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