Unit 3

Life Processes: Nutrition, Transport & Respiration

Heterotrophic Nutrition

Objectives

• To describe the structure and function of the human alimentary canal.

• To perform food tests to determine the presence of macronutrients in selected human foods.

• To discuss the roles of enzymes in the digestion of food.

• To evaluate the need for modifications to the basic balanced diet for special human populations.

Balanced Diet

• A balanced diet consists of the essential nutrients in the correct proportions.

• The essential nutrients for the balanced diet of a mammal consist of the following components:

– Metabolic fuel- carbohydrates, fats & proteins

– Vitamins

– Minerals

– Roughage

– Water

Carbohydrates

• Major source of carbohydrate are the sugars and starch, together with cellulose

• Main role: to provide energy

Fats

• Obtained from animals and plant oils

• Main role: to provide energy

• Other functions:

– Food store for animals living in cold climates

– Buoyancy in aquatic animals

– Insulation

Proteins

• Plant sources: cereals, nuts and seeds (peas and beans)

• Animal sources: meat, fish, milk, cheese and eggs

• Main role: source of twenty (20) amino acids from which the organisms own proteins are made.

Vitamins

• They are organic compounds that are required in small amounts for the maintenance of normal health.

• Most vitamins cannot be made in the body and so must be provided in the diet.

Vitamins Vitamin Major Food Source Function(s) Deficiency Disease

A Fish liver oil, Animal liver, Dairy products, All green vegetables

To keep cells lining the respiratory system healthyTo make a pigment in the retina of the eye which is needed for seeing dim light

Infection of cells lining the respiratory systemNight blindness

B Wholemeal bread, Yeast extract, Liver, Brown rice

Involved in many chemical reactions in the body (eg: respiration)

Beri-beri: causes muscular weakness and paralysis

C Potatoes, Greenvegetables, Citrus fruits

Keeps tissues in good repair Scurvy: causes pain in joints and muscles and bleeding from gums

D Fish liver oil, Butter, Margarine, Egg yolks, Made by sunlight on the skin

Promotes absorption and use of calcium and phosphate for healthy bones and teeth

Rickets: causes bones tobecome soft and deformed

K Dark green vegetables, Made by bacteria in theintestine

Essential for the normal clotting of blood

Delay in the blood- clotting mechanism

MineralsMinerals Food Source Function(s) Deficiency Disease

IronFe2+, Fe3+

Most foods particularly in meats

For making haemoglobin Anaemia: not enough red blood cells, so that the tissues are short of oxygen and cannot release energy

CalciumCa2+

MilkCheeseBread

For bones and teethIn muscles for contractionFor normal clotting of blood

Brittle bones and teeth

PhosphorusPO4

3-

Nearly all foods For bones and teeth Brittle bones and teeth

Fluorine Drinking water,tea, fluoride toothpaste

Invloved in the structure of bones and teeth, resistance of teeth to decay

Bad teeth

Iodine Sea foodsTable salt

Essential constituent of the hormones produced by the thyroid

Goitre: a swelling in the neck;Slow metabolic rate

Roughage

• Common form: outer husk of cereal grains such as oats, wheat and barley; all plant food such as fruits and vegetables

• Main role: keeps the digestive system in good working order and helps prevent constipation

Human Populations i.t.o. Diet

• Plan and present balanced diets for following persons:

1. Healthy Adult Male & Healthy Adult Female

2. Healthy Child & Healthy Elderly Person

3. Healthy Adult & Athlete

4. Healthy Adult & Diabetic

5. Malnourished Person & Obese Person

6. Anorexic & Bulimic

Assignment 6

Pre-Class Test

• Answer all four (4) questions to the best of your knowledge.

Questions

1. Define heterotrophic nutrition?

2. Label Figure 1.

3. Name one enzyme found in the alimentary canal of man.

A

B

C

Figure 1

Questions

4. State whether the following statements are True or False.

a) The structure labeled J, is called the gall bladder.

b) The canines of man are used for crushing and grinding of food.

c) The process of swallowing is known a mastication.

d) Peristalsis is the rhythmic contraction of the muscles of the esophagus.

e) Benedict’s Reagent is the chemical used to test for the presence of sugars.

Nutrition

Nutrition

Autotrophic Heterotrophic

Holozoic

Saprotrophic

Parasitic

Types of Heterotrophic Nutrition

1. Holozoic Nutrition• Food is taken into a specialized digestive system in the

organism.• The food is broken down into smaller molecules which are

then absorbed.

2. Saprotrophic Nutrition• Food is obtained from decaying organic matter. • Digestion is extracellular and the products of digestion are

absorbed.

3. Parasitic Nutrition

DIGESTION

Digestion

• Definition:

The process of breaking down food (complex substances) by mechanical and enzymatic action in the stomach and intestines into (simpler) substances that can be used by the body.

• Essential Activities: IPPMSCAD

Digestive System

• Consists of the alimentary canal and several accessory organs.

Parts of Alimentary

Canal

Mouth

Pharynx

Oesophagus/ Esophagus

StomachSmall

Intestine

Large Intestine

Anal Canal

Digestive System

Exercise

Outline the organs and parts of the alimentary canal involved in the digestion of a piece of bread, in order.

Also, state what will be the final product/ waste after digestion.

Hint: Can be done in the format of a flow chart

Tracing a Piece of Bread through the Alimentary Canal

bread Mouth Pharynx Esophagus

Stomach DuodenumRest of Small

Intestine Large Intestine

RectumAnal Canal/

Anusfaeces

Alimentary Canal

• A tube that extends from the mouth to the anus

• Consists of four layers:

1. outer layer (protects)

2. second layer (muscular; contracts and expands in wavelike motions called peristalsis)

3. third layer (vessels, nerves and glands that nourish and carry away waste)

4. innermost layer (mucous membrane that secretes mucus and digestive enzymes)

Alimentary Canal: Layers

DIGESTION1. Ingestion

Structure & Function: Mouth

• The start of the process of digestion occurs in the mouth using the teeth and tongue.

• There are four different types of human teeth:1. Incisors for cutting.2. Canines for piercing.3. Pre-molars for cutting and crushing.4. Molars for crushing and grinding.

• All teeth have the similar features.

• The process of chewing is called mastication

Oral Cavity

Tooth

Enzymes

• Enzymes are biological catalysts. They speed up chemical reactions in all living things, and allow them to occur more easily.

• They occur in plant cells and animal cells.

Enzymes: How they work?

Ingestion & Enzymes

• After the food has been mechanically broken up, it is mixed with saliva which moistens it and adds the enzyme salivary amylase which begins to digest starch.

Enzyme Location in Digestive System Function

Salivary amylase SalivaBreaks down starch to maltose

Structure & Function: Tongue

• The tongue helps to form the food into a small, moist ball called a bolus, which can be easily swallowed.

• The process of swallowing is called deglutition.

• Interesting to Know:Small raised areas called papillae are located on the tongue and they contain taste buds.

DIGESTION2. Propulsion

Structure & Function: Pharynx

• Also known as the throat.

• Transmits food into the esophagus

• Muscular tube about 5 inches long in adults

• The epiglottis (a flap of tissue) covers the trachea to prevent food from entering the larynx during swallowing which causes choking.

Pharynx

DIGESTION3. Peristalsis

Structure & Function: Esophagus

• Muscular tube about 9 to10 inches long in the adult that contracts rhythmically (peristalsis) to propel food toward the stomach.

• Contains a group of muscles called the lower esophageal sphincter that closes off the entrance to the stomach to prevent reflux of food, emesis or regurgitation (vomiting).

Esophagus

Peristalsis

DIGESTION4. Mechanical Digestion

Structure & Function: Stomach

• Pouch-like organ located in the left hypochondriac region of the abdominal cavity

Structure & Function: Stomach

• Receives bolus from the esophagus and mixes it with gastric juices to form a semi-fluid mass called chyme.

• Gastric juices contain hydrochloric acid, mucus and pepsin.

– Hydrochloric acid- provides acidic environment for the action of pepsin

– Mucus- protects inside of stomach wall by providing an alkaline layer

Churning of Food & Enzymes

Enzyme Location in Digestive System Function

Salivary amylase SalivaBreaks down starch to maltose

Pepsin Gastric juice Breaks down proteins to peptides

DIGESTION

5. Segmentation

6. Chemical Digestion

7. Absorption

Structure & Function: Small Intestine

• Consists of three parts:1. duodenum2. jejunum3. ileum

• Held in place by the mesentery which is a muscular membranous tissue that anchors both the small and large intestines to the abdominal wall

• First site of absorption and nutrients pass from the intestinal walls and into the bloodstream through the villi.

Small Intestines

DIGESTION8. Defecation

Structure & Function: Large Intestine

• Consists of four parts:1. cecum2. colon3. sigmoid colon4. rectum

• Undigested waste may remain in the large intestine from 12 to 24 hours

• A wormlike pouch (appendix) filled with lymphatic tissue extends from the cecum

• Process of turning waste material into a semisolid waste (feces) begins in the cecum

Structure & Function: Colon

• Colon consists of three parts:1. ascending colon2. transverse colon3. descending colon

• Sigmoid colon is an s-shaped structure that connects to the rectum

• Rectum connects to the anal canal

• Release of feces from the body is called defecation.

Larg

e In

test

ine

DIGESTIONAssociated Organs

Structure & Function: Liver

• Located in the right quadrant of the abdominal cavity

• Divided into right and left lobes

Structure & Function: Liver

• Converts food nutrients into usable substances

• Secretes a yellowish-brown to greenish substance called bile which is stored in the gall bladder

• Stores glucose in the form of glycogen

• Secretes bilirubin, a bile pigment that is combined with bile and excreted into the duodenum

Structure & Function: Gall Bladder

• Stores bile from the liver

• Three ducts connect the liver, gallbladder, and duodenum for the flow of bile (hepatic duct, cystic duct, and common bile duct)

• Releases bile when it is needed for the emulsification(breakdown) of fat

Gall Bladder

Structure & Function: Pancreas

• Secretes a pancreatic juice that includes various enzymes such as amylase and lipase

• Also an endocrine gland

EnzymeLocation in Digestive

SystemFunction

Salivary amylase SalivaBreaks down starch to maltose

Pepsin Gastric juice Breaks down proteins to peptides

Amylase Pancreatic juice Breakdown of starch into sugars

Lipase Pancreatic juice Forms fats

Pancreas

Essential Activities of Digestion

1. Ingestion: process of taking food into the digestive tract.

2. Propulsion: process that moves food through the alimentary canal, and includes swallowing and peristalsis.

3. Peristalsis: major means of propulsion involving alternate waves of contraction and relaxation of muscles in the organ walls. Its net effect is to squeeze food along the pathway from one organ to the next with some mixing occurring along the way.

4. Mechanical digestion: includes chewing, mixing of food with saliva by the tongue, churning food in the stomach and segmentation of the intestines.

Essential Activities of Digestion

5. Segmentation: mixes food with digestive juices and increases the rate of absorption by repeatedly moving different parts of the food mass over the intestinal wall.

6. Chemical digestion: catabolic process wherein molecules are broken down to their monomers which are small enough to be absorbed by the GI tract. Accomplished by enzymes secreted by various glands. Begins in the mouth and is essentially complete in the small intestine.

7. Absorption: the transport of end products from the GI tract to the blood or lymph. Substances must first enter the mucosal cells by active or passive transport processes. The small intestine is the major site of absorption.

8. Defecation: the elimination of indigestible substances from the body.

Food Tests

Test for Reducing & Non-Reducing Sugars

• Note: Reducing sugars are simple sugars such as glucose.

• The standard chemical test for sugar is Benedict's test.

• Results:

Test for Protein

• The standard chemical test for proteins is Biuret’s Test.

• Results:

Test for Lipids

• The standard chemical test for lipids is Emulsion Test.

• Other tests include: Grease Spot Test and the Sudan Stain Test.

• Results:

Emulsion Test Grease Spot Test Sudan Stain Test

Test for Starch

• The standard chemical test for starch is Iodine Test.

• Results:

Post-Class Test

• Answer all four (4) questions to the best of your knowledge.

Questions

1. Define heterotrophic nutrition?

2. Label Figure 1.

3. Name one enzyme found in the alimentary canal of man.

A

B

C

Figure 1

Questions

4. State whether the following statements are True or False.

a) The structure labeled J, is called the gall bladder.

b) The canines of man are used for crushing and grinding of food.

c) The process of swallowing is known a mastication.

d) Peristalsis is the rhythmic contraction of the muscles of the esophagus.

e) Benedict’s Reagent is the chemical used to test for the presence of sugars.

Assignment #7

• Read Chapter 7

Pages 61 – 79

• Answer questions 1 -7

Pages 80 – 82

• Read Chapters 10 & 11

Pages 101 - 124