The Digestive Process

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The Digestive Process

• ByMiss Burd

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Functions of the Digestive System

• 3 Main Functions
• Breaks down food into molecules the body can use
• Molecules are absorbed into the blood and carried
  throughout the body
  
• Wastes are eliminated

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Functions of the Digestive System

• Digestion- process by which your body breaks down
  food into small nutrient molecules.
  
• 2 Types
• Mechanical
• Chemical

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Functions of the Digestive System

• Mechanical Digestion
• Foods are physically broken down into smaller
  pieces.
  
• It occurs when you bite into food and chew them
  into smaller pieces.
  
• Smooth muscle in the
• stomach contract,
• mixing up food

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Functions of the Digestive System

• Chemical Digestion
• Chemicals produced by the body break foods into
  their smaller chemical building blocks
  
• Example- Starch in bread is broken down into
  individual sugar molecules
  
• Now the molecules are ready to be transported
  throughout the body
  
• Absorption- the process by which nutrient
  molecules pass through the wall of the digestive
  system into your blood.
  
• Materials that are not absorbed, such as fiber,
  are eliminated as waste.

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The Mouth

• Saliva- fluid released when your mouth waters
• Plays a role in both chemical and mechanical
  digestion
  
• Teeth- tear into food
• Saliva mixes with food and moistening them into a
  slipper mass

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The Mouth- chemical digestion

• Chemicals in saliva break down starch into sugar
  molecules (tastes sweet)
  
• Chemical digestion is accomplished by ENZYMES.
• Enzyme- a protein that speeds up chemical
  reactions in the body
  
• Each enzyme has a particular shape, which enables
  it to take part in only ONE kind of chemical
  reaction.
  
• Examples- the enzyme that breaks down starch into
  sugar can not break down proteins into amino
  acids.
  

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The Esophagus

• As you swallow, muscles in your throat
• move the food downward
• When you eat a flap of tissue in your
• throat, the epiglottis, seals off your
• windpipe, preventing food from entering.
• Food goes into the esophagus
• The esophagus is lined with mucus, a thick,
  slippery substance produced by the body
  
• Food stays in the esophagus for about 10 seconds
• Contractions of smooth muscles push the food
  toward the stomach

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The Esophagus

• Peristalsis- involuntary waves of smooth muscle
  contactions
  

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STOMACH

• Food enters the stomach from the esophagus
• Stomach- a j-shaped muscular pouch, located in
  the abdomen
  
• The stomach expands to hold all the food
• An average adult
• stomach holds 2
• liters of food

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STOMACH

• Mechanical digestion occurs in the stomach, three
  strong layers of muscle contract to produce a
  churning motion
  
• Squeezes the food and mixes it with fluids,
  similar to a washer machine
  
• Chemical digestion is taking place at the same
  time
  
• Digestive juices are produced by the lining of
  the stomach

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STOMACH

• Pepsin- enzyme in the digestive juices that
  breaks down proteins into amino acids
  
• Hydrochloric Acid- the digestive juices also
  contain a strong acid
  
• the acid kills most bacteria and pepsin works
  best in an acid environment
  
• Why doesnt the acid burn a whole in your stomach?

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STOMACH

• The digestive juices also contain mucus, which
  coats and protects the lining of your stomach
  
• Cells that line the stomach are quickly replaced
  when they are damaged or worn out
  
• Food remains in the stomach until it is in liquid
  form
  
• Most of the protein has been chemically digested
  into shorter chains of amino acids
  
• The food is now released into the next part of
  the digestive system

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• Did You Know?
• About 10 billion tiny scales of skin rub off your
  body every day. In a lifetime, you could fill
  eight 5-pound bags with dead skin.
  
• Snot is a part of your daily diet. Humans swallow
  about one quart of nose mucus every day.
  
• The hydrochloric acid in your stomach is so
  strong that it can eat up stainless steel razor
  blades.
  
• Your mouth is the most unsanitary part of your
  whole body. More than 100,000,000 microcreatures
  live there at any one time. That's more critters
  than there are people in Australia, Canada and
  Spain combined!
• Ear wax coats the inside of the ear canal to trap
  nasty stuff like dirt, dust and bugs. The wax
  dries up, forms little balls and drops out when
  you yawn, chew or swallow.