Gastrointestinal Lab Flashcards
What four types of vessel like structures would you expect to see running through the mesentery?
Arteries, veins, lymphatics and nerves
Peristalsis and segmentation
Peristalsis is responsible for the movement of food through the gastrointestinal tract, whereas segmentation is responsible for the mixing of the food with secretions and exposure of the digestive products to the absorptive surfaces. Segmentation is NOT a form of mechanical digestion.
Components of the small intestine and the function of the small intestine
The small intestine is comprised of three segments: the duodenum, the jejunum and the ileum. The primary function of the small intestine is to complete the digestion of the food material and absorb the products of digestion as well as water and salts.
Which basic tissue type must be present in the gut tube to modulate digestive motility
Nervous tissue
How does peristalsis help to move food through the small intestine?
Contraction of the smooth muscle behind the food bolus helps to propel/push food material along the GI tract at an appropriate rate.
How does segmentation assist with digestion and absorption of material in the small intestine?
By constantly turning over the chyme, it exposes the chyme to the enzymes allowing for digestion and then brings those products of digestion to the absorptive surface so that can be absorbed into the body.
Why is segmentation described as a “mixing” motility pattern, rather than a component of mechanical digestion?
Because mechanical digestion of the food has already occurred in the mouth and the stomach.
Segmentation allows for mixing of chyme with enzymes responsible for the final stages of digestion.
Stomach regions and function
The stomach is divided into four regions, the cardia, fundus, body and pylorus (sometimes referred to as the antrum). The fundus is at the proximal end (adjacent to and above the opening of the esophagus), the body is the central region of the stomach and the pylorus is the distal region of the stomach (which connects to the small intestine).
The body and pylorus (antrum) have a significantly thicker layer of smooth muscle than the fundus, which aids in increasing contractility and therefore aiding in the mechanical digestion of food material.
Two possible functions of rugae
Allows for the expansion of the stomach without increasing the pressure.
Increases the surface area of the mucosa and therefore increases the number of chief and parietal cells.
Which region of the stomach displays a greater degree of movement- the fundus or pylorus (antrum)?
Pylorus (antrum)
Motility pattern in the pylorus (antrum)
Mechanical and chemical digestion
Pyloric sphincter
Modulates the passage of chyme from the stomach into the initial part of the small intestine (the duodenum)
The esophagus pierces the diaphragm, and runs for about 3-4 cm in the abdominal cavity before it enters the stomach. At the proximal end of the stomach, the lower esophageal sphincter or cardiac sphincter is present as a thickening of smooth muscle. What is the function of this sphincter?
Constricts the esophagus to prevent reflux/backflow of stomach contents.
Regions involved with mechanical digestion
Mouth and stomach
Regions involved with storage
Stomach, colon and rectum
Regions involved with movement
Throughout the whole tract
Regions involved with mixing
Mouth, stomach, small and large intestine
Regions involved with exposure to absorptive surfaces
Small intestine (and to a lesser extent large intestine)
Expulsion
Anal canal
Exocrine components of the pancreas
In the exocrine component, the pancreas is arranged into an acinar structure (which means grape-like) and the secretions produced by each acinus are emptied into a small duct. These ducts then all join to form the main pancreatic duct, which empties into the duodenum.