1. Chapter 41- Animal Nutrition

2. Why do we have to eat? 1 . Fuel - Cellular respiration
2. Biosynthesis- The building of new material in the body

3. Why do we have to eat? 3. Obtain essential nutrients
- These nutrients cannot be made by biosynthesis in our bodies
- If these essential nutrients are not eaten, then malnourishment will result

4. Essential Nutrients:
- Essential Amino Acids - 20 different types are needed, but we can only make about half of them - If not consumed, then protein deficiency will result (most common type of malnutrition)

5. Essential Nutrients: - Animal meat- Complete protein
- Plant tissue- Incomplete protein

6. Essential Nutrients:
Essential Fatty Acids - Linoleic Acid (used in cell membrane construction)

7. Essential Nutrients:
Vitamins- Organic molecules, 13 of which are essential
- Water soluble- Vitamins B, C
- Fat soluble- A, D, E, K

8. Essential Nutrients: Minerals- Inorganic molecules
- Iron- Used in our blood
- Sodium- Used in many metabolic processes

9. Processing the Food That We Eat- 4 Steps
1. Ingestion- Eating
2. Digestion- Breaking food molecules down (by enzymatic hydrolysis) small enough that they can be absorbed
- Intracellular digestion- Digestion within a cell (occurs in a cells food vacuole)
- Extracellular digestion- The breakdown of food outside of the cells
3. Absorption
4. Elimination

11. Digestive Systems Incomplete Digestive System- One opening.
In many of the lower animals

12. Digestive Systems
Complete Digestive System - Two openings. Higher animals
- Called the alimentary canal
- Moves food by peristalsis (rhythmic contractions of muscle tissue)

13. Complete Digestive systems…
- Contains sphincters- Junctions between organs that are similar to drawstrings
- Contains accessory glands:
- Salivary- 3 pairs
- Pancreas, liver, gallbladder

15. Pathway of Digestive System in Humans
Oral cavity- Teeth and saliva (contains mucin which is a “slick” substance and amylase which hydrolyzes starch and glycogen). The tongue shapes the food into a bolus, which can then be swallowed.
Pharynx- Junction of the esophagus and windpipe. Epiglottis closes when swallowing to block the windpipe.
Esophagus- Connects the pharynx and stomach

17. Pathway of Digestive System in Humans
4. Stomach- Storage of food. - Preliminary digestion by gastric juices - Pepsin (called pepsinogen when inactive)- Hydrolysis of proteins - Hydrochloric Acid - Mucus lines the stomach to prevent self digestion - Acid chyme- The food that has been broken down by the gastric juices

19. Pathway of Digestive System in Humans
6. Pyloric sphincter- The junction between the stomach and small intestine
7. Small intestine- Longest section of the alimentary canal (6m in adults).
Hydrolysis and Absorption.
- Duodenum- First 25cm. Acid chyme is mixed with the chemicals produced by the pancreas/gallbladder/liver.

21. Small intestine continued…
- Pancreas- Produces a chemical buffer to counteract the acid chyme and protein digesting enzymes
- Liver- Produces bile (stored in the gallbladder until needed) which is used for the digestion and absorption of fats

23. Pathway of Digestive System in Humans
8. Jejunum and Ileum - Absorption of nutrients and water.
- Lined with villi (with microvilli attached to them) and sometimes called a brush border.
- Only 2 cells separate the consumed food from the blood system
- The blood system will converge into the hepatic portal vein which will carry blood to the liver and then heart for distribution

26. Pathway of Digestive System in Humans
9. Large Intestine (colon)- The junction between the large and small intestine is a “T”, and the pouch that is part of the “T” is called the cecum with the attached appendix.
- 90% of the water used in digestion is (re)absorbed in the large intestine
- Bacterial flora is present for the production of vitamins
- Rectum and anus- Terminal portion of the large intestine
KNOW THE ORDER!