New INTERNATIONAL TURKISH HOPE SCHOOL-CHITTAGONG … · 2018. 9. 6. · INTERNATIONAL TURKISH HOPE...

INTERNATIONAL TURKISH HOPE SCHOOL-CHITTAGONG BRANCH2017-2018 BIOLOGY HANDOUTTOPIC: ANIMAL NUTRITION

Teacher in Charge: ARIF ULLAH 1

EDEXCEL SYLLABUS (Section 2 - E)2.24 understand that a balanced diet should include appropriate proportions ofcarbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre2.25 identify the sources and describe the functions of carbohydrate, protein, lipid(fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water anddietary fibre as components of the diet2.26 understand how energy requirements vary with activity levels, age andpregnancy2.27 describe the structure and function of the human alimentary canal, includingthe mouth, oesophagus, stomach, small intestine (duodenum and ileum), largeintestine (colon and rectum) and pancreas2.28 understand how food is moved through the gut by peristalsis2.29 understand the role of digestive enzymes, including the digestion of starch toglucose by amylase and maltase, the digestion of proteins to amino acids byproteases and the digestion of lipids to fatty acids and glycerol by lipases2.30 understand that bile is produced by the liver and stored in the gall bladder2.31 understand the role of bile in neutralising stomach acid and emulsifying lipids2.32 understand how the small intestine is adapted for absorption, including thestructure of a villus2.33B practical: investigate the energy content in a food sample

(HUMAN BIOLOGY HAS TEETH AND FOOD PRESERVATION)

CAMBRIDGE SYLLABUS (5)(a) list the chemical elements that make up:

• carbohydrates;• fats;• proteins;

(b) describe tests for:• starch (Iodine in Potassium Iodide solution);• reducing sugars (Benedict’s solution);• protein (Biuret test);• fats (Ethanol emulsion test);

(c) list the principal sources of, and describe the dietary importance ofcarbohydrates, fats, proteins, vitamins (C and D only), mineral salts (calcium andiron only), fibre (roughage) and water;(d) name the diseases and describe the symptoms resulting from deficiencies ofvitamin C (scurvy), vitamin D (rickets), mineral salts calcium (rickets) and iron(anaemia);(e) understand the concept of a balanced diet;(f) explain why diet, especially energy intake, should be related to age, sex andactivity of an individual;(g) state the effects of malnutrition in relation to starvation, heart disease,constipation and obesity;

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(h) discuss the problems that contribute to famine (unequal distribution of food,drought and flooding, increasing population);(i) identify the main regions of the alimentary canal and the associated organs:mouth (buccal) cavity, salivary glands, oesophagus, stomach, duodenum,pancreas, gall bladder, liver, ileum, colon, rectum and anus;(j) describe the main functions of these parts in relation to ingestion, digestion,absorption, assimilation and egestion of food, as appropriate;(k) identify the different types of human teeth and describe their structure andfunctions;(l) state the causes of dental decay and describe the proper care of teeth;(m) describe peristalsis;(n) explain why most foods must be digested;(o) describe:

• digestion in the alimentary canal;• the functions of a typical amylase, protease and lipase, listing the substrates

and end-products;(p) describe the structure of a villus, including the roles of capillaries and lacteals;(q) describe the significance of villi in increasing the internal surface area;

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Living organisms require food to provide them energy for the vital activities of thebody, to maintain themselves and for movement and growth. Green plants canmake use of the energy from the sun through the process of photosynthesis butother organisms need food to supply their energy needs. Thus the food thatorganisms feed on contains a store of energy. This stored energy is calledpotential chemical energy.

This potential energy present in the food is converted into kinetic energy in ourcells which helps us to move our skeletons and contract our muscles. Howeversome of the energy is also lost as heat energy.

NUTRIENTS IN FOODNutrients are chemical substances found in the body which nourish the body. Thenutrients may be classified into two major groups.

Organic nutrients:They are the nutrients which are obtained from living organisms. They arecompounds of carbon. Examples include: carbohydrates, fats, proteins, vitaminsand dietary fibre.

Inorganic nutrients:Inorganic nutrients include water and all the mineral salts.

a) CARBOHYDRATES

Carbohydrates are organic compounds made up of the elements carbon, hydrogenand oxygen. The hydrogen and oxygen atoms are present in the same ratio as inwater, i.e. 2 : 1.

The generalized formula for carbohydrates is CnH2mOm.

In case of sucrose (C12H22O11), n= 12, and m is equal to eleven.Therefore hydrogen, which is equal to 2m equals 2(11)= 22.Carbohydrates include sugars, starch, the cellulose of plant cell walls and anumber of related substances.

FUNCTIONS OF CARBOHYDRATES:Carbohydrates are needed

As a source of energy.To form supporting structures, e.g. cell walls in plants.To be converted to other organic compounds such as amino acids and fats.For the formation of nucleic acids, e.g. DNA.To synthesise lubbricants, e.g. mucus which consists of a carbohydrate anda protein.To produce the nectar in some flowers.

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TYPES OF SUGAR

Sugars are sweet crytalline compounds whch dissolve readily in water. Two typesof sugars can be distinguished.

i) Simple sugars or monosaccharides:There are numerous simple sugars. The most common ones are the sugars withsix carbon atoms. The examples of simple sugars include glucose, fructose andgalactose. These sugars only differ in structural details and have the samechemical formula. The structural difference give them their different chemical andbiological properties.

Glucose is found in nearly all animals. Fructose is found in plants but uncommon inanimals. Whereas galactose, a component of milk sugar or lactose, is mainly foundin mammals and rare in other organisms.

ii) Complex sugars or disaccharides:These are the carbohydrates in which two molecules of simple sugars condensetogether. They have a more complex structure than monosaccharides. Examplesinclude sucrose, lactose and maltose- disaccharides have a general formula ofC12H22O11.

Sucrose occurs in sugarcane stems, sweet fruits and certain storage roots. Itconsists of a glucose and fructose molecule combined together. It is not found inmammals.

Lactose is found in milk of all mammals. It is formed from glucose and galactosecombined together.

Maltose is found in malted cereals and sprouting grains. It is formed from partialdigestion of starch and is a combination of two glucose molecules.

It is to be noticed here that the formation of one molecule of a complexsugar requires two molecules of simple sugar molecules. It results in a loss of awater molecule and such a reaction is known as a condensation reaction.

Therefore, condensation is a chemical reaction whereby two simple molecules arejoined together to form a larger molecule with the removal of one molecule ofwater.

Whereas its reverse is hydrolysis reaction in which a water molecule is added on tosplit up a complex molecule into its component units is known as hydrolysis or ahydrolytic reaction.

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iii)Polysaccharides:A polysaccharide is made up of many monosaccharide molecules joined together.The process of condensing many similar molecules to form a large molecule iscalled polymerization. Starch, cellulose and glycogen are polysaccharidesformed from the condensation of the glucose molecules.

Starch is one of the most important sources of carbohydrates in food.Starch is not formed or stored by animals.Glycogen is another polysaccharide which is also known as animal starch.It is a storage form of carbohydrate in animals and also in fungi. In mammals, it isstored mainly in the liver and muscles. It is formed when numerous glucosemolecules condense to form highly branched chains of glucose molecules.

Glycogen and starch are useful as storage materials because:

they are insoluble in water, so they do not change the osmotic pressure in cells.they are large molecules and therefore unable to diffuse through the cellmembranes.they can easily be hydrolysed to glucose when needed.their molecules have compact shapes so they occupy less space than thatoccupied by all their constituent glucose molecules.

Cellulose is the carbohydrate which forms the greatest part of the cell walls ofanimals. It is inert and very few organisms can digest it. Man cannot digest it, butit forms the bulk of undigested matter. This fibre is important to the properfunctioning of the large intestine.

b)FATS or LIPIDS: (CHO)

Fats are organic compounds made up of the elements carbon, hydrogen andoxygen; but, unlike carbohydrate, they contain much less oxygen in proportion tohydrogen.

Fats can be further split into simpler compounds by the process of hydrolysis. Forexample, when tristearin (beef fat) is hydrolysed by lipase, it breaks into glyceroland stearic acid.

There is no difference between oils and fats except their state. Fats are solid andoils are liquids at room temperature. A fat is said to be saturated when the fattyacids cannot take any more hydogen whereas in an unsaturated fat, the fatty acidcan take one or more pairs of hydrogen atoms. Saturated fatty acid chains arestraight whereas unsaturated fatty acid chains bend at the places where hydrogencan be taken in.

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FUNCTIONS OF FATS:FATS SERVE:

As an efficient source and storage of energy.As an insulating material (abundant beneath the layers of skin) to preventexcessive heat loss.As a solvent for fat-soluble vitamins and many other vital substances, includingsex and related hormones.As a means to restrict water loss from the surface of the skin. The oily layerformed on the surface of the skin by the sebaceous skins constitutes of fats.

Food that are rich in fat include: butter, cheese, fatty meat, olives, nuts, oils andmany leguminous plants. Normally, humans and other mammals can manufacturetheir own fat requirements, thus fats are not essential in their diet. Use of fatsshould be less as possible and we should try to refrain from saturated fats (fatsfound in bodies of animals) and use unsaturated fats (vegetable fats) as much aspossible as they are less risky to cause heart related diseases.

c)PROTEINS (CHONS)

Proteins are very complex organic substances containing carbon, hydrogen,oxygen and nitrogen. Sulphur and phosphorus are also often present.

Proteins are always present in protoplasm. Their molecules are the largest andmost complex of all the food substances. Every protein molecule is built up fromsimpler compounds known as amino acids— the basic units of proteins.

There are 22 naturally occurring amino acids in plant and animal proteins. Theseamino acids link up with another to form long chains. When two amino acids linkup, there is a removal of one molecule of water which means that proteins areformed by condensation reactions. The bond formed between any two aminoacids is very strong and is known as a peptide bond. If 3 or more amino acidsare linked up with peptide bonds, a polypeptide bond is formed. An average aminoacid chain contains about 500 units.

One or more of such chains together form protein molecules. The amino acidchains in a protein molecule are not straight. They are often coiled to give proteinsa special 3D shape. The coils are held in place by weak cross_links (hydrogenbonds) which are easily broken by heat, acids and alkalis. The breaking of thesecross-links causes the denaturation of protein. Now it is easily understood thatwhy enzymes, which are made of proteins have a special active site (3D structure)and why they are denatured over high temperatures (weak hydrogen bonds).

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PROTEIN DEFICIENCY:The deficiency of proteins in the diet of the children may lead to a disease knownas kwashiorkor. Such children have swollen abdomens and their skins crack andbecome scaly. Doctor suggests around 50-100 grams of daily intake of protein foran average adult.

FUNCTIONS OF PROTEINS: Proteins are:

Essential for synthesis of protoplasm.For growth and repair of worn out body cells.Used for synthesis of enzymes and hormones.Used for formation of antibodies to combat diseases.A source of energy.

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d) WATER (H2O)

Water is extremely important to survive because it is a major constituent ofprotoplasm. A person can stay longer without food than without water.

FUNCTIONS OF WATER:Water serves as:

A medium in which various chemical reactions occur.A transporting agent for:Digested food substances, Excretory products andHormonesAn essential component of:Lubricant found in joints, The digestive juices.and Blood

Moreover, it has the following functions:Needed for hydrolytic reactions (digestion).It also helps to regulate the body temperature.

e) Roughage/Dietary Fiber/Green Vegetables:It helps in the movement of food during peristalsis.It adds bulk to the food.

f) VITAMINS

Vitamins are a group of chemically unrelated organic compounds required in thediet in very minute amounts. Most of the vitamins are obtained from the plantsbut some of them are also obtained from the tissues of other animals or areproduced by microorganisms living in the gut.

Vitamins are not built in a definite pattern like carbohydrates, proteins and fats.They neither provide energy nor are they body-building food. However they arestill required for normal health and development.

Vitamins can be either fat soluble or water soluble. Fat-soluble vitamins aresoluble in fats and can be stored in the body fats, whereas water-soluble vitaminscannot be stored in the body and have to be therefore supplied in the daily diet.

Vitamin deficiency or excessive usage can both lead to serious diseases andtherefore great consideration should be used to consume appropriate proportionsof vitamins in the daily dietAr

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SOME IMPORTANT VITAMINS

VITAMIN D (FAT-SOLUBLE):Vitamin D is found in fish-liver oils, egg yolk and margarine. However, ultravioletrays in sunlight can convert a natural substance (ergosterol) in the skin to vitaminD. it is relatively resistant to heat and oxidation. Vitamin D promotes absorption ofcalcium and phosphorus from the intestines. It also enables the body to use thesecompounds in the formation of teeth and bones. Deficiency can lead to a diseaseknown as Rickets in growing children. Diseased children have poor teeth andbone formation. The soft bones bend under body weight. In adults bones soften,which is also known as osteomalacia. Excess consumption may result indemineralization of bones and calcification in many soft tissues.

VITAMIN C (WATER-SOLUBLE):It is found abundantly in fresh citrus fruits (oranges, lemons) along with otherfruits (papaya, bananas). It is also found in fresh green vegetables. It is easilydestroyed by heat (cooking and canning). It is needed for the formation ofintercellular substances. Such substances are found in between the cells and theyhold the cells together. They are also necessary for maintaining healthy epithelialtissues. Lack of it leads to scurvy- a disease characterized by swollen, bleedinggums and loosening of the teeth, internal bleeding and painful swollen joints.Excess is excreted by the body.

VITAMIN A:This is needed for the formation of a light sensitive pigment in the retina and formaintaining healthy epithelial tissues. Rich sources include dairy products andgreen leafy vegetables. Night Blindness is caused due to its lacking.

VITAMIN B COMPLEX:Several of it are important coenzymes in cellular respiration. Beri-beri, pellagraand anaemia are diseases caused by a lack of certain B vitamins. Yeast, liver andbrain are rich sources.

g) MINERALS:

Mineral elements are in organic salts which do not provide energy but arenecessary for body functions.

We obtain minerals from other animals or plants. Some minerals are required inlarge amounts whereas others are required I minute amounts. The minerals whichare required in large amounts include calcium, phosphorus, sodium, chlorine,potassium and iron.

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SUMMARY of Important VITAMINS

SUMMARY of Important MINERALS

Nutrition is the process of providing or obtaining the food necessary for healthand growth.Primary: Secondary:1.Carbohydrates. 1. Minerals.2. Fats. 2. Vitamins.3. Proteins. 3. Roughage/Dietary fiber.4. Water.

Primary food substancesare needed for living.Secondary FoodSubstances are needed tostay healthy.

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A Balanced Diet contains all the necessary nutrients like carbohydrates, proteins,fats, minerals, vitamins, water and roughage needed for healthy growth, in theright proportion.

Dietary energy requirement is related to:Activity: the more active a person is the greater the amount of energy needed.Age: teenagers and young adults need more energy per kilogram body mass thanyoung children and old people.Sex: for the same body size and age, men use more energy than women.

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The Human Digestive System:

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The Alimentary Canal/ Gut.The alimentary canal is a long muscular tube through which food is moved alongin our body. It starts with the mouth and ends with the anus.Main regions of the alimentary canal and associated organs, and their functions:

Mouth: Entrance of the buccal cavity. Food enters the buccal cavity and isswallowed or ingested.

Teeth: Chewing, i.e. cutting up food into small pieces.Tongue: Mixes food with saliva, shapes food into a bolus and helps inswallowing it.Salivary gland: Produces saliva which consists of water, mucus and anenzyme (salivary amylase) to start digestion of cooked starch.

Oesophagus: Narrow muscular tube stretching from mouth to stomach. Cellslining its walls secrete mucus.

Muscles in oesophagal wall: Send food from mouth to stomach byperistalsis-the wave-like rhythmic contractions of the alimentary canalwhich pushes food along it.

Stomach: Bag-like, muscular structure with sphincters at its entrance and exit toopen and close it.

Gastric glands in the stomach walls: Produces gastric juice made up ofwater, mucus, hydrochloric acid and enzymes. The enzymes bring aboutchemical digestion of proteins.Muscles in stomach walls: Cause churning action, breaking down foodmechanically into small pieces and mixing it with gastric juice for betterchemical digestion. The muscles also cause peristalsis to push food intothe small intestine.

Liver: Produces bile which contains water, alkali and bile salts. Bile salts help infat digestion by breaking up fat into tiny droplets (emulsification).

Gall bladder: Stores bile temporarily before sending it to the duodenum (smallintestine).

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Pancreas: Produces pancreatic juice which is sent to the duodenum. This juicecontains water, alkali, and enzymes. The enzymes digest carbohydrates, fats andproteins.

Small intestine: Six-meter long narrow, coiled tube made up of duodenum,jejunum and ileum.

Duodenum: U-shaped tube. Receives bile and pancreatic juice to digestnutrients in the chime from the stomach.Ileum: Long coiled tube. Contains intestinal glands in its walls. Walls arefolded and have villi.Intestinal glands: Produces intestinal juice which contains water, mucus,alkali and enzymes. These enzymes complete digestion ofcarbohydrates, fats and proteins.Villi: Have adaptive features that facilitate absorption of digested foodinto blood.

Large intestine: A 1.5 meter long, wide tube that is made up of the caecum andthe blindly ending appendix, colon and rectum. It completes absorption of waterand minerals, resulting in faeces formation.

Colon: Shaped like an inverted “U”. Absorption of water and mineralsfrom the indigestible food occurs here.Rectum: A short muscular tube. Stores faeces temporarily. Faecescontain indigestible food, germs, mucus and dead cells.Anus: Opening through which faeces are expelled (Egestion).

Steps of Nutrition:1. Ingestion: Food is taken into the alimentary canal.2. Digestion: Large insoluble molecules of food are broken down to small

molecules.3. Absorption: Transport of food into the blood through the intestinal walls.4. Assimilation: Conversion of absorbed food by cells in body into new

protoplasm to bring about growth.5. Egestion: Food which could not be digested or absorbed is removed from

the body

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Mechanical digestion: This is the cutting, tearing and grinding of solidfood into small pieces by chewing and churning. Food is broken down into smallpieces thus providing a large surface area which is essential for effective chemicaldigestion.

Chemical digestion: This is the process which changes complex insolublefood into simple molecules that can diffuse across cell membranes into the blood,for transporting to different parts of our body by the action of enzymes.

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Peristalsis: The rhythmic contraction and relaxation of the longitudinal andcircular muscles in order to move food along the gut.The two layers of smooth muscles cause rhythmic, wave-like contractions of thewalls of the gut. Such movements, known as peristalsis, moves food along the gut.The two sets of muscles work in such a way that when one contracts, the otherrelaxes. When the circular muscles contracts, the longitudinal muscle relaxes.

Antagonistic pairs: push and pull, opposite effect.The muscles which act oppositely to one anotheri.e. if one contracts and the other relaxes and vice versa.E.g.Animal Nutrition:1) Circular and longitudinal muscles in the gut.Support and movement:2) Biceps and triceps in the arms.

Co-ordination:3) Circular and radial muscles in the Iris.4) Suspensory and ciliary muscles in the lens.

Transport in Animals:5) Internal and external inytercostal muscles in the rib-cage.

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Summary of Digestion in Humans:

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Structure and functions of a Villus:

Features How it works

1. It is very long, about 5m in an adult. This gives plenty of time for digestion to becompleted, and for digested food to beabsorbed as it passes through.

2. It has villi. Each Villus is covered withcells which have smaller projectionson them, called microvillus.

This gives the inner surface of the smallintestine a very large surface area; the fasterfood can be absorbed.

3. Villi contain blood capillaries. Digested food passes into the blood, to betaken to the liver and then around the body.

4. Villi contain lacteals, which are part ofthe lymphatic system.

Fats are absorbed into the lacteals.

5. Villi have walls only one cell thick. The digested food can easily cross the wall toreach the blood capillaries and lacteals.

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Functions of liver:1. Storage of food substances.2. Control of blood – Glucose level.3. Detoxification – Conversion of toxic, harmful substances before

excretion.4. Protein synthesis.5. Heat production – Due to metabolic process – Catabolic and anabolic

process.6. Storage of iron – worn out RBCs are broken down into bile slats and

Hemoglobin. Hemoglobin is stored as Fe/ Iron.7. Deanimation – Excess Amino acids are broken down into ammonia

and glucose. Ammonia is converted into urea and excreted alongwith urine and glucose is stored as glycogen or used duringrespiration.

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Difference between Excretion and Egestion:Egestion Excretion

It is the removal of undigested foodsubstances.

It is the removal of metabolic wasteproducts.

It takes place through anus. It takes place through lungs kidneysand skin.

Example: Faeces. Example: Sweat, CO2, Urine.

ORT:Oral rehydration therapy (ORT) is a simple treatment for dehydration associated

with diarrhea, particularly gastroenteritis or gastroenteropathy, such as thatcaused by cholera or rotavirus. ORT consists of a solution of salts and sugars thatis taken by mouth. It is used around the world, but is most important in thedeveloping world, where it saves millions of children a year from death due todiarrhea, the second leading cause of death (after pneumonia) in children underfive.

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Food tests:Test for starch (iodine test):Add few drops of Iodine solution (KI2) to the food sample.If the color changes to blue/black, starch is present.If the color remains brown/ yellow, starch is absent.

Test for glucose (reducing sugar) – Benedict’s test:Add equal amount of Benedict’s solution to the food sample (crush the foodsample and add water if the food sample is solid). Heat the solution in a waterbath.If red precipitate is seen, glucose is present.If the color remains blue, glucose is absent.

Test for proteins (Buiret Test):Add equal amount Buiret 1 and 2 solution to the food sample.If the color remains Blue, Protein is absent.If color changes to purple, protein is present.

Test for fats:a) Emulsion/ Ethanol Test

Add the food sample to Alcohol/ Ethanolthen add water.If color is milky, fat is present.If color changes to clear, fat is absent.

b) Grease- Spot testRub the food sample on a white paper.If a translucent/ semi-transparent spot is formed, fat is present.If clear, no fat is present.

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Calorimeter:

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Teeth:Their job is to cut, tear and grind food. To give it more surface area for faster Digestion,they do mechanical digestion.Types of mammalian teeth:• Incisors: There are 4 in front of each jaw.

They act like a blade to cut food(eg. To cut a bite of a sandwich)They have a (chisel-like surface).

• Canines: There are two in each jaw.They are very pointed, in humansThey are used for the same purpose as incisors.However in carnivores they are longer and sharper and used to kill the prey.

• Premolars: There are 4 on the sides of each jawThey are used to cut and grind food

• Molars: There are 6 at the back of each jaw, 2 of them are wisdom Teeth.They have the same use as Premolars.

Note: Remember that we have two jaws, so 4 incisors in each jaw means that wehave a total of 8 incisors in our mouth. We have 16 teeth in each jaw, 32 in thewhole mouth.

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Parts of the tooth:

Enamel: made of calcium salts, it is very strong.Dentine: it is covered by the enamel and surrounds the pulp cavity.The pulp cavity: it contains the nerves and blood vessels.The part of the tooth above the gum is called the crown, the part buried in the jawbone iscalled the root. The enamel covers the crown, the root is covered by cement. And thetooth is held in place by fibres.

Tooth Decay: when we eat, some food particles stay in our mouth. Bacteria that lives inour mouth feed on these food particles, they respire anaerobically producing lactic acid.Like any acid, lactic acid reacts with the enamel and dissolves it away reaching the dentine,here we feel the toothache.

Decay is a gradual process that follows a well-recognized pattern if it is left untreated:1. The acid erodes the tooth enamel just under the surface in a small area that is hard to

detect. A small white spot may be visible. At this stage, reversing the damage is stillpossible.

2. The damage continues through the enamel until it reaches the softer dentine. At thisstage it can be said that a true cavity has formed. It can then ‘mushroom’ out ratherquickly, destroying the dentine. A lot of the structure can rot away without one knowingas the hard enamel can stay intact. Once decay reaches the dentin, the damage done ispermanent and will only progress.

3. The decay will eventually reach the dental pulp where the nerve lies. Root canal or toothextraction will be needed.

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Methods Of preventing Tooth Decay:• Reduce sugar intake to prevent bacteria respiring• Brush teeth to remove the plaque layer of bacteria and saliva on our teeth and nuetralise

mouth• Use toothpaste or water containing fluoride because it is absorbed by the teeth and

helps stopping the attack by acid• Pay regular visits to the dentist.

Advantages• Suitable amounts prevent tooth decay

• It is a cheaper method of teeth caringDisadvantages

• Too much causes teeth molting, illness and abdominal pain• It is expensive

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New INTERNATIONAL TURKISH HOPE SCHOOL-CHITTAGONG … · 2018. 9. 6. · INTERNATIONAL TURKISH HOPE...

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Transcript of New INTERNATIONAL TURKISH HOPE SCHOOL-CHITTAGONG … · 2018. 9. 6. · INTERNATIONAL TURKISH HOPE...