Parts of the The Digestive System http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter26/animation__organs_of_digestion.html

Anatomical Terms

Anatomy Terminology Medial- towards the midline of the body Lateral- away from the midline of the body Anterior (ventral)- front of the body Posterior (dorsal)- back of the body Superior (cranial)- toward the head Inferior (caudal) – away from the head Proximal- in proximity to or closer to Distal- distant from or further away from

Pathway of Food: A) Mouth (oral cavity) Hard palate- bony anterior portion of the roof of the mouth Soft palate- entirely muscular posterior part of the roof of the mouth

Tonsils- protection against disease Salivary glands- has an enzyme that are involved in chemical digestion

B) Teeth - used to break down (masticate) food

C) Pharynx - portion of the digestive tract between the mouth and the esophagus Serves as a passageway for food and also air on its way to the trachea

D) Esophagus -muscular tube passing from the pharynx through the thoracic cavity into the abdominal cavity to the stomach

Usually collapses until it receives bolus Peristalsis- rhythmic contraction that pushes food along the digestive tract Sphincter is located between the esophagus and the stomach to prevent acidic content from coming up

Heartburn/indigestions/acid reflux- when stomach contents enter the esophagus

E. Stomach “Gastric” Muscular sac that mixes food with digestive juices to form chyme which enters the small intestine Length- 25 cm Rugae- deep folds in the wall of the stomach Protein digestion begins Mechanical and chemical digestion

Gastric glands secrete gastric juices: Enzymes and HCl Stomach empties in 2-6 hours Chyme enters small intestine via a sphincter Mucous- help protect the lining of the stomach wall

Ulcer- open sore in the wall of the stomach caused by the break down of tissue.

F) Small intestine Named for its small diameter Absorb nutrients 6 m in length Bile (from the liver) and pancreatic juices (from the pancreas) are emptied into the small intestine

Bile emulsifies fats Pancreatic juices- aid in digestion and neutralize acidic content coming from the stomach The small intestine has a huge surface area- tennis court

G) Large intestine Function- absorb water, salts and vitamins Parts include: cecum, appendix, colon (ascending, transverse and descending) and rectum

When feces are forced into the rectum by peristalsis a defecation reflex occurs Stretching of intestinal wall sends a message to the spinal cord. Shortly after the rectal walls contract and the anal sphincter relaxes.

Defecation is a way in which the body maintains homeostasis Feces are ¾ water and ¼ solids- include bacteria and indigestible remains Polyps Constipation and diarrhea Diarrhea can be caused by nervous stimulation or infection

When a person is constipated, the feces are dry and hard Water and fiber will help!

Assignment Choose 10 structures/processes that have been presented about the digestive system For each structure write “who/what am I?” questions- I am a process that helps move food along the digestive tract by rhythmic contractions.... I am ______________________________