Anatomy & Physiology Mrs. Halkuff The Digestive System Anatomy & Physiology Mrs. Halkuff

Functions Digestion Absorption Elimination

2 Types of Digestion 1. Mechanical 2. Chemical Begins immediately after ingestion Mastication (chewing) with teeth Purpose is to break down food into smaller pieces Peristalsis: Squeezing of food down the esophagus 2. Chemical Accomplished by digestive enzymes Enzymes break down large molecules (Fats, Carbohydrates, & Proteins)

Enzymes Protease: Breaks down protein Lipase: Breaks down fat Amylase: Breaks down carbohydrates (starches down to sugars

Alimentary Canal Canal connecting mouth to anus. Mouth Pharynx Esophagus Stomach Small Intestines Large Intestines Colon Rectum Anus

Mouth Hard Palate: Roof of mouth (front) Soft Palate: Roof of mouth (back) Uvula: Fleshy flap that keeps food from moving up into your nasal cavity when swallowed. Epiglottis: Elastic cartilage attached to root of tongue that directs air into the trachea and food into the esophagus. Tongue : Moves food around and allows for taste. Teeth: Used to break down food into smaller pieces.

Coats Beginning with the pharynx to the anus, the walls of the alimentary canal are composed of two coats: Mucus Coat Epithelial Goblet cells line the canal producing mucus. Muscle Coat Inner muscles: Circular Outer muscles: Longitudinal Both coats facilitate movement of food.

Pharynx Throat Air, Food, Liquid all mix here.

Esophagus Connects the pharynx to the stomach Pushes food down by peristalsis. Bolus: Chewed food

Stomach “C-shaped” organ that contains acid to break down food. Food mixes with stomach acid to produce a thick cream called chyme. Has 3 Regions: Cardiac: Upper stomach region Body: Mid stomach region Pylorus: End stomach region

Stomach Sphincters: Muscular valves that control opening & closing. Cardioesphageal Sphincter: Valve connecting the esophagus to the stomach. Pyloric Sphincter: Valve connecting the pylorus to the small intestines.

Stomach: Curvy & Wrinkly Curvatures: Fundus Greater Curvature Lesser Curvature Rugae: Internal stomach wrinkles Fewer rugae when full More rugae when empty

Small Intestine Main function is absorption of nutrients Has 3 divisions: Duodenum Jejunum Ileum

Duodenum First segment of the small intestine Connects to stomach Receives chyme from stomach Regulates gastric emptying Continues digestion Signals hunger cues Stimulates the liver, gall bladder, & pancreas In gastric bypass surgery, the duodenum is usually bypassed.

Jejunum Second segment of the small intestine Finalizes food digestion

Ileum Third & final segment of the small intestine Main function is to absorb nutrients Returns bile back to liver Connects to the large intestine by the ileocecal valve

Large Intestine Watery waste is passed from the small intestine to large intestine. Main function is to absorb any water or minerals from the waste. Compresses waste into compact form for easy removal from the body. Chyme combines with mucus and bacteria and is converted to feces.

Large Intestine 4 divisions: 1. Cecum 2. Colon 3. Rectum 4. Anal Canal

Cecum First segment of large intestine. Connection at the small intestine at ileocecal valve.

Colon 4 segments named for their relation to the pelvis: 1. Ascending colon 2. Transverse colon 3. Descending colon 4. Sigmoid colon

Rectum Collects feces accumulated in the colon.

Anal Canal Short tube (1.5”) 2 muscular rings Involuntary (Internal muscle) Voluntary (External muscle) These muscles relax to allow for defecation.