MECHANICS OF BREATHING

Stand up and feel your ribs Stand up and feel your ribs! Can you feel these movements when you breathe in and out?

Breathing in = inhalation Diaphragm is lowered Rib cage is raised Chest volume increases Pressure in chest decreases Air enters the lungs to equalise the pressure

Inhalation

Breathing

Breathing Out = Exhaling Diaphragm is raised Rib cage is lowered Chest volume decreases Pressure in chest increases Air leaves the lungs to equalise the pressure

Exhalation

Test yourself!! Diaphragm Contracts Moves down Intercostal muscles Explain how the diaphragm and the intercostal muscles work together to let air into the lungs Write a paragraph using the words in the box 5 minutes Diaphragm Contracts Moves down Intercostal muscles Ribs Up & out Increases Decreases Volume Pressure Air Enter

Test Yourself: Model Answer The diaphragm contracts and moves down. At the same time, the intercostal muscles contract moving the ribs up and out. This increases the volume and decreases the pressure in the lungs. This decrease in pressure forces air to enter the lung. Give yourself a mark out of 5

Structure of the heart and blood vessels

How does the oxygen from the air reach the cells in our body?

Blood transports nutrients and gases throughout the body.

The heart circulates the blood to all parts of the body.

The heart acts like a pump that pumps the blood to all parts of the body. It allows the blood to deliver the oxygen to the cells and take up the waste products like carbon dioxide.

Circulation of blood carrying oxygen and carbon dioxide.

The heart along with blood and the blood vessels make up the circulatory system. Blood carries the nutrients and oxygen to the tissues and also takes away waste products like carbon dioxide away from the tissues. Our body contains 5 Litres of blood that gets circulated in the body, by the heart.

Oxygenated and Deoxygenated Blood.

Oxygenated blood - Blood that contains a lot of oxygen Comes from the lungs Mainly found in arteries Deoxygenated blood - Blood that does not contain much oxygen Comes from the tissues Mainly found in veins

Blood Vessels are of three types: -Artery -Vein -Capillary.

ARTERY, VEIN & CAPILLARY

Unlike arteries, veins have one-way valves in them to keep the blood moving in the correct direction.

Artery, capillary and vein connection

Carry blood away from the heart. Carries oxygenated blood. ARTERIES Carry blood away from the heart. Carries oxygenated blood. The blood in the arteries is under high pressure and so: Arteries have thick outer walls Arteries have thick layers of muscles and elastic fibres VEINS Carry blood to the heart. Carries deoxygenated blood The blood in the veins is under low pressure and so: Veins have thin walls Veins have thin layers of muscle and elastic fibres.

Capillary Connects the artery with the vein Capillary Connects the artery with the vein. It comes in close contact with the tissues. Is made up of a thin wall to allow the diffusion of oxygen into the cells and the diffusion of carbon dioxide into the blood in the capillary.

Try Squeezing a tennis ball with one hand.

Your heart beats with about the same strength it takes to squeeze a tennis ball. Squeeze a tennis ball and see how hard that is.  Now think what it must be like for your heart to do this 70 times a minute, 60 minutes an hour, 24 hours a day - for a lifetime!

Structure of the Heart

Location of the heart.

The heart is made up of cardiac muscle and is divided into 4 different chambers. The top two compartments are called atria, while the bottom two compartments are called ventricles. The right atria and ventricle receive deoxygenated blood from the body whereas the left atria and ventricle receive oxygenated blood from the lungs. The pulmonary arteries carry deoxygenated blood away from the heart to the lungs. This is unusual because almost all other arteries carry oxygenated blood.

The pulmonary vein is a large blood vessel that carries blood from the lungs to the left atrium of the heart. They carry oxygenated blood, which is unusual since almost all other veins carry deoxygenated blood. Vena Cava are the veins that return deoxygenated blood from the body into the heart. They both empty into the right atrium. The aorta is the largest artery in the body. The aorta distributes oxygenated blood to all parts of the body.

TASK – Complete the worksheet on the structure of the heart and the blood vessels, put up on the website.

Wath the circulatory system video till (1:15 min.) http://www.youtube.com/watch?v=D3ZDJgFDdk0

The heart is a DOUBLE PUMP: 1st - blood is pumped to the lungs & returns to the heart, 2nd - blood is pumped to respiring muscles & back to the heart again. 1. Deoxygenated blood is pumped from the heart to the lungs 2. The blood receives oxygen and is pumped back to the heart 4. The oxygen leaves the blood to be used for respiration in the body and the blood goes back to the heart 3. The oxygenated blood is then pumped to the rest of the body

Gas exchange

http://www.bbc.co.uk/schools/ks3bitesize/science/organisms_behaviour_health/life_processes/revise5.shtml

TASK: complete worksheet

Lung Capacities and Volumes