Nokea
Most hormones of the endocrine system are regulated by a:
- A. Negative feedback mechanism.
- B. Positive feedback mechanism.
- C. Hormone-receptor complex.
- D. Hormone-gene complex.
Correct Answer: A
Rationale: The correct answer is A: Negative feedback mechanism. This is because most hormones in the endocrine system are regulated by a negative feedback loop, where the release of a hormone is inhibited once a certain level of that hormone is reached in the body. This helps maintain homeostasis.
Incorrect choices:
B: Positive feedback mechanism - This is less common in hormone regulation as it leads to amplification of a response rather than maintaining balance.
C: Hormone-receptor complex - While hormones bind to receptors to exert their effects, this is not the primary mechanism of hormone regulation.
D: Hormone-gene complex - While hormones can affect gene expression, this is not the primary mechanism of hormone regulation in the endocrine system.
You may also like to solve these questions
Identify the glands associated with these hormones: gonadotropins, aldosterone, and epinephrine.
- A. Adenohypophysis, neurohypophysis, pancreas
- B. Adenohypophysis, anterior pituitary, adrenal cortex
- C. Adenohypophysis, posterior pituitary, adrenal medulla
- D. Anterior pituitary, adrenal cortex, adrenal medulla
Correct Answer: D
Rationale: The correct answer is D because gonadotropins are secreted by the anterior pituitary gland, aldosterone is produced by the adrenal cortex, and epinephrine is released by the adrenal medulla. The anterior pituitary gland secretes gonadotropins such as FSH and LH. The adrenal cortex synthesizes aldosterone, which regulates sodium and potassium balance. The adrenal medulla produces epinephrine, involved in the fight or flight response. Choices A and C are incorrect because they do not match the correct associations of the hormones with their respective glands. Choice B is incorrect as the adrenal cortex and adrenal medulla are not part of the anterior pituitary gland.
How many hormones are produced by the posterior pituitary?
- B. 1
- C. 2
- D. 6
Correct Answer: C
Rationale: The correct answer is C: 2. The posterior pituitary produces two hormones: oxytocin and vasopressin. Oxytocin is involved in childbirth and breastfeeding, while vasopressin helps regulate water balance in the body. Option A is incorrect because the posterior pituitary does produce hormones. Option B is incorrect as there are two hormones produced, not just one. Option D is incorrect as the posterior pituitary does not produce six hormones. In summary, the posterior pituitary gland produces two hormones, making option C the correct answer.
Which of the following is a symptom of Addison’s disease?
- A. Hypertension
- B. Weight gain
- C. Hyperpigmentation
- D. Tachycardia
Correct Answer: C
Rationale: The correct answer is C: Hyperpigmentation. Addison's disease is a condition characterized by adrenal insufficiency, leading to decreased production of cortisol and aldosterone. Hyperpigmentation is a common symptom due to elevated levels of ACTH stimulating melanin production. Other choices are incorrect because Addison's disease typically presents with hypotension, weight loss, and bradycardia, rather than hypertension, weight gain, or tachycardia.
What medication is used with thyrotoxicosis to block the effects of the sympathetic nervous stimulation of the thyroid hormones?
- A. Potassium iodide
- B. Propylthiouracil (PTU)
- C. Atenolol (Tenormin)
- D. Radioactive iodine (RAI)
Correct Answer: C
Rationale: Atenolol is a beta-blocker that helps control the sympathetic nervous system effects of thyrotoxicosis, such as tachycardia and hypertension.
Some medications for relief of cold/allergy symptoms contain pseudoephedrine, which acts as a decongestant. If a patient who is taking an MAO inhibitor takes pseudoephedrine, what is the likely outcome?
- A. Acute bronchospasm/asthma due to ACh release from the adrenal medulla
- B. Hypertensive crisis, possible stroke
- C. Heart rate and contractile force would drop significantly and quickly
- D. The cold symptoms would quickly get worse (increased secretions)
Correct Answer: B
Rationale: Step 1: MAO inhibitors prevent the breakdown of neurotransmitters like norepinephrine.
Step 2: Pseudoephedrine stimulates the release of norepinephrine.
Step 3: The combination can lead to excessive norepinephrine, causing hypertension and potential stroke.
Therefore, the likely outcome when a patient taking an MAO inhibitor also takes pseudoephedrine is a hypertensive crisis and possible stroke (Choice B).
Summary:
- Choice A (acute bronchospasm/asthma due to ACh release from the adrenal medulla) is incorrect because pseudoephedrine does not directly cause this response.
- Choice C (heart rate and contractile force would drop significantly and quickly) is incorrect as pseudoephedrine tends to increase heart rate and blood pressure.
- Choice D (the cold symptoms would quickly get worse - increased secretions) is incorrect as pseudoephedrine is a decongestant and would not worsen cold symptoms