Gastrointestinal 1
Anatomy & Physiology ( illustration ) Upper gastrointestinal tract
Mouth: teeth and salivary glands Esophagus Stomach ( illustration )
Lower gastrointestinal tract
Small intestine - digests and absorbs, mixes via peristalsis, receives secretions from liver, gallbladder and pancreas
duodenum - joins pylorus of the stomach, is about ten inches long jejunum - middle section, is about eight feet long illeum - lower section, is about 12 feet long
Colon - approximately six feet long, absorbs water and sodium ( illustration )
ascending transverse descending sigmoid rectum - last seven - eight inches of intestines
Accessory digestive organs
Liver - largest gland of the body ( illustration )
lobes dived into lobules by blood vessels and fibrous material ducts - hepatic duct from liver; cystic duct from gallbladder; common bile duct formed by hepatic duct and cystic duct and drains into duodenum functions: Metabolism of fat, carbohydrates and protein
converts glucose to glycogen for storage converts glycogen to glucose and releases into blood forms glucose from fats or proteins breaks down fatty acids into ketones stores fat synthesizes triglycerides, phospholipids, cholesterol, and choline (B complex factor) synthesizes various proteins converts amino acid to ammonia converts ammonia to urea
other functions
secretes bile, which is important in the emulsifying of fats detoxifies substances such as drugs, hormones metabolizes vitamins
Pancreas ( illustration )
fish-shaped organ extending from duodenal curve to the spleen both an endocrine and exocrine gland
pancreatic cells - empty into duodenum at the hepatopancreatic papilla; secrete enzymes which digest fats, carbohydrates and proteins islet of Langerhans
alpha cells secrete glucagon to promote liver glycogenolysis and gluconeogenesis which ultimately increases blood glucose level beta cells secrete insulin
Gallbladder ( illustration )
similar size and shape as a pear made up of smooth muscle and lined with rugae-arranged mucosa only purpose is to store bile empties bile into duodenum when fat is present there
Process of digestion
Purpose - converts foods into a form which can be absorbed and used by the body Digestive enzymes Basic processes
absorption - accomplished by active transport via intestinal cells. Water and solutes move through the intestinal mucosa in opposite direction expected in osmosis and diffusion metabolism - consists of the sum of all physical and chemical changes that take place within an organism catabolism - series of chemical reactions that take place within the cell; breaks down food molecules to produce energy
anabolism - synthesis of compounds from simpler compounds
Disorders of Stomach and Colon Pernicious anemia - anemia caused when tissues fail to absorb enough vitamin B12
Definition/etiology/risk
mucosa and parietal cells of stomach atrophy; stomach fails to produce intrinsic factor , thus cannot properly absorb vitamin B12 possibly an autoimmune disease may follow gastric resection
Pathophysiology
large RBCs - macrocytic normochromic hydrochloric acid
Findings
anemia - findings depend on severity tissue hypoxia producing fatigue, weakness, dyspnea, pallor, palpitations GI symptoms: sore tongue, anorexia, nausea, vomiting, abdominal pain, neurological symptoms neurological symptoms: paresthesia in hands and feet, weakness, impaired coordination, changes in LOC.
Complications: GI symptoms are reversible, but neurological changes are not
Diagnostics
CBC bone-marrow biopsy lack of free hydrochloric acid in stomach Schilling test
Management
lifelong vitamin B12 therapy adequate nutrition blood transfusions as needed
Nursing interventions
monitor for impaired gas exchange manage fatigue risk of injury from depressed LOC and impaired coordination knowledge deficit- need to understand chronic illness
Peptic ulcer diseases - include disorders that ulcerate any part of stomach or intestines.
Gastric ulcers
definition/etiology
incidence higher in the middle-aged and elderly; most common in men ages 45-55 risk factors: aspirin, NSAIDs, steroids, caffeine, and alcohol intake; stress pathogen: H. pylori
pathophysiology
something disrupts mucosal layer and acid diffuses back into mucosa commonest site: junction of fundus and pylorus normal gastric acid secretion
findings
pain, burning or gas, worse with food pain in left upper epigastric area nausea/vomiting bleeding; hematemesis
Duodenal ulcers
etiology/risk factors
excess production of hydrochloric acid more rapid gastric emptying familial tendency stress more frequent in people with type O blood more common in men ages 25 to 50
pathophysiology
located 0.5 to 2 cm below pylorus arteriosclerotic changes in adjacent blood vessels vagus nerve stimulation causes tissues to release gastrin , which increases secretion of hydrochloric acid
findings
pain, heartburn occur during night or when stomach is empty pain relieved by food intake melena (tarry stool; black with digested blood)
diagnostic studies
endoscopy - esophagogastroduodenoscopy complete blood count (CBC) test stool for occult blood
complications
hemorrhage
treat with tap water lavage to control bleeding administer Intra-arterial vasopressin administer Intravenous fluids and blood replacement
perforation and peritonitis
finding: severe abdominal pain finding: board-like abdomen
paralytic ileus (obstruction): scarring may obstruct pylorus
