1. Agenda 1/5 and 1/8 Digestion System Notes Practice Diagram
Review Tasks
Turn in: Video notes and workbook
Homework: Digestion Worksheet (posted on website)

2. Digestion Steps 1. Ingestion- you eat the food
2. Digestion- series of chemical reactions where the food is converted into smaller molecules
3. Absorption- Smaller molecules are absorbed into your bloodstream
4. Transport- Those smaller molecules are moved to where they are needed in your body
Digestion breaks molecules down into smaller parts. Those molecules can then be used to make larger molecules we need
Ex: Proteins you eat are broken down into amino acids. Those amino acids can then be used during protein synthesis

3. Food Molecules
Starch, glycogen, lipids, and nucleic acids are digested into monomers
Cellulose (known as dietary fiber) is undigested by our bodies
But bacteria in our gut can digest it!

4. Enzymes
As food travels through your digestive system, enzymes are added along the way to break the food down
Enzymes are specific for a specific food type
Enzymes act as catalysts for reactions
Enzymes work best at 37 degrees Celsius (body temperature)
What happens if this temperature increases too much?

5. Anatomy of Digestive System
Basically a long tube called the alimentary canal
Two accessory organs: Pancreas and liver
Connected to the canal by ducts
Begins in the mouth, ends at the anus
*draw, label, color your own digestive system diagram!

6. Digestive System Sketch

7. Alimentary Canal
Smooth muscles in the alimentary canal cause food to move through the digestive system
Smooth muscles are control by the autonomic nervous system and are involuntary
Meaning you don’t have to think about your digestive system muscles as you sit here!
Two layers of muscle: circular and longitudinal

8. Microscopic Digestive Tissue- Small Intestine

9. Pancreas
The pancreas produces insulin and glucagon which an involved in cellular respiration
It also produced three enzymes important to digestion
1. Lipase- breaks down lipids
2. Amylase- breaks down sugars
3. Endopeptidase- breaks down proteins

10. Small Intestine
The pancreas produces juice that goes into the duodenum (the first part of the small intestine)
The enzymes in that juice begin to break food particles down into smaller molecules
The smaller molecules can be absorbed by the intestines and go into the blood stream so they can be used by your body

11. Villi in Small Intestines
Villi are small folds and projections that increase the surface area that can absorb nutrients in the intestines
Epithelial cells have tiny microvilli that extend into the lumen of the intestines and absorb digested particles to be transported through the blood stream
Villi absorb: water, glucose, amino acids, nucleotides, glycerol, fatty acids, mineral ions, vitamins

12. Microscopic Cross-Section of Villi

13. Active vs. Passive Transport in Villi
Molecules move out of the lumen in the villi through active or passive transport
Simple Diffusion: Small, non- polar molecules (like fatty acids)
Facilitated Diffusion: Large or polar (like glucose)
Active: Glucose and amino acids if moving against concentration gradient

14. Role of Liver in Digestion
The liver produces bile which is stored in the gall bladder
Bile is used to break down fats
The liver has other roles- like storing glycogen for energy outside of digestion

15. Things to Label on Small Intestines
Villi
Lumen
Circular Muscle
Longitudinal Muscle