UNIT1_Anatomy&Physiology Flashcards
Mucous neck cells: ?
Mucous neck cells: Mucus-secreting eosinophilic cells
Parietal (oxyntic) cells: ?
Parietal (oxyntic) cells: Larger eosinophilic cells that secrete hydrochloric acid (HCl) and intrinsic factor (IF)
Larger eosinophilic cells that secrete hydrochloric acid (HCl) and intrinsic factor (IF) –> ?
Parietal (oxyntic) cells:
Endocrine cells:?
Endocrine cells: Modulate gastric secretions
__________ cells: Modulate gastric secretions
Endocrine cells:
Enterochromaffin-like (ECL) cells: ?
Enterochromaffin-like (ECL) cells: Release histamine in response to gastrin produced by G cells. Histamine increases gastric acid secretion.
________________ cells: Release histamine in response to gastrin produced by G cells. Histamine increases gastric acid secretion.
Enterochromaffin-like (ECL) cells:
Chief (zymogen) cells: ?
Chief (zymogen) cells: Smaller basophilic cells that secrete pepsinogen
_______________ cells: Smaller basophilic cells that secrete pepsinogen
Chief (zymogen) cells:
The principal pathological abnormalities of the GI tract consist of what?
smooth muscle atrophy and gut wall fibrosis
What is Scleroderma/PSS? and what is the predominate process?
Scleroderm/PSS = smooth muscle atroophy & gut wall fibrosis.
Myopathic process
What do the following maniiifestiaton of scleroderm/PPS lead to?
Smooth Muscle Atrophy –> ?
Smooth Muscle Atrophy –> ?
Unrepentant GERD –> ?
Smooth Muscle Atrophy –> Weak Peristalsis –> Dyspahgia.
Smooth Muscle Atrophy –> Weak LES –> GERD.
Unrepentant GERD –> Esophagitis –> Stricture
How do you dX Esophageal disease?
Esophageal manometry
Is Peristalsis preserved in spastic disoders of the esophagus?
Yes!
Sx are usually chest pain and dysphagia
What class of GI diz has a Pathophysiology related to overactivity of excitatory nerves, an impairment of inhibitory innervation or overreactivity of the smooth muscle response.
Spastic Disorders of the Esophagus
Physiology of gastric emptying:
Receptive relaxation is mediated by: ?
Liquid emptying is mediated by: ?
Solid emptying is mediated by: ?
Residual solids is mediated by: ?
_ Receptive relaxation = swallowing-induced vagal response (vagally mediated inhibition of body tone)
- Liquid emptying by tonic pressure gradient
- Solid emptying by vagally-mediated contractions
- Residual solids emptied during non-fed state by MMC every 90-120 minutes
Describe the gastric reservoir function of accommodation:
- Smooth muscle relaxation elicited by mechanical distention of the stomach (Gastric mechanoreceptors).
- Vagovagal response
__________ = stomach paralysis. impaired transit of food from the stomach to the duodenum. NOT a mechanical obstruction.
Gastroparesis:
Cx ppt:
Nausea Vomiting Early satiety Postprandial abdominal distention Postprandial abdominal pain
Etiology of Gastroparesis?
- Idiopathic (? Post-infectious)
- Post-surgical (vagal nerve injury)
Gastric
Esophageal
Thoracic surgical procedures: Lung Transplant - Diabetic
- Medication-related (opiates)
- Others Paraneoplastic Rheumatologic Neurologic Myopathic (Scleroderma!)
How do you Dx Gastroparesis?
- Gastric emptying study
Gastric scintigraphy
Low fat EggBeaters radiolabelled with 1 mCi Technetium 99.
Microwaved and served with toast, jam and water.
Abnormal: retention >60% at 2 hr or >10% at 4 hr.
How do you Tx Gastroparesis?
- Lifestyle and dietary measures
Small & frequent meals
Low-fat & low-residue diet
Glucose control in diabetics - Medications
Prokinetic agents
Antiemetics - Gastric electric stimulation
- Surgery (~2%)
Describe the difference between Neuropathic and Myopathic small bowel motility disorders.
- Neuropathic:
Normal amp but sustain burst of uncoordinated phasic contractions.
Early return of MMC.
Increased frew. of MMC - Myopathic
Decreased amp of contractions of complete lack of any motor activity.
Some bowel diz. have both!
What diz is a Major Manifestation of Small Intestinal Dysmotility?
Chronic Intestinal Psuedo-Obstruction (CIPO):
- Signs and symptoms of mechanical obstruction of the small bowel without a lesion obstructing flow of intestinal contents.
- Characterized by the presence of dilation of the bowel on imaging
What is a complication of CIPO?
Small Intestinal Bacterial Overgrowth a complication of CIPO: Stasis –> bacterial overgrowth –> fermentation and malabsorption.
What are the Etiologies of Small Intestinal Motility Disorders (and CIPO)?
- Neuropathic
Degenerative Neuropathies (eg Parkinon’s).
Paraneoplastic Autoimmune (anti-Hu Ab).
Chagas Disease: parasite Trypanosoma cruzi.
Diabetes associated (neuropathy). - Mixed Myopathic and Neuopathic
Infiltrative Conditions.
Scleroderma, Amyloidosis, Eosinophilic Gastroenteritis.
Idiopathic.
How does peds form of CIPO differ from the adult form?
In children:
Mostly congenital
Mostly primary condition (visceral neuropathy/myopathy)
Absent MMC predicts need for IV nutrition.
1/3 infants dies in 1st year
Causes of constipation:
Drugs
Mechanical
Metabolic: DM, hypoK, hyperCa, hypoMg, hypothyroid
Myopathy: Amyloid, Scleroderma
Neurogenic: Parkinson’s, spinal cord injury, MS, autonomic neuropathy, Hirschsprung’s
Other: pregnancy, immobility
IBS-C
Normal transit, slow transit, dyssynergic defecation
what test can be used to eval incontinence and constipation?
Anal Manometry
Inability to coordinate the abdominal, rectoanal and pelvic floor muscles during defecation is known as?
Pelvic Floor Dysfunction
What does an abnormal anorectal manometry reveal in Dyssynergia?
Reveals: Paradoxical contraction of the pelvic floor and external anal sphincters.
Tx: biofeedback therapy
Important normal GI motility patterns altered in disease are:
Small Bowel Peristalsis: ?
Colonic transit: ?
Sphincter dysfunction: ?
Small Bowel Peristalsis: CIPO (Scleroderma).
Colonic transit: Slow transit constipation (Scleroderma)
Sphincter dysfunction: Hirschsprung’s, Dysynergic defecation
important normal GI motility patterns altered in disease are:
Esophageal peristalsis: ?
LES relaxation: ?
LES tonic contraction: ?
Gastric emptying: ?
Esophageal peristalsis: Achalasia, Scleroderma.
LES relaxation: Achalasia.
LES tonic contraction: Scleroderma.
Gastric emptying: Gastroparesis, Functional dyspepsia.
What are the 3 stages of swallowing?
Stage 1: Voluntary (oral cavity then bolus pushed by tongue to oropharynx)
Stage 2: Involuntary (glottis covers trachea; UES relaxes)
Stage 3: Involuntary (esophageal peristalsis)
Inappropriate ____ relaxation can cause acid reflux and damage to the inner lining of the esophagus
LES: Lower Esophageal Sphincter
Failure to relax due to damage/loss of the enteric nerves of the LES wall is called achalasia and can make swallowing difficult
What are the steps involved in Emesis and how is it regulated?
- Salivation (HCO3-) & sensation of nausea.
- Reverse peristalsis from upper small intestine to stomach.
- Abdominal muscles contract & UES and LES relax.
- Gastric contents are ejected.
Centrally regulated by vomit center in the brain.
T/F?
The small intestine only has peristalsis movement.
FALSE!
Small intestine has BOTH peristaltic and segmentation motility
____________ - stomach activity stimulates movement of chyme through the ileocecal sphincter
____________ – food in stomach stimulates mass movement in colon
Gastroileal reflex - stomach activity stimulates movement of chyme through the ileocecal sphincter
Gastrocolic reflex – food in stomach stimulates mass movement in colon
Gastroileal reflex - ?
Gastroileal reflex - stomach activity stimulates movement of chyme through the ileocecal sphincter
Gastrocolic reflex – ?
Gastrocolic reflex – food in stomach stimulates mass movement in colon
What are intestinal reflexed mediated by?
Mediated by both ENS & external innervation.
enteric nerves = Localized peristaltic waves and segmentation mixing
What is the MMC?
Occurs in the absence of feeding (during fasting) – Housekeeping!
Occurs every 90-100 minutes with 3 phases starting from the stomach & propagating aborally to ileocecal valve. The hormone Motilin appears to initiate but appears to have a neural component as well.
What are the steps in the MMC?
Phase I
Quiescence occurs for 40-60% of the 90 min duration
Phase II
Motility increases but contractions are irregular
Fails to propel luminal content
Lasts 20-30% of MMC duration
Phase IIII
5-10 minutes of intense contractions
From body of stomach to pylorus to duodenum to ileocecal valve
Pylorus fully opens
What are the two types of motility in the Colon?
haustration & mass movement
Are there MMC in the colon?
NO!!!
Only haustration & mass movement
What are mass movements in the colon?
strong peristaltic waves 1-3 X/day.
Mass movement is a wave of contraction that usually follows a meal and that moves content over larger distance than with regular peristalsis; colon remains contracted for a while
Overall movement is slow (max 5-10 cm/hr)
In the mucosal defenses of the stomach, ___________ between cells prevent acid from infiltrating the layers of the wall
Tight junctions