Unit 3 Digestive System Flashcards
digestive general structure
tube with 4-layered wall: mucosa submucosa muscularis externa (propria) serosa adventitia
digestive function
ingest, digest, absorb
digestive components
- oral cavity
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
- rectum
- anus
associated digestive glands
- salivary glands
- liver
- pancreas
mucosa functions
a) selective barrier
b) secretion
c) absorption
mucosa components
a) epithelial layer
b) lamina propria – loose connective tissue
c) muscularis mucosa – smooth muscle
submucosa
- loose connective tissue
- blood and lymphatic vessels
- Meissner’s plexus – part of the autonomic nervous system
- glands in the esophagus and duodenum
muscular externa
- usually two layers of smooth muscle
2. Auerbach’s (myenteric) plexus – part of the autonomic nervous system
serosa/adventitia
- adventitia in areas where organ is embedded in other tissue
- serosa with mesothelium where there is a free surface
esophagus function
transport food from mouth to stomach
esophagus mucosa
stratified squamous nonkeratinized epithelium
esophagus submucosa
secretory glands
muscularis externa
upper 1/3 – skeletal
middle 1/3 – skeletal and smooth
lower 1/3 – smooth
serosa/adventitia
adventitia above diaphragm
serosa below diaphragm
stomach functions
- convert ingested food to acidic chyme
- secretes pepsin (exocrine)
- secrete hormones (endocrine)
stomach regions
cardia
fundus & body (histo-identical)
pylorus
stomach rugae
- longitudinal folds of mucosa and submucosa
2. not permanent – disappear when stomach fills
stomach mucosa
- pits and glands
2. cells
stomach mucosa cells
- stem cells: in neck region and mucous neck cells
- parietal cells : HCl and intrinsic factod chief cells
- Chief cells: zymogenic granules contain pepsinogen and gastric lipase
- enteroendocrine cells
stomach submucosa
course collagenous fibers, elastic fibers, blood/lymph vessels, nerves and plexus of Meissner. No glands
stomach muscularis externa
- inner oblique
- middle circular
- outer longitudinal
small intestine function
- final digestion
- absorption
- endocrine secretion
small intestine segments
- duodenum
- jejunum
- ileum
small intestine muscosa
- structural increase in SA
- crypts of Lieberkuhn
- cells
- Peyer’s patches (lamina propria of ilium)
structural increase in SA
plicae circulares (permanent folds)
villi
microvilli
cells of mucosa
a) intestinal absorptive cells
b) goblet cells
c) Paneth cells
d) enteroendocrine cells
intestinal absorptive cells
enterocytes; columnar epithelial cells with microvilli
intestinal goblet cells
protection and lubrication; increase in number as approach the ileum
intestinal Paneth cells
base of crypts; secrete lysozyme
enteroendocrine cells
(1) cholecystokinin(CCK)
(2) secretin
cholecystokinin (CCK)
stimulates secretion of pancreatic enzymes; stimulates contraction of gall bladder
secretin
stimulates pancreas to release bicarbonate and water
small intestine submucosa
Brunner’s glands in duodenum secrete alkaline mucous
large intestine functions
- absorb water
- produce mucous
- form feces
large intestine components
- cecum
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
large intestine mucosa
- no villi
- glands of Lieberkuhn
a) absorptive cells
b) goblet cells - extensive diffuse lymphoid tissue in lamina propria
large intestine muscularis externa
outer longitudinal layer – three bands called teniae coli
rectoanal junction mucosa
- epithelium changes abruptly from simple columnar to stratified squamous nonkeratinized
- muscularis mucosa disappears
rectoanal submucosa
hemorrhoidal veins
rectoanal muscularis externa
inner circular layer forms internal anal sphincter