13/06/2014 food and digestion. 13/06/2014 food types type found in uses carbohydrates fats proteins...

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Food and DigestionFood and Digestion

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Food typesFood typesTypeType Found inFound in UsesUses

Carbohydrates

Fats

Proteins

Vitamins

Minerals

Fibre

Water

Bread, potatoes, cereal

Cream, butter, milk, oil

Meat, fish, eggs

Vegetables, cereal

Meat, milk, cereal

Fruit + veg, cereal

Water!

Energy

A store of energy

Building and repairing cells

Keep things “ticking over”

Strong teeth etc

75% of the body is water

Keeps you regular!

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Food tests 1Food tests 1To investigate what happens in digestion we need to be able to test for different foods. Here are two simple tests:1) The test for starch:

Drop some iodine onto the food. If the iodine turns BLUE/BLACK then STARCH is present.

2) The test for simple sugars (e..g glucose)

Boil the food with some Benedict’s solution. If an orange “precipitate” appears then the food contains simple sugars

Iodine

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Food tests 2Food tests 2

1) The test for protein:

Add 5cm3 of dilute sodium hydroxide followed by 5cm3 of dilute copper sulphate. If protein is present it will produce a purple colour.

2) The test for fats:

Shake the food with about 10cm3 of ethanol in a test tube. Pour some of the solution into a tube containing water. If fat is present the water will turn cloudy white.

Utilisation of foodUtilisation of food• Humans ingest oragnic food via process of holozoic

nutrition which includes:– Ingestion: act of taking in food via mouth– Digestion: Breakdown of complex to simple

soluble molecules– Absorption: Diffusion of molecules into blood to

liver– Assimilation: use of food by body for respiration

growth devlpmt, diffused from small intestines to b.v. which than carry nutrients where needed

– Egestion: process of undigested food removed from body- defecation

The digestive systemThe digestive system

• The digestive system is responsible for breaking down large, complex food substances

into smaller, simpler and soluble molecules.

• The digestive system in humans is a long tube called the alimentary canal,8-9m long, that starts at the mouth and ends at the anus.

• Mucus lined to reduce friction

DigestionDigestion

• Digestion occurs by two processes:a)Physical digestionb)Chemical digestion

• Physical digestion is the physical breakdown of food into smaller pieces.

• Chemical digestion is the change of the food into simpler substances

Physical digestionPhysical digestion

• Physical digestion is the physical breakdown of food into smaller pieces. This process occurs in the mouth and also the stomach

• The mouth breaks down food by chewing. Teeth and tongue are involved in this process.

• It also occurs in the stomach when stomach muscles churn food and further breaks it down into smaller pieces called chyme

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Physical Digestion :TEETHPhysical Digestion :TEETH

• Teeth formula depending on location and number in mouth:– I 2/2 C 1/1 P 2/2 M

3/3

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TeethTeeth

• Observe shape• Observe bumps

on enamel to differentiate molars

• Different shapes of teeth have different functions

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TeethTeeth

incisors: chisel and cut Canine: rip and tear Molars/ premolars: grind and crush

• 2 sets:» decidous; milk teeth 20» Permanent; Adult teeth , consists of 32

including wisdom

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Structure of teethStructure of teeth11/04/23

Function of partsFunction of parts• Enamel: hard white outer layer

protects, dead, visible part of teeth and part of crown

• Dentine : found below enamel , living, main part of tooth

• Pulp cavity:Nerve endings connect to brain, blood vessels carry oxygen and nutrients to cells and waste away

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Function of partsFunction of parts

• Jaw bone: is the based to which teeth are attached.

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•Cement: grips teeth , holds tooth in place

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The digestive systemThe digestive systemThe whole point of digestion is to break down our food so that we can get the bits we need from it…

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Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Mouth

• Teeth bite off and chew food into a soft pulp that is easy to swallow.

• Chewing mixes the food with saliva, from salivary glands around the mouth and face, to make it moist and easy to swallow.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Mouth

• Enzymes in the saliva begin digestion of carbohydrates.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Esophagus

• The esophagus is a muscular tube. It takes food from the throat and pushes it down through the neck, and into the stomach.

• It moves food by waves of muscle contraction called peristalsis.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Stomach

• The stomach has thick muscles in its wall. These contract to mash the food into a water soup called chyme.

• The stomach lining produces strong digestive juices.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Stomach

• These create chemical reactions in the stomach, breaking down and dissolving its nutrients.

Identify and tell the Identify and tell the function of each part of the function of each part of the

digestive systemdigestive systemSmall Intestine• This part of the digestive tract is

narrow, but very long - about 20 feet.

• Enzymes continue the chemical reactions on the food.

Identify and tell the Identify and tell the function of each part of the function of each part of the

digestive systemdigestive systemSmall Intestine • The nutrients are broken down small

enough to pass through the lining of the small intestine, and into the blood (diffusion).

• Nutrients are carried away to the liver and other body parts to be processed, stored and distributed.

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The small intestineThe small intestineThis is where the “small parts” are absorbed into our blood stream…

Glucose gets absorbed into

the blood

Everything else passes

into the large intestine

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Large Intestine

• Useful substances that were not absorbed in the small intestine, such as spare water and body minerals, are absorbed through the walls of the large intestine, back into the blood.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Large Intestine

• The remains are formed into brown, semi-solid feces, ready to be removed from the body

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Rectum and Anus

• The end of the large intestine and the next part of the tract, the rectum, store the feces.

• Feces are finally squeezed through a ring of muscle, the anus, and out of the body.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Pancreas

• The pancreas, like the stomach, makes digestive juices called enzymes which help to digest food further as it enters the small intestines.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Gall Bladder

• A small baglike part under the liver.

• It stores a fluid called bile, which is made in the liver.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Gall Bladder

• As food from a meal enters the small intestine, bile flows from the gall bladder along the bile duct into the intestine.

• It helps to digest fatty foods and also contains wastes for removal.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Liver

• Blood from the intestines enters to the liver, carrying nutrients, vitamins and minerals, and other products from digestion.

Identify and tell the function Identify and tell the function of each part of the digestive of each part of the digestive

systemsystem

Liver

• The liver is like a food-processing factory with more than 200 different jobs. It stores some nutrients, changes them from one form to another, and releases them into the blood according to the activities and needs of the body.

LiverLiver

• Not part of alimentary canal but plays a role in digestion.

• Connected to ileum by hepatic portal vein

• Decides whether to store or send nutrients to body cells

• Majority of fatty acids transported by Lacteals (lymphatic system which eventually connects back to blood vessels)

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11/04/23• Found under diaphragm overlapping stomach.

• Made up of lobes• Rich blood supply from Hepatic

portal :vein and artery• Recieves mainly a.a. and glucose• Excess glucose converted into

glycogen here and reconverted and released when need by blood

• Excess a.a toxic, Altered to urea via process of Deamination

• Urea (nitrogenous waste) is removed from liver sent to kidneys to be removed as urine

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To quiz yourself over To quiz yourself over the parts of the the parts of the

digestive system, go digestive system, go to websiteto websitehttp://www.tvdsb.on.ca/west

min/science/sbi3a1/digest/digdiag.htm

Chemical digestionChemical digestion

• Chemical digestion also starts in the mouth and continues in the stomach and small intestines

• Chemical digestion occurs with the aid of enzymes, biological catalysts.

Food Simpler substance

Carbohydrates, starch ( polysaccharides)

Glucose, maltose, lactose

Prtoeins Amino acids

Lipids ( fats) Fatty Acids and glycerol

ENZYMESENZYMES• Are proteins• Specific to particular substrate;

Induced fit, lock and key mechanism• Required in small amounts, can be

reused• Work best at an optimum temp;

fastest rate of rxn• Work best at particular pH : optimum

pH

ENZYMESENZYMES

• Are inhibited or prevented from working by poisons like arsenic , cyanide

• Rxn occur quickly, each 10 degree temp rise, doubles rate of rxn

• Denatured at high temperatures, therefore enzyme structure is compromised no rxn occurs.

• Most enzymes work best around a neutral pH but pepsin @ 2.5, trypsin @8.0

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EnzymesEnzymesEnzymes are chemicals produced by the body to help _______. When they react with food they break it down into ______ pieces which can then pass into the ______:Carbohydrase breaks _______ (a carbohydrate) down into glucose:

Protease breaks _______ down into amino acids:

Lipase breaks fats (_____) down into fatty acids and glycerol:

Words – blood, lipids, proteins, digestion, starch, smaller

Part of digestive system

Food substance acted on

Enzyme used and pH of

environment

products

Mouthvia saliva

Carbohydrates Amylase( ) pH

Glucose

Stomachacidic environs provided by HCl secreted from vesicles in stomach lining : acidic pH

Proteins: Pepsin(acidic environ) pH2-3

Rennin

Amino acidsLiquid milk to solid

Small intestines; doesn’t produce enzymes they are all obtained from pancreatic juice

Carbs, rest of proteins, fats

Amylase sucrase, maltase, lactase, trypsin (pH8.5-9.0), lipase, peptidase

Glucose, amino acids, Fatty acids and glycerol.

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DIGESTIVE SYSTEM ANIMATION: http://www.kitses.com/animation/swfs/digestion.swf

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The small intestineThe small intestineThis is where the “small parts” are absorbed into our blood stream…

Glucose gets absorbed into

the blood

Everything else passes

into the large intestine