Human Digestive System

Digestion is the ability to ______in the body into a form that can be absorbed and ______or ______.

Structures

  • The______tract (GI), also called the ______canalis the system of organs that take in ______, digest it to ______nutrients and ______the waste. These organs are the mouth, pharynx, esophagus, stomach, small intestine and large intestine. Label these in the picture above.
  • Major Functions:
  • ______, Digestion, Absorption, Defecation or ______
  • ______: Organs that help with digestion but are ______part of the digestive tract. These organs are the tongue, salivary glands, liver, gall bladder, and pancreas. Label these in the picture above.

Following the Trail of Food:

  • The process begins in the mouth.
  • Chewing initiates ______breakdown of food
    and is followed by secretion of ______, which moistens
    and lubricates ______for swallowing.
  • ______also contains ______(enzymes),
    which start the chemical breakdown of______.
  • The swallowing reflex begins in the ______and initiates
    rhythmic waves of smooth muscle contractions called ______.
  • Peristaltic contractions______food to the stomach
    and allow a person to swallow even if he/she are upside down.
  • The ______contains an extra layer of muscle that aids in mechanically mixing and ______food into a semiliquid form called “______.”
  • Chemical digestion begins with proteins through the action of hydrochloric acid (______) and the enzyme, pepsin.
  • Only water and a few substances, such as aspirin and alcohol, are absorbed by the ______of the stomach.
  • As food enters the ______secretions from the liver, gall bladder and pancreas are added. Label these in the following picture.

  • The ______completes digestion of food materials by ______nutrients into the blood stream
  • The lining of the small intestine consists of tiny folds or______projections, called ______, which, in turn, are covered by ______which increase surface area
  • The villi contain capillaries and ______vessels for the absorption of nutrients
  • Microvilli have ______to hydrolyze lactose and sucrose.

______

  • ______does not contain villi and it plays no role in digestion
  • Only ______and vitamin _____ are absorbed from the large intestine
  • Undigested or unabsorbed food is ______through the ______and then anus.

Where do the nutrients get broken down?

Carbohydrate Digestion / Protein Digestion / Nucleic Acid Digestion / Fat Digestion
Mouth
Throat, Esophagus
Stomach
Small Intestine

What enzymes break down each nutrient?

(amylose is starch, a polysacch) / (amino acids are connected by “peptide” bonds) / (nucleotides are building block of DNA and RNA) / (fats are made of lipids)

Cool Facts

  • Your intestines will grow to at least 25 feet as an adult. Be glad you're not a full-grown horse their coiled-up intestines are 89 feet long!
  • Food sloshing in the stomach can last 3-4 hours
  • It takes 3 hours for food to move through the intestine
  • Food drying up and hanging out in the large intestine can last 18 hours to 2 days!
  • Americans eat over 2 billion pounds of chocolate a year.
  • In your lifetime, your digestive system may handle about 50 tons!!