CHAPTER 6 6.3 Malnutrition

8/2/2019 CHAPTER 6 6.3 Malnutrition

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CHAPTER 6: NUTRITION

6.3 Malnutrition6.4 Food digestion


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6.3 Malnutrition

Lack of one or more of the nutrients requiredin the diet to maintain good health will resultin a condition called malnutrition.

Malnutrition can caused by:

a) a reduced intake of nutrients(undernourishment)

b) an inability to use absorbed nutrients

c) the failure to meet a required increase in

nutrient intake d) nutrient losses


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There are three stages to provide

energy in cases of malnutrition. a) the carbohydrates stores in the body are

used.

b) the fat reserved are oxidised. c) proteins in the muscle are broken down.

Finally when protein levels have been

reduced to half their normal value, deathwill occur.


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Nutrient Effect of

deficiency

characteristic

Vitamin B3 Pellagra Dermatitis (skinbecomes red and

inflamed), diarrhoea and

mental disorder.

Vitamin B12 Aneamia Lack of red blood cells

or haemoglobin to

transport oxygen.

Vitamin C Scurvy Bleeding gums, bruised

skin, painful and swallen

joints, weakness.


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Nutrient Effect of deficiency characteristic

Vitamin DCalcium

a) Rickets (children)b) Osteoporosis

(aged adults)

Stunted growth ofbones and teeth,

weak bones

Brittle bones which

are easily brokenIodine a) Goitre (adults)

b) Cretinism

(children)

Enlarged thyroid

glands

Physical and mental

are easily brokenSodium Muscular cramps Sudden and painful

contraction of

muscles.


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Effects of excessive intake of specificnutrients on health.

Nutrient Effect of excessive

intake

characteristic

Carbohydrates

(sugar)

a) Obesity which may

lead to high bloodpressure, diabetes

mellitus, heart

diseases

b) Dental caries

Body weight is more

than 20% of thesuitable body weight

for particular height.

Tooth decay due to the

destruction of teethsenamel by acids which

are produced by

bacteria from

carbohydrate.


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intake

characteristic

lipids Atherosclerosis (as a result

of saturated animal fats)

The narrowing of arteries

due to saturated fats andcholesterol deposited on the

inner walls of arteries,

thereby reducing the flow of

blood and may eventuallycause blockage in artery.

proteins a) Gout

b) Stones in the kidney

which can damage thekidney

Excessive uric acid deposits

on the joint pain

Uric acid crystalises andforms stones in the kidney.


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intake

characteristic

Vitamin A Liver damaged The liver fails to

function because livercells die and fibrous

tissues form in the

liver

Mineral

(a)Sodium

a) High blood

pressure

b) Kidney damaged

Fatigue, headache, can

cause bleeding in the

brain (stoke) and

heart failureKidney are overloaded

with the task of

removing excess salts.


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intake

characteristic

(b) calcium Arteriosclerosis Calcium deposits on

the inner walls of

arteries causing the

arteries to harden andlose their elasticity.

Reduces flow of blood

or forms a blockage.


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Diet-related Diseases The following are examples of heath problems related

to unbalanced diet and the various ways to reduce itsharmful effects and risks.

a) High blood pressure i) excessive intake of food that is rich in saturated

fats and cholesterol leads to atherosclerosis and highblood pressure. The saturated fats and cholesterol are deposited on

the inner wall of arteries. This results inatherosclerosis where the lumen of the arteries t

become smaller and reduced the blood flow. If calcium is deposited and caused walls of the

arteries to harden and lose their elasticity then akind of atherosclerosis called arteriosclerosis isproduced. Hence, blood flow also reduced.


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This causes the heart to pump faster in order toproduce a higher pressure to pump the blood throughthe arteries with smaller lumen. As results, high

pressure is exerted on the arteries, causing anincrease in blood pressure. ii) High blood pressure is also caused by excessive

intake of salts, tea and coffee which can increase therate of heartbeat, thus increasing the blood pressure.

iii) ways to reduce the risk of high blood pressure: Reduced the intake of food which are rich in saturated fats

and cholesterol. Exercise frequently.

Reduce the intake of salts in food as well as tea and coffee. Do not smoke Have enough rest.


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b) Diabetes mellitus

i) Diabetes mellitus is caused by excessiveglucose in the blood and its subsequentexcretion in the urine.

ii) Excessive intake of food rich in sugar

(carbohydrates) can cause diabetes mellitus. iii) obesity can lead to diabetes mellitus.

iv) the risk of diabetes mellitus can bereduced in the following ways: Reduced the intake of food rich in sugar

( carbohydrates)

Exercise frequently.


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C) Osteoporosis i) osteoporosis occurs due to the lack of

calcium, phosphorus and vitamin D in thediet of an adult.

ii) There is low density of the bone mass

and the bones become thin and brittle,and are easily broken.iii) The risk of contacting osteoporosis can

be reduced in the following ways: intake of food rich in calcium, phosphorus

and vitamin D. Exercise frequently.


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kwashiorkor


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kwashiorkor


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Xerophthalmia


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Beri-beri


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Pellagra


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Anaemia


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Scurvy


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Rickets (children)


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0steoporosis (aged adults)


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Goitre


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Cretinism (children)


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Muscular cramps


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Obesity


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Dental caries


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Atherosclerosis


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CORONARY ARTHEROSCLEROSIS


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Gout


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Stones in kidney


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Liver damage


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Kidney damaged


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Arteriosclerosis


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Test Yourself!!

A. Tick (/) if the statement is true and (x) is false.

1. A diet that has too much or little of a specificnutrient can cause certain health problems.

2. Anaemia is caused by the lack of iron and vitaminB12.

3. Lack of iodine causes goitre and rickets.4. Excessive intake of food that is rich in

carbohydrates and lipids can cause cardiovasculardiseases.

5. High blood pressure and atherosclerosis are causedby excessive sodium and calcium intake respectively.

6. Obesity can lead to diabetes mellitus, heartdiseases and dental caries.


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7. A diet low in saturated fats can causediabetes mellitus, high blood pressureand osteoporosis.

8. Excessive intake of salts, tea andcoffee can cause high blood pressure.

9. Smoking can cause high blood pressure.

10. Osteoporosis can be prevented with

the intake of food rich in calcium,phosphorus and vitamin D.


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B. Match the nutrients with the effects ofdeficiency or excessive intake of the nutrients.

Effects of

deficiency

Nutrient Effects of excessive

intake

Scurvy Calcium High blood

pressure

Constipation Lipids AtherosclerosisAnaemia vitaminB12 obesity

Kwashiorkor Sodium

RicketsVitamin C

Carbohydrates

Fibre

Proteins


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What happen to the food after we eat it?


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Food must be broken down into

simpler substances before it can be

absorbed into the blood and carried to

cells throughout the body.


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6.4 Food Digestion

The process of breaking down large andcomplex substances into simple molecules thatcan be absorbed is called digestion.

Carbohydrates, protein and lipid are digestedin the body into simple substances such asglucose, amino acids, fatty acids and glycerols.

These simple substances can be absorbed bythe cell in the body to carry out metabolicprocess in the cells.


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Digestive SystemDigestive System


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Human Digestive System

The human digestive system comprises of thealimentary canal which starts at the mouthand ends at the anus.

The parts of the human digestive system are:

a) mouth b) oesophagus c) stomach d) duodenum (first part of small intestine) e) ileum (rest of small intestine) f) large intestine ) caecum, colon, rectum)


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Alimentary canal

A series oforgans joined in a long tube from

mouth to the anus.


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Digestion involves both physical andchemical processes.

Physical digestion is the breaking downof food particles by the teeth (chewing)into smaller food particles.

This will increase the surface area ofthe food particles for enzyme reaction.

Physical processes also involves

peristalsis which moves the food particledown the alimentary canal.


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Mechanical digestion


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Chemicaldigestion


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Organs that help in digestion are:


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What is digestion?

Process of ___________________

the _________, complex food molecules

into smaller and __________ molecules.

_____________

Digestion

_____________

Digestion

Larger pieces into

___________ pieces

_________ molecules into

simpler molecules


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Digestive System

____________ Canal Other Organs

M________Pharynx

OesophagusS_________

S_________ intestineL_______ intestine

RectumA_______

TongueS_______ glands

L_______G_____ bladderPancreas


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Identify and labelIdentify and label

the parts ofthe parts of

Digestive SystemDigestive System

a) g)

f)

d)

e)

c)

b) h)

i)


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What is digestion?

Process of breaking down

the large, complex food molecules

into smaller and simpler molecules.

Mechanical

Digestion

Chemical

Digestion

Larger pieces into

Smaller pieces

Complex molecules into

Simpler molecules


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Digestive System

Alimentary Canal Other Organs

MouthPharynx

OesophagusStomach

Small intestineLarge intestineRectumAnus

TongueSalivary glands

LiverGall bladderPancreas


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Answers:

a) Gall bladder

b) Pancreas

c) Large intestine

d) Rectume) Anus

f) Oesophagus

g) Liver

h) Stomach

i) Small intestine

Di sti n f C rb h dr t s Pr t ins nd


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Digestion of Carbohydrates, Proteins and

Lipids

i) Digestion in the mouth Food is chewed by the teeth into small

particles to increase the surface area for theaction of enzymes.

The presence of food in the mouth triggersthe secretion of saliva by the three pairs ofsalivary glands.

Saliva contains the enzymes which begins thehydrolysis of starch to maltose.

starch + water maltose

Salivary amylase


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Maltose can not be absorbed by the smallintestinal lining, therefore digestive process

occurs further along the alimentary canal toconvert maltose to glucose.

The pH of saliva is 6.5-7.5,suitable for the

action of salivary amylase. The chewed food is rolled by the tongue into a

mass a bolus in preparation for swallowing.

During swallowing, the bolus enters theoesophagus, a muscular tube lined withepithelial cells and mucus glands.


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Mucus lubricates the movement of the

bolus along the oesophagus by peristalsis,a series of wave-like muscularcontractions along the oesophageal wall.

Peristalsis squeezes the bolus down theeoesophagus until it enters the stomach.


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ii) Digestion in the Stomach The epithelial lining of the stomach contains

gastric juice which consists of mucus,hydrochloric acid and the enzymes pepsin andrennin.

The pH of hydrochloric acid in stomacharound 2.0.

Functions of hydrochloric acid: a) To destroy most bacteria that are present in

food.

b) prepares an optimal pH range of acidic mediumfor the action of the enzymes pepsin and rennin.

c) stops the action of salivary amylase.

Digestion of protein begins in the stomach


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Digestion of protein begins in the stomach. Functions of enzymes in gastric juices:

a) the enzyme pepsin hydrolyses proteininto polypeptides.

Protein + water

polypeptides b) The enzyme rennin coagulates milk by

converting the soluble milk protein(caseinogens), into the insoluble casein.

Caseinogen casein

Pepsin

Enzyme rennin


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The food remains in the stomach for three to

four hour. During this period, food is thoroughly churned

and mixed with gastric juice by theperistaltic contractions of the stomach wall.

The stomach content become a semi-fluidcalled chyme.

Relaxation of the pyloric sphincter allows the

chyme to gradually enter the duodenum.


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iii) Digestion in the Small intestine

The small intestine consists of theduodenum, jejunum and the highly coiledileum.

a) Duodenum The duodenum is the first part of the small

intestine. The duodenum does not have glands to

secrete digestive juices. It receives twosecretions from other parts of thedigestive system for digestion.


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The duodenum receives:

a) bile produced by the liver, stored andreleased from the gall bladder.

Pancreatic juice secreted by the pancreas.

Bile is alkaline and does not containenzymes.


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The functions of bile:

a) emulsifies fats by breaking up largeglobules of fats into small fat droplets inorder to increase the surface area for theaction of the enzyme lipase.

b) prepares an alkaline medium for theaction of enzymes.

c) neutralises the acids in the stomach.

Pancreatic juice is also alkaline andcontains three enzymes which are lipase,amylase and trypsin.

Function of the enzymes in pancreatic juice


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Function of the enzymes in pancreatic juice. a) the enzyme lipase hydrolyses fats into glycerol and

fatty acids.

Lipid droplets + water glycerol + fatty acids

b) enzymes amylase hydrolysed starch (undigested inthe mouth) into maltose.

starch + water maltose

c) the enzyme trypsin hydrolyses polypeptide intopeptides.

Polypeptides + water peptides

lipase

Pancreatic amylase

trypsin


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b) Ileum

The rest of the small intestine after theduodenum is the ileum.

The walls of the ileum contain many

intestinal glands which secrete intestinaljuice.

The intestinal juices is alkaline and

contains enzymes to complete thedigestion of peptides and disaccharides.


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Functions of enzymes in intestinal juices:

a) The enzymes erepsin (peptidase)hydrolyses peptide to amino acids. b) the enzyme maltase hydrolyses maltose

to glucose.

The digestion of other disaccharides: a) The enzyme sucrase hydrolyses sucrose

to glucose and fructose b) the enzyme lactase hydrolyses lactose to

glucose and galactose.

h d f h di i


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At the end of the digestion process:

a) All carbohydrates are digested into the

monosaccharides of glucose, fructose andgalactose.

b) proteins are digested into amino acids.

c) lipids are digested into fatty acids andglycerol.

Vitamin and minerals are extremely small andsoluble and need not be digested.

Cellulose cannot be digested in the humanbody as the enzymes cellulase is not producedin the alimentary canal.


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CHAPTER 6 6.3 Malnutrition

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