Digestive System

1
Digestive System

• Mrs. Thompson
• 7th Grade Science
• Eastside Junior-Senior High

2
Why is digestion important?

• When we eat such things as bread, meat, and
  vegetables, they are not in a form that the body
  can use as nourishment.
• Our food and drink must be changed into smaller
  molecules of nutrients before they can be
  absorbed into the blood and carried to cells
  throughout the body.
• Digestion is the process by which food and drink
  are broken down into their smallest parts so that
  the body can use them to build and nourish cells
  and to provide energy.

3
(No Transcript)
4
Why you need food?

• Nutrients
• substances in food that provide the raw materials
  and energy the body needs to carry out all its
  essential processes
• Energy
• Calories
• amount of energy needed to raise the temperature
  of one gram of water by one degree Celsius

Hello
5
Types of Nutrients

• Carbohydrates
• Fats
• Proteins
• Vitamins Minerals
• Water Salt

6
Carbohydrates

• Major source of energy that is composed of
  carbon, oxygen, and hydrogen
• 1 gram of carbohydrate provide your body with
  four Calories of energy
• Provides the raw materials to make cell parts
• SIMPLE CARBS (sugars) glucose a major source of
  energy for cells
• COMPLEX CARBS (starches- potatoes, rice, wheat,
  corn fiber can not be broken down, but is
  important in keeping the digestive system
  functioning properly)
• It is recommended that about 45 to 65 of total
  daily calories be from carbohydrates
• Some of our most common foods contain mostly
  carbohydrates. (bread, potatoes, legumes, rice,
  spaghetti, fruits, and vegetables -- many of
  these foods contain both starch and fiber)

7
Fats

• Energy-containing nutrients that are composed of
  H, C, O.
• Functions
• A rich source of energy for the body.
• Form part of the cell membrane
• Fatty tissue protects and supports your internal
  organs insulates your body
• Kinds
• Saturated (usually solid at room temp. meat
  dairy products contain large amounts)
• Unsaturated (usually liquid at room temp. most
  cooking oils)
• Trans fat (made when manufactures add hydrogen to
  vegetable oils to help the food stay fresh
  longer)
• Cholesterol waxy, fatlike subtance only found
  in animal products
• Important part of your bodys cells, but your
  liver can make all the cholesterol your body
  needs
• Cholesterol waxy, fatlike subtance only found
  in animal products
• Important part of your bodys cells, but your
  liver can make all the cholesterol your body
  needs

8
Proteins

• Foods such as meat, eggs, and beans consist of
  giant molecules of protein that must be digested
  by enzymes before they can be used to build and
  repair body tissues.
• An enzyme in the juice of the stomach starts the
  digestion of swallowed protein.
• Further digestion of the protein is completed in
  the small intestine. Here, several enzymes from
  the pancreatic juice and the lining of the
  intestine carry out the breakdown of huge protein
  molecules into small molecules called amino
  acids.
• These small molecules can be absorbed from the
  hollow of the small intestine into the blood and
  then be carried to all parts of the body to build
  the walls and other parts of cells.

9
Vitamins Minerals

• Absorbed from the small intestine is the class of
  chemicals we call vitamins
• Only needed in small amounts, but a lack of
  certain vitamins can lead to serious health
  problems
• Two different types of vitamins are classified by
  the fluid in which they can be dissolved
• water-soluble vitamins (all the B vitamins and
  vitamin C)
• fat-soluble vitamins (vitamins A, D, and K).
• (See chart on text page 91)

10
Water Salt

• Water is the MOST important nutrient because the
  bodys vital processes including chemical
  reactions such as nutrient breakdown take place
  in water.
• Most of the material absorbed from the cavity of
  the small intestine is water in which salt is
  dissolved.
• The salt and water come from the food and liquid
  we swallow and the juices secreted by the many
  digestive glands.

11
Food Pyramid
12
(No Transcript)
13
(No Transcript)
14
Food Labels
Allows you to evaluate a single food as well as
compare the nutritional value of two different
foods.

• How to Read
• serving size
• calories
• percent daily value (shows the nutritional
  content of one serving fits into the recommended
  diet of 2,000 calories/per day)
• ingredients (listed by order of weight)

15
Digestive Functions

• Digestion (Break down food into molecules the
  body can use
• Absorption (These molecules are absorbed into the
  blood and carried throughout the body)
• Elimination (Wastes are removed from the body)

16
The Digestive Process

• 1. MOUTH
• Mechanical digestion teeth cut up food
• Chemical digestion enzymes (proteins that
  speed up chemical reactions) in the saliva breaks
  down the molecules
• Chewed softened food is pushed toward the
  back of the mouth (muscle movements of tongue
  mouth) into the throat (pharynx) to be swallowed
• As you swallow, the epiglottis
• (ep uh GLAHT is) flap of tissue seals off you
  windpipe so your food goes into your esophagus

17
The Digestive Process

• 2. Esophagus (ih SAHF uh gus)
• - a mucus-lined, muscular tube that connects
  mouth to stomach
• After food enters, contractions of smooth muscles
  (peristalsis (pehr ih STAWL sis)) push the food
  toward the stomach keeps food moving in one
  direction
• At the end of the esophagus, a sphincter
  (muscular ring) allows food to enter stomach
  squeeze shut to keep food or fluid from flowing
  back up

18
The Digestive Process

• 3. The Stomach
• Mechanical digestion as three strong layers
  of smooth muscle contract and produce a churning
  motion
• Chemical digestion occurs as the churning
  food makes contact with digestive juices (acids
  enzymes that is produced by cells in the lining
  of the stomach)
• pepsin (enzyme) chemically breaks down
  proteins into short chains of amino acids
• hydrochloric acid kills many bacteria that
  you swallow with your food
• --- after few hours, your solid food is now in
  thick liquid form (chyme)
• --- when at the right consistency, the
  walnut-sized muscular tube at the outlet of the
  stomach (pylorus) squirts the chyme down into the
  small intestine

19
(No Transcript)
20
The Digestive Process

• 4. Small Intestine (final digestion absorption)
• Where almost ALL chemical digestion absorption
  of nutrients takes place
• About 6 meters long (18 feet) 2 to 3
  centimeters wide (about ½1/2 of the large
  intestine)
• 2/3 of the digestive system
• Chemical digestion The chyme mixes with enzymes
  secretions that are produced by the small
  intestine, liver, pancreas
• Absorption after chemical digestion creates
  small nutrient molecules, the villi (VIL eye)
  finger-shaped structures inside the small
  intestine absorbs them and pass them into the
  blood stream for use by body cells throughout the
  body

21
(No Transcript)
22
The Digestive Process

• Liver (part of the small intestines chemical
  digestion)
• Located in upper right portion of abdomen
• Largest organ inside the body
• Breaks down medicines helps eliminate nitrogen
  from the body
• Plays roles in many body processes
• Digestive system role produce bile substance
  that breaks up fat particles
• Bile flows from the liver to the gallbladder
  organ that stores bile until body is ready for
  use

23
(No Transcript)
24
The Digestive Process

• Pancreas (part of the small intestines chemical
  digestion)
• Triangular organ that lies between stomach 1st
  part of the small intestine
• Plays roles in many body processes
• Digestive system role produces enzymes that flow
  into the small intestine and help break down
  starches, proteins, and fats
• Makes insulin (keeps the level of sugar in the
  blood stable)

25
(No Transcript)
26
The Digestive Process

• 5. Large Intestine
• Approx. 1.5 meters long (4 1/2 feet)
• Contains bacteria that feed on the material
  passing through helpful because some make
  certain vitamins (K)
• Main function remove water from the undigested
  matter and form solid waste (feces)
• Made up of three parts
• Cecum (joins the small large intestine
  includes appendix)
• Colon (absorb fluids salts bacteria help
  digest remaining food products)
• Rectum (where feces is stored until they leave
  the digestive system through the anus opening in
  which solid wastes are removed)

27
(No Transcript)
28
(No Transcript)