2. 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 ed by the beginning of class. (NO TIME SHOULD BE WASTED WAITING FOR YOUR .)

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

4. Digestive System

6. 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

7. 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

8. 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

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

10. Accessory Organs Teeth Tongue Salivary Glands Liver Gall Bladder
Pancreas

11. 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

12. Pharynx
Motility: pharyngeal constrictors force food down during swallowing

13. Esophagus Straight muscular tube about 1 foot long
Straight muscular tube about 1 foot long
Motility: muscular contraction moves food towards stomach

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

15. Rugae in the Stomach
Rugae- folds in the stomach lining that allow it to expand with more food
How do we vomit?

16. Pyloric Sphincter Ring of smooth muscle
Regulates the passage of material from the stomach into the duodenum

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

18. Small Intestine
2 meters long, 1 inch in diameter, 5-6 meters in cadaver
Functions:
Chemical Digestion
Nutrient Absorption
Motility

19. Small Intestine

20. 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

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

22. Large Intestine

23. 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

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

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

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

27. 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

28. 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

29. 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

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

31. 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

32. 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)

33. 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

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

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

36. 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

37. Digestive System Reinforcement

38. 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.

39. 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.

40. 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.

41. 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.

42. 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.

43. 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.

44. Eukaryotic Cell