Digestive System – Objectives Describe and understand the basic functions of the primary components of the digestive system. Compare the functions and locations of the digestive organs in man and animals. Differentiate between and identify digestive systems of man and animals.
Digestion Digestion is the breakdown of large, complex organic molecules into smaller components that can be used by the body. Molecules need to be small enough to diffuse across plasma membranes.
Four Components of Digestion Ingestion – this is the consumption of or taking in of nutrients. Digestion – the chemical breakdown of large organic molecules into smaller components by enzymes. Absorption – the transport or delivery of digested nutrients to body tissues. Egestion – the elimination of food waste materials from the body.
Ingestion Food enters the human digestive tract through the mouth or oral cavity. Humans are considered chunk feeders because they consume chunks of food that are then mechanically broken down.
Mouth Teeth mechanically break down food into small pieces. Tongue mixes food with saliva (contains amylase, which helps break down starch).
Mouth Epiglottis is a flap-like structure at the back of the throat that closes over the trachea preventing food from entering it.
Esophagus Approximately 10” long Functions include:1. Secrete mucus2. Moves food from the throat to the stomach using muscle movement called peristalsis If acid from the stomach gets in here that’s heartburn.
Esophagus: muscular tube that connects mouth to stomach – Peristaltic waves send feed down the esophagus, (muscle contractions). – Reverse Peristalsis = blowing chunks – The cardia, located at the end of the esophagus prevents feed in the stomach from coming back into the esophagus. ( non- ruminants only)
Stomach J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces. Mixes food with digestive juices that contain enzymes to break down proteins and lipids. Acid in the stomach kills bacteria. Food found in the stomach is called chyme. 12
Small Intestine Small intestines are roughly 7 meters long Lining of intestine walls has finger-like projections called villi, to increase surface area. The villi are covered in microvilli which further increases surface area for absorption. 13
Small Intestine Nutrients from the food pass into the bloodstream through the small intestine walls. Absorbs: – 80% ingested water – Vitamins – Minerals – Carbohydrates – Proteins – Lipids * Secretes digestive enzymes 14
Large Intestine About 5 feet long Accepts what small intestines don’t absorb Rectum (short term storage which holds feces before it is expelled).
Large Intestine Functions – Bacterial digestion • Ferment carbohydrat es • Protein breakdown – Absorbs more water – Concentrate wastes
Accessory Organs Not part of the path of food, but play a critical role. Include: Liver, gall bladder, and pancreas
Liver Directly affects digestion by producing bile – Bile helps digest fat • filters out toxins and waste including drugs and alcohol 18
Gall Bladder Stores bile from the liver, releases it into the small intestine. Fatty diets can cause gallstones
Pancreas Produces digestive enzymes to digest fats, carbohydrates and proteins Regulates blood sugar by producing insulin
Understanding the Digestive Systems Ruminants Non-ruminants
A RUMINANT ANIMAL Has four distinctive compartments in its stomach, which swallows its food essentially unchewed, regurgitates, and chews it thoroughly and reswallows it again. Examples include cattle, sheep, goats, deer, rhinos, and elk.
Rumination (regurgitation) After rumen if full, it lies down to ruminate (chew its cud) Cattle spend from 5-7 hours ruminating, broken up into 6-8 periods Regurgitation is the process of forcing the feed back into the mouth for chewing Done through a series of muscular contractions and pressure in the rumen and reticulum
A NONRUMINANT ANIMAL Has a single compartment in its stomach, which swallows its food after chewing and does not regurgitate its food. Examples include pigs, humans, bears, and dogs.
Nonruminant Digestion food is swallowed directly into the single stomach compartment it is mixed with digestive juices
What do animals need to live? Animals make energy using: – food food – oxygen Animals build bodies using: – food for raw materials ATP • amino acids, sugars, O 2 fats, nucleotides mitochondria – ATP energy for synthesis
How do animals get their food? filter feeding living in your food fluid feeding bulk feeding
Getting & Using Food Ingest – taking in food Digest – mechanical digestion • breaking up food into smaller pieces intracellular – chemical digestion digestion • breaking down food into molecules small enough to be absorbed into cells • enzymes Absorb – absorb nutrients across cell membranes • diffusion • active transport Eliminate – undigested material passes out of body extracellular digestion
Different diets; different bodies Adaptations of herbivore vs. carnivore – teeth – length of digestive system – number & size of stomachs
Herbivores & Length of digestive omnivores system – long digestive systems – harder to digest cellulose (cell walls) • bacteria in intestines help Carnivores appendix – short digestive systems – protein easier to digest than cellulose
Fun Facts• HOW LONG ARE YOUR INTESTINES? Atleast 25 feet in an adult. Be glad youre not afull-grown horse -- their coiled-up intestinesare 89 feet long!• Food drying up and hanging out in thelarge intestine can last 18 hours to 2 days!• In your lifetime, your digestive system mayhandle about 50 tons!!
Write the name of each colored organ: Green: Red: Pink: Brown: Purple: Green: Yellow:
How’d you do? Green: Esophagus Red: Stomach Pink: Small Intestine Brown: Large Intestine Purple: Liver Green: Gall Bladder Yellow: Pancreas Great Job!