S2 BiologyMadras College

• It is important to maintain a healthy balance of :

• Carbohydrates.• Proteins• Fats• Vitamins and

Minerals• Fibre• Water

• Carbohydrates are found in these foods above• We need carbohydrates for energy

• Proteins are found in foods such as :

• Red meat• Fish• Eggs• Cheese

We need proteins for growth and repair

• Fats are high in any fried or ‘fast’ food

• We need some fats for:• Proper function of the

heart• Maintenance of the

blood system • Brain development and

function

Excess fat is stored under our skin or around our organs

• Vitamins and Minerals are substances which the body needs in very small quantities to work properly.

Vitamin/Mineral Function

Vitamin A Eye function

Vitamin B group Energy from food (respiration)

Vitamin C Maintain healthy skin and gums

Iron Production of Red Blood Cells

Calcium Healthy bones and teeth (with Vit. D)

Iodine Maintain normal cell function

• ‘Junk Food’ contains many ingredients which are generally bad for you. These are generally known as…

• Junk food is alright to have ‘ once in a while’, but should not be eaten regularly.

Crown

Root

Enamel

Dentine

Gum

Pulp Cavity

Cement

Bone

• An adult has 32 teeth in total.

Incisors

Canines

Pre-molarsM

olar

s Molars

Wisdom teeth

• Bacteria on teeth use sugar from our food. The Bacteria multiply to form plaque.

• The Bacteria make acid.• The acid slowly burns

through the enamel to create a cavity.

• The bacteria continue to make acid using food stuck in the cavity. Eventually, the cavity extends to the pulp cavity and causes toothache!

• It is important to brush your teeth regularly!

• Use a good toothbrush.

• You may wish to use mouthwash too.

Regular brushing is important for all members of the family!

Mouth

Gullet

LiverStomach

Gall Bladder Pancreas

Large Intestine

Small Intestine

Appendix Rectum

Anus

• Teeth begin mechanical breakdown of food.

• Saliva contains Amylase (Carbohydrase) enzyme to begin digestion of Carbohydrates.

• Passes food from the Mouth to the Stomach.

• Food is moved along the gut by a process called PERISTALSIS.

• Fibre in the diet helps the gut move food along easily.

Muscles in gullet wall contract behind bolus

Bolus squeezed along gut.

Bolus of food

Gullet

• The Stomach churns our food.

• It makes Protease enzyme for Protein digestion.

• It makes Hydrochloric Acid to kill germs.

• The Liver makes Bile.• Bile is stored in the

Gall Bladder.• Bile breaks down fat

into small droplets.• This is

EMULSIFICATION.

LiverGall Bladder

Fat

Bile

Lipase enzyme can now digest fat easier

• The Pancreas makes enzymes for the digestion of Carbohydrates, Proteins and Fats.

• It also helps control blood/sugar levels.

Liver

Stomach

Gall Bladder & Bile Duct

Small Intestine

PancreasPancreas

• Digestion is completed in the Small intestine.• Small and soluble food particles pass into the blood by absorption.• The Small intestine has a very large surface area due to Villi.

VillusSmall Intestine

Blood capillary

Large food molecules broken down by enzymes

Small soluble food molecules pass into the blood.

• Mostly undigested food and Fibre passes into the Large Intestine.

• Water and Minerals are absorbed into the blood here.

• This is the breakdown of large insoluble molecules into small soluble molecules.

• Digestion allows food to be absorbed by the blood.

Large Insoluble Food Molecule

Small Soluble Food Molecules

If the name ends in –ase,

it’s an enzyme

• Starch is broken down into Sugar (Glucose).• Amylase is a Carbohydrase enzyme.

Starch

Amylase

Simple Glucose can now be absorbed into the bloodstream

Amylase breaks bonds between Sugar molecules

• Proteins are broken down into Amino Acids.• Pepsin from the Stomach is a Protease enzyme.

PepsinPepsin breaks down the long proteins into shorter proteins

Other Protease enzymes break down short protein chains into Amino Acids.

Amino Acids are absorbed into the blood

• Lipase digests Fat.• Fat is broken down into Glycerol and Fatty Acids.

Fatty AcidsGlycerol

Lipase enzyme

Fatty Acids and Glycerol absorbed separately into bloodstreamA Fat Molecule

• This is the process which your cells use to make energy.

Larynx (voice box)

Trachea (windpipe)

Bronchi

Bronchioles

Diaphragm muscle

Rib

Rib muscle Alveoli or air sacs are found at the ends of the Bronchioles

Deoxygenated blood from

heart

Oxygenated blood back to

heart

Film of moisture

Capillary

Diaphragm contracts and moves downwards.

Rib muscles contract and ribcage moves upwards and outwards.

Volume in chest increases.

Pressure in chest decreases.

Air is Inhaled.

Diaphragm relaxes and moves upwards.

Rib muscles relax and ribcage moves downwards and inwards.

Volume in chest decreases.

Pressure in chest increases.

Air is Exhaled.

• Inhaled air is 78% Nitrogen, 20% Oxygen, 1% Carbon Dioxide and 1% Rare gases.

• Exhaled air contains less Oxygen (16%) and more Carbon Dioxide (5%).

Nitrogen(78%)

Nitrogen(78%)

Oxygen(20%)

Oxygen(16%)

Carbon Dioxide

Rare Gases

Normal Air Exhaled Air

In Exhaled air, the candle goes out sooner because there is less Oxygen in it.

0 seconds2 seconds4 seconds6 seconds8 seconds10 seconds

Exhaled AirCarbon Dioxide gas turns Limewater cloudy

Limewater

Water turns blue Cobalt chloride paper pink

Cobalt Chloride paper

The cilia beat and move mucus containing dirt and germs up to the back of the throat

Cilia

Mucus

Trapped dirt and germs are moved towards the mouth