Nokea
A newly developed pesticide has been observed to bind to an intracellular hormone receptor. If ingested, residue from this pesticide could disrupt levels of .
- A. melatonin
- B. thyroid hormone
- C. growth hormone
- D. insulin
Correct Answer: B
Rationale: Step-by-step rationale for why choice B (thyroid hormone) is correct:
1. Thyroid hormone is a key hormone that regulates metabolism and growth.
2. Intracellular hormone receptors are specific to certain hormones.
3. Disruption of thyroid hormone levels can lead to metabolic disorders.
4. Pesticide binding to the thyroid hormone receptor can interfere with its normal function.
Summary of why other choices are incorrect:
A: Melatonin regulates sleep-wake cycles, not metabolism.
C: Growth hormone regulates growth and development, not metabolism.
D: Insulin regulates blood sugar levels, not metabolism.
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Which division of the nervous system sends signals to the adrenal glands during moments of danger?
- A. Central nervous system
- B. Sympathetic division
- C. Parasympathetic division
- D. Peripheral nervous system
Correct Answer: B
Rationale: The correct answer is B: Sympathetic division. This division of the autonomic nervous system is responsible for the body's "fight or flight" response during moments of danger. When an individual perceives a threat, the sympathetic division activates to prepare the body for action, including sending signals to the adrenal glands to release adrenaline and cortisol, which help increase heart rate, blood pressure, and energy levels. The other choices are incorrect because:
A: The central nervous system consists of the brain and spinal cord, which are responsible for processing and transmitting information within the body, but it does not directly send signals to the adrenal glands.
C: The parasympathetic division is responsible for the body's "rest and digest" functions and works in opposition to the sympathetic division. It does not send signals to the adrenal glands during moments of danger.
D: The peripheral nervous system consists of nerves outside the brain and spinal cord, including sensory and motor nerves, but it does not specifically send signals
A child overdoses on a drug that affects both the autonomic and somatic nervous systems. As blood level of the drug rises, he experiences hypertension and tachycardia, accompanied by skeletal muscle tremor. Further elevations of the drug cause all the expected signs and symptoms of autonomic ganglionic blockade, plus weakness and eventual paralysis of skeletal muscle. Which of the following drugs did the child most likely ingest?
- A. Bethanechol
- B. Nicotine
- C. Pilocarpine
- D. Scopolamine
Correct Answer: B
Rationale: The correct answer is B: Nicotine. Nicotine affects both the autonomic and somatic nervous systems. Initially, the child experiences hypertension, tachycardia, and skeletal muscle tremor due to stimulation of both systems. As the blood level rises, autonomic ganglionic blockade occurs, leading to weakness and paralysis. Bethanechol (A) is a cholinergic agonist, unlikely to cause these symptoms. Pilocarpine (C) is also a cholinergic agonist but does not affect the somatic nervous system. Scopolamine (D) is an anticholinergic drug, which would not cause the symptoms described.
Iodine is:
- A. used by the adenohypophysis to synthesize TSH.
- B. necessary for the synthesis of calcitonin by the thyroid gland.
- C. necessary for the synthesis of thyroid hormones.
- D. necessary for the synthesis of both PTH and calcitonin.
Correct Answer: C
Rationale: The correct answer is C because iodine is essential for the synthesis of thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) in the thyroid gland. These hormones play a crucial role in regulating metabolism and growth. Choice A is incorrect because the adenohypophysis produces TSH, not iodine. Choice B is incorrect because calcitonin is produced by the parafollicular cells of the thyroid gland and does not require iodine for its synthesis. Choice D is incorrect because PTH (parathyroid hormone) is produced by the parathyroid glands and does not require iodine for its synthesis.
Dobutamine is used in the treatment of:
- A. Hypertension
- B. Heart failure
- C. Glaucoma
- D. Arrhythmia
Correct Answer: B
Rationale: Dobutamine is a positive inotrope that increases cardiac contractility, making it a suitable choice for treating heart failure by improving cardiac output. It is not typically used for hypertension, glaucoma, or arrhythmias. Hypertension is usually managed with antihypertensive medications like ACE inhibitors or beta-blockers. Glaucoma is treated with medications that reduce intraocular pressure. Arrhythmias are commonly managed with antiarrhythmic drugs or procedures such as ablation. Therefore, choice B, heart failure, is the correct answer for the use of dobutamine.
Which of the following produce antagonistic results?
- A. calcitonin and parathryroid hormone
- B. FSH and LH
- C. ADH and vasopressin
- D. oxytocin and prolactin
Correct Answer: A
Rationale: The correct answer is A: calcitonin and parathyroid hormone. Calcitonin decreases blood calcium levels, while parathyroid hormone increases blood calcium levels. They have opposing actions, thus producing antagonistic results.
Summary:
- FSH and LH (choice B) work together in the reproductive system.
- ADH and vasopressin (choice C) are different names for the same hormone.
- Oxytocin and prolactin (choice D) have complementary roles in milk production and breastfeeding.