VERTEBRATE DIGESTIVE SYSTEM
Functions:
- mechanical breakdown - big lumps of food to small
- chemical breakdown - digestion → monomers
- absorption of monomers
- compact waste → feces, extract water → eliminate
Common features:
- longitudinal tube through body
- regional specializations along length
- basic wall plan common to all vertebrate groups
Trends:
- simple → complex as diet harder to digest
- easily digested food: simple, short gut
(filter-feeders, carnivores)
- "tough" food: gut longer, more complex (herbivores)
FISH DIGESTIVE SYSTEM
Trends:
no oral salivary glands - water lubricates food
no separate stomach in some species
intestine surface area for absorption increased:
-long tube, folded/coiled in coelom
-mucosa folded internally
-spiral valve
-villi
HUMAN LIP (H108) ORAL EPITHELIUM
TELEOST ESOPHAGUS CROSS-SECTION (CVH138)
TELEOST ESOPHAGUS: SECRETORY AND
NON-SECRTORY REGIONS (CVH138)
mucus-secreting
columnar cells
non-secreting region
stratified squamous/cuboidal
epithelium
ELASMOBRANCH ESOPHAGUS (CVH60)
ELASMOBRANCH ESOPHAGEAL MUCOSA
- GLANDULAR REGION (CVH60)
simple columnar
epithelium with
goblet cells
GUT-ASSOCIATED LYMPHOID TISSUE IN
ELASMOBRANCH ESOPHAGUS (CVH60)
muscularis externa
Leydig's organ
large unencapsulated lymphocyte
population
DOGFISH STOMACH, FUNDUS REGION (CVH72)
DOGFISH STOMACH WALL - FUNDUS (CVH72)
SM
ME
mucosal glands
GLANDULAR MUCOSA IN DOGFISH FUNDUS (CVH72)
LP
DOGFISH STOMACH, PYLORUS REGION (CVH71)
mucosal
glands
SM
ME
DOGFISH STOMACH WALL, PYLORUS REGION (CVH71)
lamina
propria
glandular
epithelium
MM
SM
ME
GLANDULAR MUCOSA IN PYLORUS OF
DOGFISH STOMACH (CVH71)
LP
MM
SPIRAL VALVE IN DOGFISH INTESTINE (CVH133)
wall of
intestine
leaflet of
spiral valve
TROUT INTESTINE CROSS-SECTION (CVH145)
villi
TROUT INTESTINE WALL (CVH145)
LP
ME
TROUT VILLI
(CVH145)
columnar epithelium (absorptive)
brush
border
goblet
cells
LP
LP
MUCOSA ON DOGFISH SPIRAL VALVE (CVH133)
small villi
on valve
submucosal core of spiral valve
DOGFISH LARGE INTESTINE (CVH66)
DOGFISH LARGE INTESTINE WALL (CVH66)
mucosa with goblet
cells
ME
AMPHIBIAN DIGESTIVE SYSTEM
Trends:
ciliated oral epithelium
esophagus short, wide, ciliated
stomach regions: fundus, pylorus
-glands short tubular
small intestine coiled
-large mucosal villi, no glands
large intestine → cloaca
FROG ORAL EPITHELIUM - CUBOIDAL
SURFACE CELLS, CILATED (CVH21)
FROG ESOPHAGUS WALL (CVH26)
SM
ME
FROG ESOPHAGEAL GLANDS IN SUBMUCOSA
MUCO-SEROSAL (CVH26)
FROG ESOPHAGEAL MUCOSA - GOBLET CELLS AND
CILIATED COLUMNAR CELLS (CVH26)
SALAMANDER ESOPHAGEAL MUCOSA
- GUT-ASSOCIATED LYMPHATIC TISSUE (CVH50)
SALAMANDER STOMACH WALL
- THICK MUSCULARIS EXTERNA (CVH55)
SM
ME
SALAMANDER STOMACH MUCOSA - COLUMNAR EPITHELIUM
- SHORT TUBULAR GLANDS
(CVH55)
- SURFACE GOBLET CELLS
LP
MM
VILLI IN FROG SMALL INTESTINE (CVH16)
FROG INTESTINAL VILLI STRUCTURE (CVH16)
ME
FROG VILLI: COLUMNAR ENTEROCYTES - ABSORPTION
GOBLET CELLS (CVH16)
SALAMANDER GOBLET CELLS RELEASING MUCUS (CVH46)
SALAMANDER LARGE INTESTINE CROSS-SECTION
- MUCOSA FOLDED (CVH45)
SALAMANDER LARGE INTESTINE MUCOSA
- FOLDS → WIDE GLANDS (CVH45)
SM
ME
REPTILIAN DIGESTIVE SYSTEM
-regional structure similar to amphibian gut
Trends:
gizzard: enlarged pylorus
- grind food
cecae: pouches off intestine
-more time for digestion
SNAKE TONGUE CROSS-SECTION (CVH174)
oral
epithelium
CVH174
oral epithelium
nerve
skeletal
muscle
TURTLE ESOPHAGUS (CVH91)
SM
ME
TURTLE ESOGPHAGUS MUCOSA - GOBLET CELLS (CVH91)
WALL STRUCTURE IN TURTLE STOMACH (CVH94)
glandular
mucosa
submucosa
muscularis
externa
GLANDULAR MUCOSA OF TURTLE STOMACH (CVH94)
mucous cells
at surface
simple tubular glands:
HCl
digestive enzymes
lamina propria
between glands
TURTLE SMALL INTESTINE - TYPICAL REPTILIAN (CVH85)
mucosa
folded
muscularis
externa
STRUCTURE OF FOLDS IN TURTLE
SMALL INTESTINE (CVH85)
simple columnar
epithelium:
- enterocytes
- goblet cells
lamina propria
in core of fold
BIRD DIGESTIVE SYSTEM
Trends:
keratinized beak - no teeth in modern birds
keratinized tongue - aids mechanical breakdown
crop: expanded esophagus
food reservoir - regurgitation for young
herbivores/seed eaters:
gizzard - mechanical breakdown
using stones, grit to grind food
MAMMALIAN DIGESTIVE SYSTEM
Diet-related specializations:
length of gut related to digestion time
-carnivores - chemical digestion fast, gut short
-herbivores - chemical digestion slow, gut longer
keratinized esophagus - rodents, herbivores
fermentation - extra chambers for bacterial action
to break down plant cellulose
-foregut fermenters
-intestinal fermenters
GUINEA PIG ESOPHAGUS (E) AND TRACHEA (T)
CROSS-SECTION (CVH196)
T
E
WALL OF GUINEA PIG ESOPHAGUS
- KERATINIZED EPITHELIUM (CVH196)
keratin
EPI
LP
MM
SM
ME