Esophagus and StomachPresented by: Enrique, Jason, Carson, and Aidan Lov♥

Relative Size and Location of Organs

Esophagus ● Size: In the average adult male the esophagus is about 25cm in length and

1.5 - 2 cm in diameter.

● Location: Starts in the back of the throat, ends at stomach opening. Behind rib cage, trachea and heart, in front of spinal column.

Stomach● Size: Relative to the approximate size of the individual's fist.

● Location: Left side of upper abdomen, behind rib cage, in front of spinal column.

What is peristaltic movement and how does it function in the esophagus?

● A peristaltic movement is an involuntary movement of a longitudinal and circular muscle

● In the esophagus, peristaltic waves contract behind the food bolus pushing it further along the digestive tract.

Does any digestion occur in the esophagus?

● No digestion of food occurs in the esophagus

● It is where the partially broken down food is pushed from the mouth to the

stomach

What are the primary functions of the stomach?

● The stomach stores the food. Then, the stomach commences the digestion of carbs and proteins to convert the meal into chyme. Then the stomach discharges the chyme into the small intestine.

What is chyme and how does the stomach mix this material?

● Chyme is a thick, semifluid mass of partially digested food. In the stomach, gastric juices are formed by gastric glands that mixes with the chyme; the juices include the enzyme pepsin that breaks down proteins and hydrochloric acid.

What role does the stomach play in decontaminating the incoming food matter?

● The acid in the stomach kills potentially harmful bacteria.

● The stomach releases enzymes which kill bacteria

What cells in the stomach function to form enzymes and acids?

● Chief cells produce pepsinogen and gastric lipase enzymes when exposed to hydrochloric acid.

● Parietal cells produce hydrochloric acid.

● These cells are located in the mucosa (inside lining) of the stomach

Why doesn’t gastric juice digest the inside of the stomach?

● The epithelial cells in the stomach produce a solution that coats the stomach lining. The solution is Bicarbonate rich making it an alkaline substance.

● Alkaline substances neutralize acids like the hydrochloric acid in the stomach and in gastric juices.

● Sphincters are ring like muscles that contract to close a bodily opening.● The two sphincters in the stomach are the Esophageal Sphincter

(Esophagus and Stomach) and the Pyloric Sphincter (Small intestine and Stomach).

● The Esophageal Sphincter relaxes to allow food to pass from the esophagus into the stomach

● The Pyloric Sphincter relaxes to allow chyme in the stomach to pass into the small intestine.

What are sphincters and how are they related to the stomach?

What mechanical and chemical digestion occurs in the stomach?

● Mechanical digestion is the physical division of food into smaller masses

while chemical digestion is the chemical breakdown of larger molecules

into smaller molecules. The mixing action of the stomach walls allows

mechanical digestion to occur in the stomach. While food is being mixed

with gastric juices, chemical digestion occurs when enzymes in the juice

break down large molecules in the chyme to smaller molecules.

References ● http://www.webmd.com/digestive-disorders/picture-of-the-stomach (Sphincters)● http://www.britannica.com/EBchecked/topic/1081754/human-digestive-system/45317/

(Esophagus)● http://www.webmd.com/digestive-disorders/picture-of-the-stomach (Stomach)● http://www.edinformatics.com/math_science/where_is_food_digested.htm (digestion)● http://www.britannica.com/EBchecked/topic/117464/chyme (chyme)● http://www.innerbody.com/image_digeov/dige11-new.html (enzymes and acid)● http://health.howstuffworks.com/human-body/systems/digestive/question464.htm (How stomach

is not digested)