Introduction Pathophysiology Flashcards
____ is the constant low level of contractions that maintain smooth muscle in the walls of the GI tract
Tone
aka bowel sounds
“like a rubber band”
Tone declines over time as you get older - bloating, distention after eating, etc
Tone is important in maintaining a _______ _______. on the contents of the GI tract as well as in preventing its walls from remaining permanently stretched following distention.
steady pressure
The 4 functions of elaborate mechanisms
- motility
- secretion
- digestion
- absorption
The accessory organs of the digestive system are:
salivary glands, pancreas, biliary system, liver, and gallbladder
The intestine is ______ feet
30
21 - SI
9 - LI
The GI tract includes these organs:
mouth, pharynx, esophagus, stomach, duodenum, jejunum, ileum, cecum, ascending, transverse, descending, and sigmoid colons, rectum, anus
The 3 types of motility are:
superimposed on this ongoing tone
- Peristalsis (propulsive movements) - PSNS
- Segmentation (mixing movements)
- Sphincters or valves (TONIC CONTRACTIONS)
Peristalsis _______ contents forward through the GI tract at varying speeds.
propels
Involuntary contractions of smooth muscle
like a tidal wave - move things from point to point
“catch a wave and push you back to the shoreline”
to move things through the 30 ft of intestine
Slower in SI than esophagus
Segmentation promotes _______ digestion of food.
mechanical
sloshes things side to side
Exposes intestinal contents to the absorbing surfaces of the GI tract creating larger chance of absorption to occur
Involuntary contractions of smooth muscle
mainly occurs in stomach and SI - not everywhere like peristalsis
When sphincters ______ they are open, when they _______ they are closed
relax
contract
involuntary contractions - neural control
reflexes
The ______ _________ _________ separates pharynx from the esophagus
Upper Esophageal Sphincter (UES)
The ______ _________ _________ separates the esophagus from the stomach
Lower Esophageal Sphincter (LES)
The _______ ________ separates the stomach from the duodenum
Pyloric Sphincter
The _______ ________ separates the ileum from the cecum
Ileocecal Sphincter
The ______ _________ _________ separates the LI from the anus internally.
Internal Anal Sphincter
The ______ _________ _________ separates the LI from the anus externally
External Anal Sphincter
The ______ of _______. regulates the movement of contents of common bile duct into the duodenum.
Sphincter of Oddi
Not a GI sphincter but leads into it and regulates the flow of bile and pancreatic juice into the duodenum
A prime source of pathology in the GI system is sourced to the ___________.
sphincters
The voluntary actions contained in the GI regarding motility are contained in the _____ and the ______ ______ _______.
throat
external anal sphincter (EAS)
chewing, swallowing, defecation
The secretion of the GI tract _____ and ______ fluid.
makes
secretes
Secretion in the GI tract involves the diverse processes by which water, electrolytes are exported out of the cells. It is remarkable for both its magnitude and diversity. In a typical day the human body makes approx. ____ L of secretions.
9
- 5 L saliva
- 5L gastric juice
- 5L bile
- 5L pancreatic juice
- 0L intestinal secretions (small & large)
- 0L mucus (throughout the entire GI tract)
Digestion occurs ______, _______, and ________.
physically, mechanically, and chemically
The main chemical reaction that happens in chemical digestion is ___________.
hydrolysis
_________ are imbedded in the wall of the SI in the brush border of the SI.
Enzymes
The brush border is made up of epithelial cells that make up the mucosal surface of the GI tract.
Digestion occurs mainly in the ______ and the ______ _______.
stomach
small intestine
May of the enzymes are secreted into the GI tract lumen from places like the _______ and _________.
stomach
pancreas
________ as it occurs in the GI tract solves 2 remarkable problems.
Absorption
From the daily input of 9L only _____ mL gets put in the stool daily with the rest recycled.
100
When contents escape from the GI tract lumen there will be symptoms that often indicate GI _________.
dysfunction
To absorb nutrients effectively w/ water the molecular mechanisms by which they are carried out by involve both _______ and ________ transport.
active
passive
In __________ gastric juice penetrates the gastric mucosal barrier, injuring the gastric wall with its acidic and enzymatic contents.
Peptic Ulcer Disease (PUD)
The wall can erode all the way through and things escape - bleeding ulcer, leaches out of stomach into abdominal cavity.
In ______ _________ pancreatic juices escape the pancreas and/or the duodenum. The pancreatic digestive enzymes in the juice can cause widespread destruction of pancreatic tissue and possible hemorrhage.
acute pancreatitis
The pathogenesis of acute pancreatitis usually involves active secretion of pancreatic juice while the main pancreatic duct is obstructed at its entrance into the duodenum. The build up of obstructed secretions greatly increases the pressure within the duct system, causing the ducts to rupture and the pancreatic juice to escape.
In the case of a _______ _________ the colon wall tears open, allowing intestinal bacteria (flora) to except into the abdominal and pelvic cavities causing peritonitis or even death.
ruptured appendix
tears away from the wall of the cecum - intestinal contents into abdominal cavity
The two surfaces of the GI tract wall are the _____ and ______ surfaces
mucosal and serosal
The 4 layers of the GI tract wall are the _______, _______, _______ _______, and the ________. The thickness of these layers depends on where its located.
Mucosa
Submucosa
Muscularis externa - thickest in stomach
Serosa
The _______ layer of the GI tract consists of epithelial cells, lamina propria, and muscularis mucosae. Some places are curved and some are flat. This is the most outward layer to the lumen.
mucosa
The _______ layer of the GI tract consists of collagen, elastin, glands, and blood vessels. The glands secrete mucus into the lumen. This is the the second layer from the lumen.
submucosa
The _______ ______ layer or the GI tract is a circular and longitudinal muscle that is responsible for peristalsis (longitudinal) and segmentation (circular)
muscularis externa
The ______ is a thin serous membrane of the GI tract like a thin layer of saran wrap.
serosa
The GI nervous system layers include the ______ _______ _________ or ________ _________ _______.
Enteric Nervous System
Intrinsic Nervous System
All of the nervous tissue contained in the wall of the GI tract - subdivided into different layers (submucosal plexus - Meissner’s, myenteric plexum (Auerbach’s))
Nerves that originate outside the GI tract and innervate the various GI organs, namely, nerve fibers from both branches of the ANS. This is part of the _________ __________ system.
Extrinsic Nervous
PSNS -Vagus Nerve innervate: esophagus stomach SI ascending colon
Vagus are mixed nerves - 75% afferent (sensory) 25% efferent (motor)*
The Pelvic Nerves (Pelvic Splancnic) innervate the lower GI tract and derive from spinal nerve pairs ____, _____, and ______.
S2, S3, S4
innervate transverse, descending, and sigmoid colons, anal canal.
The majority of the PSNS, post-ganglionic neurons servicing the GI system are __________.
cholinergic (acetylcholine)
some are peptidergic - release peptide neurotransmitters
The GI tract also receives SNS innervation. 3 sympathetic ganglia that serve the GI tract are:
celiac
superior mesenteric
inferior mesenteric
These post-ganglionic fibers are adrenergic. 50% afferent, 50% efferent
SNS Slowing down digestion, secretion, motility
ANS nerves influence GI tract motility and secretion either by:
modifying ongoing activity in the enteric nervous system
altering the level of GI ____ secretion
acting directly on smooth muscle and glands
hormone
The principal glands of salivation are the ______, ________, and _______ glands
Parotid (largest of these glands)
Submandibular, and
Sublingual
In addition there are many small buccal glands. The daily secretion of saliva normally ranges between 800-1500mL.
Salivary gland secretions aid in lubrication and digestion of food, and enhance _____, _______, and swallowing. It also dissolves and washes out food particles from between the teeth.
speech, taste
-
-
acinus (grape-like sac like alveoli in lungs) blind end a branching duct system. Have lots of ducts that drain them
intercalated duct - salivary duct
striated duct
**The acinus merges into intercalated which merges into striated ducts)
*The striated ducts merge into bigger ducts that will drain saliva into oral cavity.
The ________ is comprised of a central lumen surrounded by pyramidal shaped cells. Each acinus is surrounded by a layer of __________ cells, which are elongated or star-shaped non secreting cells with long branching processes.
acinus
myoepithelial
Myoepithelial cells are also present in the intercalated ducts. When stimulated by neural input, the myoepithelial cells contract to eject saliva into the mouth.
-
-
serous
mucous
mixed - both mucous and serous
Stenson’s duct drains the _______ gland.
parotid
Is located near the upper 2nd molar
Wharton’s duct drains the _______ gland.
submandibular
is located at the base of understructure of tongue
striated ducts merge into Wharton’s duct
Unlike the parotid and submandibular glands, the sublingual gland lacks a single _________ duct. It is drained by approximately 10 small ducts (the Ducts of Rivinus) which exit the superior aspect of the gland along the sublingual fold on the floor of the mouth.
dominant.
The % of ____ electrolytes and protein makes up saliva w/ 99.5% water.
0.5%
pH 6-7.5
<5.5 enamel erosion (bulemia)
_________ is a salivary enzyme that begins digestion of carbohydrates in the mouth.
salivary alpha amylase
amylase = carbs
________ is a salivary enzyme that begins digestion of lipids in the stomach.
lingual lipase
lipase = lipids
**doesn’t work in mouth, only in stomach where the pH in stomach is more acidic and needs this++