Digestive System Journey Project You will be handed an index card with a portion of the digestive system. Research the function of the part and create a minimum of 1-2 slide presentation on that part. Prepare to present this short presentation on Wednesday, February 26. All PPT/Prezi must be emailed by the beginning of class. (NO TIME SHOULD BE WASTED WAITING FOR YOUR EMAIL.)

The Journey of Food What happens to our food as it travels through our digestive system? http://www.youtube.com/watch?v=e3O1AdlC8bI& oref=http%3A%2F%2Fwww.youtube.com%2Fwa tch%3Fv%3De3O1AdlC8bI&has_verified=1 http://www.youtube.com/watch?v=lm3oIX6jjn4

Digestive System

Functions of the Digestive System Ingestion: intake of nutrients Digestion: breakdown of large particles into smaller ones Absorption: uptake of nutrient molecules Defecation: elimination of undigested residues

Actions of the Digestive System 1. Motility Breaks up food Moves food through the GI tract (Peristalsis) Mixes with digestive enzymes Secretion Release of enzymes and hormones for chemical digestion and regulation Membrane Transport - Absorption of nutrients from the tissues by the blood and lymph for transport

Stages of Digestion Mechanical: physical breakdown of food Chemical: digestive enzymes hydrolyze food particles to break larger molecules into smaller ones Some nutrients are absorbed with out digestion Vitamins, minerals, cholesterol, water

Anatomy of the Digestive System Oral Cavity Pharynx Esophagus Stomach Pyloric Sphincter Small Intestine Large Intestine

Accessory Organs Teeth Tongue Salivary Glands Liver Gall Bladder Pancreas

Oral Cavity Functions: Mechanical Mastication Chemical A. Ingestion: cheeks lips and tongue mobilize food B. Digestion: Mechanical Mastication Chemical 3 salivary glands Digests some starches and fat

Pharynx Motility: pharyngeal constrictors force food down during swallowing

Esophagus Straight muscular tube about 1 foot long www.mywebmd.ca.com Straight muscular tube about 1 foot long Motility: muscular contraction moves food towards stomach

Stomach Muscular sac on the left side of the peritoneal cavity Functions: Food storage Mechanical digestion Chemical digestion

Rugae in the Stomach Rugae- folds in the stomach lining that allow it to expand with more food How do we vomit? http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion

Pyloric Sphincter Ring of smooth muscle Regulates the passage of material from the stomach into the duodenum http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion

Digestion in the Stomach Mechanical Digestion: Muscular contraction Chemical Digestion: Secretes digestive enzymes and HCl

Small Intestine http://www.afns.ualberta.ca/bbo/1/ANATOMY/SI1.asp 2 meters long, 1 inch in diameter, 5-6 meters in cadaver Functions: Chemical Digestion Nutrient Absorption Motility

Small Intestine

Functions of the Small Intestine Microvilli Motility: smooth muscle contract Digestion: chemical enzymes received from the pancreas, liver and gall bladder Nutrient reabsorption: microvilli increase surface area

Large Intestine Functions Motility Reabsorbtion of Water and Electrolytes Symbiotic bacteria Synthesis Vitamins B & K

Large Intestine

Enzymes Involved in Chemical Digestion Saliva: Amylase: breaks down starch Lipase: breaks down fats when it enters the stomach Low pH of the stomach activates the enzyme

Enzymes Involved in Chemical Digestion Stomach: Digestive chemicals- HCl: activates enzymes, breaks up foods Pepsin: digests proteins Renin: digests milk

Pepsin Formation Interactions between Cells Chief Cells make pepsinogen Parietal Cells make HCl Pepsinogen is cleaved by HCl into Pepsin

Enzymes Involved in Chemical Digestion Small Intestine Two sources of enzymes Liver and Gall bladder Pancreas

Enzymes Involved in Chemical Digestion in the Small Intestine Liver secretes bile that is active in the small intestine Bile: aids in fat digestion and absorption Activates pancreatic enzymes Synthesized from cholesterol Bacteria in the small intestine use bilirubin to make your feces brown Gall bladder stores and concentrates bile

Enzymes Involved in Chemical Digestion in the Small Intestine Pancreas: secretes pancreatic juice Amylase: breaks down starch Lipase: breaks down fats Ribonuclease (RNAase): breaks down RNA Deoxyribonuclease (DNAase): breaks down DNA Zymogens: inactive enzymes that activate in the small intestine

Mechanism of Absorption Membrane Transport: Nutrients pass through membrane surface The greater the membrane surface area, the greater the amount of nutrients that can be transported Surface Area Rugae Microvilli

Final Destinations of Digestion Products Starches  bloodstream Fats  lymph vessels (lacteals) Proteins  bloodstream

Macromolecules Large organic compounds that are essential to life Proteins: Serve many functions; include enzymes Nucleic Acids: Direct protein production; include DNA and RNA Carbohydrates: Provide energy and structure; include sugars, starch, and cellulose Lipids: Not soluble in water; many functions; include fats, waxes, and hormones

Carbohydrates All have formula: CnH2nOn Classified as Monosaccharides (one) Disaccharides (two) Polysaccharids (many) Function in humans: Energy storage Living things contain inorganic compounds (nacl) Some organic compounds (plastic) not found in living things Think about words: condensation (dehydration synthesis), hydrolysis Think about word: carbohydrate Glucose (monosaccharide)

Lipids Type Function Triglycerides (fats & Oils) Diverse, but all are non-polar (thus hydrophobic) Type Function Triglycerides (fats & Oils) Energy storage, insulation Steroids (including cholesterol) Hormones, part of cell membrane Phospholipids Chief component of cell Membrane; Covers Nerves Vitamins (A, E, K) Vital for many functions Living things contain inorganic compounds (nacl) Some organic compounds (plastic) not found in living things Think about words: condensation (dehydration synthesis), hydrolysis Think about word: carbohydrate Sucrose = plant form of glucose

Amino Acids Proteins are folded-up chains of amino acids. There are 20 commonly occurring amino acids.

Protein structure 2050 variations in primary structure of a 50 aa protein. That 1 X 10^65

Functions of Proteins Function Example Details Enzymes lactase Breaks down lactose Movement myosin & actin Slide past each other to cause muscle contraction Transport hemoglobin Carries oxygen in blood Structural collagen Tough fiber that provides strength Hormones insulin Regulates blood sugar Defense immunoglobins Antibodies Partial list only! 2050 variations in primary structure of a 50 aa protein. That 1 X 10^65

Digestive System Reinforcement

I. Function of the Digestive System The main job of the digestive system is to take food and change it into energy for our cells. The digestive system takes food into the mouth and then it breaks it down through mechanical and chemical digestion. Any food not digested or absorbed by the body are eliminated (gotten rid of) by the digestive system.

II. What happens when we eat? When we eat, food is broken down into smaller molecules that can move from the digestive system to the circulatory system (the blood). After the nutrients move into the blood, they can be taken to the rest of the cells in your body.

III. Pathway of Food Digestion in Our Bodies Food enters through the mouth where mechanical digestion begins as the teeth chew. Chemical digestion also happens in the mouth as the salivary glands in your mouth secrete saliva. Saliva contains an enzyme called amylase which breaks down starches into smaller sugars called glucose.

III. Pathway of Food Digestion in Our Bodies After the food is molded into a ball by the tongue, it is swallowed and enters the esophagus. The esophagus is a muscular tube which connects the mouth to the stomach. Food moves down the esophagus by peristalsis. Peristalsis is a series of involuntary, smooth muscle contractions along the walls of the digestive tract.

III. Pathway of Food Digestion in Our Bodies Once the food reaches the stomach, glands in the stomach lining secrete gastric juices which are made up of an enzyme called pepsin as well as hydrochloric acid (HCl). The stomach is a muscular, pouch-like enlargement of the digestive tract where both mechanical & chemical digestion occur. Mechanical digestion: Walls of the stomach contract to mix food. Chemical digestion: Glands in the stomach secrete gastric juices made up of pepsin and HCl which break down food into smaller molecules.

III. Pathway of Food Digestion in Our Bodies Food leaves the stomach and enters the small intestine. Food digestion is completed n the small intestine through mechanical and chemical digestion. Mechanical digestion: Muscles contract to help break down food. Chemical digestion: The pancreas and the liver secrete fluids which help neutralize the acid from the stomach as well as enzymes which break down the food substances even more.

Eukaryotic Cell