Green - Small Intestine And Pancreatic Secretions Flashcards
Surface of the small intestine. Formed from microvilli on surface of eptihelial cells lining the intestine
Brush border
Proliferative cells at the base of the villus in the small intestine; form both enterocytes and goblet cells
Secrete fluid and electrolytes
Crypt cells
Cells in villus that synthesize digestive enzymes, absorb nutrients, and secret fluids
Enterocytes
Cells in villus that secrete mucuous
Goblet cells
Lack of or decrease in contractile activity in absence of obstruction
Ileus
Major contraction in the small intestine where only parts of the intestine contract w/o peristalsis
Segmentation contraction
Longitudinal folds on the surface of the small intestine
Fold of kerckring
Type of intestinal contraction
Circular muscle contracts and relaxes in isolated segment of wall, displacing chyme in both directions. This displaces chyme and then returns it to its original position
Causing mixing of chyme and digestive enzymes
These happen more frequently in proximal small intestine than distal, causing a net movement of chyme towards colon.
This is the most common type of intestinal contraction
Segmentation
Type of contraction that causes the propulsion of chyme towards the colon.
Occurs only over short distances
Contraction and relaxation pairing to move the chyme
Peristaltic
Type of intestinal contraction.
Occurs every 90 minutes when fasting in an effort to remove excess chyme from small intestine
Migrating myoelectric complex
The frequency of intestinal slow waves ______ distally
Decreases
Type of intestinal reflex
Overdistention of one segment of small intestine prevents contractions from occurring in the other segments
Keeps intestine from overfilling already distended section of bowel
Intestinointestinal reflex
What is the intestinointestinal reflex?
Over-distention of one segment of bowel results in the decrease in contraction of other segments.
This prevenets the movement of material into a severely distended segment of bowel
What is the peristaltic reflex?
Contractions that push intestinal content along small intestine.
Caused either by the distention of a section of bowel or by irritation to the mucosa by chyme
Also can be caused by severe cases of infectious diarrhea
What is the gastroileal reflex?
Gastric emptying and secretion triggers the increase of peristalsis in the ileum which causes relaxation of the ileocecal sphincter and the movement of ileal contents into the large intestine
Explain the gastrocolic reflex
The urge to defecate shortly after a meal
The presence of food in the stomach triggers increased colonic motility
Eventually leads to the evacuation of the colon
What is an ileus?
The lack or reduction of contractile activity of the small intestine without obstruction.
Caused by irritation of the peritoneum
Usually secondary to surgery, an acute or systemic illness, or electrolyte imbalance
What are the 3 types of pancreatic cells
Acinar
Centroacinar
Duct cells
What do acinar cells of the pancreas produce?
Peptidase (digest protein)
Lipases (digest fat)
Amylases (digest carbohydrates)
What do centroacinar and duct cells of the pancreas do?
The secrete pancreatic juices which are high in bicarb and neutralize the gastric acid in the duodenum, bringing pH to a more optimal level for enzymatic digestion of nutrients
At what rates of secretion are pancreatic juices isotonic with plasma?
All rates of secretion
At lowest flow rates, pancreatic juice is primarily ____ and _____
Na and Cl
At highest flow rates, pancreatic juice is primarily ____ and ____
Na
Bicarb
Bicarb in pancreatic juice is always _______ compared to plasma
Higher in concentration
Venous blood from actively secreting pancreas has slightly more _____ pH than blood from nonsecretive
Acidic
Pancreatic _______ and _______ are secreted in the active forms
Amylases
Lipases
Pancreatic ________ are secreted in the inactive form
Proteases
(Trypsin and chymotrypsin)
Activated in the small intestine
