Digestive Play

Digestive systems Everybody’s got one!

Functions of the digestive system: Ingest food and convert to energy. Absorb nutrients Eliminate waste Alimentary Canal or GI tract: Broken into sections with different jobs. Mouth > Esophagus > Stomach > Small Intestine > > Large Intestine > Sigmoid Colon > Rectum > Anus Many other organs help along the way.

Mouth: Chief function is to receive food and begin digestion process. Teeth: Incisors-Cut Canines-Tear Pre-molars and Molars for grinding and crushing. Tongue helps to manipulate food, move it, and taste it. Salivary Glands: Saliva to soften and digest food. amylase helps break down starch.

After food is softened and balled up it is called a bolus. Salivary Glands: Parotid Sublingual Sub mandibular After food is softened and balled up it is called a bolus.

The bolus passes through the pharynx and goes into the Esophagus Swallowing is a reflex action. We start the process, but the food is pushed down the Esophagus tube involuntarily. Peristalsis- Rhythmic contraction that pushes food along GI tract. Esophagus connects mouth to stomach. Entrance to stomach controlled by valve like muscle called esophageal sphincter. “Heart Burn”

Stomach: Diameter changes to accommodate food and fluid. Folds called rugae that disappear as stomach expands. Four sections: Cardiac Fundic Body Pyloric

Fig. 15.4a

Stomach: Functions to mechanically and chemically digest food. Contraction of muscle helps separate food into small pieces and mix it with digestive enzymes. Chemical digestion: H Cl made by gastric cells in stomach-breaks down connective tissue and activates pepsin enzyme. Also functions in protection from bacteria. Pepsin breaks down protein. Chyme: soupy liquid that leaves stomach.

Chyme leaves the stomach through the pyloric sphincter and enters into small intestine. Roughly 6m in length but small in diameter. Three sections: Duodenum, jejunum and ileum

Site of chemical digestion of all food contents: Receives input of digestive enzymes from liver and pancreas. Bile from liver and pancreatic juice. Absorption of nutrients. Villa and micro villa help increase the surface area to maximize absorption. Passes non-digestible products to large intestine. Passes through the ileocecal valve.

Large Intestine: Shorter in length, but wider in diameter compared to the small intestine. Cecum Colon: Ascending Transverse Descending Sigmoid Rectum Anal Canal

Fig. 15.9a

Large Intestine: Functions to absorb water and transport waste to rectum. Also an important site or vitamin production by resident bacteria. (B and K) Waste then leaves through the anal opening.

Pancreas: Functions as an endocrine and exocrine gland. Pancreatic Juice contains: Sodium bicarbonate: raises pH Amylase: digests starches Trypsin: digests proteins Lipase: digests lipids. Nucleases: digest nucleic acids

Liver: Largest organ of the body (not counting skin)

Function of Liver: Blood enters and toxins are removed and detoxified. Stores vitamins and iron. Helps regulate cholesterol level and aids in production of blood plasma proteins. Produces bile which is stored in the gall bladder. Bile is a fat emulsifier.

Disorders: Maintains blood sugar level. Jaundice Hepatitis Cirrhosis Removes excess glucose and stores it as glycogen. Glycogen is broken down and glucose released when level is low. Produces glucose if needed. Disorders: Jaundice Hepatitis Cirrhosis