Nokea
A patient presents with food poisoning that is attributed to botulism (Botulinum toxin poisoning). Which of the following is a correct characteristic, finding, or mechanism associated with this toxin?
- A. Complete failure of all cholinergic neurotransmission
- B. Favorable response to administration of pralidoxime
- C. Impairment of parasympathetic, but not sympathetic, nervous system activation
- D. Massive overstimulation of all structures having muscarinic cholinergic receptors
Correct Answer: A
Rationale: The correct answer is A: Complete failure of all cholinergic neurotransmission. Botulinum toxin inhibits acetylcholine release at neuromuscular junctions, leading to complete failure of all cholinergic neurotransmission. This results in flaccid paralysis and characteristic symptoms of botulism. Choice B is incorrect because pralidoxime is used to treat organophosphate poisoning, not botulism. Choice C is incorrect as botulinum toxin affects both parasympathetic and sympathetic nervous systems. Choice D is incorrect as botulinum toxin does not cause overstimulation but rather inhibits neurotransmission.
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Which hormone is produced by the pancreas and acts on the liver to increase blood glucose levels?
- A. glucagon; liver
- B. melatonin; liver
- C. glucagon; kidney
- D. calcitonin; thyroid
Correct Answer: A
Rationale: The correct answer is A: glucagon is produced by the pancreas and acts on the liver to increase blood glucose levels. Glucagon triggers the liver to break down glycogen into glucose, releasing it into the bloodstream. Melatonin is a hormone produced by the pineal gland and is not involved in glucose regulation. Glucagon does not act on the kidney but specifically targets the liver. Calcitonin is produced by the thyroid gland and plays a role in calcium regulation, not glucose metabolism.
Which of the following statements regarding pituitary hormones is false?
- A. The hypothalamus makes oxytocin and antidiuretic hormone, which are transported to the posterior pituitary for storage.
- B. Antidiuretic hormone, released by the posterior pituitary, causes urine volume to increase and blood volume to decrease.
- C. Luteinizing hormone, an anterior pituitary hormone, triggers ovulation of an egg from the ovary and causes the ruptured follicle to produce progesterone and some estrogens.
- D. Hyposecretion of follicle-stimulating hormone or luteinizing hormone leads to sterility in both males and females.
Correct Answer: B
Rationale: Step 1: Antidiuretic hormone (ADH) is released by the posterior pituitary, and its main function is to increase water reabsorption in the kidneys, leading to decreased urine volume and increased blood volume.
Step 2: If ADH causes urine volume to increase and blood volume to decrease, it would be counterproductive to its known physiological role.
Step 3: Therefore, Choice B is false as it contradicts the established function of ADH.
Summary:
- Choice A is true because oxytocin and antidiuretic hormone are indeed produced in the hypothalamus and stored in the posterior pituitary.
- Choice C is true as luteinizing hormone does trigger ovulation and stimulates the production of progesterone and some estrogens.
- Choice D is true because hyposecretion of follicle-stimulating hormone or luteinizing hormone can lead to infertility in both males and females.
Which of the following is a trigger for the onset of Graves' disease?
- A. Trauma
- B. Iodine deficiency
- C. Stressful life events
- D. Bacterial infection
Correct Answer: C
Rationale: The correct answer is C: Stressful life events. Graves' disease is an autoimmune disorder where the immune system mistakenly attacks the thyroid gland, causing it to produce excess thyroid hormone. Stressful life events can trigger or exacerbate autoimmune conditions like Graves' disease by impacting the immune system's functioning. Trauma, iodine deficiency, and bacterial infection are not direct triggers for Graves' disease. Trauma can cause thyroid issues but not specifically Graves' disease. Iodine deficiency can lead to goiter but is not a direct trigger for Graves' disease. Bacterial infections can cause thyroiditis but are not a common trigger for Graves' disease.
Diabetes mellitus occurs due to deficiency of:
- A. Glucagon
- B. Thyroxin
- C. Insulin
- D. Melatonin
Correct Answer: C
Rationale: Step-by-step rationale for why choice C (Insulin) is correct:
1. Insulin is a hormone produced by the pancreas that regulates blood sugar levels.
2. Diabetes mellitus is a condition characterized by high blood sugar levels due to inadequate insulin production or ineffective use of insulin.
3. The deficiency of insulin leads to the inability to properly regulate blood sugar levels, resulting in diabetes mellitus.
4. Glucagon (choice A) is a hormone that increases blood sugar levels, so its deficiency would not cause diabetes.
5. Thyroxin (choice B) is a hormone produced by the thyroid gland and is not directly related to diabetes.
6. Melatonin (choice D) is a hormone that regulates sleep-wake cycles and is not involved in blood sugar regulation.
Summary:
Insulin is the correct choice because its deficiency directly leads to diabetes mellitus, while the other choices do not play a significant role in the development of this condition.
What ion is sometimes used as a second messenger of amino acid-base hormones?
- A. Iron
- B. Calcium
- C. Sodium
- D. Chlorine
Correct Answer: B
Rationale: The correct answer is B: Calcium. Calcium ions are commonly used as second messengers for amino acid-base hormones due to their ability to trigger various cellular responses. When the hormone binds to its receptor on the cell surface, it activates specific signaling pathways that lead to an increase in intracellular calcium levels. This rise in calcium ions then initiates downstream signaling cascades, ultimately regulating processes such as gene expression, cell growth, and metabolism.
Choice A - Iron: Iron is not typically involved in signaling pathways for amino acid-base hormones. It is more commonly known for its role in oxygen transport and storage in hemoglobin.
Choice C - Sodium: While sodium ions play essential roles in cellular functions, they are not typically utilized as second messengers for amino acid-base hormones. Sodium is more commonly associated with maintaining cell membrane potential and fluid balance.
Choice D - Chlorine: Chlorine ions are not typically involved in signaling pathways for amino acid-base hormones. Chlorine is primarily known for its role in maintaining