Diseases of Upper GI Tract Flashcards
Describe the function of the GI tract
Transfers nutrients and water from the external environment to the internal environment, where the circulatory system delivers nutrients to the cells
Define GI absorption
Passage of end products of digestion from the GI tract into the blood or lymph
Name and describe the three phases in the swallowing process
- ORAL PHASE - sucking, chewing, and moving food/liquid into the throat (voluntary)
- PHARYNGEAL PHASE - Starting the swallow, squeezing food down the throat, epiglottis closes off and protects airway from aspiration & prevents choking
- ESOPHAGEAL PHASE - relaxing & tightening the sphincters at top (UES) and bottom (LES) of esophagus; peristalsis
What is the chief function of the esophagus?
Motility
Describe the difference between Primary and Secondary Peristalsis
- PRIMARY - occurs with swallowing; travels the full length of the esophagus which secretes mucus (normal)
- SECONDARY - occurs in response to esophageal distention or irritation caused by gastric reflux
What are the two main sites of absorption in the GI tract?
Duodenum and Jejunum
Describe the sympathetic nervous system’s role in digestion
**Carried by SPLANCHNIC NERVES
•Slows secretion and motility
•Prepares body for sudden stress, increases HR and blood flow
•Constantly active at basal level
•”Fight or flight” response
*Neurotransmitters: Primarily NOREPINEPHRINE
Describe the parasympathetic nervous system’s role in digestion
**Carried by the VAGUS NERVE
•Primarily uses ACETYLCHOLINE as neurotransmitter
•Vagal activity increases esophageal activity (secretion and motility)
-Swallowing is triggered by a signal transmitted by the vagus nerve
Summarize the functions of the parasympathetic nervous system (using an acronym)
SLUDD: •Salivation •Lacrimation •Urination •Digestion •Defecation
Describe the Lower Esophageal Sphincter (LES) and its role in digestion
Ring of thickened, circular, smooth muscle of the esophagus
•At rest, LES maintains a high-pressure zone
•Relaxes before the esophagus contracts, allowing food to pass to stomach
•After food passes, LES constricts to prevent regurgitation
_____ and _____ are the reservoir function of the stomach
FUNDUS and BODY are the reservoir of the stomach
Contractions are great in the _____ of the stomach
ANTRUM
Name three important hormones of the GI tract
- Gastrin
- Cholecystokinin
- Secretin
_____ in the gastric pit secrete mucus
MUCOUS CELLS
G cells secrete ______.
Where?
GASTRIN
Released in: stomach, duodenum, and the pancreas
Describe gastrin
A peptide hormone that stimulates HCl secretion by the parietal cells of the stomach and aids in gastric motility.
Chief cells secrete ______ and ______
PEPSINOGEN and GASTRIC LIPASE
Intrinsic factor is needed for the absorption of ______ and is secreted by __________
Intrinsic factor is needed for the absorption of VITAMIN B12 and is secreted by GASTRIC MUCOSA - PARTIETAL CELLS
_________ secrete HCl
PARIETAL CELLS
What 3 things stimulate the parietal cells secretion of HCl?
- Gastrin
- Acetylcholine
- Histamine
Seeing, smelling, tasting, and chewing food triggers the _________ to stimulate ________, causing increased acid production
Seeing, smelling, tasting, and chewing food triggers the VAGUS NERVE to stimulate PARIETAL CELLS, causing increased acid production
_____, ________, and ______ send neural messages to increase gastrin release, which increases ________.
STOMACH DISTENTION, HIGH PH, AND PEPTIDES send neural messages to increase gastrin release, which increases HCl PRODUCTION
Name and describe the three phases of gastric secretions
- CEPHALIC PHASE - before food enters stomach; from sight, smell, etc of food
- GASTRIC PHASE - stimulated by presence of protein, stomach distension, alcohol and caffeine; produces gastric secretions
- INTESTINAL PHASE - Inhibitory phase; slows gastric secretions; Stomach distention, increased fat, acid, osmolality releases 2 hormones: cholecystokinin and secretin - act on smooth muscle to slow motility
Acid reflux induces _______ of the esophagus which returns ~90% of the acid and food to the stomach
SECONDARY PERISTALSIS
What is the pH of saliva? Why is this important?
7.8-8.0
Is rich in bicarbonate, which neutralizes residual acid coating the esophagus after second peristaltic wave
Describe the body’s two-step method for impaired esophageal clearance
- Peristalsis clears gastric fluid from the esophagus
2. Swallowing saliva neutralizes any remaining acid
Give the six points in the etiology of GERD
- Decreased salivation
- Impaired esophageal clearance
- Impaired tissue resistance
- Transient LES relaxation
- Delayed gastric emptying
- Decreased resting tone of LES
Describe Impaired Tissue Resistance in the etiology of GERD
- The ability of the esophageal mucosa to withstand injury can determine if reflux disease will develop; influenced by AGE and NUTRITIONAL STATUS
- Tissue resistance protects against acid injury by limiting the rate of H ions diffusing into epithelium
- The esophagus produces BICARBONATE and MUCUS which forms a protective barrier on epithelial surface
- PEPSIN in acid refluxate damages esophagus by digesting epithelial protein (esophageal mucosa is less resistant to acid damage than stomach)
_______ is the dominant cause of reflux. Explain.
Transient LES Relaxation (TLESR)
- cause of ~82% of reflux episodes
- vagal nerve mediates noncholinergic inhibitory reflex in LES
- TLESRs are short lived (<30s)
- Not nexessary to treat GERD that exists from TLESR
Describe how Delayed Gastsric Emptying can be a cause of GERD
When gastric emptying is delayed the gastric fluid volume is increased, thus increasing amount of fluid available for reflux
Describe how Decreased Resting Tone of LES can be a cause of GERD
- Low-pressure LES allows reflux every time pressure in stomach>LES
- Usually associated with severe ESOPHAGITIS
Name and describe the symptoms of GERD
- HEARTBURN - most common GERD symptom; caused by reflux of gastric contents into the esophagus
- DYSFUNCTIONAL SWALLOWING - DYSPHAGIA - impairment in movement of swallowed material from pharynx to stomach; may occur b/c abnormal peristalsis, inflammation, or a stricture
- ODYNOPHAGIA - Sharp pain beneath sternum that occurs when swallowing; result of erosive esophagitis; may inhibit eating due to pain
- REGURGITATION - bitter/acid taste in mouth from acid refluxing; not vomiting b/c lack of abdominal wall & GI contraction
- CHEST PAIN - may be sharp or dull
Describe the pulmonary symptoms of GERD
If refluxed material gets past UES it can aspirate into larynx and tracheobronhial tree
Symptoms: asthma, chronic coughing, bronchitis, wheezing, aspiration pneumonia, interstitial fibrosis
~45-65% of adult asthmatics have GERD
Describe the oral symptoms of GERD
- Waterbath - spontaneous appearance of high volumes of saliva in mouth; caused by vagally mediated reflex initiated by acid in esophagus
- Gingivitis & Tooth Decay - caused by contact with acidic refluxate