Digestive System Study Guide: Functions, Bile Breakdown, Identification
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Models
1. Oral Cavity
- Function: Entry point for food, where both mechanical (chewing) and chemical digestion begin.
Nutrient Breakdown:
- Carbohydrates: Breakdown starts here via the enzyme salivary amylase, which begins digesting starches into simpler sugars.
2. Lips
- Function: Helps to close the mouth, involved in articulation and eating.
3. Teeth
Types:
- Incisor: Cutting food.
- Canine: Tearing food.
- Bicuspid (Premolar): Crushing and grinding food.
- Molar: Grinding food.
Mechanical Digestion: Chewing by teeth breaks food into smaller particles, increasing surface area for enzymatic action.
4. Salivary Glands
Types:
- Parotid: Produces serous fluid with enzymes.
- Submandibular: Produces a mix of mucous and serous fluid.
- Sublingual: Produces mainly mucous.
- Secretion: Saliva contains salivary amylase for carbohydrate digestion.
5. Tongue
- Function: Assists in mechanical digestion and positioning food for swallowing.
- Papillae and Taste Buds: Detect taste, help manipulate food.
6. Tonsils
- Palatine, Lingual, Pharyngeal: Part of the immune system; protect against pathogens entering through the mouth.
7. Hard Palate, Soft Palate, and Uvula
- Function: Separates oral and nasal cavities, directs food down the pharynx.
8. Pharynx
Parts:
- Oropharynx: Pathway for food and air.
- Laryngopharynx: Leads to esophagus.
- Nasopharynx: Primarily for air passage.
- Function: Directs food into the esophagus.
9. Esophagus
- Function: Transports food to the stomach via peristalsis.
- No Significant Nutrient Breakdown here.
10. Cardiac Sphincter
- Function: Prevents backflow of stomach contents into the esophagus.
11. Stomach
Parts:
- Cardia: Entry point of the stomach.
- Fundus: Upper part that stores undigested food.
- Body: Main part where digestion occurs.
- Pylorus: Connects to the small intestine.
Chemical Digestion:
- Proteins: Breakdown starts here with pepsin (activated by stomach acid) breaking down proteins into smaller peptides.
- Fats: Small amount of lipid digestion by gastric lipase.
- Pyloric Sphincter (Valve): Controls passage of chyme (partially digested food) to the duodenum.
- Rugae: Folds that allow the stomach to expand when full.
12. Small Intestine
Sections:
- Duodenum: First section, where most chemical digestion occurs.
- Jejunum: Middle section, primary site of nutrient absorption.
- Ileum: Final section, absorbs vitamin B12 and bile salts.
Chemical Digestion:
- Carbohydrates: Pancreatic amylase (from pancreas) and brush border enzymes break down complex carbs into simple sugars.
- Proteins: Pancreatic enzymes (trypsin, chymotrypsin) and brush border enzymes further digest proteins into amino acids.
- Fats: Emulsified by bile from the liver/gallbladder; broken down by pancreatic lipase into fatty acids and glycerol.
Absorptive Structures:
- Plicae Circularis: Circular folds increase surface area.
- Villi: Finger-like projections for absorption.
- Microvilli: Microscopic folds on villi to increase absorptive area.
- Ileocecal Valve: Controls passage of contents into the large intestine.
13. Large Intestine
Sections:
- Cecum: First part, receives material from ileum.
- Appendix: Lymphatic tissue with immune function.
- Ascending, Transverse, Descending, Sigmoid Colon: Absorbs water and electrolytes, compacts waste.
- Function: Water absorption, formation of feces.
- Haustra: Pouches allowing expansion and storage.
- Taenia Coli: Muscle bands that aid in movement of waste.
14. Rectum, Anal Canal, and Anus
- Function: Stores and expels waste.
15. Pancreas
- Function: Produces digestive enzymes and bicarbonate (neutralizes stomach acid in the small intestine).
Enzymes Produced:
- Pancreatic Amylase: Continues carbohydrate digestion.
- Pancreatic Lipase: Digests fats.
- Proteases (trypsin, chymotrypsin): Break down proteins into amino acids.
16. Liver
- Function: Produces bile to emulsify fats, processes nutrients from blood.
Ducts:
- Right and Left Hepatic Ducts: Drain bile from liver.
- Common Bile Duct: Bile flows into the duodenum.
- Bile Production: Aids fat digestion and absorption.
17. Gall Bladder
- Function: Stores and concentrates bile, releases it into the small intestine.
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Liver Microanatomy Model
1. Lobule: Functional unit of the liver.
2. Central Vein: Drains blood from lobule.
3. Hepatocytes: Liver cells that process nutrients, detoxify substances.
4. Triads:
- Portal Vein: Supplies nutrient-rich blood.
- Hepatic Artery: Supplies oxygen-rich blood.
- Bile Duct: Transports bile.
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Slides
1. Tooth
- Parts: Root, crown, neck.
- Tissues: Dentin, enamel, cementum.
- Gingiva, Pulp Cavity, Pulp: Contains nerves, blood vessels for nutrition and sensation.
2. Tongue
- Papillae and Taste Buds: For taste; helps position food.
3. Esophagus
- Epithelium: Stratified squamous; protects from abrasion.
4. Stomach
- Epithelium: Simple columnar; secretes mucus to protect lining.
- Protein Digestion: Pepsin begins protein breakdown.
5. Small Intestine
Duodenum:
- Brunner’s Glands: Secretes alkaline mucus to neutralize stomach acid.
- Epithelium: Simple columnar with villi.
Ileum:
- Peyer’s Patches: Lymphatic tissue for immune defense.
- Epithelium: Simple columnar with absorptive cells.
6. Large Intestine
- Epithelium: Simple columnar, with goblet cells for mucus secretion.
- Function: Absorption of water, vitamins, and minerals.
7. Pancreas
- Acinar Cells: Produce digestive enzymes for the small intestine.
- Pancreatic Islets: Produce insulin and glucagon for blood glucose regulation.
8. Liver
- Lobule: Hepatocytes process nutrients, produce bile.
- Central Vein: Collects blood after filtration.
- Triad: Contains portal vein, hepatic artery, bile duct for nutrient-rich blood flow and bile transport.
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