The Digestive System Daniel Condo 11 th Grade

The Digestive System Daniel Condo 11 th Grade Health

Functions of the Digestive System 1. Ingestion 2. Digestion 3. Movement/Propulsion 4. Absorption 5. Elimination

Order of Digestion • • Mouth Pharynx Esophagus Stomach Small Intestine Large Intenstine Rectum and Anus

Mouth Functions: Ingestion, Digestion, and Movement -Ingestion: - Taking in food and chewing -Digestion: - Mechanical breakdown= Teeth (chewing) - Chemical breakdown= Saliva (Enzymes) -Movement: -Tongue pushes food to back of mouth - Swallowing Reflex starts in mouth, moving food into the Pharynx

Extra Credit Question How many teeth are in your mouth? Answer = 32

Pharynx - Commonly known as the Throat Functions: Movement -Movement: - Swallowing Reflex - Tongue blocks food from going back into mouth - Nasal passage is blocked off - Larynx or Windpipe is blocked off - Constrictor muscles move food to the esophagus

Esophagus Function: Movement -Movement: - Upper Sphincter* opens allowing food in from the Pharynx, then closes - Peristalsis** moves the food down the Esophagus - Lower Sphincter opens to pass food into the Stomach, then closes *Sphincter = muscular opening **Peristalsis = Involuntary , wave-like muscular movement

Stomach Functions: Digestion, Absorption, Movement -Digestion: - Mechanical breakdown occurs when involuntary muscles of stomach churn food with Gastric Juices (stomach acid) - Chemical breakdown occurs when gastric juices (including enzymes) separate food into smaller molecules - Lower Sphincter of Esophagus closes when mixing to keep out gastric juices

Stomach cont. -Absorption: - Now broken down into smaller molecules some nutrients can be absorb by the stomach wall - Stomach wall (Rugae) unfolds allowing more surface area for absorption -Movement: -Sphincter opens at base of the stomach to allow food (Chyme) into Small Intestine - Peristalsis of stomach moves it into SI

Better Understanding of the Stomach https: //www. youtube. com/watch? v=URHBBE 3 R KEs

Small Intestine Functions: Digestion, Absorption, Movement -Digestion: - Chyme is exposed to more enzymes from ducts lining the SI - Majority of digestion is done in the Small Intestine; mainly chemically - Nutrients are now broken down into easily absorbable compounds

Small Intestine cont. -Absorption: - SI is the longest section of the Digestive System to maximize absorption - Also takes the longest for food to travel to again maximize absorption - SI is lined with small finger-like folds called Villi which absorb nutrients while creating more surface area -Movement: - SI is lined with two layers of muscle that pass chyme into the Large Intestine through peristalsis

Large Intestine Functions: Absorption, Movement -Absorption: - Large Intestine absorbs water and electrolytes from remaining chyme - LI also forms remaining chyme, which is mainly waste, into feces - Movement: - LI utilizing peristalsis to some extent - Main movement is cause by large muscular contractions 2 -3 times a day

Rectum Function: Elimination -Elimination: - Main function of the rectum is store feces until an appropriate time for excretion

Anus Function: Elimination -Elimination: - Anus has 2 Sphincters - Internal sphincter opens involuntary and brings on the sensation of having to “go” - The External sphincter is controlled voluntarily and allows to choose when you “go”

What you need to know • Functions of Digestive System • Order of Digestion • Main job of each organ