The only insulin that can be administered intravenously is
- A. Lente
- B. Semi-Lente
- C. regular
- D. NPH
Correct Answer: C
Rationale: Only regular insulin is approved for intravenous administration due to its rapid onset and shorter duration of action.
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The cluster of cells in the pancreas that secrete hormones are:
- A. Nodules
- B. Islets of Langerhans
- C. Pancreatic medulla
- D. Pancreatic cortex
Correct Answer: B
Rationale: The correct answer is B: Islets of Langerhans. These clusters of cells in the pancreas are responsible for secreting hormones such as insulin and glucagon. Islets of Langerhans contain different types of cells that regulate blood sugar levels. Nodules (A), pancreatic medulla (C), and pancreatic cortex (D) are not associated with hormone secretion in the pancreas. Nodules are more general and not specific to the pancreas, while pancreatic medulla and cortex do not house the endocrine cells responsible for hormone secretion.
Which of the following drugs does not pass the blood-brain barrier:
- A. Ephedrine
- B. Propranolol
- C. Clonidine
- D. Guanethidine
Correct Answer: D
Rationale: The correct answer is D: Guanethidine. Guanethidine is a quaternary amine, which prevents it from passing the blood-brain barrier due to its charge. The blood-brain barrier is selective and only allows certain molecules to pass through. In contrast, choices A, B, and C (Ephedrine, Propranolol, Clonidine) are all capable of crossing the blood-brain barrier to some extent due to their chemical properties. Ephedrine is a weak base, Propranolol is lipophilic, and Clonidine is relatively small in size, allowing them to penetrate the blood-brain barrier.
Complete the following sentence: Lipid-soluble hormones are…
- A. Constantly produced within the anterior pituitary gland and released into the blood stream
- B. Hydrophilic and are transported in an un-conjugated form in the blood
- C. Interact with intracellular receptors and evoke changes in gene expression
- D. Formed from amino acids
Correct Answer: C
Rationale: The correct answer is C because lipid-soluble hormones can freely diffuse through cell membranes to interact with intracellular receptors, leading to changes in gene expression. This mechanism is characteristic of lipid-soluble hormones, such as steroid hormones. Choice A is incorrect because lipid-soluble hormones are not constantly produced in the anterior pituitary gland. Choice B is incorrect as lipid-soluble hormones are hydrophobic, not hydrophilic, and are often transported bound to carrier proteins in the blood. Choice D is incorrect because lipid-soluble hormones are not formed from amino acids; rather, they are derived from cholesterol or similar compounds.
Antidiuretic hormone (ADH) and oxytocin:
- A. are secreted by the neurohypophysis.
- B. are mineralocorticoids.
- C. are secreted by the islets of Langerhans.
- D. stimulate the kidney to excrete Na+ and water.
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. ADH and oxytocin are peptide hormones.
2. They are synthesized in the hypothalamus.
3. They are transported and stored in the neurohypophysis.
4. Upon stimulation, they are released from the neurohypophysis.
5. Therefore, both ADH and oxytocin are indeed secreted by the neurohypophysis.
Summary of why other choices are incorrect:
B: ADH and oxytocin are not mineralocorticoids; they regulate water balance and uterine contractions, respectively.
C: Islets of Langerhans secrete insulin and glucagon, not ADH or oxytocin.
D: ADH promotes water reabsorption in the kidneys, opposite to excreting Na+ and water.
Narcolepsy is treated with:
- A. Amphetamine
- B. Adrenaline
- C. Isoprenaline
- D. Salbutamol
Correct Answer: A
Rationale: The correct answer is A: Amphetamine. Amphetamine is a central nervous system stimulant that helps manage narcolepsy symptoms by promoting wakefulness. It increases levels of neurotransmitters like dopamine and norepinephrine, enhancing alertness. Adrenaline (B), Isoprenaline (C), and Salbutamol (D) are not typically used to treat narcolepsy as they do not directly target the underlying cause of excessive daytime sleepiness. Adrenaline and Isoprenaline are more commonly used for acute situations like anaphylaxis or cardiac arrest. Salbutamol is a bronchodilator used for conditions like asthma.