Digestion of FoodGrade 9

Lebanese CurriculumJinan Karameh Shayya

Food

Types of FoodMineral Substances- inorganic food

Organic

Proteins Lipids Carbohydrates Vitamins

Types of Foodorganic Food

Amino acids

Proteins

• Peptides• Complex

Proteins

1. Simple (reducing) Sugars a. Monosaccharides b. Disaccharides2. Complex sugar or polysaccharides

Carbohydrates

Lipids are made up of two types of single molecules:

1. Fatty acids2. Glycerol

Lipids

http://faculty.kirkwood.edu/apeterk/learningobjects/biologylabs.htm

Biuret Test for Peptides Coagulation test for complex proteins Iodine test for starch Fehling test for simple sugar Translucent spot test for lipids and oils Heat for water Silver nitrate for chlorides test

Identification Test

Apply The following experiment was conducted to study

the organic constituent of potato.

1. Describe the experiment2. Analyze this experiment3. Explain the results

Answers1. The following experiment shows a potato tuber

that was partly peeled and, with a dropper, few drops of brownish iodine were added to the peeled part. A dark blue color was observed.

2. As few drops were added to the peeled part of the potato tuber, the color of the peeled potato changed into dark blue color

3. The dark blue color indicates the presence of starch in potato since iodine reacts with starch to produce dark blue color.

Digestive System

Digestive tube

Mechanical digestion It is the breaking down of food physically without

changing its chemical identity.

Mechanical Digestion

Swallow

Chewing

Peristalsis

Churning

Mastication- Chewing and swallowing

https://youtu.be/4FMnXz6o2vI

Peristalsis

Churning

Chemical Digestion of food Chemical Digestion is the breaking down of food

chemically in the presence of water and specific enzymes at specific conditions.

Enzymes

Properties of enzymes

1. Specificity 2. Suitable PH3. 37 degree temperature

Chemical Digestion of Starch

Substrate

Juice Enzyme Organ Medium /PH

Products

Cooked Starch

Saliva Salivary Amylase

Mouth Neutral PH=7

Maltose

Uncooked Starch

Pancreatic Juice

Pancreatic Amylase

Small Intestine

Basic PH>8

Maltose

Intestinal Maltase

Intestinal Juice

Intestinal Maltase

Small Intestine

Basic PH>8

Glucose

Chemical Digestion of Proteins

Substrate

Juice Enzyme Organ Medium/ PH

Products

proteins Gastric pepsin stomach Acidic PH<2

peptides

Proteins pancreatic

Trypsin Small intestine

Basic PH>8

Peptides and amino acids

Peptides Intestinal Peptidase Small intestine

Basic PH>8

Amino acides

Chemical Digestion of Lipids

Substrate

Juice Enzymes Organ Medium/PH

Products

Lipids Bile (secreted by Liver)

- Small Intestine

Basic PH>8

Emulsified Lipids

Emulsified Lipids

Pancreatic Lipase Small Intestine

Basic PH>8

Fatty acids and Glycerol

Emulsified lipids

Intestinal Lipase Small Intestine

Basic PH>8

Fatty acids and Glycerol

Chemical DigestionThe whole picture

https://www.youtube.com/watch?v=aQX8AkbuzjY

Intestinal Absorption The crossing of nutrients, By diffusion, through the

intestinal walls to blood (sugars, minerals and amino acids) and lymph ( fatty acids and Glycerol)

Intestinal Characteristics favoring Absorption

1. Large surface area2. Thin walls3. Richness of blood vessels

Let us play digestion

http://kitses.com/animation/swfs/digestion.swf