Digestive system

Digestive system

1. List organs of digestive system & their functions

   • Mouth
     • Biting, chewing, mixing, swallowing
   • Pharynx
   • Stomach
     • Churning
     • Acid breakdown of food
   • Oesophagus
   • Small intestine
   • Large intestine
     • Reabsorb H2O & electrolytes
     • Absorbs vit K & B
   • Rectum
   • Anus
   • Liver: Metabolises proteins, fats & carbohydrates
     • Stores carbohydrates, fats, vitamins & minerals

2. List accessory organs & their functions

   • Teeth
     • Mechanical breakdown of food
   • Tongue
     • Skeletal muscle
     • Helps in chewing, swallowing & speech
   • Salivary glands
     • 99.5% H2O, 0.5% Solutes
     • Moisten
     • Inhibit bacteria
     • Bind food "bolus"
     • Neutralise acidic foods
   • Pancreas (Spleen)
     • Balances stomach acid
     • produces enzyme
   • Liver
     • Makes & secretes bile
       • Bile emulsifies fat
   • Gallbladder
     • Stores & concentrates bile

3. Define ingestion, propulsion, secretion, digestion, absorption & defecation

   • Ingestion: Selective intake of food & drink
   • Secretion: H2O, HCL, salts, buffers, digestive enzymes
   • Propulsion: Moving food along the digestive tract from one part to the next
   • Digestion:
     • Mechanical - Physical breakdown of food into smaller pieces
     • Chemical - Breakdown of foods by digestive enzymes & acids
   • Absorption: Uptake nutrients into digestive cells, blood & lymph
   • Defecation: Elimination of undigested material
   • Incredible Singing Panda Does A Dance

4. List the digestive enzymes of each organ & their functions

   • Stomach
     • Annilase
     • Lipase

5. Define peristalsis, mass peristalsis and segmentation

   • Peristalsis
     • Movement/propulsion of food by smooth muscle
   • Mass peristalsis
     • Strong, progressive & vigourous peristaltic waves
     • Begins in transverse colon, propels contents to rectum/anus
   • Segmentation
     • Alternating ring-like, evenly spaced contractions of small intestines
     • Mixes chyme, bile & intestinal fluids

6. Briefly explain anatomy of layers of GI tract

   • Mucosa
     • Innermost GI layer
     • Epithelium type depends on lining function
       • Stomach - secreton
       • Intestine - absorption
     • 3 Layers
       • Epithelium
       • Lamina propria
       • Muscularis mucosa
   • Submucosa
     • Highly vascular areolar connective tissue
     • Contains most GI nerves
   • Muscularis
     • Smooth muscle, except:
       • Mouth
       • Pharynx
       • Upper oesophagus
     • 2 muscle layers
       • Inner circular
       • Outer longitudinal
   • Serosa
     • Attaches to surrounding structures
     • Secretes serous fluid

7. Describe effects of aging on digestive system