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The Digestive System

Milan

Diego

Mika

Steven

What is it?

The digestive system is uniquely designed for breaking down food into nutrients which then pass into the circulatory system and are taken to where they are needed in the body.They are used for energy, growth and cell repair.

What is it?

Four stages of food processing

Four Stages

1.Ingestion: taking in food

2.Digestion: breaking down food into nutrients

3.Absorption: taking in nutrients by cells

4.Egestion: removing any leftover wastes

Mouth

  • The mouth is the beginning of the digestive tract.
  • In fact, digestion starts here as soon as you take the first bite of a meal.
  • Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.

Mouth

Tongue

  • Not only one muscle
  • It is a group of muscles
  • We use the Tongue to taste
  • We are able to taste:
  • Bitter;salt;sweet;sour;umami
  • (Umami is a savoury taste)

Tongue

Throat

  • Also called the pharynx, it behind and below the mouth
  • When food and fluids leave the mouth, they pass through the throat
  • Swallowing of food and fluids begins voluntarily and continues automatically
  • A small muscular flap (epiglottis) closes to prevent food and fluids from going down the windpipe (trachea) toward the lungs

Throat

Esophagus

  • The esophagus is a muscular tube extending from the pharynx to the stomach.
  • By means of a series of contractions, called peristalsis, the esophagus delivers food to the stomach.
  • Just before the connection to the stomach there is a "zone of high pressure," called the lower esophageal sphincter; this is a "valve" meant to keep food from passing backwards into the esophagus.

Esophagus

Stomach

  • The stomach is a sac-like organ with strong muscular walls.
  • In addition to holding the food, it's also a mixer and grinder.
  • The stomach secretes acid and powerful enzymes that continue the process of breaking down the food.
  • When it leaves the stomach, food is the consistency of a liquid or paste. From there the food moves to the small intestine.

Stomach

Small Intestine

  • Made up of three segments, the duodenum, jejunum, and ileum, the small intestine is a long tube loosely coiled in the abdomen.
  • The small intestine continues the process of breaking down food by using enzymes released by the pancreas and bile (compound that aids in the digestion of fat and eliminates waste products from the blood) from the liver.
  • Peristalsis (contractions) is also at work in this organ, moving food through and mixing it up with digestive secretions.
  • The duodenum is largely responsible for continuing the process of breaking down food, with the jejunum and ileum being mainly responsible for the absorption of nutrients into the bloodstream.

Small Intestine

Pancreas

  • Among other functions, the oblong pancreas secretes enzymes into the small intestine.
  • These enzymes break down protein, fat, and carbohydrates from the food we eat.

Pancreas

Liver

  • Makes and secretes bile
  • Cleanses and purifies the blood coming from the small intestine containing the nutrients just absorbed.

Liver

Gallbladder

  • The gallbladder is a pear-shaped reservoir that sits just under the liver and stores bile. Bile is made in the liver then if it needs to be stored travels to the gallbladder through a channel called the cystic duct. During a meal, the gallbladder contracts, sending bile to the small intestine.
  • Once the nutrients have been absorbed and the leftover liquid has passed through the small intestine, what is left of the food you ate is handed over to the large intestine, or colon.

Rectum

  • The rectum is an 8-inch chamber that connects the colon to the anus.
  • It is the rectum's job to receive stool from the colon, to let you know there is stool to be evacuated, and to hold the stool until evacuation happens.
  • When anything comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not.
  • If they can, the sphincters (muscles) relax and the rectum contracts, expelling its contents.
  • If the contents cannot be expelled, the sphincters contract and the rectum accommodates, so that the sensation temporarily goes away.

Rectum

Anus

  • The anus is the last part of the digestive tract. It consists of the pelvic floor muscles and the two anal sphincters (internal and external muscles).
  • The lining of the upper anus is specialized to detect rectal contents. It lets us know whether the contents are liquid, gas, or solid.
  • The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to.
  • The anal sphincters provide fine control of stool. The internal sphincter keeps us from going to the bathroom when we are asleep, or otherwise unaware of the presence of stool. When we get an urge to go to the bathroom, we rely on our external sphincter to keep the stool in until we can get to the toilet.

Anus

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