Ch 41 Pt 2 Flashcards
2 types of digestion
Mechanical and Chemical
Intracellular Digestion
Food particles are engulfed by phagocytosis and liquids by pinocytosis
Extracellular digestion
Specialized compartments that are contiguous with outside of the body
Most common strategy
Crop
Storage site for food, fluid is added
Gizzard
Contains hard materials to help break down food mechanically
Typhosole
Folds in the intestine to increase surface area
Gastric Ceca
(Insects, Birds) storage area used to help break down plant material
Mammals have a rudimentary cecum
Digestion first 10 seconds
Oral cavity, pharynx, esophagus
Food triggers release of saliva
Saliva contains
Mucus, antibacterial agents, salivary amylase, etc
Digestion next few hours
Peristalsis (waves of coordinated muscle contractions)
Stomach stores food and begins chemical breakdown
Stretch receptors
Sensation of fullness
Mucus Cells
Secrete mucus to protect stomach lining
Chief Cells
Secrete pepsinogen
Parietal Cells
Secrete HCl
Ulcers
Generally causes by bacterial infection
Destroy protective mucus lining, allowing gastric juices to penetrate stomach wall
Small Intestine
Duodenum (enzymatic hydrolysis and nutrient absorption)
Jejunum (contributes to nutrient and water absorption)
Ileum (primarily absorbs b12 bile salts and anything jejunum missed)
Villi
Large folds in Intestine lining to increase absorption
Each epithelial cell has many microvilli
Lacteal
Vessels of lymphatic system, absorb fat
Colon
Reclaimed water to makes feces more solid (diarrhea and constipation caused by disruption of this)
Rectum
Stores feces until elimination through anus
Regulation of the Digestion System
Enteric division of the nervous system
Endocrine system regulates digestion through hormone transport and release
Dietary adaptations
Dentition
Extensive cecum/colon (herbivores)- more water absorption
Ruminant stomach (4 chambers)
Gut microbes change
Throughout life
Mutualistic colon bacteria contain
Hydrolysis enzymes for cellulose digestion into simple sugars
