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Duodenum 1st section of small intestines pancreas liver gall bladder Most digestion acid food from stomach mixes with digestive juices from: pancreas liver gall bladder

Pancreas Involved in the digestion of the three types of food molecules: carbohydrates, proteins, and lipids. Digestive enzymes: digest proteins trypsin, chymotrypsin digest starch Amylase Endocrine Function -secrete insulin and glucagon Buffers neutralizes acid from stomach

Liver Organ involved with excretion, the recycling of useable materials, and the production of urea & bile bile stored in gallbladder until needed

The liver The average human liver weighs about 3.1 pounds and is about the size of a football!! It provides a multitude of functions including: Acts as a source for detoxifying the body of alcohol and poisons. Builds proteins Produces bile salts which are used to break down fats. Metabolize and store carbohydrates, which are used as the source for the sugar (glucose) in blood that red blood cells and the brain use Can supply quick energy to the body by releasing sugar.

Gall bladder Pouch structure located near the liver which concentrates and stores bile Bile duct – a long tube that carries bile. The top half of the common bile duct is associated with the liver, while the bottom half is associated with the pancreas, through which it passes on its way to the small intestine.

Bile Bile is a bitter, greenish-yellow alkaline fluid, stored in the gallbladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion. Bile acts like a detergent to emulsifies lipids (physically breaks apart FATS) bile contains colors from old red blood cells collected in liver = iron in RBC rusts & makes feces brown

mouth break up food digest starch kill germs moisten food stomach kills germs break up food digest proteins store food liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & starch

Appendix Vestigial organ / bacteria storage? Sac-like structure in humans found below the junction of the small and large intestine Vestigial organ / bacteria storage?

Large Intestine Specialized compartment of the digestive tube designed to collect undigested materials and reabsorb water Prepares waste (feces) to be expelled from the body Broken into 3 main parts: Cecum Colon Rectum

Large Intestine Solid materials pass through the large intestine. These are undigestible solids (fibers). Water is absorbed. Vitamins K and B are reabsorbed with the water. Rectum- solid wastes exit the body.

Large intestines (colon) Function re-absorb water use ~9 liters of water every day in digestive juices > 90% of water reabsorbed not enough water absorbed diarrhea too much water absorbed constipation

Large Intestines cont… ** Undigested food and water enter the large intestine where water is absorbed. Strong peristaltic action forces feces out through the rectum and the anus.

You’ve got company! Living in the large intestine is a community of helpful bacteria Escherichia coli (E. coli) produce vitamins vitamin K; B vitamins generate gases by-product of bacterial metabolism methane, hydrogen sulfide

Rectum Last section of colon (large intestines) undigested materials eliminate feces undigested materials extracellular waste mainly cellulose from plants roughage or fiber masses of bacteria

Defecation the act or process by which organisms eliminate solid or semisolid waste material from the digestive tract. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum. Undigested food may also be expelled this way; this process is called egestion

MECHANISM FOR CHEMICAL DIGESTION Hydrolysis - the splitting of large, insoluble molecules into small, soluble molecules with the addition of water

Hydrolysis cont.. ** In organisms, this process is regulated by hydrolytic (digestive) enzymes and is illustrated by the following: 1. Maltose + water ----> simple sugars (glucose) 2. Proteins + water ---> amino acids 3. Lipids + water ---> 3 fatty acids + glycerol

Hydrolysis cont… In a similar fashion, polysaccharides such as starch are completely hydrolyzed to simple sugars. + =

Ingestion Mechanical Digestion Chemical Digestion

Mouth Salivary amylase - Breaks down starches into disaccharides Lingual lipase – breaks down triglycerides into Free fatty acids, and mono- and diglycerides

Stomach Pepsin – breaks proteins down into polypeptides

Small Intestine (from pancreas) Pancreatic Amylase – continues breakdown of starches Trypsin – hydrolyzes proteins and large polypeptides into smaller polypeptides Nucleases – break down nucleic acids Pancreatic Lipase – Breaks down fat with help from bile

Action of Bile Bile is not an enzyme It allows enzymes to interact more effectively with enzymes secreted by the pancreas Non-polar regions cling to fat molecules and the like polar regions repel Fatty molecules are pulled off of large fat molecules increasing surface area, making them easier to break down

Small Intestine Maltase, Sucrose and lactase – continue breakdown of carbohydrates Peptidases-Break down dipeptides into amino acids

Practice Tracing Food through the Digestive System: http://kitses