Nokea
The normal endocrine controls can be directly overridden by the __________ system.
- A. nervous
- B. circulatory
- C. digestive
- D. reproductive
Correct Answer: A
Rationale: The correct answer is A: nervous system. The nervous system can directly override normal endocrine controls through the release of neurotransmitters that can stimulate or inhibit hormone release from endocrine glands. The nervous system can rapidly respond to immediate changes in the internal or external environment, allowing for quick adjustments in hormone levels.
Summary of why the other choices are incorrect:
B: The circulatory system is not involved in directly overriding endocrine controls.
C: The digestive system primarily regulates the breakdown and absorption of nutrients, not endocrine controls.
D: The reproductive system is responsible for the production of sex hormones and gametes, but it does not directly override normal endocrine controls.
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A morbidly obese person visits the local bariatric (weight loss) clinic seeking a pill that will help shed weight. The physician prescribes dextroamphetamine. In addition to causing its expected centrally mediated anorexigenic (appetite-suppressant) effects, it causes a host of peripheral adrenergic effects that, for some patients, can prove fatal. The main mechanism by which dextroamphetamine or amphetamines in general, cause their peripheral autonomic effects is
- A. Activates MAO
- B. Blocks NE reuptake via the amine pump/transporter
- C. Displaces, releases, intraneuronal NE
- D. Enhances NE synthesis, leading to massive neurotransmitter overproduction
Correct Answer: C
Rationale: Rationale for Correct Answer (C): Dextroamphetamine causes peripheral adrenergic effects by displacing, releasing, intraneuronal NE. Amphetamines disrupt the storage and release of NE from intraneuronal vesicles, leading to an increase in synaptic NE levels. This excess NE can stimulate adrenergic receptors in the periphery, causing adverse effects like hypertension, tachycardia, and potentially fatal outcomes.
Summary of Incorrect Choices:
A: Activating MAO would increase NE breakdown, not cause peripheral adrenergic effects.
B: Blocking NE reuptake would increase NE levels in the synapse, not intraneuronally, leading to central effects.
D: Enhancing NE synthesis would not directly lead to peripheral adrenergic effects, as it would require release and action at the synapse.
A patient has been receiving a large dose of prednisone for the relief of arthritic pain for 6 months. He suddenly stops taking his medication. What is the most serious concern?
- A. His arthritic pain will recur.
- B. He will develop an acute adrenal insufficiency.
- C. He will continue to exhibit symptoms of Cushing syndrome.
- D. He will develop a moon face and buffalo hump.
Correct Answer: B
Rationale: The correct answer is B: He will develop an acute adrenal insufficiency. When a patient abruptly stops taking a large dose of prednisone after long-term use, it can suppress the body's natural production of cortisol. This sudden withdrawal can lead to adrenal insufficiency, a potentially life-threatening condition. The adrenal glands may not be able to produce enough cortisol to meet the body's needs, causing symptoms such as fatigue, weakness, low blood pressure, and even shock. This is a serious concern that requires medical attention.
Incorrect choices:
A: His arthritic pain will recur - While this is a valid concern, it is not the most serious issue compared to acute adrenal insufficiency.
C: He will continue to exhibit symptoms of Cushing syndrome - Cushing syndrome is a result of prolonged exposure to high levels of cortisol, not sudden withdrawal.
D: He will develop a moon face and buffalo hump - These are physical symptoms associated with Cushing syndrome, not acute adrenal
The secretion of parathyroid hormone is a good example of __________.
- A. pituitary gland stimuli
- B. humoral stimuli
- C. neural stimuli
- D. hormonal stimuli
Correct Answer: B
Rationale: The correct answer is B: humoral stimuli. Parathyroid hormone secretion is regulated by the concentration of calcium in the blood, which is an example of humoral stimuli. When blood calcium levels decrease, parathyroid hormone is released to increase calcium levels. Pituitary gland stimuli (A), neural stimuli (C), and hormonal stimuli (D) are not directly involved in the regulation of parathyroid hormone secretion.
The hypersecretion of growth hormone leads to:
- A. Cretinism
- B. Myxoedema
- C. Acromegaly
- D. Graves disease
Correct Answer: C
Rationale: The correct answer is C: Acromegaly. Hypersecretion of growth hormone in adults leads to acromegaly, characterized by enlarged hands, feet, and facial features. This occurs due to excess GH after epiphyseal plate closure.
A: Cretinism is caused by congenital hypothyroidism, not GH hypersecretion.
B: Myxoedema is a severe form of hypothyroidism, not related to GH.
D: Graves disease is an autoimmune disorder causing hyperthyroidism, not GH hypersecretion.
An example of a hormone that under certain circumstances is regulated by positive feedback is:
- A. calcitonin.
- B. histamine.
- C. oxytocin.
- D. melatonin.
Correct Answer: C
Rationale: Rationale:
1. Oxytocin is released during childbirth to stimulate uterine contractions.
2. As contractions increase, oxytocin secretion is further stimulated in a positive feedback loop.
3. This positive feedback mechanism amplifies the contractions until delivery.
4. Calcitonin regulates calcium levels, histamine is involved in allergic responses, and melatonin regulates sleep-wake cycles.
Summary:
- Calcitonin, histamine, and melatonin do not exhibit positive feedback regulation like oxytocin during childbirth.