Quick Study Flashcards
Mucous neck cells secrete…
Mucus and bicarbonate
Parietal cells secrete…
HCl and intrinsic factor
Chief cells secrete…
Pepsinogen
Enteroendocrine cells secrete…
Various hormones
G cells are in…and secrete…
Pyloric antrum and duodenum; gastrin
I cells are in…and secrete…
Small intestine; CCK
S cells are in…and secrete…
Duodenum; secretin
D cells are in…and secrete…
pyloric antrum, body of stomach and pancreas; somatostatin
M cells are in…and secrete…
Duodenum and jejunum; motilin
Enterochromaffin-like cells (ECL) are in…and secrete…
Body of stomach; histamine
Fundic glands
- Greater proportion of parietal and chief cells
- D cells inhibit acid secretion
Cardiac glands
-Mostly mucous cells (protects esophagus from reflux)
Pyloric glands
-G and D cells stimulate or inhibit acid secretion, respectively
Parietal cells look like
Acidophilic (pink) fried eggs
Chief cells look more ______ compared to parietal
Purple
Small intestine functions
- Adds bile from liver
- Adds digestive enzymes from pancreas
- Raises pH of food bolus
- Absorbs nutrients
Plicae circularis
Folds of mucosa and submucosa
Villi
Folds of mucosa only (contain lacteal -lymphatic duct-at core)
Microvilli
On enterocytes, may be visible as brush border
Enterocytes
- Columnar cells with microvilli
- Absorptive
Goblet cells
-Mucus-releasing cells that increase in number as they move towards the large intestine
Paneth cells
- At base of intestinal glands
- Acidophilic granules containing lysozymes
Duodenum
- Receives and neutralizes acidity of stomach contents
- Controls release of pancreatic enzymes and bile into digestive tract
- Brunner glands (alkaline secretions)
Jejunum
- “Typical” small intestine
- Villi broad and often have visible lacteal
- NO SPECIAL STRUCTURES
Ileum
-Peyer’s patches (aggregated lymphoid nodules)
Large intestine
- Recovers water and electrolytes from bolus
- Wide lumen
- Tenia coli
- Has haustra (visible compartments)
- Still has intestinal glands/crypts with Goblet cells and enterocytes
Appendix
- Narrow lumen
- Lymphatic nodules in LP
- Replenish intestinal flora
Anus
- Apocrine sweat glands
- Stratified squamous
- Hair follicles and sebaceous glands
- Large veins in submucosa can become affected by hemorrhoids
Gut tube layers from out to in
- Adventitia/serosa
- Muscularis externa longitudinal
- Myenteric/Auerbach’s plexus
- Muscularis externa circular
- Submucosa (contains Submucosal/Meissner’s plexus)
- Muscularis mucosa
- LP
- Epi
- Lumen
Secretin
- S cells in duodenum
- (+) fluid and bicarb from pancreas
- (+) bicarb from liver
- inhibit acid secretion and gastrin release
- Stimuli : acidification of small intestine
Gastrin
-G cells in antrum and duodenum
- (+) acid secretion by parietal cells
- (+) somatostatin secretion by D cells (indirectly)
-Stimuli:
Vagal Stimulation
- Ach (Acetylcholine)
- GRP (Gastrin Releasing Peptide)
Distension of stomach
Amino acids/peptides in duodenum
CCK
-I cells in small intestine
- (+) enzymatic secretion of pancreas
- (+) gall bladder contraction, relax sphincter of Oddi > bile delivery to duodenum
- (+) pancreatic growth
- inhibit gastric emptying
-Stimuli:
Presence of following in small intestine:
- Fatty Acids (strongest stimulus)
- Peptides/Amino acids
GIP
-Endocrine cells of duodenum, jejunum
- (+) insulin secretion by endocrine pancreas
- inhibit gastric acid secretion
- Stimuli
Presence of following in small intestine
- Carbohydrates (strongest stimulus)
- peptides/amino acids
- fatty acids
Motilin
- M cells in duodenum and proximal jejunum
- Stimulate MMC during fasting (gastric and intestinal motility pattern during fasting, “housekeeper”
- Stimuli: interaction with enteric NS to stimulate MMC during fasting
Somatostatin
- D cells in antrum and oxyntic (fundic) gland area
- inhibit gastrin (G cells), histamine (ECL), acid (parietal) release
- Stimuli: low pH in antrum
Histamine
- ECL cells
- Acid secretion
Hirschsprung’s disease
- ENS missing from end of bowel
- Failure of bowel colonization by enteric neural crest derived precursor cells during fetal development
- Region tonically contracted > functional obstruction
- Symptoms: abdominal distension, vomiting, severe constipation, failure to grow, bowel inflammation and early death
Regions of phasic contractions
Esophagus, anrtal sotmach, small intestine (busy regions)
Regions of tonic contractions
Non-busy regions (sphincters, orad stomach)
Interstitial cells of Cajal
- Form network in space between circular and longitudinal muscle layers in regions of gut that generate segmental or phasic contractions
- Generate slow waves and conduct them to smooth muscle cells via gap junctions
General response to meal
- Gut distention by bolus
- Stretching is sensed and stimulates nerves to release neurotransmitters into the smooth muscle at the site
- Membrane potential is depolarized (in response to the neurotransmitter)
- Slow wave passes through this sensitized smooth muscle
- Spike potential form = contraction
- Contraction moves in a coordinated fashion because muscle cells are electrically coupled through gap junctions
Stomach autonomic innervation (symp and para)
T5-9; vagus
Liver and gall bladder autonomic innervation (symp and para)
T6-9; vagus
Pancreas autonomic innervation (symp and para)
T5-11; vagus
Small intestine autonomic innervation (symp and para)
T9-11; vagus
Colon and rectum autonomic innervation (symp and para)
T8-L2; vagus/S2-4
Kidney autonomic innervation (symp and para)
T10-L1; vagus
Ureter autonomic innervation (symp and para)
T10-L1; vagus/S2-4
Greater splanchnic nerve level
T5-9
Lesser splanchnic nerve level
T10-11
Least splanchnic nerve level
T12
Referred pain from gallbladder
Right shoulder
Right side right above umbilicus
Referred pain from pancreas
Upper abdomen and back
Referred pain from small intestine
Umbilicus
Referred pain from large intestine
1 inch below umbilicus
