LO9 Flashcards
functions of the GI
Provides nutrients for the body through absorption
○ Expels waste products as feces
○ Disturbances in normal bowel function can be the first indication that there is a problem with the GI tract or another body system
Anatomy of the GI
The GI tract begins at the mouth and
continues through to the anus.
* The mouth, esophagus, and stomach receive
food where initial digestion occurs.
* The duodenum, jejunum, and ileum are
where most digestion and absorption occurs.
* The cecum, colon, and rectum store and
then eliminate waste.
* Salivary glands, liver, and pancreas are
accessory organs that aid in digestion.
* Also functions as a specialized immune
system.
The mouth
Point of entry into the GI tract.
○ Breaks down nutrients into usable sizes and forms.
○ Saliva dilutes and softens the food for easier swallowing and commences
digestion of carbohydrates.
○ Swallowed food (bolus) enters the esophagus through the relaxed upper
esophageal sphincter
the esophagus
Provides a passage to the stomach.
○ Epiglottis blocks the trachea during swallowing.
○ Smooth muscle layers the esophagus and provides peristaltic contractions to
move food.
○ Mucous membranes secrete mucus that aids in the lubrication of food.
○ Sphincters on either end prevent air from entering and reflux of stomach
contents into the esophagus.
the stomach
Performs several tasks:
○ Storage of swallowed food and liquid
○ Mixing of food with liquid and gastric digestive juices
○ Controlled emptying of contents into the small intestine.
○ Produces two key GI hormones:
○ Gastrin: stimulates gastric acid secretion
○ Ghrelin: has growth hormone releasing activity and stimulates food
intake and digestion.
○ Pepsin breaks down proteins into amino acids.
○ Chyme: dissolved and partially digested bolus.
small intestine
Consists of the duodenum, jejunum, and ileum.
○ Duodenum:
○ Connects the stomach to the jejunum
○ Contains the opening for the common bile duct and main pancreatic duct.
○ Jejunum:
○ Primary function is absorption of carbohydrates & proteins.
○ Ileum:
○ Specializes in the absorption of water, certain vitamins, irons, fats, and bile
salts.
○ Most nutrients and electrolytes are absorbed in the small intestine.
large intestine
The lower GI tract.
○ Primary organ of bowel elimination and is divided into the cecum, colon, and
rectum.
○ Colon is divided into the ascending, transverse, and sigmoid colon.
○ Eliminates large quantities of waste and gas.
○ 3 functions – absorption, secretion, and elimination.
○ Two types of muscular contractions occur in the colon:
○ Slow-mixing contractions – move contents through the colon to the
mucosa where absorptions of sodium and chloride causes water
absorption and develops feces.
○ Mass peristalsis – push the feces toward the rectum
anus and rectum
Feces and flatus are expelled from the rectum through the anal canal and the
anus.
○ Contraction and relaxation of the internal anal sphincter are under autonomic
control.
○ External anal sphincter is under somatic neural control.
factors effecting normal bowel elimination
Diet
○ Fibre provides the bulk of fecal material. High fibre diet is recommended.
○ Fluid Intake
○ Fluid liquefies intestinal contents to ease their passage through the colon.
○ Unless contraindicated, adults should consume 1.5-2 L of fluid/day.
○ Physical Activity
○ Promotes peristalsis.
○ Personal Bowel Elimination Habits
○ Establish a regular and consistent time
○ Privacy
○ Maintain privacy & sensitivity for all patients.
constipation
Causes of constipation:
○ Medications – a major issue for patients taking opioids for pain.
○ Rectal or anal disorders (hemorrhoids)
○ Obstruction
○ Metabolic, neurologic, and neuromuscular conditions
○ Endocrine disorders
○ Dietary habits, lack of exercise, and stress.
○ Diseases of the colon commonly associated with constipation include:
○ IBS
○ Diverticular disease
three classes of constipation
Functional constipation: normal transit mechanism of mucosal transport. Most
common and successfully treated with fibre and fluids.
○ Slow-transit constipation: caused by inherent disorders of the motor function of
the colon. Characterized by infrequent bowel movements.
○ Defecatory disorders: caused by dysfunctional motor coordination between the
pelvic floor and anal sphincter. Can also cause fecal incontinence.
what is diarrhea the result of
- Increased intestinal secretions
○ Decreased mucosal absorption
○ Altered motility
other causes of diarrhea
○ Medications
○ Enteral tube feeds
○ Metabolic & endocrine disorders
○ Viral & bacterial processes
pathophysiology of diarrhea
Secretory – high volume & often associated with bacterial toxins
○ Osmotic – occurs when water is pulled into the intestine by osmotic pressure
of unabsorbed particles
○ Malabsorptive – absorption of nutrients is inhibited due to malnutrition
○ Infectious – infectious agents invading the intestinal mucosa (C.Diff).
○ Exudative – caused by changes in mucosal integrity, epithelial loss or tissue
destruction by radiation or chemotherapy.
○ May also be caused by laxative misuse
Borborygmus
intestinal rumbling
loperamide
to reduce the severity of diarrhea
what is a risk that could occur from diarrhea
potential for cardiac dysrhythmias due to electrolyte and fluid loss especially potassium
pathophysiology of fecal incontinence
- Anal sphincter weakness
○ Neuropathies
○ Disorders of the pelvic floor
○ Inflammation
○ Central nervous system disorders
○ Diarrhea
○ Fecal impaction with overflow
○ Behavioural disorders
○ More common in older age.
factors associated with IBS
○ Heredity
○ Psychological stress
○ Depression/anxiety
○ Diet high in fat and irritating foods
○ Alcohol
○ Smoking
○ Diagnoses is made in the absence of structural or other disorders.
Pathophysiology of IBS
Results from a functional disorder of intestinal motility
○ Changes in motility may be a result of:
○ Neuroendocrine dysregulation
○ Infections or inflammatory disorders
○ Vascular or metabolic disturbances
○ Peristaltic waves are affected at specific segments of the intestine.
○ No evidence of inflammation or tissue changes in the intestinal mucosa.
