The Body in ActionThe Body in Action

The Need for EnergyThe Need for Energy

Mr G DavidsonMr G Davidson

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Using Energy

We use up energy as we go about our everyday lives.All foods contain some energy, however different foods contain different amounts.

– 1g carbohydrate 17kJ– 1g protein 17kJ– 1g fats 38kJ

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Using EnergyThe amount of energy needed by the body changes during life.It depends on the person’s age, sex, job and lifestyle. E.g.

Infant 3000kJ5 yr old 6300kJ15 yr old boy 15 000kJ15 yr old girl 13 000kJActive woman 10 500kJActive man 15 000kJ

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Carbon dioxide in AirWe need oxygen to release the energy from our food.A waste product, CO2 is produced during this process.We obtain O2 and get rid of CO2 by breathing.

The air we breathe in is called INHALED AIR.The air we breathe out is called EXHALED AIR.The 2 are VERY different.

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Carbon Dioxide in Air

Indicator

Breathe gently

Air inAir outAA BB

Exhaled air contains more CO2 than inhaled air.Exhaled air contains more CO2 than inhaled air.

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Oxygen ContentTo compare the oxygen content of inhaled and exhaled air we can compare their ability to support burning.To obtain a sample of exhaled air.

Breathe out

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Oxygen Content

Exhaled airInhaled air

The candle in the exhaled air goes out first because The candle in the exhaled air goes out first because there is less oxygen in this jar.there is less oxygen in this jar.

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Oxygen Content

Oxygen Carbon Dioxide Nitrogen

Inhaled air 20.96% 0.03% 79%

Exhaled air 16.4% 4.1% 79%

Exhaled air is also warmer and contains more Exhaled air is also warmer and contains more water than inhaled airwater than inhaled air

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Human Thorax

Our lungs allow us to take in oxygen and give out CO2.Our lungs and heart are in the chest which is a sealed unit called the thorax.

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Human Thorax

Nasal cavityMouth

EpiglottisTracheaBronchi

RibIntercostal muscle

Lungs

Diaphragm

Oesophagus

BronchiolesBlood capillaries

Alveoli

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Lungs

These are spongy organs which have a very large surface area.The bronchioles end in tiny air sacs called alveoli which are lined with moisture.Oxygen dissolves in this moisture and diffuses into the blood while CO2 diffuses in the opposite direction.

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Lungs

The lungs are well designed for gas exchange and the following features ensure this.

Large surface area.Good blood supply.Moist lining.Thin walls.

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Alveolus

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BreathingMovements of the thorax wall help us to take in and give out air.The diaphragm and intercostal muscles between the ribs are used to help us breathe.As we breathe, our thorax changes in size.Our lungs expand and contract.Breathing movements help to change the volume and pressure of the thorax.

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Air Passages

Air contains dust and germs which can damage the lungs and therefore have to be removed.The air we breathe in is cleaned by cells lining the air tubes.These cells have small hairs (cilia) which move in waves towards the mouth.

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Air Passages

A slippery liquid called mucus, which traps the dirt and germs, is made by the cells.The mucus acts like a conveyor belt which is moved by the beating cilia.In this way, dirt and germs are carried up to the mouth where they are swallowed.

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Air PassagesCilia

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Heart

Oxygen and food are carried to all body cells by blood in the blood vessels.The heart pumps the blood around the body.

Heart animation

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Heart

Bicuspid valve

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Heart

Right atriumRight atrium

Vena cavaVena cava

Right ventricleRight ventricle

Tricuspid valveTricuspid valve

Pulmonary arteryPulmonary artery AortaAorta

Pulmonary veinPulmonary vein

Left atriumLeft atrium

Left ventricleLeft ventricle

Bicuspid valveBicuspid valve

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HeartThe atria have very thin walls while the ventricles have thicker walls.The wall of the left ventricle is much thicker than the right due to a higher pressure required to pump blood all around the body.The heart has valves to stop blood flowing in the wrong direction.

Circulation animation

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Arteries, Veins and CapillariesBlood is carried to all body cells in vessels.Blood leaves the heart in arteries, is carried through organs and tissues in tiny vessels called capillaries and returns to the heart in veins.

Arteries have thick muscular walls and no valves.Veins have thin walls and valves all along their length.Capillaries are only one cell thick to allow diffusion.

If all the capillaries in your body were laid end If all the capillaries in your body were laid end to end, they would go twice round the world.to end, they would go twice round the world.

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Red Blood Cells

Blood is made up of cells floating in a liquid called plasma.Red blood cells are very small and can only be seen with the aid of a high power lens on a microscope.Red blood cells contain a pigment called HAEMOGLOBIN which is used to carry oxygen around the body.When oxygen joins it, it forms OXYHAEMOGLOBIN.

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Blood

Blood contains other kinds of materials e.g. white blood cells and platelets.White blood cells fight invading bacteria and destroy them by engulfing them.Platelets help the blood to clot at a cut.

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Blood Cells

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Blood Plasma

Blood cells float in a liquid called PLASMA.It also carries substances round the body like CO2, products of digestion, waste materials like urea, etc….The body cells give up their CO2 to the blood and receive oxygen from the blood.