Digestive system Flashcards
What is the function of the digestive system ?
- break down the foods you eat,
- release their nutrients, - absorb those nutrients into the body
What is the function of the alimentary canal?
to nourish the body
What are the 4 layers of the alimentary canal?
- Mucosa
- Submucosa
- Muscularis
- Serosa
What is the mucosa layer?
-Epithelium
- Lamina propria
-muscularis mucosa
- Responsible for production of mucus
What is the Submucosa layer ?
Dense connective tissue
- blood and lymphatic vessels (transport nutrients)
- submucosal glands release digestive secretions
What is the muscularis layer?
- Double layer of smooth muscle (inner = circular layer) (outer = longitudinal layer)
What is the Serosa layer?
- Present only within the abdominal cavity
- layer of visceral peritoneum and loose connective tissue
- Holds the alimentary canal in place near the ventral surface of the vertebral column
What is the epithelium in the mouth pharynx, esophagus and anal canal?
Non keratinized, stratified squamous epithelium
What is the epithelium in the stomach and the intestines?
Simple columnar epithelium
What are accessory cells of the gastrointestinal epithelium ?
- Goblet cells = mucus + fluid in lumen
- Enteroendocrine cells = hormones into the interstitial space btwn cells
What is the lamina propria and what is its function?
- loose connective tissue with numerous blood and lymphatic vessels
- Function : Houses cluster of lymphocytes = immune
What are peyer’s patches and what are their function?
Lymphocyte clusters in the distal ileum
-function: defence against pathogens in the alimentary canal.
What is the function of the muscalaris externa layer?
- Promote mechanical digestion
- expose more food to digestive chemical
- move food along the canal (peristalsis)
What is the peritoneum and what is its function?
- serous membrane sac of squamous epithelial tissue surrounded by connective tissue
- Holds the digestive organs in place within the abdominal cavity.
What are the two peritoneum layers and what do they line?
- Parietal peritoneum = abdominal wall
- Visceral peritoneum = envelop abdominal organs
Where does mechanical digestion occur?
- mouth (chewing)
- Stomach (churring)
- Small intestine (segmentation)
Where does mechanical digestion occur?
- mouth (chewing)
- Stomach (churring)
- Small intestine (segmentation)
What is the difference between peristalsis and segmentation?
Peristalsis = Propulsion allowing food to move along the alimentary tract.
Segmentation = contract smooth muscles along the small intestine back and forth
What are the accessory organs and their function?
- Liver : production of bile salts
- Gallbladder : stores, concentrates and releases bile
- Pancreas: produces digestive enzymes and bicarbonate = neutralizes chyme
What are gastric pits and their function?
- Are the entry points along the epithelium to gastric glands which secrete complex digestives fluid (gastric juice)
What are the 3 regions of the small intestine?
- Duodenum
- Jejunum
- Ileum
What are the three unique features of the mucosa and submucosa layers of the small intestine?
- Circular folds
- Villi
-Microvilli
Explain the mechanical digestion that occurs in the small intestine?
Called segmentation: separates chyme and pushes it back together to mix it up and provide more time for digestion and absorption.
What is the main focus of digestion in the small intestine?
Lipids
Although the small intestine finishes the digestion of proteins and carbs.
What facilitates absorption in the small intestine ?
Intestinal juices + pancreatic juices
Where is most of water absorption occuring?
Small intestine
Where does enzymatic digestion occur in the small intestines?
Lumen and the luminal surfaces of mucosal cells