Nokea
Giving a single IV injection of phenylephrine can be used to normalize a rapid heart rate in paroxysmal supraventricular tachycardia (PSVT). How does phenylephrine do this?
- A. It blocks the beta-receptors on the heart
- B. It stimulates norepinephrine release from sympathetic nerves to the heart
- C. It raises blood pressure, slowing the heart via the baroreceptor reflex
- D. It stimulates ACh esterase at parasympathetic nerves to the heart
Correct Answer: C
Rationale: Correct Answer: C
Rationale:
1. Phenylephrine is a vasoconstrictor that raises blood pressure.
2. Increased blood pressure activates the baroreceptor reflex.
3. Baroreceptor reflex detects elevated blood pressure and sends signals to the brain.
4. The brain then signals the heart to slow down, thus normalizing the rapid heart rate in PSVT.
Summary:
A: Blocking beta-receptors would have the opposite effect, as beta-blockers slow down the heart rate.
B: Stimulating norepinephrine release would increase heart rate, not slow it down.
D: ACh esterase is involved in the breakdown of acetylcholine, not relevant to the mechanism of action of phenylephrine in PSVT.
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A patient with renal failure and high magnesium level would later have ________ and
- A. Cardiac Arrest
- B. Respiratory Paralysis
- C. Liver Encephalopathy
- D. Death From Hemorrhage
Correct Answer: A
Rationale: The correct answer is A: Cardiac Arrest. High magnesium levels in renal failure can lead to cardiac arrest due to the inhibitory effect on neuromuscular transmission and cardiac muscle activity. Magnesium impairs calcium entry into cells, affecting muscle contraction, potentially leading to fatal arrhythmias and cardiac arrest. Respiratory paralysis (B) is unlikely as magnesium does not directly affect respiratory muscles. Liver encephalopathy (C) is unrelated to high magnesium levels. Death from hemorrhage (D) is not a typical consequence of elevated magnesium levels in renal failure.
Identify the hormone that stimulates uterine contraction and the release of milk during nursing.
- A. ADH.
- B. glucagon
- C. oxytocin
- D. prolactin
Correct Answer: C
Rationale: Rationale:
1. Oxytocin is the hormone responsible for stimulating uterine contractions during labor and delivery.
2. Oxytocin also triggers the release of milk during nursing by causing contraction of the cells around the milk-filled alveoli.
3. ADH (A) regulates water balance, glucagon (B) regulates blood sugar levels, and prolactin (D) stimulates milk production but not milk release.
Summary: Oxytocin is the correct answer because it specifically stimulates uterine contractions and milk release during nursing, while the other choices are not directly related to these functions.
How do hormones differ from neurotransmitters?
- A. Hormones travel through the synaptic cleft while neurotransmitters travel through the bloodstream.
- B. Hormones act on receptors while neurotransmitters do not.
- C. Hormones use speedy electrical impulses, while neurotransmitters take several seconds from the gland to the target tissue.
- D. Hormones travel through the bloodstream while neurotransmitters travel across the synaptic cleft between neurons.
Correct Answer: D
Rationale: The correct answer is D. Hormones travel through the bloodstream while neurotransmitters travel across the synaptic cleft between neurons. Hormones are secreted by endocrine glands into the bloodstream to target distant tissues, while neurotransmitters are released by neurons into the synaptic cleft to transmit signals locally between neurons. Choice A is incorrect as hormones do not travel through the synaptic cleft, and neurotransmitters do not travel through the bloodstream. Choice B is incorrect as both hormones and neurotransmitters act on specific receptors. Choice C is incorrect as hormones do not use electrical impulses; instead, they travel through the bloodstream.
Mr. R, a 52-year-old patient with hyperthyroidism, is experiencing a thyroid storm. Which of the following symptoms would indicate the need for immediate intervention?
- A. Hypothermia
- B. Low blood pressure
- C. Severe tachycardia
- D. Weight gain
Correct Answer: C
Rationale: Severe tachycardia is a hallmark of thyroid storm and requires immediate intervention to prevent life-threatening complications such as heart failure or stroke.
Why is the posterior pituitary gland called the neurohypophysis?
- A. The posterior pituitary gland is an extension of the hypothalamus.
- B. The neurohypophysis secretes releasing hormones.
- C. The posterior pituitary gland secretes hormones that regulate adenohypophyseal function.
- D. The posterior pituitary gland secretes releasing hormones.
Correct Answer: A
Rationale: The correct answer is A because the posterior pituitary gland is an extension of the hypothalamus. The hypothalamus produces hormones that are stored and released by the posterior pituitary gland. This connection between the two structures allows for direct neural control over hormone release.
Option B is incorrect because the neurohypophysis does not secrete releasing hormones; rather, it releases hormones produced by the hypothalamus. Option C is incorrect because the posterior pituitary gland does not regulate adenohypophyseal function; instead, it stores and releases hormones produced by the hypothalamus. Option D is incorrect because the posterior pituitary gland does not secrete releasing hormones; it releases hormones produced by the hypothalamus.