Small & Large Intestine Flashcards
Segments of Small Intestine
Duodenum
Jejunum
Ileum
Duodenum
Receives chyme from the stomach and digestive secretions from the pancreas and liver
Jejunum
Bulk of chemical digestion and nutrient absorption
Ileum
Absorbs vitamin B12, bile salts and remainder of nutrients
Absorption facilitated by:
Movement: smooth muscle Large surface area: tube length, plicae circulates, villi, microvilli Enzymes: in lumen Protection: epithelial cells Absorption: transporters
Digestive Tract Layers
Mucosa
Submucosa
Muscularis Externa
Serosa
Mucosa
Inner lining
Exposed to lumen
Mucous membrane
Epithelium
Submucosa
Surrounds mucosa
Dense connective tissue
Blood vessels and lymphatics
Muscularis Externa
Smooth muscle: circular layer and longitudinal layer
Mechanical processing
Movement
Serosa
Surrounds musuclaris externa
Secretes lubricating fluid
Reduces friction
Plicae Circulares
Folds of the submucosa
Increases surface area of absorption
Covered with villi
Mostly found in jejunum
Intestinal Villi
Finger-like projections of mucosa
Increase surface area
Villi contain a lacteal and a capillary network each to absorb fats and nutrients
Goblet cells secrete mucous
Columnar epithelial cells absorb nutrients
Microvilli
Project from epithelial cells
“Brush border”
Contain integral BB enzymes and transporters
Epithelial cells absorb nutrients
Small Intestine Blood Supply
Arteries - branch off celiac trunk artery - superior mesenteric artery Veins - hepatic portal vein - superior mesenteric vein
Sections of Large Intestine
Ascending
Transverse
Descending
Features of the Large Intestine
Taeniae Coli - bands of longitudinal muscle
Haustra - pouches permitting expansion and elongation of the colon
Fatty appendices - storage of fat
Large Intestine Function
- Absorption of water
- Absorption of remaining nutrients
- Houses gut flora
- Compaction of material into faeces
- Storage
Cecum
Collects and stores material from the ileum
Ileocecal valve controls passage
Appendix
Attached to cecum
Organ of lymphatic system
Storage of gut flora
Inflammation: appendicitis
Rectum
Expandable/temporary storage
Expansion of the rectum triggers urge to defecate
Features:
- Anal canal
- Anal columns
- Internal (involuntary) and external (voluntary) anal sphincters
- Anus
Large Intestinal Wall
Serosa Muscular layer: longitudinal layer, circular layer Submucosa Musuclaris mucosae Goblet cells Intestinal gland Aggregated lymphoid nodule Simple columnar epithelium Thinner wall than small intestine Lack of villi and place circulates Abundance of goblet cells
Large Intestine Blood Supply
Hepatic portal vein Superior mesenteric vein Inferior mesenteric vein Superior mesenteric artery Inferior mesenteric artery
