Nokea
Which glands are responsible for the regulation of calcium levels in the blood?
- A. Parathyroid and thyroid
- B. Adrenal medulla and pancreas
- C. Testes
- D. Parathyroid and thymus
Correct Answer: A
Rationale: The correct answer is A: Parathyroid and thyroid. The parathyroid glands produce parathyroid hormone (PTH), which regulates calcium levels in the blood by increasing calcium absorption from the intestines and releasing calcium from bones. The thyroid gland produces calcitonin, which helps lower blood calcium levels by promoting calcium deposition in bones. The other choices (B: Adrenal medulla and pancreas, C: Testes, D: Parathyroid and thymus) are incorrect because they do not play a direct role in regulating calcium levels in the blood.
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Ritodrine is a drug indicated for suppressing uterine contractions in premature labor. The drug also causes bronchodilation. It has no vasoconstrictor effects, nor any effects on the size of the pupil of the eye. Which of the following is the most likely classification of this drug?
- A. α-adrenergic agonist
- B. Antimuscarinic drug
- C. β-adrenergic agonist
- D. β-adrenergic blocker
Correct Answer: C
Rationale: The correct answer is C: β-adrenergic agonist. Ritodrine is indicated for suppressing uterine contractions, which is a typical effect of β-adrenergic agonists. Bronchodilation is also a known effect of β-adrenergic agonists. Since the drug has no vasoconstrictor effects and does not affect the size of the pupil of the eye, it is unlikely to be an α-adrenergic agonist or an antimuscarinic drug. Additionally, the fact that ritodrine causes bronchodilation further supports its classification as a β-adrenergic agonist.
The endocrine gland responsible for the body’s circadian rhythm is:
- A. Thymus
- B. Pineal
- C. Parathyroid
- D. Pituitary
Correct Answer: B
Rationale: The correct answer is B: Pineal gland. The pineal gland secretes melatonin, a hormone that regulates the body's circadian rhythm. Melatonin helps control the sleep-wake cycle, making the pineal gland crucial for maintaining our internal body clock. The other choices, Thymus, Parathyroid, and Pituitary glands, are not directly involved in regulating circadian rhythms. Thymus is responsible for immune function, Parathyroid regulates calcium levels, and Pituitary gland controls various hormones but not specifically circadian rhythm. Hence, the pineal gland is the correct choice for this question.
The posterior pituitary stores and releases .
- A. prolactin and oxytocin
- B. oxytocin and antidiuretic hormone (ADH)
- C. ADH and growth hormone
- D. growth hormone and prolactin
Correct Answer: B
Rationale: The correct answer is B: oxytocin and antidiuretic hormone (ADH).
1. The posterior pituitary stores and releases oxytocin and ADH.
2. Oxytocin is responsible for uterine contractions and milk ejection.
3. ADH regulates water balance by controlling water reabsorption in the kidneys.
Therefore, B is the correct answer.
A, C, and D are incorrect because prolactin, growth hormone, and other hormones are not stored or released by the posterior pituitary.
Blood levels of which of the following substances is decreased in Graves disease?
- A. Triiodothyronine (T3)
- B. Thyroxine (T4)
- C. Diiodotyrosine (DIT)
- D. Thyroid-stimulating hormone (TSH)
Correct Answer: D
Rationale: In Graves disease, there is an overproduction of thyroid hormones due to autoimmune stimulation. Thyroid-stimulating hormone (TSH) is decreased because the excessive thyroid hormones suppress its production through negative feedback. A and B are incorrect because both T3 and T4 levels are elevated in Graves disease. C is incorrect as DIT is a precursor to thyroid hormones and its levels may not necessarily be decreased in Graves disease.
The parathyroid glands maintain adequate levels of blood calcium. This is accomplished through ________.
- A. blocking the action of growth hormone
- B. targeting the bone and activating osteoclasts so that calcium will be released
- C. antagonizing the synthesis of calcitonin
- D. slowing the activity of tissues that require calcium for activity
Correct Answer: B
Rationale: The correct answer is B because the parathyroid glands target the bone and activate osteoclasts to release calcium into the bloodstream. This process helps maintain adequate blood calcium levels. By activating osteoclasts, calcium is released from the bone into the blood, ensuring a balance of calcium levels.
A: Blocking the action of growth hormone is unrelated to the function of parathyroid glands in maintaining blood calcium levels.
C: Antagonizing the synthesis of calcitonin is not the primary mechanism through which parathyroid glands regulate blood calcium levels.
D: Slowing the activity of tissues that require calcium for activity would not help maintain adequate blood calcium levels as it does not address the direct release of calcium from bone by activating osteoclasts.