Nokea
Normal development of the immune response is due in part to hormones produced by the ________.
- A. adrenal medulla
- B. pancreas
- C. thyroid gland
- D. thymus gland
Correct Answer: D
Rationale: The correct answer is D: thymus gland. The thymus gland is crucial for the development and maturation of T cells, a type of immune cell. The hormones produced by the thymus gland, such as thymosin, play a key role in the proper functioning of the immune system. Without a functional thymus gland, the immune response would be compromised.
Explanation for why other choices are incorrect:
A: Adrenal medulla does not play a direct role in immune response development.
B: Pancreas primarily produces hormones related to blood sugar regulation, not immune response.
C: Thyroid gland produces hormones that regulate metabolism, not directly related to immune response development.
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A student is in a car accident, and although not hurt, immediately experiences pupil dilation, increased heart rate, and rapid breathing. What type of endocrine system stimulus did the student receive?
- A. humoral
- B. hormonal
- C. neural
- D. positive feedback
Correct Answer: C
Rationale: The correct answer is C: neural. In this scenario, the student experiences the fight or flight response, which is controlled by the sympathetic nervous system. The pupil dilation, increased heart rate, and rapid breathing are all physiological responses triggered by the activation of neural pathways in response to a perceived threat or stress. The other choices are incorrect because:
A: Humoral stimuli involve changes in blood levels of certain substances triggering hormone release.
B: Hormonal stimuli involve the release of hormones in response to other hormones.
D: Positive feedback is a mechanism that amplifies a response, not directly related to the immediate physiological responses seen in this case.
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.
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.
Donepezil is a reversible anti-cholinesterase used in the treatment of:
- A. Glaucoma
- B. Bradycardia
- C. Urine retention
- D. Alzheimer disease
Correct Answer: D
Rationale: Donepezil is used in the treatment of Alzheimer's disease because it is a reversible anti-cholinesterase that helps improve cognitive function by increasing levels of acetylcholine in the brain. This neurotransmitter is important for memory and learning, which are affected in Alzheimer's disease.
Choice A (Glaucoma) is incorrect because Donepezil does not treat this condition. Choice B (Bradycardia) is incorrect because Donepezil does not affect heart rate. Choice C (Urine retention) is incorrect because Donepezil does not have any impact on urinary function.
In summary, the correct answer is D (Alzheimer's disease) because Donepezil's mechanism of action aligns with the cognitive deficits seen in this condition, while the other choices are not related to the drug's pharmacological effects.
A congenital condition that includes mental retardation, short disproportional body size, and a thick tongue and neck is caused by __________.
- A. insulin deficiency
- B. deficiency of thymosin
- C. deficiency of thyroxin
- D. excess of synthetic growth hormone
Correct Answer: C
Rationale: Step 1: The congenital condition described points towards a disorder affecting growth and development.
Step 2: The symptoms of mental retardation, short body size, and thick neck suggest hypothyroidism.
Step 3: Thyroxin is a hormone produced by the thyroid gland that regulates metabolism and growth.
Step 4: A deficiency of thyroxin in congenital hypothyroidism leads to the described symptoms.
Step 5: Therefore, the correct answer is C: deficiency of thyroxin.
Summary:
A: Insulin deficiency does not match the symptoms described.
B: Thymosin deficiency is not related to growth and mental retardation.
D: Excess of synthetic growth hormone would not cause mental retardation and thick neck.