GI Small Group #1 Flashcards
Superimpose a ‘normal’ set of pressure recordings on the figure above
sphincter is not closing very well in this enough. intraabdominal pressure is normally 2-4, so this pressure is abnormally high. LES is more relaxed than normal. Pressure should be lower before diaphragm, and should have a spike to about 30 immediately after the diaphragm. After that, no different.
High pressure due to contraction (tonus) of LES located at the level of diaphragm.
How would you locate the diaphragm in the pressure recordings from a normal individual?
Look for a spike to about 20-30 mm Hg.
In a normal individual:
Below diaphragm (intra-abdominal)
2 mm Hg at end of expiration and 6 mm Hg at end of inspiration.
At diaphragm: 20-30 mm Hg
Above diaphragm: 1 mm Hg at end of expiration and -5 mm Hg at end of inspiration.
How do the patient’s pressure data vary from the normal? Diagram a normal
intraluminal pressure profile from pharynx to stomach.
sphincter is not closing very well in this enough. intraabdominal pressure is normally 2-4, so this pressure is abnormally high. LES is more relaxed than normal. Pressure should be lower before diaphragm, and should have a spike to about 30 immediately after the diaphragm. After that, no different.
High pressure due to contraction (tonus) of LES located at the level of diaphragm.
Explain the patient’s heartburn in light of the pressure data.
Heartburn occurs because of nonfunctional LES. We can tell that because of the lack of pressure spike below the diaphragm.
Fetus is increasing the intra-abdominal pressure. Hormones relaxing the LES.
Dysfunctional LES + high pressure below diaphragm
Gastric reflux
H+ sensitive pain receptors in esophageal wall
burining sensation
What mechanism normally protects against reflux into the esophagus when intraabdominal pressure is raised by bending or lying down?
tonic closer to LES. vagal tone and sympathetics
tight contraction of LES
What are some causes of gastroesophageal reflux in general? During pregnancy?
Hiatal hernia, obesity
Increased pressure below diaphragm weakening LES contraction
Pregnancy: increased intra-abdominal pressure and loss of LES tone. Loss of LES tone due to increased abdominal pressure and high progesterone levels.
General: obesity, hernia, inflammation, certain foods, beverages, smoking, congenital abnormalities
coffee: caffeine leads to Ca-release from SR in SM»_space; activation of Ca-dependent K channels»_space; MP repol.»_space; SM relaxation
nutrients: nutrients in stomach stimulate acid secretion increased tendency to reflux.
Explain the dysphagia, pain, and regurgitation by comparing this man’s esophageal function to the normal one. Why did atropine relieve the pain?
The SMOOTH MUSCLE LAYER of esophagus does not have normal peristalsis and the LES does not relax in response to swallowing. Atropine relieved the pain because it blocks the muscarinic receptors, weakening contraction and reducing pain.
Achalasia = a neurogenic esophageal disorder causing decrease or impairment of esophageal peristalsis and LES relaxation;
Dysphagia is a subjec (look up later
Regurgitation is a consequence of feeble contractions and lack of relaxation of LES
Atropine reduces peristalsis by blocking muscarinic receptors
Why does the Valsalva maneuver help the patient?
Expiring against a closed glottis increases intrathoracic pressure and decreases intra-abdominal pressure. The lower pressure means a more favorable pressure gradient and less reflux.
Increased intraesophageal pressure forces opening of gastroesophageal sphincter and emptying the esophagus relieving congestion and associated pain.
What nerves are involved in the myenteric plexus? Why didn’t atropine relax the sphincter? Describe the neural control of the LES (lower esophageal sphincter).
The myenteric plexus has both sympathetic and parasympathetic input, and arises from the vagus nerve. Atropine doesn’t relax the sphincter because there are no muscarinic receptors affecting the LES (nicotinic) and atropine only affects muscarinic receptors.
The LES has sympathetic and parasympathetic inputs which activate and inhibit it respectively.
Motor outputs are mainly muscarinic
Contration: vagal cholinergic fibers - nicotinic and a-adrenergic sympathetic
relaxation: inhibitory vagal stimulation and inhibition of excitatory vagal stimulation
What is the probable mechanism of the disease?
Unknown. Imbalance of controls.
Likely to be degeneration of myenteric plexus
1) What are the signs and symptoms of mechanical obstruction of the small bowel?
Pain, acid reflux, LES not functioning.
Tenderness to palpation and pain in the periumbilical area, nausea, and vomiting. Fever suggests inflamation and bacterial infection (obstruction»_space; stasis»_space; ischemia»_space; bacterial proliferation»_space; in
2) What findings suggested a strangulated loop problem and the need for surgery?
dilated loops with fluid in them
x-rays
3) What does the elevated white blood cell count indicate?
necrosis attracts WBCs to the area (see number 1
4) What are some other causes of intestinal obstruction? If surgery is not immediate,
how could the pain be alleviated?
Tumor, adhesions
