Digestion Flashcards
Digestion
Turning food into monomers
Carbs digested into?
Glucose == ATP
Lipids digested into?
Phospholipids, cholesterol, fats, triglycerides
Proteins digested into?
amino acids
Five Stages of Digestion
Ingestion Digestion Absorption Compaction Defecation
Ingestion
Voluntary intake of food
Digestion
Mechanical = physical breakdown
- mastication - segmentation = "MIXING" - 2 directions - parastalsis = one directional movement
Chemical = adding substances to act on SA of food from mechanical digestion
-HCl, H2O, enzymes, bile
Absorption
- Glucose/AA monomers into blood
- lipids into lacteals (lymphatic system)
- OCCURS IN SMALL INTESTINES
Compactoin
Storing of waste products
_OCCURS IN LARGE INTESTINE
Defecation
Voluntary voiding of feces
Layers of Alimentary Canal (Superficial to Deep)
Mucosa -epithelium (SPECIFIC TO AREA) -Thin SM layer Muscularis -circular muscle (INNER) - segmentation -longitudinal muscle (OUTER) - parastalsis Serosa -connective tissue
Mouth
-Epithelium: stratified squamous
-Tongue = skeletal muscle used in mech. digestion
-teeth present
-Salivary glands (EXOCRINE gland) secretes:
mucus: slick alkaline mucus
serous cells: enzyme amalyse for carb digestion
Teeth are/are not bone?
Parts of tooth
NOT BONE
- Top = crown
- Bottom = root
- *blood and nerve supply through roots
- Outer Layer = enamil (hardest biological substance)
- Inner Layer = Dentin
- Gomphosis Joint holds tooth in socket
4 Functions of Stomach
- Bulk food storage (1-2 hours)
- Mechanical Digestion
- Chemical Digestion
- Production of intrinsic factor necessary to absorb vit. B
Mech. Digestion of Stomach
mixing, churning
Chem. Digestion of Stomach
- HCl (Activates pepsinogen)
- Pepsingogen = pepsin (when active)
- digests proteins
- active only at ACID (low) pH
Gastric Glands
Found in Gastic Pits of Stomach (from superficial to deep)
- Mucus Cells - secrete alkaline mucus to protect stomach from HCl
- Parietal Cells - HCl & Intrinsic Factor
- Chief Cells - Pepsinogen
- Gastric Cells - gastrin = histamine release = increased gastric juice
Activity of HCl and Pepsinogen in Stomach
- *As proteins are broken down, they bind to H+ ions causing a increased pH, which causes HCl secretion until pH remains low (all protein digested)
- Pepsinogen becomes active, pepsin, when pH is low from secreted HCl
3 Stages of Stomach Digestion
Cephalic Stage
Gastric Stage
Intestinal Phase
Cephalic Stage
- Initiated by sight/smell of food
- Begins gastric juice secretion (lasts about 10 min)
Gastric Stage
- When food enters stomach
- Initiated by stretch of stomach walls
- Mech/Chem digestion continues
- Para increased,
- Sym increased (only enough to keep sphinctors closed)
Intestinal Phase
- Gastric juice secretion stops via CCK
- Increased secondary organ secretions
- start chyme entry to Small intestine
Small Intestine Parts and Funtions (Stomach Region to Large intestine)
Duodenum
- Recieves chyme & accesory organ secretion
- Bruner’s Gland secrete alkaline mucus (turns OFF pepsin)
Jejunum
-MOST ABSORPTION HERE
Illium
- Lymphatic tissue present
- nodules in sub-mucosa (MALT)
Amino Acids absorbed how and to where?
Active transport through small intestine to bloodstream
