Nokea
Which sequence is part of the life cycle of a very large mass star?
- A. red giant → planetary nebula + neutron star
- B. red giant → planetary nebula + black hole
- C. red supergiant → supernova → neutron star
- D. red supergiant → supernova → black hole
Correct Answer: D
Rationale: The correct answer is D: red supergiant → supernova → black hole. This sequence is part of the life cycle of a very large mass star. Red supergiants are massive stars in the later stages of their evolution. When a red supergiant goes supernova, it explodes in a massive stellar explosion, leaving behind a remnant that can collapse into a black hole due to the immense gravitational forces. Choices A and B are incorrect because planetary nebulae form from the outer layers of lower mass stars, not very large mass stars. Choice C is incorrect as neutron stars are more likely to form from the remnants of less massive stars.
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With regard to carbohydrate digestion:
- A. salivary amylase works best at alkaline pH
- B. approximately 40% of adult Europeans are lactose intolerant
- C. oligosaccharidase deficiency results in osmotic diarrhoea
- D. salivary amylase continues to digest carbohydrates in the stomach
Correct Answer: C
Rationale: Step-by-step rationale for choice C being correct:
1. Oligosaccharidase deficiency impairs breakdown of oligosaccharides in the small intestine.
2. Undigested oligosaccharides draw water into the intestines, causing osmotic diarrhea.
3. This leads to increased fluid content in the stool, resulting in osmotic diarrhea.
4. This process does not involve salivary amylase or lactose intolerance.
X is a drug that contains a mixture of amphetamines. It is used for managing Attention-Deficit/Hyperactivity disorder (ADHD). The drug causes autonomic effects that can be fatal if an overdose is taken. How does X work in the body?
- A. Blocks muscarinic receptors, causing what is basically 'atropine poisoning'
- B. Blocks β2 receptors on airway smooth muscle, causing bronchoconstriction
- C. Inhibits MAO, leading to a 'shut-down' of the sympathetic nervous system
- D. Releases neuronal noradrenaline, causing excessive sympathetic effects, e.g., severe rises of blood pressure
Correct Answer: D
Rationale: The correct answer is D because X, a mixture of amphetamines, works by releasing neuronal noradrenaline, causing excessive sympathetic effects like severe rises in blood pressure. This is how the drug helps manage ADHD symptoms. The other choices are incorrect because A (blocking muscarinic receptors) would not be related to the autonomic effects seen with X, B (blocking β2 receptors) would not explain the fatal autonomic effects, and C (inhibiting MAO) would not lead to the described autonomic effects. Therefore, D is the correct choice based on how X works in the body to produce its effects on the sympathetic nervous system.
Nervousness, increased body temperature, and increased blood-pressure are indications of _______.
- A. diabetes mellitus
- B. hypoglycemia
- C. hypothyroidism
- D. hyperthyroidism
Correct Answer: D
Rationale: The correct answer is D: hyperthyroidism. Nervousness, increased body temperature, and increased blood pressure are classic symptoms of hyperthyroidism. This condition is characterized by an overactive thyroid gland, leading to an excess production of thyroid hormones. These hormones can cause an increase in metabolism, leading to symptoms such as nervousness, heat intolerance, and elevated heart rate. Diabetes mellitus (A) is not associated with increased body temperature or blood pressure. Hypoglycemia (B) is characterized by low blood sugar levels, leading to symptoms such as dizziness and confusion, not increased body temperature. Hypothyroidism (C) is characterized by an underactive thyroid gland, leading to symptoms such as fatigue, weight gain, and cold intolerance, not increased body temperature or blood pressure.
Thyroxine:
- A. is mostly bound to albumin in the plasma, since this has the largest capacity
- B. is 2-5 times more potent that triiodothyronine (T3)
- C. stimulates TSH release
- D. ∼33% is deiodinated in the liver to T3
Correct Answer: D
Rationale: The correct answer is D. Thyroxine is deiodinated in the liver to T3, so approximately 33% of thyroxine is converted to the more active form, triiodothyronine. This conversion is important for regulating metabolic processes in the body. Choices A and C are incorrect because thyroxine is primarily bound to thyroxine-binding globulin in the plasma, not albumin, and it does not stimulate TSH release. Choice B is incorrect because T3 is actually more potent than thyroxine, not the other way around.
A 35-year-old female presents to your office for a regular check-up. Her only complaint is recurrent migraine headaches, which have increased in frequency over the years. On examination, her blood pressure is elevated at 150/70. You decide to start her on antihypertensive therapy that is also used for prophylaxis of migraines. Which medication is it?
- A. Clonidine
- B. Prazosin
- C. Hydrochlorothiazide
- D. Propranolol
Correct Answer: D
Rationale: The correct answer is D: Propranolol. Propranolol is a beta-blocker that is commonly used for migraine prophylaxis. It helps reduce the frequency and severity of migraines by blocking the action of adrenaline on blood vessels in the brain. In this case, the patient has elevated blood pressure and migraines, so starting her on propranolol can address both issues effectively.
Choice A: Clonidine is an alpha-2 agonist used for hypertension, but it is not commonly used for migraine prophylaxis.
Choice B: Prazosin is an alpha-1 blocker primarily used for the treatment of hypertension, but it is not typically used for migraine prophylaxis.
Choice C: Hydrochlorothiazide is a diuretic used for hypertension by reducing blood volume, but it is not effective for migraine prophylaxis.
In summary, propranolol is the most appropriate choice as it addresses both the elevated blood pressure and the recurrent