The Digestive System

1. The Digestive System Presented By: Sam Lund, Donovan Parker, Tom Srebernak

2. Goals of the Digestive System 1. Extract nutrients from food 2. Transform nutrients into useful forms Ex. Oreo= Glucose (sugar) 3. Absorb nutrients and distribute them where they are needed

3. 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

4. Actions of the Digestive System 1. Intake • Breaks up food • Moves food through the GI tract (Peristalsis) • Mixes with digestive enzymes 2. Secretion • Release of enzymes and hormones for chemical digestion and regulation 3. Membrane Transport - Absorption of nutrients from the tissues by the blood and lymph for transport

5. 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 without digestion • Vitamins, minerals, cholesterol, water

6. Anatomy of the Digestive System • Oral Cavity • Pharynx • Esophagus • Stomach • Small Intestine • Large Intestine

7. Small Intestine • 6 meters in length • Functions: • Chemical Digestion • Nutrient Absorption • Nutrient Transportation

8. Functions of the Small Intestine • Digestion and absorption of food • Digestive enzymes secreted by the pancreas • Enter the small intestine via the pancreatic duct.

9. Anatomy of the Small Intestine • Duodenum (25 cm) • Food mixes with bile from the gallbladder. • Jejunum (2.5m) • Absorbs nutrients into the bloodstream. • Ileum (3.6 m) • Reabsorbs bile acids.

10. Large Intestine • 1.5 meters long • Responsible for absorption of water from the indigestible residue of food

11. Anatomy of the Large Intestine Ascending Colon: Descending Colon: Up the right side Down the left side Cecum: Sac on Sigmoid Colon: lower right side S-shaped

12. Anatomy of the Large Intestine • Ascending Colon-Removes water and other nutrients • Transverse Colon-Expulsion of waste materials, continues leaching out • Descending Colon-Absorbs water from fecal matter. Stores food particles that are to be emptied into the rectum. • Sigmoid Colon- Make and eliminate feces. Contains 60 varieties of bacteria • Rectum- Temporary storage for fecal matter before it’s eliminated from the body through the anal canal.

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

14. Pharynx Purpose: Pharyngeal constrictors force food down during swallowing Divided into 3 parts: • Epipharynx • Mesopharynx • Hypopharynx

15. Esophagus • Straight Muscular tube about 1 foot long • Purpose: Muscular contraction moves food towards stomach

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

17. Enzymes Involved in Chemical Digestion • Saliva: • Amylase: Breaks down starch • Lipase: Breaks down fats when it enters the stomach • Stomach: • HCL: Activates enzymes, breaks up foods • Pepsin: Digests proteins • Renin: Digests milk

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