SECTION 9SECTION 9

NUTRITION IN NUTRITION IN HUMANSHUMANS

IntroductionIntroductionHumans and other mammals are adapted for Humans and other mammals are adapted for feeding and digestion.feeding and digestion.

We use the essential molecules from food to We use the essential molecules from food to provide energy for the cells in our bodies.provide energy for the cells in our bodies.

Foods at the supermarket are usually grouped Foods at the supermarket are usually grouped into dairy, meat, fruit and vegetables etc. In into dairy, meat, fruit and vegetables etc. In Biology foods are grouped according to their Biology foods are grouped according to their chemical composition.chemical composition.

IntroductionIntroduction

Any one food may be a complex mixture of Any one food may be a complex mixture of substances, these can be classified substances, these can be classified according to their chemical structure. according to their chemical structure.

Food GroupsFood Groups

Humans eat a range of different foods Humans eat a range of different foods which supply energy, allow growth and which supply energy, allow growth and repair in the body.repair in the body.

Common foods such as milk, bread or Common foods such as milk, bread or potatoes each contain a mixture of different potatoes each contain a mixture of different food groups.food groups.

Food GroupsFood Groups

Carbohydrates

Fats

Protein

Vitamins

Minerals

starch and sugars

cellulose

NotesNotes

Read pages 222 to 225 in the text book. Read pages 222 to 225 in the text book.

Copy the names of the 5 main food Copy the names of the 5 main food groups.groups.

Name the food groups most plentiful in Name the food groups most plentiful in cow’s milk.cow’s milk.

Name the different types of carbohydrate Name the different types of carbohydrate found in food.found in food.

Content of Nutrients in MilkContent of Nutrients in MilkAnimalAnimal FatFat ProteinProtein CarbohydrateCarbohydrate CalciumCalcium PhosphorousPhosphorous VitaminVitamin

CC

CowCow 3.53.5 3.53.5 4.94.9 118118 9393 11

GoatGoat 4.04.0 3.23.2 4.64.6 129129 106106 11

HumanHuman 4.04.0 1.11.1 9.59.5 3333 1414 55

SheepSheep 7.07.0 6.06.0 5.355.35 193193 …… 2.462.46

Content per 100 grams of whole milk (or whey)

Composition of Different FoodsComposition of Different Foods

You are familiar with the composition of You are familiar with the composition of different types of milk.different types of milk.

Other foods contain different food groups Other foods contain different food groups in different proportions.in different proportions.

Use the table on page 225 to find the 3 Use the table on page 225 to find the 3 foods richest in carbohydrate, fat and foods richest in carbohydrate, fat and protein – copy and complete the table.protein – copy and complete the table.

Chemical StructureChemical Structure

Carbohydrate, protein and fat contain Carbohydrate, protein and fat contain large, complex molecules.large, complex molecules.

These large molecules are made up of These large molecules are made up of smaller molecules joined together.smaller molecules joined together.

The small molecular units are made up The small molecular units are made up of atoms of just a few chemical elements.of atoms of just a few chemical elements.

NotesNotes

Collect a “Food Molecules” hand-out and Collect a “Food Molecules” hand-out and fill in the missing words, glue into your fill in the missing words, glue into your jotter.jotter.Use the information to answer the think Use the information to answer the think box questions – discuss these with the box questions – discuss these with the person next to you.person next to you.Complete the Check-Test.Complete the Check-Test.If you finish – copy the vitamin and nutrient If you finish – copy the vitamin and nutrient tables into your jotter.tables into your jotter.

Alimentary CanalAlimentary Canal

The food we eat passes from the mouth The food we eat passes from the mouth into a long tube called the into a long tube called the alimentary alimentary canalcanal (or gut).(or gut).

This tube runs down the body to the anus, This tube runs down the body to the anus, as food passes through it is processed in as food passes through it is processed in various ways.various ways.

Processing involves muscular action and Processing involves muscular action and various juices which the alimentary canal various juices which the alimentary canal and associated organs secrete.and associated organs secrete.

Parts of the Alimentary CanalParts of the Alimentary Canal

The The alimentary canal (or gut)alimentary canal (or gut) is the tube is the tube within the body through which food passes within the body through which food passes and is processed in various ways.and is processed in various ways.

There are several different organs that are There are several different organs that are not part of the canal but are joined to it.not part of the canal but are joined to it.

These are the These are the associated organsassociated organs, they , they provide various substances that are used provide various substances that are used to digest food in the alimentary canal.to digest food in the alimentary canal.

NotesNotes

The meaning of the term “alimentary The meaning of the term “alimentary canal”.canal”.

The labelled and coloured diagram.The labelled and coloured diagram.

A list stating the associated organs of the A list stating the associated organs of the alimentary canal.alimentary canal.

Role of the MouthRole of the Mouth

The mouth is the opening at the start of The mouth is the opening at the start of the alimentary canal.the alimentary canal.

This is where food first enters the canal This is where food first enters the canal and also where the processing of the food and also where the processing of the food starts.starts.

Chewing (or mastication) stimulates saliva production which will act as a lubricant to condense food into a bolus.

Role of the MouthRole of the Mouth

Saliva contains starch-digesting enzymes Saliva contains starch-digesting enzymes which will start the breakdown of the food.which will start the breakdown of the food.

As the food stays in the mouth for only a As the food stays in the mouth for only a short time, there is very little or no short time, there is very little or no breakdown of the starch.breakdown of the starch.

Muscles of the Alimentary CanalMuscles of the Alimentary Canal

Food has to be kept moving along the Food has to be kept moving along the alimentary canal while at the same time alimentary canal while at the same time being mixed with various juices.being mixed with various juices.

These actions are produced by muscles in These actions are produced by muscles in the walls of the canal - a person has little or the walls of the canal - a person has little or no conscious control over this.no conscious control over this.

Muscles of the Alimentary CanalMuscles of the Alimentary Canal

The fibres of these muscles run along the The fibres of these muscles run along the length of the canal and are called length of the canal and are called longitudinal muscles.longitudinal muscles.

Other muscle fibres occur in rings around Other muscle fibres occur in rings around the canal and are called the canal and are called circular muscles.circular muscles.

The 2 types of muscles work together in The 2 types of muscles work together in a squeezing motion that pushes food along a squeezing motion that pushes food along the alimentary canal, this is called the alimentary canal, this is called peristalsis.peristalsis.