Animal Nitrition IGCSE Notes

8/15/2019 Animal Nitrition IGCSE Notes

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Animal nutrition:

Definition of Balanced Diet:

A diet that contains carbohydrates, proteins, fats, vitamins, minerals, water and

fibre in the correct amount and proportions to maintain good health is called a

balanced diet.

Definition of Assimilation:

The movement of digested food molecules in to the cells of the body where they

are used, becoming part of the cells

Malnutrition is the result of not eating a balanced diet. There may be:

• wrong amount of food: too little or too much

• incorrect proportion of main nutrients

• lacking in one or more key nutrients

Effects of malnutrition

Fat and heart Disease:

• Fat found in animal is called saturated fat

• More likely to get heart disease

• Can get deposited inside the coronary arteries

•Cholesterol can stick to the walls of arteries, gradually blocking them, and

can get stiffer and narrower.

• This cause less supply of oygen and blood to the heart leading to improper

working of heart.


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• This is called coronary heart disease.

• !egetable oils are unsaturated oils which are good and do not increase the

risk of heart disease.

Obesity:

• "eing very fat is called obesity, #bese people are more likely to get

coronary heart disease, strokes and diabetes.

Staration

!oo little food can result in starvation.

$treme slimming, diet which does not contain carbohydrate diet results in the

disease called anore"ia nerosa.

#hildhood protein$energy malnutrition %&'ashiorkor(

%rong proportion of nutrients e.g. too much carbohydrates &starchy foods'

and a lack of protein can lead to (washiorkor in young children.

• Common between the age of nine months and two years

#haracteristics:

• )nderweight, look fat due to carbohydrate diet,

• *f they are put on high protein diet, they usually begin to grow normally


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Marasmus:

+evere shortage of energy in the diet causes marasmus.

#haracteristic is the child has very less body weight when compared to thenormal body weight and looks very thin and weak

)itamin* Minerals* Fibre and +ater

,utrient Function Deficiency Food sources)itamin # To maintain healthy

skin and gums, to

make stretchy protein

collagen in the skin,keeps tissues in good

repair

+curvy, causes pain in

the oints and

muscles, bleeding of

gums and other places

Citrus fruits such as

orange, lime, Mango,

tomato, raw

vegetables

)itamin D -elps calcium to be

absorbed, for making

bones and teeth

ickets in which

bones become soft

and deformed

"utter, egg yolk, milk

cheese, can be made

by the skin when

sunlight falls on it.-ron* Fe For making

haemoglobin, in red

pigment in bloodwhich carries oygen

Anemia, in which

there are not enough

red blood cells so thetissues do not get

enough oygen

delivered to them

ed meat, liver, egg

yolk, dark green

vegetables

Fibre Maintain peristalsis Constipation, long

term deficiency leads

to bowel cancer

!egetable, fruit,

whole meal bread

#alcium For bones and teeth/

for blood clotting

"rittle bones and

teeth/ poor blood

clotting

Milk and other dairy

products, bread

+ater Formation of blood

cytoplasm

+olvent for transport

of nutrients and

removal of wastes

&)rine'

0ehydration 0rinks, fruits,

vegetables


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$n1ymes only works

in solution

Digestion:

2arge insoluble molecules of food are broken down in to small molecules

!here are t'o types of digestion

Mechanical digestion: The breakdown of food into smaller pieces without

chemical change of the food molecule

#hemical digestion: The breakdown of large insoluble molecules into small

soluble molecules

3. -ngestion: Taking in pieces of food into the mouth

4. Digestion: The breakdown of large, insoluble food molecules into smaller

more soluble ones by chemical and mechanical means.

5. Absorption: Taking the digested food molecules into the cells

6. Assimilation: Making use of the digested food molecules for eample to

release energy or grow etc.

7. Egestion: The elimination of undigested food materials through the anus

!eeth:

• Teeth help in ingestion and mechanical digestion of food we eat.


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• The food is crushed in to small pieces of food thus giving the food large

surface area, which helps the en1ymes to work on the food in the digestive

system.

Structure of !ooth:

The part of the tooth which is embedded in the gum is called the root.

The part which can be seen is called the cro'n

The crown is coered 'ith enamel

$namel is the hardest substance made by animals.

*t is very difficult to break or chip it off

"ut it can be dissolved by acids

"acteria feed on sweet food left on the teeth

This makes acids, which dissolves the enamel and decay sets in.

)nder the enamel there is a layer of dentine, which is like bone.

0entine is hard but not hard as enamel

*n the middle of the tooth is the pulp caity, which contains nerves and

blood vessels, which supply the cytoplasm in the dent with food and oygen

The root of the tooth is covered with cement


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This has fibres growing out of it.

These attach the teeth to the awbone, but allow it to move slightly when

biting or chewing

• Mammals also differ from other animals in having two sets of teeth

• The first set is called the milk teeth or the deciduous teeth

• These starts to grow when the child is five months old

• "y the age of 46 to 58 months the child will have a set of 48 teeth.


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• The first set falls when the child is 9 year old, twenty teeth replace. The one

which fall out and the 34 set of new teeth make up the complete set of

permanent teeth.

• All together there are 54 teeth/ most people will have all their permanent

teeth by about 39 years of age

Dental decay:

• Tooth decay and common dental problems are caused by bacteria

!o get rid of tooth decay:

• 0o not eat too much sugar

• 0rinking water which contain fluoride and brushing teeth with a fluoride

toothpaste makes your teeth more resistant to decay

• egular brushing also helps to remove plaue, which will prevent gum

disease and reduce decay

• Make regular visit to dentist

Alimentary canal:

The alimentary canal is a long tube which stars at the mouth, runs through the

stomach and intestines and finishes at the anus. *t is part of the digestive system.

Functions of the regions of the digestive system:

Organ Function

Mouth • 0igestion starts from the mouth

• The teeth cuts and grinds the food


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• This is mied with saliva

• This contains amylase to break starch down into

maltose &+ugar'

• Forms it in to a bolus

%hen the bolus is swallowed a piece of cartilage covers

the entrance of the trachea which is call epiglottis

• There is a sphincter muscle at the entrance of the

stomach

• The muscle relaes to let the food pass in to the

stomach

Oesophagus • "oluses of food pass through the oesophagus through

peristalsis from mouth to stomachStomach • Muscular walls suee1e on food by contracting and

relaing to make it in to semi;liuid called chyme

•


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• 0igested foods are assimilated here. For eample,

glucose is stored as glycogen, etra amino acids are

deaminated.

Small intestine • 0uodenum and *leum

Duodenum • The first part of the small intestine.

• *t receives pancreatic uice containing protease, lipase

and amylase.

• s the inner lining of all parts of the small intestine

• The small intestine is covered with millions of tiny

proections which are called as villi.

• Cells covering the villi makes en1ymes

• The en1yme does not come out of the lumen of the

small intestine

• These complete the digestion of food

• The carbohydrase en1yme maltase breaks down

maltose to glucose•


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0arge -ntestine • #aecum* appendi"* #olon and 1ectum, only

undigested food reached here. %ater is absorbed in this

part

• Caecum and appendi have no function

1ectum • This stores Faeces until it is egested.

Anus • This has muscles to control when faeces is egested

from the body,

1emoal of the faeces from the body through the

anus is called Egestion

En2ymes and gastric 3uice:

,utrients En2ymes or gastric 3uice Small molecules

produced

+tarch Amylase Maltose


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breast feeding babies

Fat 2ipase Fatty acid and glycerol

Fat "ile "reaks down in to small

fat droplets

Acidic food from the

stomach


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!illi contain blood capillaries Monosaccharides, amino acids, water,

minerals and vitamins, and some fats, pass

into the blood, to be taken to the liver and

then round the body

!illi contain lacteals, which are parts of the

lymphatic system.

Fats are absorbed into lacteals

!illi have walls only one cell thick The digested nutrients can easily cross the

wall to reach the blood capillaries andlacteals

Diarrhoea:$

0iarrhoea is the loss of watery faeces

*t happens when enough water is not absorbed from the faeces

+ome time the condition goes on for long time and it>s dangerous

+ince the person can lose dangerous amount of water and salt from their body, this

causes some of their tissues and organs to stop working.

The best treatment is oral rehydration therapy, which contain water with small

amount of salt and sugar dissolved in it

The main cause of diarrhoea is infection by a bacterium, which causes cholera

This bacterium is spread through water, which has been contaminated with faeces

from an infected person


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Cholera bacterium lives in breads in the small intestine

The bacteria produce a toin that stimulates the cell lining the intestine to chloride

ion

%hich accumulates in the lumen of small intestine, this increases the concentration

of the fluid in the lumen lowering water potential.

#nce this water potential becomes lower than the water potential of the blood

which is flowing through the vessels in the walls of the intestine

%ater moves out of the blood and into the lumen of the intestine by osmosis

2arge amount of water is lost from the body/ this fluid lost must be replaced


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Assimilation:$

After the food is absorbed in the blood

The nutrients are taken to the liver by hepatic portal vein

The liver process those, some of the nutrients are broken down


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+ome substances are converted and stored the nutrients are the dissolves in blood

plasma

Taken to different parts of the body, where they may become assimilated as part of

a cell

The liver has important role to play in the metabolism of glucose

*f there is more glucose than necessary in the blood

Then liver converts some of it to the polysaccharide glycogen and store it

Animal Nitrition IGCSE Notes

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