form2 nutrition

7/29/2019 Form2 Nutrition

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Living processes and our body function To do work

Good health and fight diseases

Growth and repair damaged cell


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Classesof food

FibresCarbohydrate

Protein

fatsVitamins

water

minerals


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Made up of the elements carbon, hydrogenand oxygen Carbohydrates include starch, cellulose,

sugars and glycogen

Function:

- Sources of energy for physical activities


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Consist of long chains ofamino acids whichcontain the elements carbon, hydrogen, oxygenand nitrogen (some proteins contain sulphur and

phosporus)

Rich in fish, meat, milk, egg, beans, nuts and so on

Function:

- Growth and repair of body tissues

- Gives energy during extreme starvation

- Formation of enzymes, hormones and antibodies Lack of protein can cause kwashiorkor


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Made up ofcarbon, hydrogen and oxygen Fat consists ofsmaller units of fatty acids

combined with glycerol

Excess fats in our body can cause heart disease

Functions:- Sources energy (twice as much as the same

amount of carbohydrates)

- Acts as an insulator and keep our body warm

- As a medium for transporting vitamins A,D,E and K


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Made up ofcellulose from plant cell walls andcannot be broken down by our digestivesystem

Function:

- provides bulk to the intestinal contens

- Stimulates peristalsis that help the foodmove along the digestive system

Lack of fibre can cause constipation


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A person can live without food for severalweeks but cannot survive without water formore than three days

We lose a lot of water in our urine, sweat andexhaled water. This lost must be replaced

A person needs an average of 6 to 8 glassesof water a day


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Importance of water:- About 70% of our body made up of water- Water transports digested food and waste

materials

- Acts as an solvent for many chemicals and

needed for chemical reaction in the body- Needed in the production of mucus that helps

keep cells, tissues and organs moist

- Regulate our body temperature


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Discuss the functions of minerals andvitamins


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A balanced diet

Consist of carbohydrates, proteins,fats, vitamins, minerals, fibre andwater taken in the right amounts tomeet the daily requirements of thebody


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Factors thatdeterminethe balanceddiet

Age

Sex

Body size

Physical activity andoccupation

State of health

Climate


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The calorific valueof food is defined as theamount of energy released from one gramfrom of a particular type of food

The calorific value of food is measured incalories (cal) orjoules (J)


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1 calorie = 4.2 joules1000 calories (cal) = 1 kilocalorie(kcal)1000 joules ( J) = 1 kilojoule (kJ)

Class of food Energy value

Carbohydrates 17

Proteins 18fats 39


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Food Calorific value per100g(kJ)Tose 154

Nasi lemak 492

Orange juice 202

Meat dumpling 235

Milk 276

Guava 290


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Meal A Meal B100 g tose 180 g meat dumpling

150 g nasi lemak 100 g milk

200 g orange juice 120 g guava


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To ensure that the diet is balanced, we haveto choose a food type from each groupshown in the food

On a balanced diet, the body has sufficientenergy to function physical, grow andmaintain good health


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The food pyramid


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The food that we eat are mainly large and

indiffusible molecules such as starch, protein, andfat

These large and indiffusible molecules must bebroken down by our body into smaller and

diffusible food substances The process of breaking down food into soluble

and diffusible molecules is called digestion


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Physical digestion Chemical digestion Physical digestion involves the mechanical process of

breaking down large pieces of food into smaller particles

using the teeth and churning movements of the alimentarycanal

Chemical digestion involves the action of various enzymes inbreaking down complex food molecules


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Mouth Oesophagus Stomach Duodenum

Smallintestine

LargeintestineRectumAnus


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Digestive System


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Enzymes speed up the digestion of food

Each enzymes can only act on certain foodsubstance known as subtrate

Enzymes require mediums with a specific pH tofunction properly

There are three main types of digestive enzyme

- Amylase

- Proteases

- Lipases


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The food is chewed into smaller pieces by teeth

The chemical digestion takes place when salivaryamylase in saliva speeds up the breakdown ofstarch into maltose

Saliva also have mucus to soften the food particlesto form a lump called bolus

The bolus is swallowed into the oesophagus


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The muscular wall of the oesophagus contracts and relaxes to

produce a wavelike movement called peristalsis

Peristalsis pushes the bolus from the oesophagus into thestomach and causes them to break into smaller particles


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The stomach wall secretes gastric juices which contains

hydrochloric acid, proteases and water The function of hydrochloric acid:

- to kill bacteria that may be found in the food

- To provide acidic medium for the action of proteases

- To stop the action of salivary amylase

The stomach also secretes mucus to protect the stomach wallfrom being corroded by acidic gastric juice

Protease catalyse the breakdown of proteins intopolypeptides or peptones


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The small intestine is the longest part of thealimentrary canal

Made up of three parts : duodenum, jejunum andileum


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Is the first part of the small intestine

Chyme is mixed with bile and pancreatic juice The function of the bile:

- Provides an alkaline medium for the action of enzymes in thesmall intestine

- Emulsifies fats into smaller oil droplets so that the surface

area of fats for the action of enzymes is bigger Funtions of enzymes in the pancreatic juice

- Pancreatic amylase breaks down starch into maltose

- Lipase breaks down fats into fatty acids and glycerol

- Protease breaks down proteins into polypeptides


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http://www.google.com.my/imgres?imgurl=http://video.ecb.org/badger/download/vlc/images/VLC181_Small_intestine.jpg&imgrefurl=http://explore.ecb.org/videos/VLC_media?P1=VLC181&REFERER=OTHER&usg=__C3KI76k5oEykxYKupFXyhkeOwzg=&h=480&w=640&sz=65&hl=en&start=17&zoom=1&tbnid=f4M8nNfLpIYxUM:&tbnh=103&tbnw=137&ei=jilMT46UA4PKrAfyuKmEDw&prev=/search?q=small+intestine&hl=en&sa=X&gbv=2&tbm=isch&prmd=ivns&itbs=1


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Jejunum and ileum are lower parts of the small intestine

An alkaline intestinal juice is secreted by the ileum Functions of enzymes in the intestinal juice:

- Protease breaks down polypeptides into amino acids

- Lipase breaks down fats into fatty acids and glycerol

- Maltase breaks down sucrose into fructose and glucose

- Lactase breaks down lactose into galactose and glucose

- Cellulose is not digested in our body because we do notproduce enzyme cellulose


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Complete the following table in yournotebook

Part of alimentarycanal secretion Characteristic ofsecretion Enzyme Digestive action


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Mouth Saliva StarchMaltose

Stomach Gastric juice

small intestine(Duodenum)

Pancreatic juice Alkaline

Protein

Polypeptide

Bile Alkaline

Small intestine(Jejunum and

ileum)

Intestinal juice Protease


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After digestion, food consists of smaller moleculesthat are soluble and easily absorbed

These digested foods- glucose, amino acids,glycerol


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What is the meaningof absorption?????


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intestinal absorption isthe uptake from theintestinal lumen of fluids,solutes, proteins, fats,and other nutrients intothe intestinal epithelialcells, blood, lymph, orinterstitial fluids.


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Absorbtion of end product of digestion takes placein the small intestineThe walls of the small intestine are particularlyadapted to the process of absorption

The absorbed nutrient will be transported to theliver. Then from the liver to the heart to be pumpedto all parts of the body


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The intestinalwall has thefollowingfeatures

Has many foldsthat are coveredwith millions offinger-likeprojection calledvilli

Has many bloodcapillaries forabsorption

Intestinal musclecan contract andrelax toenhances theabsorption

Small intestine isvery long (6metre) for greaterabsorption

The intestinalwall is verythin

Contain moistlining


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The undigested food is sent to the largeintestine and kept there temporarily

As the residue passes through the largeintestine , a lot of water, together with

dissolved minerals and vitamins are absorbedinto the blood

The residue then will become faeces andstored in the rectum and will be removed

from body through anus (defecation)

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