Digestive%20System

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Digestive System
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Functions

• 1. Breaks down the food so that the body can use
  it
• 2. Molecules are absorbed in the blood and
  carried throughout the body
• 3. Solid wastes are eliminated from the body

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An overview of the process
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• Digestive Process
• Begins

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4 Processes of Digestion

• Ingestion Getting food into our bodies
• Digestion Breaking down food into smaller
  nutrients
• Absorption Getting those nutrients into our
  bloodstream, so that our cells can use them
• Elimination Getting rid of solid waste products

• Eat it!
• Break it Down!
• Soak It Up!
• Go to the Bathroom!

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2 Types of Digestion

• Digestion means breaking down food into smaller
  particles, called nutrients
• There are 2 kinds of digestion
• Mechanical Food is broken down by physical
  processes (chewing, grinding, moving etc.)
• AND
• Chemical Food is broken down by chemicals
  (saliva and acids)

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What are nutrients?

• Nutrients are things that our bodies need to
  survive
• Water H2O
• Proteins
• Carbohydrates
• Fats
• Vitamins
• Minerals

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Mouth

• Functions
• Mechanically breaks down food by chewing
• Wets the food with saliva
• Chemically breaks down food with enzymes in saliva

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Saliva

• Saliva-fluid that is released to help break down
  food
• chemical digestion- enzymes in saliva mechanical
  digestion- soften the bolus for easier swallowing

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Teeth

• Digestion starts here. The job of the teeth is to
  start tearing and crushing the food down into
  small enough pieces so that it can fit down our
  throats.

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Epiglottis

• Epiglottis- A flap called the epiglottis closes
  over the top of the trachea (windpipe) when
  swallowing, so that food does not enter the
  respiratory tract
• Mucus helps food go down easier

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Esophagus
Functions Involuntary smooth muscles contract
and push food toward the stomach
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Peristalsis

• The walls of the digestive tract from the
  esophagus to the anus are muscular, and contract
  rhythmically to move food. The muscular
  contractions are called peristalsis

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Stomach

• Functions
• The lining releases digestive juice, which
  contains
• Pepsin- Enzyme that breaks down protein
• Hydrochloric Acid (HCl) - Strong Acid to kill any
  bacteria you may have ingested
• Thick stomach muscles create a churning motion to
  mechanically digest food
• What type of internal stimulus causes vomiting?

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Whats that sound?

• Stomach growling occurs when the stomach
  receives signals from your brain to begin
  digestion but the stomach is empty.
• Your brain might sense you're running low on
  energy or even seeing or smelling something you
  want to eat can get things going.
• The motion of the stomach muscles begins, but
  the organ is hollow.
• The movement of the muscles mixing the acids of
  the stomach in the hollow space of the stomach
  produces vibrations we hear as growling, or
  rumbling, or gurgling.

See slide note
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Pancreas

• Attached near the first part of the small
  intestine
• Produces enzymes that help breaks down starches,
  fat and proteins that goes into the small
  intestines
• Does not break down fiber

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Liver and Gallbladder

• LIVER
• Breaks down medicines, other substances and helps
  break down nitrogen
• Produces Bile- breaks up fat particles into small
  droplets
• Gallbladder-stores the bile
• After you eat the bile passes through a tube from
  the gallbladder into the small intestine.

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Small Intestine

• Functions
• Peristalsis (contraction and relaxation of
  muscles) to push the food through
• Chemical Digestion through enzymes
• Absorption of nutrients to the blood

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Blood

• Functions
• Blood Vessels are found within the villi of the
  small intestine, here they absorb nutrients and
  deliver to the entire body

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Drying Out and Exiting the Body

• By the time the food that was eaten leaves the
  small intestine, most of the usable nutrients
  have been digested and absorbed.
• The remaining undigested material moves into the
  large intestine where large amounts of water are
  removed and the final undigested wastes exit the
  body through the rectum (stored waste material)
  and anus (comes out).
• The large intestines also contain large amounts
  of bacteria (some sources say over 700 types!)
  that digest some of the remaining material and
  produce certain vitamins.
• These bacteria also produce GAS as a by product!

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Fun Digestive Facts

• On average, the stomach produces 2 -2.5 liters of
  Hydrochloric Acid daily.
• After you eat, it takes usually between 24 and 72
  hours in healthy adults for the complete process
  of digestion to occur.
• In the mouth, food is either cooled or warmed to
  a more suitable temperature.
• Food stays in your stomach for 2 to 3 hours.
• The average male will eat about 50 tons of food
  during his lifetime in order to sustain a weight
  of 150 pounds.

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More Fun Digestive Facts

• The liver is the largest and heaviest internal
  organ of the body and weighs about 1.6 kilos.
• The Liver is the only organ of the body, which
  has the capacity to regenerate itself completely
  even after being removed almost completely.
• Scientists estimate that the average adult
  releases between 12 and 122 cubic inches of
  intestinal gas each day. Most of that gas is made
  up of hydrogen and methane produced by the
  bacteria as they ferment the fiber that was not
  digested in the stomach or small intestine.