SECTION 9 Problems of Ingestion, Digestion, Absorption, and Elimination
43
Assessment: Gastrointestinal System
Kara Ann Ventura
http://evolve.elsevier.com/Lewis/medsurg/
CONCEPTUAL FOCUS
Elimination Nutrition
Fluids and Electrolytes
LEARNING OUTCOMES
1. Describe the structures and functions of the organs of the 6. Obtain significant subjective and objective assessment
gastrointestinal tract. data related to the gastrointestinal system from a
2. Describe the structures and functions of the liver, patient.
gallbladder, biliary tract, and pancreas. 7. Perform a physical assessment of the gastrointestinal system
3. Distinguish the processes of ingestion, digestion, using appropriate techniques.
absorption, and elimination. 8. Distinguish normal from abnormal findings of a physical
4. Explain the processes of biliary metabolism, bile assessment of the gastrointestinal system.
production, and bile excretion. 9. Describe the purpose, significance of results, and nursing
5. Link the age-related changes of the gastrointestinal system responsibilities related to diagnostic studies of the
to the differences in assessment findings. gastrointestinal system.
KEY TERMS
absorption Kupffer cells
bilirubin melena, Table 43.10
borborygmi, Table 43.10 pyrosis, Table 43.10
cheilosis, Table 43.10 pyorrhea
digestion steatorrhea, Table 43.10
endoscopy tenesmus, Table 43.10
hematemesis, Table 43.10 Valsalva maneuver
ingestion
The gastrointestinal (GI) system, also called the digestive system, STRUCTURES AND FUNCTIONS OF
consists of the GI tract and its associated organs and glands.
Included in the GI tract are the mouth, esophagus, stomach,
GASTROINTESTINAL SYSTEM
small intestine, large intestine, rectum, and anus. The associated The GI tract extends around 30 ft (9 m) from the mouth to the
organs are the liver, pancreas, and gallbladder (Fig. 43.1). Prob- anus. The GI tract is essentially a tube composed of 4 layers.
lems that change physiologic processes or associated organs From the inside to the outside, these layers are (1) mucosa lin-
affect a person’s ability to maintain nutrition status and elimi- ing; (2) submucosa connective tissue, which contains glands,
nate waste. blood vessels, and lymph nodes; (3) muscle; and (4) serosa.
987
,988 SECTION 9 Problems of Ingestion, Digestion, Absorption, and Elimination
Parotid gland
Tongue Esophagus Fundus
Submandibular
Lower esophageal Body
salivary gland
sphincter (LES)
Pharynx Sublingual
salivary
Larynx gland Serosa
Longitudinal
Pyloric Submucosa
Trachea muscle layer
sphincter
Muscularis
Esophagus Mucosa Circular
Diaphragm muscle layer
Stomach Oblique
muscle layer
Spleen
Liver
Gallbladder
Transverse colon Pylorus
Duodenum Rugae Antrum
Ascending colon
B
Small
Descending
intestine
colon
Cecum
Appendix Sigmoid
Rectum colon
Anal canal
A
Fig. 43.1 (A) Location of organs of the GI system. (B) Parts of the stomach.
There are 3 smooth muscle layers: the oblique (inner) layer, cir- IMA. The GI tract and accessory organs receive 25% to 30% of
cular (middle) layer, and longitudinal (outer) layer. the cardiac output at rest and 35% or more after eating. Because
Parasympathetic and sympathetic branches of the autonomic such a large percent of the cardiac output perfuses these organs,
nervous system (ANS) innervate the GI tract. The parasympa- the GI tract is a major source from which to divert blood flow
thetic (cholinergic) system is mainly excitatory. The sympa- during exercise, stress, or injury.
thetic (adrenergic) system is mainly inhibitory. For example, The peritoneum almost completely covers the abdominal
parasympathetic stimulation increases peristalsis, and sympa- organs. The 2 layers of the peritoneum are the parietal layer,
thetic stimulation decreases it. Both sympathetic and parasym- which lines the abdominal cavity wall, and the visceral layer. It
pathetic afferent fibers relay sensory information. covers the abdominal organs. The peritoneal cavity is the poten-
The GI tract has its own nervous system: the enteric ner- tial space between the parietal and visceral layers. The 2 folds
vous system (ENS) or intrinsic nervous system. The ENS sys- of the peritoneum are the mesentery and omentum. The mes-
tem regulates motility and secretion along the entire GI tract. entery attaches the small intestine and part of the large intestine
The ENS is composed of 2 networks: (1) Meissner plexus in the to the posterior abdominal wall. It contains blood and lymph
submucosa and (2) Auerbach (myenteric) plexus between the vessels. The omentum hangs like an apron from the stomach to
muscle layers. The submucosal plexus controls secretion and is the intestines. It contains fat and lymph nodes.
involved in many sensory functions. The myenteric plexus is the The main function of the GI system is to supply nutrients to
major nerve supply to the GI tract and controls GI movements. body cells. This is accomplished through the processes of (1)
Although the ENS receives innervation from the ANS, it func- ingestion (taking in food), (2) digestion (breaking down food),
tions independently of the brain and spinal cord. and (3) absorption (transferring food products into circulation).
Circulation in the GI system is unique in that venous blood Elimination is the process of excreting the waste products of
draining the GI tract organs empties into the portal vein, which digestion.
then perfuses the liver. This allows the liver to clean the blood of
bacteria and toxins from the GI tract. The celiac artery, superior Ingestion
mesenteric artery (SMA), and the inferior mesenteric artery Ingestion is the intake of food. Appetite, the desire to ingest food,
(IMA) supply arterial blood to the GI tract. The stomach and influences how much food a person eats. We have an appetite cen-
duodenum receive their blood supply from the celiac axis. The ter in the hypothalamus. Several factors, including hypoglycemia,
distal small intestine to mid large intestine receives its blood an empty stomach, and a decrease in body temperature, stimulate
supply from branches of the hepatic and SMA. The distal large appetite. The hormone ghrelin released from the stomach mucosa
intestine through the anus receives its blood supply from the plays a role in appetite stimulation. Another hormone, leptin, is
, CHAPTER 43 Assessment: Gastrointestinal System 989
involved in appetite suppression. See Chapter 48 for more about intestine. The stomach absorbs only small amounts of water,
ghrelin and leptin. The sight, smell, and taste of food can stimu- alcohol, electrolytes, and certain drugs.
late appetite. Stomach distention, illness (especially accompanied The stomach is usually J shaped and lies obliquely in the epi-
by fever), hyperglycemia, nausea and vomiting, and certain drugs gastric, umbilical, and left hypochondriac regions of the abdomen
(e.g., amphetamines) inhibit appetite. (Fig. 43.5, later in the chapter). It always contains gastric fluid and
Deglutition, or swallowing, is the mechanical portion of mucus. The 3 main parts of the stomach are the fundus (cardia),
ingestion. The organs involved in deglutition are the mouth, body, and antrum (Fig. 43.1). The pylorus is a small portion of the
pharynx, and esophagus. antrum proximal to the pyloric sphincter. The LES and pyloric
sphincter guard the entrance to and exit from the stomach.
Mouth The stomach wall has 4 layers. The serous (outer) layer of the
The mouth consists of the lips and oral (buccal) cavity. The lips stomach is continuous with the peritoneum. The muscular layer
surround the opening of the mouth and function in speech. The consists of the longitudinal (outer) layer, circular (middle) layer,
hard and soft palates form the roof of the oral cavity. The oral and oblique (inner) layer. The mucosal layer forms folds called
cavity contains the teeth, used in mastication (chewing), and rugae that have many small glands. In the fundus, the glands
the tongue. The tongue is a solid muscle mass. It aids in chew- contain (1) chief cells, which secrete pepsinogen, and (2) parietal
ing and moving food to the back of the throat for swallowing. cells, which secrete hydrochloric (HCl) acid, water, and intrinsic
The taste receptors (taste buds) are on the sides and tip of the factor. HCl acid makes gastric juice acidic. This acidic pH helps
tongue. The tongue is also important in speech. protect us against ingested organisms. Intrinsic factor promotes
Within the oral cavity are 3 pairs of salivary glands: parotid, cobalamin (vitamin B12) absorption in the small intestine.
submaxillary, and sublingual glands. These glands produce
saliva. Saliva consists of water, protein, mucin, inorganic salts, Small Intestine
and salivary amylase. The primary functions of the small intestine are digestion and
absorption, the uptake of nutrients from the gut lumen to the
Pharynx bloodstream. The small intestine is a coiled tube about 23 ft
The pharynx is a muscular tube lined with mucous membrane. (7 m) in length and 1 to 1.1 in (2.5 to 2.8 cm) in diameter. It extends
It has 3 divisions: nasopharynx, oropharynx, and laryngeal from the pylorus to the ileocecal valve. The small intestine is com-
pharynx. The mucous membrane is continuous with the nasal posed of the duodenum, jejunum, and ileum. The ileocecal valve
cavity, mouth, auditory tubes, and larynx. During ingestion, the prevents reflux of large intestine contents into the small intestine.
oropharynx is the route for food from the mouth to the esopha- The mucosa of the small intestine is thick, vascular, and glan-
gus. Food or liquid stimulates receptors in the oropharynx, ini- dular. The functional units of the small intestine are villi. They
tiating the swallowing reflex. During swallowing, the epiglottis are minute, fingerlike projections in the mucous membrane.
closes over the opening to the larynx and prevents food from Villi contain epithelial cells that produce the intestinal digestive
entering the respiratory tract. The tonsils and adenoids, com- enzymes. The epithelial cells on the villi also have microvilli. The
posed of lymphoid tissue, help the body prevent infection. circular folds in the mucous and submucous layers, along with
the villi and microvilli, increase the surface area for digestion
Esophagus and absorption.
The esophagus is a hollow, muscular tube that receives food from The digestive enzymes on the brush border of the microvilli
the pharynx and moves it to the stomach. It is 7 to 10 in (18 to 25 chemically break down nutrients for absorption. Between the
cm) long and 0.8 in (2 cm) in diameter. The esophagus is in the tho- bases of the villi lie the crypts of Lieberkühn, which contain the
racic cavity. It is structurally composed of 4 layers: inner mucosa, multipotent stem cells. These are the precursors for the other
submucosa, muscularis propria, and outermost adventitia. The epithelial cell types. Brunner’s glands in the submucosa of the
upper third of the esophagus is composed of striated skeletal mus- duodenum secrete an alkaline fluid containing bicarbonate that
cle. The distal two thirds are composed of smooth muscle. neutralizes acidic fluids and protects the mucosa. Intestinal
Between swallows, the esophagus is collapsed and the upper goblet cells secrete mucus that protects the mucosa.
esophageal sphincter (UES) closed. With swallowing, the UES
relaxes, and a peristaltic wave moves the bolus into the esopha- Physiology of Digestion
gus. The muscular layers contract (peristalsis) and propel the food Digestion is the physical and chemical breakdown of food into
to the stomach. The lower esophageal sphincter (LES) at the distal absorbable substances. The timely movement of food through
end of the esophagus controls the opening of the esophagus into the GI tract and the secretion of specific enzymes promote diges-
the stomach. It stays contracted except during swallowing, belch- tion. These enzymes break down food to particles of appropriate
ing, or vomiting. The LES is an important barrier that normally size for absorption (Table 43.1).
prevents reflux of acidic gastric contents into the esophagus. The process of digestion begins in the mouth, where food
is chewed, mechanically broken down, and mixed with saliva.
Digestion and Absorption Saliva helps us swallow by lubricating food. Saliva contains
Stomach amylase, which breaks down starches to maltose. Chewing and
The stomach’s functions are to store food, mix food with gastric the sight, smell, thought, and taste of food stimulate the release
secretions, and empty contents in small boluses into the small of saliva. A person makes about 1 L of saliva each day. After
43
Assessment: Gastrointestinal System
Kara Ann Ventura
http://evolve.elsevier.com/Lewis/medsurg/
CONCEPTUAL FOCUS
Elimination Nutrition
Fluids and Electrolytes
LEARNING OUTCOMES
1. Describe the structures and functions of the organs of the 6. Obtain significant subjective and objective assessment
gastrointestinal tract. data related to the gastrointestinal system from a
2. Describe the structures and functions of the liver, patient.
gallbladder, biliary tract, and pancreas. 7. Perform a physical assessment of the gastrointestinal system
3. Distinguish the processes of ingestion, digestion, using appropriate techniques.
absorption, and elimination. 8. Distinguish normal from abnormal findings of a physical
4. Explain the processes of biliary metabolism, bile assessment of the gastrointestinal system.
production, and bile excretion. 9. Describe the purpose, significance of results, and nursing
5. Link the age-related changes of the gastrointestinal system responsibilities related to diagnostic studies of the
to the differences in assessment findings. gastrointestinal system.
KEY TERMS
absorption Kupffer cells
bilirubin melena, Table 43.10
borborygmi, Table 43.10 pyrosis, Table 43.10
cheilosis, Table 43.10 pyorrhea
digestion steatorrhea, Table 43.10
endoscopy tenesmus, Table 43.10
hematemesis, Table 43.10 Valsalva maneuver
ingestion
The gastrointestinal (GI) system, also called the digestive system, STRUCTURES AND FUNCTIONS OF
consists of the GI tract and its associated organs and glands.
Included in the GI tract are the mouth, esophagus, stomach,
GASTROINTESTINAL SYSTEM
small intestine, large intestine, rectum, and anus. The associated The GI tract extends around 30 ft (9 m) from the mouth to the
organs are the liver, pancreas, and gallbladder (Fig. 43.1). Prob- anus. The GI tract is essentially a tube composed of 4 layers.
lems that change physiologic processes or associated organs From the inside to the outside, these layers are (1) mucosa lin-
affect a person’s ability to maintain nutrition status and elimi- ing; (2) submucosa connective tissue, which contains glands,
nate waste. blood vessels, and lymph nodes; (3) muscle; and (4) serosa.
987
,988 SECTION 9 Problems of Ingestion, Digestion, Absorption, and Elimination
Parotid gland
Tongue Esophagus Fundus
Submandibular
Lower esophageal Body
salivary gland
sphincter (LES)
Pharynx Sublingual
salivary
Larynx gland Serosa
Longitudinal
Pyloric Submucosa
Trachea muscle layer
sphincter
Muscularis
Esophagus Mucosa Circular
Diaphragm muscle layer
Stomach Oblique
muscle layer
Spleen
Liver
Gallbladder
Transverse colon Pylorus
Duodenum Rugae Antrum
Ascending colon
B
Small
Descending
intestine
colon
Cecum
Appendix Sigmoid
Rectum colon
Anal canal
A
Fig. 43.1 (A) Location of organs of the GI system. (B) Parts of the stomach.
There are 3 smooth muscle layers: the oblique (inner) layer, cir- IMA. The GI tract and accessory organs receive 25% to 30% of
cular (middle) layer, and longitudinal (outer) layer. the cardiac output at rest and 35% or more after eating. Because
Parasympathetic and sympathetic branches of the autonomic such a large percent of the cardiac output perfuses these organs,
nervous system (ANS) innervate the GI tract. The parasympa- the GI tract is a major source from which to divert blood flow
thetic (cholinergic) system is mainly excitatory. The sympa- during exercise, stress, or injury.
thetic (adrenergic) system is mainly inhibitory. For example, The peritoneum almost completely covers the abdominal
parasympathetic stimulation increases peristalsis, and sympa- organs. The 2 layers of the peritoneum are the parietal layer,
thetic stimulation decreases it. Both sympathetic and parasym- which lines the abdominal cavity wall, and the visceral layer. It
pathetic afferent fibers relay sensory information. covers the abdominal organs. The peritoneal cavity is the poten-
The GI tract has its own nervous system: the enteric ner- tial space between the parietal and visceral layers. The 2 folds
vous system (ENS) or intrinsic nervous system. The ENS sys- of the peritoneum are the mesentery and omentum. The mes-
tem regulates motility and secretion along the entire GI tract. entery attaches the small intestine and part of the large intestine
The ENS is composed of 2 networks: (1) Meissner plexus in the to the posterior abdominal wall. It contains blood and lymph
submucosa and (2) Auerbach (myenteric) plexus between the vessels. The omentum hangs like an apron from the stomach to
muscle layers. The submucosal plexus controls secretion and is the intestines. It contains fat and lymph nodes.
involved in many sensory functions. The myenteric plexus is the The main function of the GI system is to supply nutrients to
major nerve supply to the GI tract and controls GI movements. body cells. This is accomplished through the processes of (1)
Although the ENS receives innervation from the ANS, it func- ingestion (taking in food), (2) digestion (breaking down food),
tions independently of the brain and spinal cord. and (3) absorption (transferring food products into circulation).
Circulation in the GI system is unique in that venous blood Elimination is the process of excreting the waste products of
draining the GI tract organs empties into the portal vein, which digestion.
then perfuses the liver. This allows the liver to clean the blood of
bacteria and toxins from the GI tract. The celiac artery, superior Ingestion
mesenteric artery (SMA), and the inferior mesenteric artery Ingestion is the intake of food. Appetite, the desire to ingest food,
(IMA) supply arterial blood to the GI tract. The stomach and influences how much food a person eats. We have an appetite cen-
duodenum receive their blood supply from the celiac axis. The ter in the hypothalamus. Several factors, including hypoglycemia,
distal small intestine to mid large intestine receives its blood an empty stomach, and a decrease in body temperature, stimulate
supply from branches of the hepatic and SMA. The distal large appetite. The hormone ghrelin released from the stomach mucosa
intestine through the anus receives its blood supply from the plays a role in appetite stimulation. Another hormone, leptin, is
, CHAPTER 43 Assessment: Gastrointestinal System 989
involved in appetite suppression. See Chapter 48 for more about intestine. The stomach absorbs only small amounts of water,
ghrelin and leptin. The sight, smell, and taste of food can stimu- alcohol, electrolytes, and certain drugs.
late appetite. Stomach distention, illness (especially accompanied The stomach is usually J shaped and lies obliquely in the epi-
by fever), hyperglycemia, nausea and vomiting, and certain drugs gastric, umbilical, and left hypochondriac regions of the abdomen
(e.g., amphetamines) inhibit appetite. (Fig. 43.5, later in the chapter). It always contains gastric fluid and
Deglutition, or swallowing, is the mechanical portion of mucus. The 3 main parts of the stomach are the fundus (cardia),
ingestion. The organs involved in deglutition are the mouth, body, and antrum (Fig. 43.1). The pylorus is a small portion of the
pharynx, and esophagus. antrum proximal to the pyloric sphincter. The LES and pyloric
sphincter guard the entrance to and exit from the stomach.
Mouth The stomach wall has 4 layers. The serous (outer) layer of the
The mouth consists of the lips and oral (buccal) cavity. The lips stomach is continuous with the peritoneum. The muscular layer
surround the opening of the mouth and function in speech. The consists of the longitudinal (outer) layer, circular (middle) layer,
hard and soft palates form the roof of the oral cavity. The oral and oblique (inner) layer. The mucosal layer forms folds called
cavity contains the teeth, used in mastication (chewing), and rugae that have many small glands. In the fundus, the glands
the tongue. The tongue is a solid muscle mass. It aids in chew- contain (1) chief cells, which secrete pepsinogen, and (2) parietal
ing and moving food to the back of the throat for swallowing. cells, which secrete hydrochloric (HCl) acid, water, and intrinsic
The taste receptors (taste buds) are on the sides and tip of the factor. HCl acid makes gastric juice acidic. This acidic pH helps
tongue. The tongue is also important in speech. protect us against ingested organisms. Intrinsic factor promotes
Within the oral cavity are 3 pairs of salivary glands: parotid, cobalamin (vitamin B12) absorption in the small intestine.
submaxillary, and sublingual glands. These glands produce
saliva. Saliva consists of water, protein, mucin, inorganic salts, Small Intestine
and salivary amylase. The primary functions of the small intestine are digestion and
absorption, the uptake of nutrients from the gut lumen to the
Pharynx bloodstream. The small intestine is a coiled tube about 23 ft
The pharynx is a muscular tube lined with mucous membrane. (7 m) in length and 1 to 1.1 in (2.5 to 2.8 cm) in diameter. It extends
It has 3 divisions: nasopharynx, oropharynx, and laryngeal from the pylorus to the ileocecal valve. The small intestine is com-
pharynx. The mucous membrane is continuous with the nasal posed of the duodenum, jejunum, and ileum. The ileocecal valve
cavity, mouth, auditory tubes, and larynx. During ingestion, the prevents reflux of large intestine contents into the small intestine.
oropharynx is the route for food from the mouth to the esopha- The mucosa of the small intestine is thick, vascular, and glan-
gus. Food or liquid stimulates receptors in the oropharynx, ini- dular. The functional units of the small intestine are villi. They
tiating the swallowing reflex. During swallowing, the epiglottis are minute, fingerlike projections in the mucous membrane.
closes over the opening to the larynx and prevents food from Villi contain epithelial cells that produce the intestinal digestive
entering the respiratory tract. The tonsils and adenoids, com- enzymes. The epithelial cells on the villi also have microvilli. The
posed of lymphoid tissue, help the body prevent infection. circular folds in the mucous and submucous layers, along with
the villi and microvilli, increase the surface area for digestion
Esophagus and absorption.
The esophagus is a hollow, muscular tube that receives food from The digestive enzymes on the brush border of the microvilli
the pharynx and moves it to the stomach. It is 7 to 10 in (18 to 25 chemically break down nutrients for absorption. Between the
cm) long and 0.8 in (2 cm) in diameter. The esophagus is in the tho- bases of the villi lie the crypts of Lieberkühn, which contain the
racic cavity. It is structurally composed of 4 layers: inner mucosa, multipotent stem cells. These are the precursors for the other
submucosa, muscularis propria, and outermost adventitia. The epithelial cell types. Brunner’s glands in the submucosa of the
upper third of the esophagus is composed of striated skeletal mus- duodenum secrete an alkaline fluid containing bicarbonate that
cle. The distal two thirds are composed of smooth muscle. neutralizes acidic fluids and protects the mucosa. Intestinal
Between swallows, the esophagus is collapsed and the upper goblet cells secrete mucus that protects the mucosa.
esophageal sphincter (UES) closed. With swallowing, the UES
relaxes, and a peristaltic wave moves the bolus into the esopha- Physiology of Digestion
gus. The muscular layers contract (peristalsis) and propel the food Digestion is the physical and chemical breakdown of food into
to the stomach. The lower esophageal sphincter (LES) at the distal absorbable substances. The timely movement of food through
end of the esophagus controls the opening of the esophagus into the GI tract and the secretion of specific enzymes promote diges-
the stomach. It stays contracted except during swallowing, belch- tion. These enzymes break down food to particles of appropriate
ing, or vomiting. The LES is an important barrier that normally size for absorption (Table 43.1).
prevents reflux of acidic gastric contents into the esophagus. The process of digestion begins in the mouth, where food
is chewed, mechanically broken down, and mixed with saliva.
Digestion and Absorption Saliva helps us swallow by lubricating food. Saliva contains
Stomach amylase, which breaks down starches to maltose. Chewing and
The stomach’s functions are to store food, mix food with gastric the sight, smell, thought, and taste of food stimulate the release
secretions, and empty contents in small boluses into the small of saliva. A person makes about 1 L of saliva each day. After
