Class notes
Nur 211 Bowel Elimination Notes
- Course
- NUR211
- Institution
- Georgian Court College
This is a comprehensive and detailed note on bowel elimination for Nur 211. *Essential!!
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ELIMINATION: BOWELTAYLOR 39: BOWEL ELMINATION
STOMACH
The stomach stores food during eating, secretes digestive fluids, churns food to aid in digestion, and pushes
the partially digested food, called chyme, into the small intestine. The pyloric sphincter, a muscular ring that
regulates the size of the opening at the end of the stomach, controls the movement of chyme from the
stomach into the small intestine.
SMALL INESTINE
The small intestine is about 20 ft (6 m) long and about 1 in (2.2 cm) wide.
The small intestine is made up of three parts: the first is the duodenum, the middle section is the
jejunum, and the distal section that connects with the large intestine is the ileum.
The small intestine secretes enzymes that digest proteins and carbohydrates.
Digestive juices from the liver and pancreas enter the small intestine through a small opening in the
duodenum.
The small intestine is responsible for digestion of food and absorption of nutrients into the
bloodstream.
LARGE INTESTINE
The connection between the ileum of the small intestine and the large intestine is the ileocecal, or
ileocolic, valve. This valve normally prevents contents from entering the large intestine prematurely and
prevents waste products from returning to the small intestine.
The large intestine, the primary organ of bowel elimination, is the lower, or distal, part of the
gastrointestinal tract.
The large intestine, also known as the colon, extends from the ileocecal valve to the anus. The colon in
adults is about 5 ft (1.5 m) long, but variations in length are normal.
Width also varies; at its narrowest point, the colon is about 1 in (2.5 cm) wide; at its widest point, it is
about 3 in (7.5 cm). The diameter of the colon decreases from the cecum to the anus
From the cecum, the first part of the large intestine, the digestive contents enter the colon, which
consists of several segments. The ascending colon extends from the cecum upward toward the liver,
where it turns to cross the abdomen. This turn is called the hepatic flexure. Upon turning, this portion
of the colon becomes the transverse colon, crossing the abdomen from the right to the left. The colon
then turns at the splenic flexure to become the descending colon.
The descending colon passes down the left side of the body to the sigmoid, or pelvic, colon.
The sigmoid colon contains feces, solid waste products that have reached the distal end of the colon
and are ready for excretion. Once excreted, feces are called stool. The sigmoid colon empties into the
rectum, the last part of the large intestine.
The rectum is about 12 cm (5 in) long, 2.5 cm (1 in) of which is the anal canal. In the rectum, three
transverse folds of tissue are present that may help to hold the fecal material in the rectum
temporarily.
Vertical folds also are present, each of which contains an artery and a vein. If the veins become
abnormally distended, hemorrhoids occur.
The rectum is empty except immediately before and during defecation (the process of bowel
elimination; a bowel movement). Feces are excreted from the rectum through the anal canal, which is
approximately 2.5 to 3.8 cm (1 to 1.5 in) long, and out through an opening called the anus.
Functions of the large intestine include the absorption of water, the formation of feces, and the
expulsion of feces from the body.
, The products of digestion, chyme, move from the small intestine, passing through the ileocecal valve,
and enter the cecum. Approximately 1,500 mL of chyme enters the large intestine daily. Its contents are
liquid or watery. While passing through the large intestine, most water is absorbed. About 800 to 1,000
mL of liquid is absorbed daily by the intestinal tract, allowing for the formed, semisolid consistency of
the normal stool.
NERVOUS SYSTEM CONTROL
The autonomic nervous system innervates the muscles of the colon. The parasympathetic nervous
system stimulates movement, while the sympathetic system inhibits movement.
Contractions of the circular and longitudinal muscles of the intestine, peristalsis, occur every 3 to 12
minutes, moving waste products along the length of the intestine continuously.
Mass peristalsis often occurs after food has been ingested, accounting for the urge to defecate that
often occurs after meals.
One third to one half of ingested food waste is normally excreted in the stool within 24 hours, and the
remainder within the next 24 to 48 hours.
The internal sphincter in the anal canal and the external sphincter at the anus control the discharge of
feces and flatus (intestinal gas).
DEFECATION
Defecation refers to the emptying of the large intestine. Two centers govern the reflex to defecate, one
in the medulla and a subsidiary one in the spinal cord. When parasympathetic stimulation occurs, the
internal anal sphincter relaxes and the colon contracts, allowing the fecal mass to enter the rectum
Voluntary contraction of the muscles of the abdominal wall by holding one’s breath, contracting the
diaphragm, and closing the glottis increases intra-abdominal pressure up to four or five times the
normal pressure, which helps expel feces.
Simultaneously, the muscles on the pelvic floor contract and aid in expulsion of the fecal mass.
Defecation is eased by flexing the thigh muscles, which increases abdominal pressure, and by the sitting
position.
When a person bears down to defecate, the increased pressures in the abdominal and thoracic cavities
result in decreased blood flow to the atria and ventricles, thus temporarily lowering cardiac output.
This technique of bearing down, termed the Valsalva maneuver.
DEVELOPMENTAL CONSIDERATIONS
INFANT: breastfed infants can pass from 2 to 10 stools daily, whereas bottle-fed infants typically pass 1
or 2 stools daily. At the age of 1 year, all infants commonly pass one or two stools a day.
TODDLER: Between the ages of 18 and 24 months, the nerve fibers innervating the internal and
external anal sphincters become fully developed, at which point voluntary control of defecation
becomes possible.
ADULT: Irritable bowel syndrome (IBS), which is common in the adult population, can present with
constipation, diarrhea, or both. The symptoms may be brought on by diet, stress, depression, or
anxiety.
OLDER ADULT: Constipation is often a chronic problem for older adults. The rectal receptors in older
adults have a decreased response to stretching, which can lead to a decreased urge to move the bowels
despite a large amount of stool in the rectum. Diarrhea, fecal impaction (prolonged retention or an
accumulation of fecal material that forms a hardened mass in the rectum), or fecal incontinence
(involuntary or inappropriate passing of stool or flatus) can also result from physiologic or lifestyle
changes.
AGE-RELATED CHANGES
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