BIOL373 UNITS 6-8 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++
4 major functions of GI tract
motility, secretion, digestion, absorption
Material isn't in the GI tract until it has pass through the
gut epithelium
The digestive system interacts with the circulatory system by
absorption and exchange
GI system: digestion
bream nutrients/macromolecules down into forms that can be transported across
epithelium
GI system: absorption
transport nutrients, water, ions, vitamins across epithelium
GI system: secretion
release of enzymes into gut lumen
GI system: motility
keep the gut contents moving
peptic and duodenal ulcers
-deterioration in the wall of the stomach or duodenum caused by Helicobacter pylori
infection
-failure of barrier function
,GI lining is the largest area of contact between internal and external environment
true
GI lining increases...
surface area
protection in GI lining from pathogens mediated by...
epithelial barrier, mucus, digestive enzymes, acid, GALT/MALT
What provides a barrier from ulcers?
mucus
What is a barrier to pathogens?
acid
GALT/MALT
*gut-associated lymphoid tissue
*mucosa-associated lymphoid tissue
needs to react to pathogens but not to foreign proteins associated with food
Additional considerations of GI function
-needs to digest macromolecules but not itself
-needs to allow entry of undigested nutrients but not pathogens
-needs to maintain balance between water input/output (balance between secretion and
reabsorption)
Consequence of imbalance between water input/output
diarrhea, lots of water is secreted into GI tract
Water balance and GI tract
,Fluid input = 9.0 L total into lumen
-ingestion = 2.0 L food and drink
-secretion = 7.0L by GI tract
Fluid output = 9.0 L removed from lumen
-absorption = 7.5L from small intestine + 1.4L from large intestine
-excretion = 0.1L in feces
rugae of stomach
-folds inside the stomach
-smooths out when stomach expands (full)
Examples of mucosal surfaces
stomach, small intestine and large intestine
Mucosal surface layers
1)Mucosa - epithelium, lamina propria, Muscularis mucosa
2)Submucosa - Meissner's plexus
3)Muscularis externa (smooth muscle layers) - circular and longitudinal muscles,
Myenteric plexus (run b/w circular and longitudinal muscles)
4)Serosa
The stomach is a bag rather than a tube. Explain this statement.
The stomach has to contract in more dimensions (circular, longitudinal and oblique
muscles in the Muscularis externa). It expands and rugae smooths out when it is full.
The stomach is is involved in exocrine or endocrine secretion?
exocrine (mucus is secreted out onto the surface)
microanatomy of stomach
, - mucosa is covered in simple columnar glandular epithelium
- apical regions of its cells are filled with mucin which becomes mucus after secreted
- mucosa and submucosa are flat when stomach is full but will wrinkle when empty
(forms gastric ridge)
difference between small intestine and stomach wrt to Muscularis externa
-Small intestine has circular and longitudinal muscles
-Stomach has circular, longitudinal and oblique muscles
Plica in the small intestine
-circular folds of mucosa and submucosa in the small intestine
-increase surface area for absorption
-permanent structures, does not depend on state of distension in small intestine (don't
disappear as intestine stretches or shrinks unlike rugae of stomach)
Crypt of the small intestine
provide renewal of stem cells in intestinal epithelium
Peyer's patches
-collections of lymphatic tissue found in the submucosa of the small intestine
-indicator you're in the ileum of small intestine
-immune cells
Lacteal
a lymph tubule located in the villus that absorbs fatty acids
two major patterns of contraction in the gut
peristalsis and segmental contractions
peristalsis
COMPLETE SOLUTIONS GRADED A++
4 major functions of GI tract
motility, secretion, digestion, absorption
Material isn't in the GI tract until it has pass through the
gut epithelium
The digestive system interacts with the circulatory system by
absorption and exchange
GI system: digestion
bream nutrients/macromolecules down into forms that can be transported across
epithelium
GI system: absorption
transport nutrients, water, ions, vitamins across epithelium
GI system: secretion
release of enzymes into gut lumen
GI system: motility
keep the gut contents moving
peptic and duodenal ulcers
-deterioration in the wall of the stomach or duodenum caused by Helicobacter pylori
infection
-failure of barrier function
,GI lining is the largest area of contact between internal and external environment
true
GI lining increases...
surface area
protection in GI lining from pathogens mediated by...
epithelial barrier, mucus, digestive enzymes, acid, GALT/MALT
What provides a barrier from ulcers?
mucus
What is a barrier to pathogens?
acid
GALT/MALT
*gut-associated lymphoid tissue
*mucosa-associated lymphoid tissue
needs to react to pathogens but not to foreign proteins associated with food
Additional considerations of GI function
-needs to digest macromolecules but not itself
-needs to allow entry of undigested nutrients but not pathogens
-needs to maintain balance between water input/output (balance between secretion and
reabsorption)
Consequence of imbalance between water input/output
diarrhea, lots of water is secreted into GI tract
Water balance and GI tract
,Fluid input = 9.0 L total into lumen
-ingestion = 2.0 L food and drink
-secretion = 7.0L by GI tract
Fluid output = 9.0 L removed from lumen
-absorption = 7.5L from small intestine + 1.4L from large intestine
-excretion = 0.1L in feces
rugae of stomach
-folds inside the stomach
-smooths out when stomach expands (full)
Examples of mucosal surfaces
stomach, small intestine and large intestine
Mucosal surface layers
1)Mucosa - epithelium, lamina propria, Muscularis mucosa
2)Submucosa - Meissner's plexus
3)Muscularis externa (smooth muscle layers) - circular and longitudinal muscles,
Myenteric plexus (run b/w circular and longitudinal muscles)
4)Serosa
The stomach is a bag rather than a tube. Explain this statement.
The stomach has to contract in more dimensions (circular, longitudinal and oblique
muscles in the Muscularis externa). It expands and rugae smooths out when it is full.
The stomach is is involved in exocrine or endocrine secretion?
exocrine (mucus is secreted out onto the surface)
microanatomy of stomach
, - mucosa is covered in simple columnar glandular epithelium
- apical regions of its cells are filled with mucin which becomes mucus after secreted
- mucosa and submucosa are flat when stomach is full but will wrinkle when empty
(forms gastric ridge)
difference between small intestine and stomach wrt to Muscularis externa
-Small intestine has circular and longitudinal muscles
-Stomach has circular, longitudinal and oblique muscles
Plica in the small intestine
-circular folds of mucosa and submucosa in the small intestine
-increase surface area for absorption
-permanent structures, does not depend on state of distension in small intestine (don't
disappear as intestine stretches or shrinks unlike rugae of stomach)
Crypt of the small intestine
provide renewal of stem cells in intestinal epithelium
Peyer's patches
-collections of lymphatic tissue found in the submucosa of the small intestine
-indicator you're in the ileum of small intestine
-immune cells
Lacteal
a lymph tubule located in the villus that absorbs fatty acids
two major patterns of contraction in the gut
peristalsis and segmental contractions
peristalsis
