Nokea
Which of the following cell(s) produce a compound that insulates nerve axons and greatly increases the speed of transmission (conductance)?
- A. node of Ranvier
- B. Schwann cells and oligodendrocytes
- C. any neuron
- D. astrocytes and ependymal cells
Correct Answer: B
Rationale: The correct answer is B: Schwann cells and oligodendrocytes. Schwann cells produce myelin in the peripheral nervous system, while oligodendrocytes produce myelin in the central nervous system. Myelin insulates nerve axons, allowing for saltatory conduction, greatly increasing the speed of transmission. Nodes of Ranvier are gaps in the myelin sheath where action potentials are regenerated, not where myelin is produced. Neurons themselves do not produce myelin. Astrocytes and ependymal cells have supportive roles in the nervous system but do not produce myelin.
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Which of these structures prevents food from entering the windpipe?
- A. Epiglottis
- B. Esophageal sphincter
- C. Pyloric sphincter
- D. Lower esophageal sphincter
Correct Answer: A
Rationale: The correct answer is A: Epiglottis. The epiglottis is a flap of tissue that covers the opening to the trachea (windpipe) during swallowing, preventing food from entering the airway. This action ensures that food goes down the esophagus to the stomach. The other choices (B, C, D) are involved in controlling the flow of food in the digestive system at different points, but they do not specifically prevent food from entering the windpipe like the epiglottis does.
What laboratory findings are expected in ulcerative colitis as a result of diarrhea and vomiting?
- A. Increased albumin
- B. Elevated white blood cells (WBCs)
- C. Decreased Na+, K+, Mg+, Cl'“, and HCO3'“
- D. Decreased hemoglobin (Hgb) and hematocrit (Hct)
Correct Answer: C
Rationale: In ulcerative colitis, diarrhea and vomiting lead to electrolyte imbalances, resulting in decreased levels of sodium, potassium, magnesium, chloride, and bicarbonate.
Which statement about the oral phase of digestion is INCORRECT?
- A. About 2% of the energy content of food is expended during the action of chewing and swallowing it.
- B. Swallowing involves contraction and relaxation of at least 14 groups of muscles in about 10 seconds in healthy subjects
- C. The biofilm covering tooth enamel contains several salivary and bacterial enzymes
- D. Salivary amylase digests the dextran film on tooth enamel formed from dietary sucrose
Correct Answer: D
Rationale: Correct Answer: D
Rationale: Salivary amylase primarily digests carbohydrates in the oral cavity, breaking down starch into simpler sugars like maltose. It does not directly target the dextran film on tooth enamel formed from dietary sucrose. This film is typically broken down by dental plaque bacteria, not salivary amylase. Therefore, option D is incorrect.
Summary of Incorrect Choices:
A: This statement is correct. Chewing and swallowing do require energy expenditure.
B: This statement is correct. Swallowing involves the coordinated action of multiple muscle groups.
C: This statement is correct. The biofilm on tooth enamel contains enzymes from both saliva and bacteria, contributing to oral digestion.
Following a Billroth II procedure
- A. a patient develops dumping syndrome. The nurse should explain that the symptoms associated with this problem are caused by
- B. distention of the smaller stomach by too much food and fluid intake.
- C. hyperglycemia caused by uncontrolled gastric emptying into the small intestine.
- D. irritation of the stomach lining by reflux of bile salts because the pylorus has been removed.
Correct Answer: D
Rationale: Dumping syndrome occurs when food moves too rapidly into the small intestine, causing fluid to shift into the bowel and leading to symptoms like nausea, diarrhea, and abdominal cramping.
Patients with a paralytic ileus typically have:
- A. Intravenous fluid replacement and a nasogastric tube connected to suction.
- B. Surgical correction of the problem.
- C. Endoscopic injection of botulinum toxin or esophageal dilation.
- D. Endoscopy to allow biopsy followed with broad-spectrum antibiotics.
Correct Answer: A
Rationale: Paralytic ileus is typically managed with intravenous fluids to correct electrolyte imbalances and a nasogastric tube to decompress the bowel.