The Digestive System

Nutrients… substances in food that provide energy and materials for cell development, growth, and repair.

Classes of Nutrient - Organic Carbohydrates: main source of energy Proteins: used for growth.  Fats: provide energy (stored) helps body absorb vitamins Vitamins: organic nutrients that help your body to use other nutrients.

Classes of Nutrients - Inorganic Minerals: Inorganic nutrients that regulate many chemical reactions Water: Enables chemical reactions to take place in your cells.

Enzymes - Review speed up the rate of chemical reactions They do this without being changed or used up. speed up reactions by reducing amount of energy necessary for a chemical change to begin.

Digestive Enzymes AMYLASE secreted in the mouth; breaks down carbohydrates (starches). PEPSIN, found in the stomach, breaks down proteins. Lipase made in pancreas; breaks down fats

Additional Chemical Digestives Gastric Juice – found in stomach; very acidic; (3 million times more acidic than your bloodstream) a combination of HCL and Pepsin; breaks proteins Bile – made in liver; first process in breaking fats.

Digestion Processes Chemical: chemicals in the body break large molecules into smaller ones Mechanical: physical, using teeth or muscle to help break food down

The Alimentary Canal Mouth - chemical digestion glands in mouth produce saliva, which contains amylase, which breaks down starch

Mouth Mechanical Digestion: Teeth and tongue break food into smaller pieces

Digestive System Esophagus: muscular tube connects throat to stomach. Moves food down by squeezing (peristalsis)

Peristalsis Rhythmic contraction of esophagus to move food to stomach. https://www.youtube.com/watch?v=rJS-Kh5wCQU

Your Digestive System Stomach: muscular bag Chemical Digestion: pepsin; gastric acid Mechanical Digestion: stomach contractions; food stays here ~2-6 hours, End Product: chyme: afood sludge

Digestive System Liver: produces bile; stored in gallbladder. Bile breaks up large particles of fats into smaller particles.

Some of Liver’s Jobs filters the blood coming from the digestive tract detoxifies chemicals and metabolizes drugs. secretes bile (breaks down fats) makes proteins important for blood clotting

Your Digestive System Gall Bladder: small sac that stores bile produced by liver (breaks down fats)

Your Digestive System Pancreas: produces substances that stop the action of stomach acid produces lipase which breaks fats

Pancreas’ Other Jobs excretes enzymes to break down the proteins, lipids, carbohydrates, and nucleic acids in food. as an endocrine gland, secretes the hormones insulin and glucagon to control blood sugar levels throughout the day.

Digestive System Small Intestine: digestive juices from liver and pancreas are added villi increase surface area for absorption of nutritents from chyme

Villi

Small Intestines absorbs about 90% of the nutrients from the food we eat. only 1 inch in diameter, making it less than half the diameter of the large intestine. https://www.youtube.com/watch?v=CFjlRhs1rR8

3 Parts of Small Intestine - FYI duodenum connects to the pyloric sphincter of the stomach. Partially digested food, or chyme, from the stomach is mixed with bile from the liver and pancreatic juice from the pancreas to complete its digestion in the duodenum.

3 Parts of Small Intestine - FYI The jejunum is the middle section; primary site of nutrient absorption The ileum is the final section and completes the absorption of nutrients that were missed in the jejunum.

Digestive System Large Intestine: absorbs (removes) water from undigested food; unabsorbed materials become more solid (waste - poop).

Your Digestive System Rectum: where muscles control the release of wastes from the body https://www.youtube.com/watch?v=Ujr0UAbyPS4

The Human Digestive System http://www.dnatube.com/video/8362/Digestive-System-Animation