Nokea
Which is TRUE?
- A. adenosine triphosphate is a low energy phosphate
- B. reduction involves loss of hydrogen or electrons
- C. oxidative phosphorylation occurs in the endoplasmic reticulum
- D. ATP is precursor of cyclic AMP
Correct Answer: D
Rationale: Step-by-step rationale for choice D being correct:
1. ATP is an energy carrier molecule.
2. Adenosine triphosphate (ATP) is a precursor of cyclic AMP.
3. Cyclic AMP is a secondary messenger involved in cellular signaling.
4. Therefore, choice D is true.
Summary of incorrect choices:
A: Adenosine triphosphate is a high-energy phosphate, not low.
B: Reduction involves gain, not loss, of electrons.
C: Oxidative phosphorylation occurs in the mitochondria, not the endoplasmic reticulum.
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ADH ________.
- A. increases urine production
- B. promotes dehydration
- C. is produced in the adenohypophysis
- D. is inhibited by alcohol
Correct Answer: D
Rationale: The correct answer is D because alcohol inhibits the release of antidiuretic hormone (ADH) from the pituitary gland. ADH helps regulate water balance by promoting water reabsorption in the kidneys, reducing urine output. Alcohol impairs this process, leading to increased urine production and dehydration. Choices A, B, and C are incorrect because ADH decreases urine production, prevents dehydration, and is produced in the neurohypophysis (posterior pituitary), not the adenohypophysis (anterior pituitary).
A patient presents with tiredness, weakness, anorexia, apathy, abdominal pain, hyperpigmentation and postural hypertension. Upon infection he appears to be in cardiogenic shock and his blood volume is depleted. His sodium levels are low, potassium levels are high. Which of the following would also be elevated?
- A. TSH
- B. T4
- C. Adrenal hormone
- D. ACTH
Correct Answer: D
Rationale: The correct answer is D: ACTH. In this scenario, the patient is exhibiting symptoms of adrenal insufficiency, specifically Addison's disease. ACTH levels would be elevated due to the lack of negative feedback from cortisol, which is typically low in adrenal insufficiency. TSH (A) and T4 (B) would be normal or low due to the hypofunction of the adrenal gland, not the thyroid. Adrenal hormones (C) would be low in adrenal insufficiency, not elevated.
What is the most critical need for the child with newly diagnosed cretinism?
- A. Thyroidectomy
- B. Administration of a radioactive cocktail of 131I (radioactive iodine)
- C. Replacement dose of thyroid hormones
- D. Replacement dose of calcitonin
Correct Answer: C
Rationale: The correct answer is C: Replacement dose of thyroid hormones. In newly diagnosed cretinism, there is a deficiency of thyroid hormones, leading to developmental delays and other health issues. Administering replacement thyroid hormones is crucial to normalize hormone levels and support proper growth and development. Thyroidectomy (choice A) is not necessary in this case as the goal is to supplement the missing hormones. Option B, the administration of radioactive iodine cocktail, is used to treat hyperthyroidism, not hypothyroidism. Choice D, replacement dose of calcitonin, is not relevant as calcitonin is involved in calcium regulation, not thyroid hormone production. Thus, the most critical need for the child with newly diagnosed cretinism is the replacement dose of thyroid hormones to address the underlying hormonal deficiency.
Which of the following drugs is a direct stimulant of β1 and β2 adrenoceptors:
- A. Noradrenaline
- B. Isoprenaline
- C. Salbutamol
- D. Amphetamine
Correct Answer: B
Rationale: The correct answer is B: Isoprenaline. Isoprenaline directly stimulates both β1 and β2 adrenoceptors. It is a non-selective β-adrenergic agonist, leading to increased heart rate (β1 stimulation) and bronchodilation (β2 stimulation).
Incorrect choices:
A: Noradrenaline mainly acts on α-adrenoceptors.
C: Salbutamol is a selective β2 agonist, not stimulating β1 receptors.
D: Amphetamine primarily acts on catecholamine release and reuptake inhibition, not direct β-adrenoceptor stimulation.
The relatively constant internal environment of the body is maintained by _______.
- A. negative feedback.
- B. positive feedback.
- C. homeostasis.
- D. metabolism.
Correct Answer: C
Rationale: The correct answer is C: homeostasis. Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. It involves various physiological mechanisms to regulate temperature, pH, blood sugar levels, and more. Negative feedback (choice A) is a key component of homeostasis, where the body reverses a deviation from the set point to restore balance. Positive feedback (choice B) amplifies a response and does not contribute to maintaining stability. Metabolism (choice D) is the sum of all chemical processes in the body and is necessary for homeostasis but does not directly regulate the internal environment.