The Human Digestive System

Cells, Tissues, Organs & Systems The basic structure in the human body is the CELL There are over 200 different types of cells in the human body Cells of the same type combine to form TISSUES Different tissues combine to form organs (structures that work towards a common goal)

Cells, Tissues, Organs & Systems Groups of organs working together towards a common goal are called SYSTEMS

The Digestive System

Digestion The transformation of food into smaller molecules that can be used by the body Two ways: Physical Transformation: breaking food down physically and moving it along through the tube Chemical Transformation: enzymes produced by the body break apart different molecules

Anatomy of the Digestive System Digestive Tract Mouth Esophagus Stomach Small Intestine Large Intestine (Colon)

Anatomy of the Digestive System Digestive Glands Salivary glands Pancreas Liver Gastric glands Intestinal glands

The Mouth

The Mouth The Tongue Teeth Responsible for moving food around to different parts of the mouth Teeth Incisors: four front teeth (top & bottom); used to cut pieces of food Canines: pointy teeth beside incisors; used to shred food (especially meat) Premolars: towards the back from canines; used to grind and crush food Molars: at the very back; used to grind and crush food

The Mouth

The Mouth The Pharynx (throat) Salivary glands Cavity at the back of the mouth Place where digestive and respiratory tubes meet Salivary glands Produce saliva Saliva is used to kill bacteria and begin the digestion of starch molecules Three sets: parotid glands, sublingual glands and submandibular glands

The Mouth

The Esophagus A tube, roughly 25 cm long and 3 cm in diameter Peristaltic contractions of the walls of the esophagus push food down to the stomach

The Esophagus

The Stomach The stomach has valves at both ends The cardiac sphincter (entrance) The pyloric sphincter (exit) The gastric glands produce gastric juice (a mix of enzymes, hydrochloric acid and mucus) Function: mixes food with gastric juice to begin digesting protein and sugars

The Stomach

The Small Intestine About 7 m long and 3 cm in diameter Three sections The Duodenum: first 25 cm at the exit of the stomach The Jejunum: next 2 m The Ileum: the final 5 m ending at the colon Intestinal Glands: produce intestinal juice (a mix of enzymes used to digest protein and carbohydrates)

The Small Intestine

The Liver The largest gland of the human body Produces BILE, a liquid that is stored in the GALL BLADDER Bile drains down to the duodenum when needed and is used to break fats into smaller droplets

The Liver

The Pancreas A long, leaf-shaped gland below and behind the stomach Produces PANCREATIC JUICE, a liquid that drains to the duodenum and is used to digest protein Also produces INSULIN, a hormone used to help sugars leave the blood and enter cells

The Pancreas

Absorption At the end of the digestive process (in the small intestine), simple nutrients are ready to enter the bloodstream Carbohydrates: simple sugars (glucose, galactose and fructose) Protein: amino acids Fat: fatty acids and glycerol Vitamins Minerals

Absorption Simple nutrients pass through VILLA in the walls of the small intestine

The Large Intestine (Colon) About 2 m long and 8 cm in diameter Begins with the cecum and the appendix Ends with the rectum and the anus Divided into three sections: Ascending colon Transverse colon Descending colon

The Large Intestine (Colon) Water is absorbed into the blood Some vitamins are produced by bacteria living in the colon and then absorbed

The Large Intestine (Colon)

All together now… http://kitses.com/animation/swfs/digestion.swf