Unit #5

Chapter 16 in Textbook

Pages 506 - 529

Introduction to Digestion

Organs and Organ Systems

What is Digestion?

the mechanical and chemical breakdown of complex food into simple nutrients that cells can use

It is considered an open system

DIGESTION IS

Two Types of Digestion

Mechanical• Breaking food into

small pieces using

• Teeth

• Tongue

• Smooth muscle

Chemical• Breaking food into

small pieces using

• Chemicals

Complex FoodFood that is not

in a form that could be used by cells

Simple Nutrients Food that is broken

down to molecules that cells can absorb and use.

Levels of Organization

Atom – Oxygen (O) Molecule – Water (H2O) Organelle - mitochondria Cell – animal cell Tissue - muscle Organ - stomach Organ System - digestive Organism - human

Six Basic Simple Food Nutrients

Fats Carbohydrates Proteins Vitamins Minerals Water

What does “food” give your body

Materials for growing and repairing body tissue

Energy for everything you do

Carbohydrates (simple or complex)

Supply quick energy to cells• Sugars, glucose, starches and fiber

Fats

Supply energy, but fats are usually stored

Two Types• Saturated – solid at room temperature

• Unsaturated – liquid at room temperature

Proteins(complete and incomplete)

Used by cells for growth and repair Two Types

• Complete – animal sources

• Incomplete – plant sources

Vitamins

Substances that help control growth and normal body function

Minerals

Inorganic substances that help control growth and normal functions

Water

Main compound in a living body • Makes up 50-60%

Needed for chemical reactions

Food Guide Pyramid

A changing model

New vs Old

Updating Again

MyPlate is part of a larger communications initiative based on 2010 Dietary Guidelines for Americans to help consumers make better food choices.

Food Labels

Provide Nutrition Information

Nutrition information provided on food labels

Nutrition Facts

Ingredient List

Nutrition Claims

Health Claims

INGREDIENTS: Whole wheat, wheat bran, sugar/glucose-fructose, salt, malt (corn flour, malted barley), vitamins (thiamine hydrochloride, pyridoxine hydrochloride, folic acid, d-calcium pantothenate), minerals (iron, zinc oxide).

“Good source of fibre”

“Part of a heart healthy diet…”

What food products have Nutrition Facts?

Almost all prepackaged foods have Nutrition Facts.

Some exceptions are:

• fresh fruit and vegetables, raw meat, poultry, fish and seafood;

• foods prepared or processed at the store:

• bakery items, sausage, salads;

• foods that contain very few nutrients:

• coffee beans, tea leaves, spices;

• alcoholic beverages.

Use Nutrition Facts…• to easily compare similar foods

• to look for foods with a little or a lot of a specific nutrient

• to select foods for special diets

…to make informed food choices

The Ingredient List

• Lists all of the ingredients for a food by weight, from the most to the least.

• Is a source of information for certain nutrients.

• Is a source of information for people with food allergies

Nutrition Claims

Are regulated statements made when a food meets certain criteria.

They are optional, and may be found only on some food products.

Health Claims Disease risk reduction

claims

Structure and Function of the Mouth and Pharynx

Human Mouth Structure

Mouth

Structure Function Mechanical Digestion Chemical Digestion

• Enzymes and mucus

Contains• Teeth

• Tongue

Salivary Glands

Structure Function Produce Saliva

• Breaks down starch into sugar

• Produce 1 ½ liters per day

Lubricate and hold chew food together• bolus

Pharynx (area)

Structure Function Swallow food Respiratory and Digestive

Systems meet Area contains

• Epiglottis

• Sinuses

• Trachea

• Eustachian tubes

• Esophagus

Structure and Function of Organs in the Digestive

System

Human Digestive System

Esophagus

Structure Function To get food to the

stomach by muscular “squeezing”• Peristalsis

• Example:

• Tennis ball and sock

Stomach

Structure Function Temporarily store food

• Muscular sphincters control the flow of food

Mix food with gastric juices

Gastric Juices contain

Mucus• Protects stomach wall

Hydrochloric Acid• Kills germs

• Aids in protein digestion

Pepsin• Works with HCl to

digest protein

Chyme

Mixture of food and gastric juice

Soupy and ready for the small intestine

Released when sphincter opens

Small Intestine

Structure 6 meters long 3 cm across

Function Finish chemical digestion To absorb nutrient

molecules Divided into 3 parts

• Duodenum

• Jejunum

• Ileum

Pancreas (helper organ)

Structure Function Produces pancreatic juice

• Mixture of chemicals

• containing enzymes

• Alkaline secretion of the pancreas

Liver (helper organ)

Structure Function Produces bile

• Breaks up fats

Gall Bladder (helper organ)

Structure Function Storage of bile

Villi (helper structure)

Structure Function Increase surface area of

small intestine Absorb simple nutrient

molecules

Appendix

Structure Function Unknown May be a store house for

good bacteria

Colon (Large Intestine)

Structure Function Absorb

• Water

• Vitamins

• Minerals

Contents contain• Fiber from plants

• Bacterial

• Body wastes