygenated blood from the muscles, under low pressure,
back to the heart. They have thin walls, are non-elastic and have large holes in the
middle to allow blood to pass through easily. They also contain one way valves which
prevent blood flowing in the wrong direction.
• Capillaries – are the smallest of the blood vessels, have extremely thin walls, but their
function is vital as it’s in the capillaries that gaseous exchange takes place. Oxygen is
passed from the blood into the working muscles and Carbon Dioxide and other waste
products are passed into the blood in order to be transported away and removed.
Work Sheet 4.9 – Structure of the Heart
• The heart is divided into two sides, the right and the left, by a wall of muscle called the
septum. The inside of the heart is hollow and is made up of four different hollow areas
called chambers. The top two chambers are called atria and the bottom two are called
ventricles. The atria receive blood from the body and the ventricles are responsible for
pumping blood out of the heart.
• In order to ensure that blood flows in one direction only, the heart has a series of one
way valves between each atria and ventricles known as the tricuspid, bicuspid and
semi-lunar valves.
• The main blood vessel which transports de-oxygenated blood into the heart is the vena
cava and the pulmonary vein carries de-oxygenated blood from the heart to the lungs.
• The pulmonary vein carries oxygenated blood from the lungs into the heart and the
aorta carries oxygenated blood from the heart to the working muscles.
Work Sheet 4.10 – Function of the Cardiovascular System
The blood follows this path when travelling through the heart and around the body:
1. De-oxygenated blood from the working muscles travels through the vena cava and enters the
right atrium
2. The right atrium contracts and pushes the blood through the tricuspid valve into the right
ventricle
3. The ventricle contracts pushing the blood through the semi-lunar valve and out of the heart
through the pulmonary artery into the lungs in order to release carbon dioxide which is a biproduct of aerobic respiration and to receive oxygen which has been inhaled (gaseous
exchange)
4. Oxygenated blood then enters the left atrium in the heart via the pulmonary vein
5. The left atrium contracts and pushes the blood through the bicuspid valve into the left ventricle
6. The ventricle contracts pushing the blood through the semi-lunar valve and out of the heart
through the aorta where it’s transported to the working muscles before starting the cycle once
again.
The cardiovascular system is also responsible for maintaining the body’s core temperature of
37ºC. If this was not done then the body would overheat, putting a strain on the vital organs
due to severe loss of fluid (due to sweating), it would then shut down and eventually die. It
regulates the temperature by enlarging the blood vessels close to the skin surface so that heat
from the blood can be radiated into the atmosphere. The body then begins to sweat and this
cools the skin surface.