nutrition in organisms

7/30/2019 Nutrition in organisms

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The processes of nutritionThe processes of nutrition

ingestion digestion absorption

assimilationegestion


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IngestionIngestion

a process by which food is taken in

through the mouth a reflex action which is involuntary

it occurs when the food is put at theposterior position of the tongue


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external structure internal structure

enamel

dentine

blood capillaries

nerve fibres

cement

jaw bone

gum

crownneck

root

pulp cavity

(pulp tissues)

Teeth StructuresTeeth Structures


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enamel

crownneck

root

- outermost & hardest layercovering the crown (97% Ca,

3% organic matter)

- It is thickened and

strengthened by food, saliva

and drink

- Fluoride ions increase its

resistance to decay.

external structureTeeth StructuresTeeth Structuresinternal structure


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dentinecrownneck

root

- hard like bone but

softer than enamel

,living tissue, thread ofcytoplasm are running

through it. It is

hardened by vitamin D



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crownneck

root

blood capillaries

nerve fibres

pulp cavity(living tissues)

- supply food & oxygen for

growth & maintaining alive

- produce sensation

of pain when

stimulated



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crownneck

root

blood capillaries

nerve fibres

pulp cavity(living tissues)

made up of connective tissueswhich make up your dentine

and keep tooth alive.



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crownneck

root

- In cement are embedded

tuff fibers which pass into

bone of jaw and anchor thetooth in its position

- Bone covering the root

cement



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Teeth StructuresTeeth Structures

gumcrownneck

root

jaw bone

Periodontal membrane

-fibres attachingtooth to

jawbone

external structure internal structure


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Two sets of teethTwo sets of teeth milk teeth

in young child before approximately six years

oldwithout molar

20 teeth

permanent teeth no replacement for lost

32 teeth (including wisdom teeth)


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Types of teethTypes of teeth

Types of

TeethShape Functions

Incisor

Chisel-like &

sharp

Biting &

cutting food

CaninePointed,

curved & long

Killing prey &

tearing flesh

Premolar

& Molar

2 blunted

points of

cusps

Crushing &

grinding food


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DentitionDentition dental formula

e.g. Human (permanent set) = 2123

2123 other dentitions :


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Tooth decayTooth decay

bacteria together with food

remains,

forming plaque

bacteria produce acid which

dissolves the enamel of

tooth acid penetrates into dentine

bacteria infect pulp cavity

causing toothache

Causes:


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Diseases

Dental decay (dental

cavities)

Gum disease


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Effect of Acid on

a


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What do you find on the covered and uncovered parts of

the tooth ?Ans: The acid dissolves the exposed enamel and leaves a

small hole on the uncovered part, but holes do not

appear on the covered part.

tooth covered with wax dilute hydrochloric acid

probingscraping


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Does the acid take place in causing tooth decay ?Ans: Actually the acid produced by bacteria in the mouth

is not very strong. Tooth decay is due to bad habits

over a long period of time.

tooth covered with wax dilute hydrochloric acid

probingscraping


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Prevention of Tooth DecayPrevention of Tooth Decay

have a balanced diet (include Ca, P &

vitamin D) adding fluoride in water to

strengthen the enamel of our

teeth(NOT chlorine which kills bacteria in water)

avoid sugary food & drinks between meals


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use dental floss(to remove food

remain between teeth)


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form a good tooth-cleaning habit by

using dental disclosing agent



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brush our teeth at least twice a day

replace your toothbrush when it wears out

do not bite hard materials

have a dental check-up at least once a year



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Movement of FoodMovement of Food

oesophagustrachea

epiglottis

Mouth:Food chewed by teeth

mixed with saliva to form bonus

swallowed down the oesophagusthrough pharynx

[Note: Epiglottis (a piece of cartilage) covers the

entrance to the trachea while swallowing to prevent

food going down into lungs.]


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Movement of FoodMovement of Food

muscle

contraction

muscle

relaxation

Oesophagus:

Outer longitudinal & inner

circular muscles contract &

relax alternately (peristalsis)

Push food bolus to stomach


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A process by which large food moleculesare broken down into smaller pieces


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Why is digestionWhy is digestionneeded?needed?


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Because:Because:

food pieces and their molecules

(e.g. starch, protein & fat) are

usually too large to pass throughthe wall of our body for absorption

(Note: Simple sugars, water, vitamins &

minerals are small enough to be

absorbed immediately.)


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So,So,

food pieces should be broken down

into smaller pieces and then into

substances with molecular size which

is small enough to be absorbed


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Human Digestive SystemHuman Digestive System

salivary

glands

epiglottis

oesophagus

diaphragm

cardiac sphincterstomachspleen

pyloric sphincter

coloncaecum

rectumanus

large

intestine

pancreas

buccal cavity

tonguetooth

trachea

liver

duodenum

ileum

appendix

small

intestine

gall bladder


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Mechanical DigestionMechanical Digestion

Chewing :break down food into smaller

pieces by teeth to increase

the surface area for enzyme

action (physical digestion)


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Chemical DigestionChemical Digestion

Enzymatic Reactions which digest

food into simpler chemical forms


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To show the Differential

Permeability of Dialysis Tubingto Starch & Glucose


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Why is it necessary to rinse the dialysis tubing with tap

water ?Ans: In order to remove any starch and glucose that may

remain on the outside of the dialysis tubing.

Starch-

glucose

mixture

thread

Test for

glucoseTest for

starch


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Which food substance is present in water surrounding the

dialysis tubing 30 minutes after the beginning of theexperiment ? Explain your answer.

Ans: Glucose. As dialysis tubing is selectively permeable,

starch molecules are too large to pass through the

holes in the tubing...

Starch-

glucose

mixture

thread

Test for

glucoseTest for

starch


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Which food substance is present in water surrounding the

dialysis tubing 30 minutes after the beginning of theexperiment ? Explain your answer.

Ans: Only glucose molecules are small enough to pass

through the dialysis tubing in this experiment.

Starch-

glucose

mixture

thread

Test for

glucoseTest for

starch


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Which part of the body is presented by the dialysis

tubing and the water in the boiling tube respectively ?Ans: Ileum and blood are represented by the dialysis

tubing and water respectively.

Starch-

glucose

mixture

thread

Test for

glucoseTest for

starch


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Where is foodWhere is fooddigested?digested?


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Sites where digestion occurs:Sites where digestion occurs:Alimentary canal (gut)

1. Buccal

cavity

2. Stomach3. Small

intestine


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How is food digestedHow is food digested

in these sites?in these sites?


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Digestion in Buccal CavityDigestion in Buccal Cavity There are 3 pairs of salivary glands

Saliva contains water, mucus & enzyme(amylase)

Water: moistens dry food

Mucus: lubricates food

Amylase: digests about 5% of starch in

mouth


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Action of Amylase

on Starch


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What are the results of the iodine test and Benedicts testfor tube A ?

Ans: The result of iodine test is negative while the result

of the Benedicts test is positive.

A B Cthermometer

water bath

at 37

after 30 minutes

each test

tube

test withBenedicts

solution

test sample

with iodine

solution


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What are the results of the iodine test and Benedicts testfor tube B ?Ans: The result of iodine test is positive while the result of

the Benedicts test is negative.

A B Cthermometer

water bath

at 37

after 30 minutes

each test

tube

test withBenedicts

solution

test sample

with iodine

solution


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What are the results of the iodine test and Benedicts testfor tube C ?

Ans: The result of iodine test is positive while the result of

the Benedicts test is negative.

A B Cthermometer

water bath

at 37

after 30 minutes

each test

tube

test withBenedicts

solution

test sample

with iodine

solution


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Why is the temperature of the water bath set at 37?Ans: Because enzymes work best at 37.

A B Cthermometer

water bath

at 37

after 30 minutes

each test

tube

test withBenedicts

solution

test sample

with iodine

solution


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What is the action of amylase on starch ?

Ans: Amylase is an enzyme in saliva which helps to

digest starch into maltose.

A B Cthermometer

water bath

at 37

after 30 minutes

each test

tube

test withBenedicts

solution

test sample

with iodine

solution


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What is the effect of boiling on amylase ?

Ans: Amylase denatured after boiling.

A B Cthermometer

water bath

at 37

after 30 minutes

each test

tube

test withBenedicts

solution

test sample

with iodine

solution


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Chemical DigestionChemical Digestion

break down of starch molecules intomaltose molecules by salivary amylase

(from salivary glands)

Starch

maltoses

salivaryglands


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StomachStomach

(Physical Digestion)(Physical Digestion)

Stomach Entrance: Cardiac Sphincter

Stomach Exit: Pyloric Sphincter

Relaxation of cardiac sphincter & contraction ofpyloric sphincter enable storage of food in

stomach for a longer period of time


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Stomach (Physical Digestion)Stomach (Physical Digestion)

Squeezing & churning

actions of stomach break

down the partly digested

food into smaller pieces

which forms a semi-fluid

calledChyme


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digestive juice : gastric juice (pH 2)

(by gastric glands)

enzymes :protease

break down of protein molecules intopolypeptides or dipeptides

StomachStomach

(Chemical Digestion)(Chemical Digestion)


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StomachStomach

(Chemical Digestion)(Chemical Digestion)hydrochloric acid :

to provide acidic medium for

maximum activity of enzymeto kill bacteria

to stop the activity of salivaryamylase

(Stomach wall secretes a mucous layer to cover its inner

surface:prevents autodigestion by protease)


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Small IntestineSmall Intestine

(mainly chemical digestion)(mainly chemical digestion)Digestion of various food substances

by several kinds of digestive juices

Digestive juices foundin small intestine:

1. Bile

2. Pancreatic juice

3. Intestinal juice


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BileBile

with bile salts (not an

enzyme)

produced in liver stored in gall bladder

duodenum

livergall bladder


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transport to duodenum through bile duct

take action in duodenum

bile pigment (excretory waste from breakingdown of haemoglobin)

liver

gall bladder

BileBile


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BileBile

- contain bile salts which emulsify lipids intosmaller droplets without chemical change

( NOT digest fats)

- provide alkaline medium for enzymes to work

oil

oil droplets


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Effect of Bile Salt

on Fat


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What happens to the

mixtures in tubes A & B ?

Ans: In tube A, bile saltemulsifies the

vegetable oil to

droplets. In tube B, the

oil floats on top of watersince oil and water do

not mix well.

1cm3 of

vegetative

oil

shaking

shakingobserve

observe

10 drops of bile

salt solution

A

B


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What is the action of bile

salt on oil ?

Ans: The bile salt reduces

the surface tension of

oil and emulsifies oil to

droplets.

1cm3 of

vegetative

oil

shaking

shakingobserve

observe

10 drops of bile

salt solution

A

B


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Pancreatic JuicePancreatic Juice

produced in pancreas

action in duodenum

Pancreas

Duodenum


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Pancreatic JuicePancreatic Juice

- contain enzymes of 3 categories:

1.Carbohydrase (Amylase)

2.Proteases

3.Lipases

- provide alkaline medium forenzymes to work


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pancreatic amylasestarch maltose

starch maltose


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pancreatic

proteasesprotein

Dipeptides/polypeptides

protein

dipeptide

protease


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pancreatic lipases glycerol + 3 fatty acids

lipase

glycerol

fattyacids

lipid

lipid


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Intestinal Juice

produced and take action in

small intestine (duodenum& ileum) to complete the

digestion of food

ileumduodenumsmall

intestine

Digestion in ileumDigestion in ileum


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Intestinal JuiceIntestinal Juice

- Contain enzymes of 2 categories:

1. Carbohydrase (eg. maltase)

2. Protease


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disaccharides

(eg. maltose)

monosaccharides

(eg. glucose)

carbohydrase

disaccharide

intestinal

carbohydrase

monosaccharide


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intestinal

proteasesdipeptides amino acids

proteaseamino acid


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AbsorptionAbsorption

stomach : absorbs alcohol &

drugs

ileum : absorbs digested food(with a large amount of water)

( it absorbs the largest amount

of water) colon : absorbs water & mineral

salts

Ab i f f dAb i f f d


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It is long, with many finger-like villi

to provide large surface area

for absorption of digested food

It has thin wall

to decrease the diffusion distance

for easy diffusion of food

It has well developed transportsystem (blood capillaries & lacteal)

to maintain high concentration

gradient for the diffusion of food

Absorption of foodAbsorption of food

in ileumin ileum


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lacteal

Epithelial

cell

arteriole

venule

blood

capaillaries

lymph

vessel

villi

Structure of a VillusStructure of a Villus


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glycerol

nucleus

fatty acid

glucose

amino acid

fat

capillarylacteal

Micro-

villus

epithelial

cell

Transverse Section of a villus

showing food absorption


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Transportation of absorbedTransportation of absorbed

food in villifood in villi blood capillaries : absorb glucose & amino

acids (which are smaller molecules)

lacteal : absorb fatty acids & glycerol (which

are larger molecules)

transport fats (glycerol & fatty acidsrecombine together after being absorbed)

involve both diffusion & active transport


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Large intestineLarge intestine caecum & appendix

no function in human ( small in

size)

colon

absorbs water & mineral salts

failure to reabsorb water:

Diarrhoea

rectum

stores faeces temporarily

for egestion (defaecation)

caecum

appendix

colon

rectum


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Caecum & Appendix in RabbitCaecum & Appendix in RabbitIt is very large in size

to store plant for long time for bacteria to secrete cellulase

to digest cellulose to glucose

The rabbit should re-ingest faeces for absorptionof glucose

( absorption of food only proceeds in ileum)


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Digestive System in RabbitDigestive System in Rabbit


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Alimentary canal of a rat


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EgestionEgestion

(Defaecation)(Defaecation)removal of undigested or unabsorbed food

substancesfaeces: semi-solid brown mass (includes

undigested food, dead & live bacteria)

faeces is temporarily stored in rectum &

eventually be expelled through anus


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AssimilationAssimilation

a process which absorbs foodincorporated as a part of body cells

digested food is transported to liver

by hepatic portal vein

lacteal transports fat into lymph

vessels & then into the bloodstream

malfunction of pancreas to secrete

insulin:Diabetes

diabetes


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Functions of LiverFunctions of Liver

changes excess blood glucose toglycogen & stores in liver to

regulate blood glucose level

deaminates excess amino acids

to urea which is excreted

by kidney

toglycogenfor energy storage


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Functions of LiverFunctions of Liver storesvitamins A, D, E, K(which are fat

soluble) iron & glycogen

changes Carotene to Vitamin A secretes bile for fat emulsification

Detoxification:

turns mild toxins into harmless substances


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~~ ENDEND ~~

nutrition in organisms

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