1. First Five Describe the differences between: digestion and absorption
physical/mechanical digestion and chemical digestion
ingestion and egestion

2. Announcements Turn in the worksheets that were assigned last week:
Photosynthesis & Respiration
Human Digestive System
Quiz on Monday (3/31) or Tuedsay (4/1): Digestive system, Respiration & Photosynthesis
Finish all Coursework by Friday at 4:45 p.m.
Work times: Mon, Wed, Thurs during LRL;
Mon – Thurs after school until 5:30 p.m.

3. Human Digestion

4. Nutrition Definition:
Taking in, absorbing and assimilating nutrients for energy, growth, and tissue repair

5. Types of Nutrients Micronutrients- vitamins, minerals, & water
Macronutrients- proteins, lipids, carbohydrates

6. Four Parts of Nutrition
Ingestion
Digestion
Absorption
Egestion

7. Four Parts of Nutrition
Ingestion
taking substances into the body through the mouth
Digestion
Absorption
Egestion

8. Four Parts of Nutrition
Ingestion
Digestion
break-down of large, insoluble food molecules into small, water-soluble molecules using mechanical and chemical processes
Absorption
Egestion

9. Four Parts of Nutrition
Ingestion
Digestion
Absorption
movement of digested food molecules through the wall of the intestine into the blood
Egestion

10. Four Parts of Nutrition
Ingestion
Digestion
Absorption
Egestion
passing out of food that has not been digested, as feces, through the anus

11. Human digestive system

12. Ingestion takes place in the mouth
mechanical digestion
teeth break up food
chemical digestion
saliva
amylase: an enzyme that digests starch
mucin: a protein present in mucus that protects soft lining of digestive system and lubricates food for easier swallowing
buffers: neutralize acid to prevent tooth decay
anti-bacterial chemicals: kill bacteria that enter mouth with food

13. Esophagus
Food moves through the Esophagus to the Stomach by Peristalsis
Peristalsis: a series of involuntary wave-like muscle contractions which move food along the digestive tract

14. Stomach: function food storage disinfect food chemical digestion
can stretch to fit ~2L food
disinfect food
HCl [pH 2] kills bacteria
chemical digestion
pepsin: an enzyme that breaks down proteins
Food is further broken down into a thin liquid called chyme.

15. Which type of digestion is the following?
Chewing a saltine? -
2. Saliva breaking the saltine down into molecules of glucose? -
3. Your tongue breaking pieces of a hamburger apart?
4. Pepsin (an enzyme) in your stomach breaking the hamburger into amino acids?
Mechanical
Chemical
Mechanical
Chemical

16. Accessory Organs
Pancreas
Liver
Gall Bladder

17. Pancreas
An organ which secretes both digestive enzymes (exocrine) and hormones (endocrine)
Pancreatic juice contains enzymes which digest all major nutrient types.
Pancreatic juice moves through the pancreatic duct into the duodenum (small intestine).

18. Pancreatic Juice Digestive enzymes amylase breaks down starch trypsin
breaks down proteins to polypeptides
lipase
breaks down fats to fatty acids and glycerol
Buffers
neutralize acid from stomach

19. Liver
converts excess glucose (monosaccharide) to glycogen (polysaccharide) for storage
converts excess proteins and amino acids to other substances, such as fats, for storage
produces bile for use in digestion

20. Gall bladder
Stores bile until needed in the duodenum (small intestine)
Moves bile through the bile duct
The top half of the common bile duct is associated with the liver, while the bottom half of the common bile duct is associated with the pancreas, through which it passes on its way to the intestine.

21. Bile Bile is a bitter, greenish-yellow alkaline fluid
stored in the gallbladder between meals
discharged into the duodenum(small intestine) upon eating
aids the process of digestion
Bile emulsifies lipids
physically breaks apart large drops of fat into small drops of fat

23. Small intestine Functions: chemical digestion
absorption of nutrients through lining
small intestine has huge surface area = 300 m2 (~size of tennis court)
About every 20 seconds, the stomach contents are mixed by the churning action of smooth muscles.
As a result of mixing and enzyme action, what begins in the stomach as a recently swallowed meal becomes a nutrient-rich broth known as acid chyme.
At the opening from the stomach to the small intestine is the pyloric sphincter, which helps regulate the passage of chyme into the intestine.
A squirt at a time, it takes about 2 to 6 hours after a meal for the stomach to empty.

24. Small intestine duodenum = mostly digestion
Structure: 3 sections
duodenum = mostly digestion
jejunum = absorption of nutrients & water
ileum = absorption of nutrients & water
About every 20 seconds, the stomach contents are mixed by the churning action of smooth muscles.
As a result of mixing and enzyme action, what begins in the stomach as a recently swallowed meal becomes a nutrient-rich broth known as acid chyme.
At the opening from the stomach to the small intestine is the pyloric sphincter, which helps regulate the passage of chyme into the intestine.
A squirt at a time, it takes about 2 to 6 hours after a meal for the stomach to empty.

25. Duodenum the final stages of digestion are completed in the duodenum
1st section of small intestine
acidic food from stomach mixes with digestive juices from:
pancreas
liver
gall bladder
the final stages of digestion are completed in the duodenum

26. Absorption by Small Intestines
Absorption: movement of digested food molecules through the wall of the intestine into the blood

27. Absorption by the Small Intestine
Digested nutrient molecules are small enough to pass through the wall of the small intestine into the blood.
Water, mineral salts, and vitamins are also absorbed in the small intestine
Villi
finger-like projections in the wall of the small intestine
increase the surface area of the small intestines
greater surface area provides better absorption of materials

28. Absorption by Small Intestines
Villi: finger-like projections that increase surface area for absorption

29. VILLI

30. Large Intestine/Colon
Functions:
reabsorption of water
movement of undigested solid materials (fibers)
Structure:
shorter and wider than the small intestine

31. Rectum Last section of colon (large intestine) Eliminates feces
undigested materials
mainly cellulose from plants
roughage or fiber

32. 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
small intestine
finishes digestion
absorption of
nutrients
contains villi
pancreas
produces enzymes to
digest proteins & starch
large intestine
finishes digestion
absorption of
nutrients
contains villi

33. Digestive System Classwork
1) Go through the digestive system animation to visualize how the digestive system works ) Complete Build-A-Body: Digestive System. -- Build the digestive system -- Read through the Case Studies to answer the questions on the handout. ivesystem/ 3) Answer the follow-up questions on the handout.
Finish as homework