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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