Nokea
Target cells for hypothalamic releasing hormones are in the
- A. thyroid
- B. hypothalamus
- C. anterior pituitary
- D. posterior pituitary
Correct Answer: C
Rationale: The correct answer is C: anterior pituitary. Hypothalamic releasing hormones target cells in the anterior pituitary to stimulate the release of specific pituitary hormones. The hypothalamus produces releasing hormones that travel through the hypophyseal portal system and bind to receptors on cells in the anterior pituitary, triggering the release of hormones such as ACTH, TSH, LH, FSH, and GH. This interaction between the hypothalamus and anterior pituitary forms the hypothalamic-pituitary axis, regulating various physiological processes. Choices A (thyroid) and D (posterior pituitary) are incorrect as they are not the primary targets of hypothalamic releasing hormones. Choice B (hypothalamus) is also incorrect as releasing hormones do not target cells within the hypothalamus itself, but rather the anterior pituitary.
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A deficiency of ADH most likely:
- A. elevates blood glucose levels.
- B. causes diabetes mellitus.
- C. induces polyuria.
- D. expands blood volume.
Correct Answer: C
Rationale: Step-by-step rationale:
1. ADH (antidiuretic hormone) regulates water balance by increasing water reabsorption in the kidneys.
2. A deficiency of ADH leads to decreased water reabsorption, resulting in increased urine output (polyuria).
3. Polyuria causes dehydration, electrolyte imbalances, and concentrated urine.
4. Elevated blood glucose levels (choice A) and diabetes mellitus (choice B) are not directly related to ADH deficiency.
5. Expanding blood volume (choice D) would not occur due to decreased water reabsorption.
Summary:
A deficiency of ADH most likely induces polyuria by decreasing water reabsorption in the kidneys. Elevated blood glucose levels, diabetes mellitus, and expanding blood volume are not direct consequences of ADH deficiency.
Which of the following is not a category of endocrine gland stimulus?
- A. enzyme
- B. humoral
- C. neural
- D. hormonal
Correct Answer: A
Rationale: The correct answer is A: enzyme. Endocrine glands are stimulated by three main categories: humoral (based on blood levels of certain substances), neural (stimulation by nerves), and hormonal (stimulation by other hormones). Enzymes do not directly stimulate endocrine glands. They are biological catalysts that facilitate biochemical reactions, not a category of stimulus for endocrine glands. Therefore, A is the correct answer. Choices B, C, and D are incorrect as they are valid categories of endocrine gland stimulus based on blood levels, nerves, and hormones respectively.
In type 1 diabetes there is an osmotic effect of glucose when insulin deficiency prevents the use of glucose for energy. Which classic symptom is caused by the osmotic effect of glucose?
- A. Fatigue
- B. Polyphagia
- C. Polydipsia
- D. Recurrent infections
Correct Answer: C
Rationale: Polydipsia is caused by the osmotic effect of glucose, leading to excessive urination and increased thirst.
The Glucagon is:
- A. accelerates the conversion of glycogen into glucose.
- B. slows down glucose formation from lactic acid.
- C. decreases the conversion of glycogen into glucose.
- D. speeds up protein synthesis within cells.
Correct Answer: A
Rationale: The correct answer is A because glucagon stimulates the breakdown of glycogen into glucose, increasing blood glucose levels. Glucagon does not slow down glucose formation from lactic acid (B), decrease glycogen conversion (C), or speed up protein synthesis (D). Glucagon's primary function is to raise blood glucose levels in response to low blood sugar levels.
We have a 48-year-old female patient with a history of myasthenia gravis. She has been treated with an oral acetylcholinesterase inhibitor for several years and has done well till now. She presents with muscle weakness and other signs and symptoms that could reflect either a cholinergic crisis (excess dosages of her maintenance drug) or a myasthenic crisis (insufficient treatment). We will use a rapidly acting parenteral acetylcholinesterase inhibitor (AChE) to help make the differential diagnosis. Which of the following drugs would be most appropriate for this use?
- A. Edrophonium
- B. Malathion
- C. Physostigmine
- D. Pralidoxime
Correct Answer: A
Rationale: The correct answer is A: Edrophonium. Edrophonium is a short-acting acetylcholinesterase inhibitor that can help differentiate between a cholinergic crisis and a myasthenic crisis. In this scenario, administering edrophonium will temporarily increase acetylcholine levels at the neuromuscular junction. If the patient's symptoms improve following edrophonium administration, it suggests a myasthenic crisis due to insufficient treatment. On the other hand, if the symptoms worsen, it indicates a cholinergic crisis due to excess dosages of the maintenance drug.
Choice B: Malathion is an organophosphate insecticide and is not used for diagnosing myasthenia gravis.
Choice C: Physostigmine is a longer-acting acetylcholinesterase inhibitor and is not appropriate for rapidly assessing the patient's condition in this scenario.
Choice D: Pralidoxime is used as an antidote for organophosphate