13 - Stomach-Peritoneum Flashcards
What is the enteric nervous system
brain of the gut
consists of >100 million neurons from the esophagus to the anus
(sensory, motor, interneurons)
capable of generating local reflexse
What are the plexuses of the enteric nervous system
influenced by autonomic input
myenteric plexus – controls motility (ex. perstalsis)
- between circular and longitudinal muscle layers
submucosal plexus – controls secretions
- in submucosa
What nerve controls the parasympathetic plexuses of the ENS
vagus nerves (CN X)
What controls the sympathetic plexuses of the ENS
celiac, sup & inf mesenteric ganglia
What is the peritoneum
largest serous membrane of the body
What are the layers of the peritoneum
parietal peritoneum
visceral peritoneum
What do the peritoneal folds do
support the abdominal organs by acting as a highway for nerve, bv and lympahtics
What are the five folds of the peritoneum
falciform ligament – between left and right lobe of liver
lesser omentum – from inferior surface of liver to lesser curvature of stomach
greater omentum – from greater curvature of stomach to transverse colon
mesocolon – from posterior abdominal wall to transverse and sigmoid colon
messentery – suspends most of small intestine for posterior wall
What are the retroperitoneal organs
organs only covered by peritoneum on their anterior surface
abdominopelvic cavity
- pancreas
- duodenum
- ascending and descending colon
- kidneys
What are the four layers of the gastric walls
same layers in esophagus
mucosa (inside) – contains rugae (innermost, oblique muscle layer)
submucosa
muscularis
serosa - lubricating fluid
What does the stomach do
holding reservoir and mixing chamber – no absorption
What does the stomach connect
Where is it located
esophagus to duodenum
inferior to the diaphragm
What are the four main regions of the stomach
cardia (closest to the heart)
fundus (tip of stomach)
body (major part)
pylorus (at pyloric sphincter)
What does rugae do
accomodates the stretching of the mucosa
Where does the most intense churning occur
pyloric antrum
Where does the stomach receive blood from
branches of the celiac trunk
What arteries lie at the lesser curvature of the stomach
right and left gastric arteries
What arteries lie at the greater curvature of the sotmach
left and right gastroomental arteries
What are the layers of the muscularis
muscularis (longitudinal layer) – outermost
circular layer
oblique layer – innermost
What are the parts of the pylorus
pyloric antrum (the blender)
- connects to the body of the stomach
pyloric canal
- connects to the duodenum
what does the submucosa of the gastric wall do
provides innervation and blood supply to the overlying mucosa
What do gastric pits do
specialized cells that secrete gastric juice (2-3 liters a day) and a protective muscous
What is the pH of gastric secretions
1.5 and 3.5
What are the cell types in gastric pits
mucus cells - secrete bicarbonate-rich mucus to protect the gastric lining from stomach acid
parietal cells - secrete hydrochloric acid and intrinsic factor (vit B12 absorption)
chief cells - secrete pepsinogen (digestive enzyme pepsin) and gastric lipase
G cells - secrete the endocrin hormone gastrin
- gastrin increases parietal and cheif cell secretion // increases gastric motility (more churning) and LES tone (nice and tight) // decreases pyloric sphincter tone
How is HCl produced
chloride anion and a proton combined seperately in the lumen of the stomach
- makes pH really low in the stomach
What is HCl secretion regulated by
gastrin (from enteroendocrin G cells)
ACh (from parasympathetic fibers)
- tells stomach to make more acid
Histamine (from mast cells)
- glue epithelium down
- protection –> makes more acid
Cortisol (from adrenal cortex)
- slows down stomach in stress
What causes gastric ulcers to form
form on the mucosal lining of the stomach if protective mucus production is insufficient or gastric acid secretion is excessive
- can lead to perforation of the gastric wall
What are the phases to digestion
- cephalic
- receptors for sight, smell, and taste of food activated
- thoughts of food
(cortex & hyopthalamus –> medulla oblongata –> parasympathetic output) - gastric
- stretch receptors detect distention of the stomach
- chemoreceptors detect increased pH of gastric juice
(submucosal plexus - intestinal
- stretch receptors detect distension of the duodenum
- chemoreceptors detect fatty acids and glucose in the duodenum
How do neural and endocrine signals help regulate digestion
regulating motility and digestive enzyme secretion
What are the factors promoting gastric emptying
neural
- parasympathetic (vagus)
hormonal
- gastrin
composition of chyme
- carbohydrates & water –> quick emptying
What are the factors inhibiting gastric emptying
neural
- sympathetic
- enterogastric reflex
hormonal
- CCK
- secretin
composition of chyme
- high protein = moderate emptying
- high fat = slow emptying
