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72 Cards in this Set

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  • Back
difficulty swallowing =
The most obvious functions of the GI tract are to:
-separate ingested food into essential nutrients & unnecessary wastes
-absorb the former while getting rid of the latter

To successfully carry out these tasks, the GI tract has developed a number of elaborate mechanisms involving what four functions:
Smooth muscle in the walls of the GI tract maintains a constant low level of contractions known as
tone or bowel sounds
Superimposed on ongoing tone are 3 basic types of motility:
1) propulsive or peristalis
2) mixing movements or segmentation
two fold function
-promote mechanical digestion
-facilitate absorption by exposing all portions of intestinal contents to absorbing surfaces of GI tract
3) tonic contractions of sphincters or valves
Smooth muscles are responsible for GI movements with two exceptions where motility involves skeletal muscle:
the mouth through the early portion of the esophagus

the external anal sphincter
Secretion in the GI tract involves the diverse processes by which water, electrolytes and proteins are exported out of cells. It is remarkable for both its magnitude and diversity. In a typical day, the human body makes over:
1.5 L saliva
2.5 L gastric juice
0.5 L bile
1.5 L pancreatic juice
1.0 L intestinal secretions
2.0 L mucus
A disorder where secretions from the SI are far in excess of the absorptive capacity of the colon, resulting in life-thretening diarrhea and dehydration.
The breakdown process whereby the structurally complex foodstuffs of the diet are converted into smaller absorbable units:
Occurs ___________ via motility and _________ via enzymes.
digestion, mechanically, chemically
The breaking up of large molecules of carbohydrate, lipid and protein into their components.
Insertion of H+ and OH- ions derived from water. The underlying mechanism of most chemical digestion.
Many of the enzymes are secreted into the GI tract lumen from places like the stomach and pancreas, whereas others are part of the plasma membrane of ________ (brush border enzymes), the epithelial cells that make up the mucosal surface of the GI tract.
The accessory digestive organs include the:
-salivary glands
-biliary system (liver & gall bladder)
Below the diaphragm, the GI organs reside in the _________ cavity, the largest of the ventral body cavities.
The slick serous membrane of the abdominopelvic cavity:
The ___________ covers the external surfaces of most digestive organs and is continuous with the ____________ that lines the walls of the abdominopelvic cavity.
visceral peritoneum
parietal peritoneum
Between the two peritoneums is the _____________, a slit-like space containing peritoneal fluid secreted by the two membranes.
peritoneal cavity
Inflammation of the peritoneum, may occur when one suffers a piercing wound of the abdomen, a perforating ulcer, or a ruptured appendix.
A condition characterized by the accumulation of peritoneal fluid.
Peritoneal fold that binds SI to posterior abdominal wall:
Peritoneal fold that binds the large intestine to the posterior abdominal wall.
Peritoneal fold that attaches the liver to the anterior wall and diaphragm.
falciform ligament
Peritoneal fold that hangs loosely from the transverse colon and SI.
greater omentum
Peritoneal fold that suspends the stomach and duodenum from the liver.
lesser omentum
This peritoneal fold contains considerable adipose tissue and lymph nodes and contributes macrophages and anti-body producing plasma cells that help combat an infection of the GI tract and prevent an infection from spreading:
greater omentum
When HCl or gastric juice penetrates the gastric mucosal barrier, injuring the gastric wall with its acidic and enzymatic contents.
peptic ulcer disease
Occurs when pancreatic juice escapes the pancreas and/or 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 ____________ 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.
main pancreatic duct
In the case of a _________________, the colon wall tears open, allowing intestinal bacteria ("flora") to escape to the abdominal and pelvic cavities, causing peritonitis or even death.
ruptured appendix or perforated diverticulitis
Contents: stomach (gastritis), pancreas (acute pancreatitis) spleen, majority of the heart, lower left lung
liver (acute hepatitis), gall bladder (acute cholecystitis), duodenum (duodenal ulcer), pancreas (acute pancreatitis)

heart, lower right lung
Contains descending & sigmoid colon (diverticulosis)
Contains appendix (appendicitis)
The innermost layer of the GI tract in contact with the contents of the lumen.
This serves as a protective surface as well as being modified in particular areas for secretion and absorption. What layer of the GI tract is this in?
mucous membrane, mucosa
Mucouse membranes (mucosa layer of GI tract) contain _______ cells for secretion of digestive juices, __________ cells for secretion of GI hormones and ________ cells specialized for absorbing digestive nutrients.
exocrine, endocrine, epithelial
A thick layer of connective tissue that supports the mucose structurally and provides the GI tract with its distensibility and elasticity.
Contained within the submucosa is a collection of neurons called the:
submucosal (Meissner's) plexus
Major smooth muscle coat of the GI tract:
muscularis externa
The muscularis externa, in most parts of the tract, consists of what two layers?
inner circular layer and outer longitudinal layer
Between the circular muscle layer and the longitudinal muscle layer of the muscularis externa is a group of neurons known as the
myenteric (Aurbach's) plexus
Outer connective covering of the GI tract.
Serosa (Visceral peritoneum)
Secretes watery serous fluid that lubricates and prevents friction between the digestive organs and the surrounding viscera
serosa (visceral peritoneum)
One cause of hernias is __________ tearing.
Some smooth muscle cells are "pacemaker" cells that display rhythmic, spontaneous variations in membrane potential.
The prominent type of self-induced electrical activity in digestive smooth muscle is called _______________, alternatively referred to as the GI tract's ________________(BER) or pacemaker potential
slow-wave potential, basal electrical rhythm (BER)
These two plexuxes are often termed the intrinsic nerve plexuses or the enteric nervous system (ENS).
Some are sensory neurons, which possess receptors that respond to specific local stimuli (e.g. - pain) in the GI tract
Others are motor neurons that innervate smooth muscle cells, exocrine cells & endocrine cells of the GI tract to directly affect GI tract motility, secretion of digestive juices, and secretion of GI hormones
submucosal plexus and myenteric plexuse
The neurons of the submucosal and myenteric plexuses are often termed the intrinsic nerve plexuses or ______________________.
the enteric nervous system (ENS)
These nerves originate outside the GI tract and innervate the various GI organs -- namely, nerve fibers from both branches of the autonomic nervous system.

Autonomic nerves influence GI tract motility and secretion either by
-modifying ongoing activity in the enteric nervous system
-manipulating BER (basal electrical rhythm)
-altering the level of GI hormone secretion
-acting directly on smooth muscle and glands
Extrinsic nerves
GI (Gut) Hormones
The mucosa of certain regions of the GI tract contain ______ cells that secrete hormones
GI hormones are carried through blood to other areas of the GI tract, where they exert either _________ or _______ influences on smooth muscle and exocrine cells.
endocrine, excitatory, inhibitory
Salivary gland secretions aid in lubrication and digestion of food, and enhance speech, taste and swallowing. Moreover, patients who cannot produce saliva (a rare condition known as ___________) suffer from dental caries (cavities), dry mouth and inflammation of the buccal mucosa.
The principal glands of salivation are the _______, __________, _________ glands; in addition, there are many small _________ glands. The daily secretion of saliva normally ranges between 800 - 1500 ml.
parotid, submandibular, sublingual, buccal
Saliva is composed of about 99.5% water and 0.5% _________ and _______.
electrolytes, protein
An enzyme that begins digestion of carbohydrates in the mouth:
salivary amylase
Part of saliva that mixes with water to become mucus, which lubricates food.
Antibodies in saliva that provide the first immunologic defense against bacteria and viruses.
Found in saliva; attacks the bacteria in the saliva
Found in saliva; protects tooth enamel.
proline-rich proteins
This exists in the mouth, but is inactive and it is an enzyme that begins digestion of lipids in the stomach.
lingual lipase
Salivary secretion is under ______ control. The continuous, spontaneous secretion of saliva, even in the absence of apparent stimuli, is due to constant low-level stimulation by the _______________ nerve endings that terminate in the salivary glands. This basal secretion is important in keeping the mouth and pharynx moist at all times.
neural, parasympathetic
An unconditioned ___________ occurs when chemoreceptors and pressure receptors within the oral cavity respond to the presence of food. On activation, these receptors initiate impulses in ______ nerve fibers that carry the information to the salivary center of the _______. The salivary center sends impulses via the extrinsic autonomic nerves (VII and IX) to the salivary glands to promote increased salivation.
salivary reflex, afferent, medulla
The SNS and PNS responses in the salivary glands are not _______________.
Both SNS and PNS stimulation increase salivary secretion. ___________, which exerts the dominant role in salivary secretion, produces a prompt and abundant flow of watery saliva that is rich in enzymes. ______________ stimulation, on the other hand, produces a much smaller volume of thick saliva that is rich in mucus.
parasympathetic nervous system, SNS
__________ and other _____________ blocking agents reduce salivary secretion.
atropine, cholinergic blocking agents
Swallowing = _____________, is a reflex response that is triggered by afferent impulses in CNs ___________(3 of them). These impulses are integrated in the _______ of the brainstem.
deglutition, V, IX, X, medulla

The efferent fibers that pass to the pharyngeal musculature and the tongue during swallowing (_________) are CNs ____________(6 of them)
deglutition, V, VII, IX, X, XII

Swallowing consists of what three phases:
1) oral or voluntary phase
--swallowing is initiated by the voluntary action of collecting the oral contents on the tongue and propelling them backward to the pharynx (oral phase).
2) pharyngeal phase
--This starts a wave of involuntary contraction in the pharyngeal muscles that pushes the material into the esophagus, as the upper esophageal sphincter (UES) relaxes and opens (pharyngeal phase).
3) esophageal phase
--Once food enters the esophagus, peristalsis takes over (esophageal phase).
--Inhibition of respiration and stimulation of glottic closure are part of the reflex response. Also, the material tilts the epiglottis backward and down over the closed glottis as further protection from food entering the respiratory airways. Swallowing is difficult if not impossible when the mouth is open, as anyone who has spent time in the dentist's chair feeling saliva collect in the throat is aware.
A polymicrobial lung infection that results from inhaling food or secretions. This common consequence of failure to properly coordinate breathing and swallowing is due to impaired oropharyngeal motility. Proper positioning of these patients is crucial.
aspiration pneumonia
__________involves a progressive wave of ring-like smooth contractions that propels food down to the ______________ (LES). Once triggered by swallowing, esophageal peristalsis will occur whether or not food is present, although the presence of food will ______ the peristaltic contractions. If the primary peristaltic wave fails to move food into the stomach, the persistence of the food bolus in the esophagus will set off secondary peristaltic waves to complete the job.
esophageal peristalsis, lower esophageal sphincter, intensify
The LES, like most sphincters, is tonically contracted. However, this tonic contraction can be influenced either to relax (thereby opening the LES) or to contract further. In a condition called ___________, the LES fails to relax; food that has been swallowed has difficulty passing into the stomach, and the esophagus above the LES becomes enlarged. One or several meals may lodge in the esophagus and pass slowly into the stomach over time. There is danger of aspiration of esophageal contents into the lungs when the person lies down.
Various agents have been showed to decrease LES pressure, which in turn, decreases it's closing strength. This permits reflux of acidic gastric contents into the esophagus ____________. This common condition causes heartburn and __________ and can lead to ulceration and stricture of the esophagus due to scarring. Furthermore, current research indicates that there may a strong causal relationship between GERD and esophageal ____________.
GERD (gastroesophageal reflux disease), esophagitis, adenocarcinoma
Complications can result from persistent reflux, producing a cycle of mucosal damage that causes edema and erosion of the luminal surface. These complications include strictures and a condition called ____________ esophagus.
_________ are caused by a combination of scar tissue, spasm and edema. They produce narrowing of the esophagus and cause dysphagia when the lumen becomes sufficiently constricted.
____________ is characterized by a repair process in which the squamous mucosa that normally lines the esophagus is gradually replaced by columnar epithelium (________) resembling that in the stomach and intestines. It, too, is associated with increased risk of developing esophageal cancer.
Barrett's esophagus, metaplasia