6.4 Food Digestion

JANGAN PERNAH BERHENTI

BELAJAR_

TERUSKAN USAHA

August/02/2012 NURULHUDA:SMKSEGAMBUT2012BIOLOGI6.4FOOD DIGESTION 1

6.4 FOOD DIGESTION

I LOVE FOOD!!!~

1.4 Analysing fooddigestion

Discuss the following:a) glucose, amino acids and lipidsare always required by the cell to carry out metabolic processes,b) complex substances like carbohydrates, proteins and lipids need to be digested.Draw and label parts of the human digestive system.A Discuss the functions of digestivejuices, including saliva, gastricjuice, pancreatic juice, intestinaljuice and other substances, i.e.hydrochloric acid and bile that aidthe process of digestion.Discuss the digestion ofcarbohydrates, proteins and fats onthe following aspects:a) specific location of eachdigestive process,b) chewing of food,c) movement of food,d) glands involved,e) digestive enzymes,f) suitable pH for each enzymeaction,g) substrates and products.Identify the parts of digestivesystem in ruminants and rodents.Discuss the digestion of cellulosein ruminants (eg. cow) and rodents(rabbit).Use graphic organiser to compareand contrast the process ofcellulose digestion in humans,ruminants and rodents.design experiments to study thedigestion of starch and proteinsin food samples,? describe problems related tofood digestion.

A student is able to:? state the substances required bythe cell to carry out metabolicprocesses,? list the complex substances thatneed to be digested,? explain the necessity fordigestion of complexsubstances,? draw and label the humanDigestive system,

substances that aid in theprocess of digestion in human,? describe the functions of thedigestive juices and substances,? explain the digestion ofcarbohydrates, proteins andlipids in the human body,? identify parts of digestive systemin ruminants and rodentsinvolved in the digestion ofcellulose,? describe the digestion ofcellulose in ruminants androdents,? compare and contrast thedigestive process in humans,

ruminants and rodents,design experiments to study thedigestion of starch and proteinsin food samples,? describe problems related tofood digestion.

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SUBSTANCES NEEDED IN CELL METABOLISM

1. METABOLISM : Chemicals reactions in cells that keep them alive, growing and dividing.

1. Metabolic processes are divided into : Catabolism – breaking down substances to

produce energy and simple molecules Anabolism – using energy (ATP) to synthesise

new cell components from simple molecules


Substances needed for metabolic

process in cells

GLUCOSE

AMINO ACIDS

LIPIDS

Broken down to produce chemical energy, (ATP) adenosine triphosphate, supply energy for all metabolic activities

1. Basic building blocks of proteins2. 22 different amino acids are used

to synthesise the different types of proteins required by the human body

1. Triglycerides : energy storage molecules2. Phospolipids : major building blocks for cell membrane3. Hormones4. vitamins


Digestion of Complex

Substances

CARBOHYDRATES

PROTEINS

LIPIDS (fats)

Simple sugar (glucose)

Amino acids

Fatty Acids + Glycerols

into

into

into


Human Digestive System


1. Human digestive system consists of a muscular tube (alimentary canal)/ gut

2. About 9 meter long from mouth to anus.3. Alimentary canal :

consists of 4 different layers of tissues


Alimentary canal / GutAugust/02/2012 9NURULHUDA:SMKSEGAMBUT2012BIOLOGI6.4FOOD DIGESTION

Alimentary Canal

1. Inner mucosa 2. Sub- mucosa

4. Serosa3. Muscle Layer

1. Secretes mucus to lubricate the food we eat

2. Protects alimentary canal from damage

3. In mouth, stomach, small intestine; secretes digestive juices

1. Contain blood and lymph vessels take away absorbed nutrients

2. Network nerves that coordinate muscular contractions peristalsis

1. Is build by inner circular muscle layer and outer longitudinal muscle layer

1. Protects the gut wall from friction with other organs in the abdomen


The Main Parts of the Alimentary Canal1. MOUTH

Swallowing Food


1. For chewing….2. No chemical digestion of proteins and lipids

in the mouth!!3. Digestion of carbohydrates ---->>>

a) Carbohydrates : begins in mouth, continue and completed in small intestine, BUT NOT digested in STOMACH!!!

b) Solid broken down by chewingc) Three pairs of salivary glands –

the parotid, sublingual, and mandibular glands(all secretes saliva into the mouth)


Saliva has 5 MAIN components :1. Water : moisten and soften the food2. Lysozyme : kill bacteria3. Mucus : Lubricate food in the mouth4. Sodium salts (NaHCO3, Na3PO4) : Provide an

alkaline and medium for amylase to catalyse the conversion of cooked starch and glycogen into maltose

5. Amylase : hydrolyses starch and glycogen (animal starch) to maltose.

amylaseSTARCH + water ----------------- > maltoseAugust/02/2012 15NURULHUDA:SMKSEGAMBUT2012BIOLOGI

6.4FOOD DIGESTION

During The Chewing

1. The tongue pushes the bolus into the pharynx

2. The tongue blocks the mouth3. Soft palate closes off the nose and the larynx

(voice box) rises so that the epiglottis closes off the trachea

4. Easing the bolus through the pharynx into the oesophagus.


• The tongue helps to mix food with saliva and assists in the formation of BOLUS!!!!


2. OESOPHAGUS


1.Esophagus is a muscular tube from the pharynx to the stomach

2.No DigestioN!!! & No AbsorBTioN!!!!....take place here!! NO!!!!

3.Mucus secretion by the epithelial cells of the mucosa…~

4.Movement of bolus downward to the stomach by muscular contraction called PERISTALSIS!!!


3. STOMACH

1. Food enter stomach when cardiac sphinter relaxes!!!

2. Very little starch digestionn!!! & NO LipiD digestion!!!...occur here….

3. “Chemical DIGESTION of PROTEIN start here!!! ”


4. Tiny pits in stomach epithelium called gastric glands secrete gastric juice that contain following :

a) Pepsin (an enzyme)b) Rennin ( an enzyme)c) Mucus (protect stomach wall from HCl and pepsin)

d) Hydrochloric acid

5. …during this, stomach wall contracts to churn up and mix the food with gastric juices.


6. Pepsin and rennin are secreted in an inactiveform called pepsinogen and prorennin :

Pepsinogen + HCl PepsinProrennin + HCl Rennin


7. Pepsin is protease that hydrolyses proteins into peptides :

pepsin PROTEIN + water polypeptides8. Rennin curdles milks by transforming

caseinogen into insoluble casien.


TAKE FIVE~ resttt Zzzz


THE DIGESTIVE SYSTEM OF COWRUMINANT

• Vertebrate • Human


Do not produce cellulase to digest plant cellulose

Problems of Food Digestion


• Incomplete digestion of food

• Gall stones preventing the flow of bile

• Reduced production of specific digestive enzymes

Incomplete Digestion of Food


6.4 Food Digestion

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