What effect does aldosterone secretion have on electrolyte levels?
- A. Calcium levels are decreased
- B. Sodium levels are increased
- C. Potassium levels are increased
- D. Magnesium levels are decreased
Correct Answer: B
Rationale: Aldosterone is a hormone that primarily acts on the kidneys to increase the reabsorption of sodium and water into the bloodstream. As a result, sodium levels are increased. Choices A, C, and D are incorrect. Aldosterone does not significantly affect calcium, potassium, or magnesium levels.
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Which of the following hormones is secreted by the posterior pituitary gland?
- A. Growth hormone
- B. Luteinizing hormone
- C. Adrenocorticotropic hormone
- D. Antidiuretic hormone
Correct Answer: D
Rationale: The correct answer is D: Antidiuretic hormone. Antidiuretic hormone (ADH), also known as vasopressin, is produced by the hypothalamus and stored in the posterior pituitary gland. It plays a key role in regulating the body's water balance by controlling the amount of water reabsorbed by the kidneys. Choices A, B, and C are incorrect because Growth hormone is produced by the anterior pituitary gland, Luteinizing hormone is produced by the anterior pituitary gland, and Adrenocorticotropic hormone is produced by the anterior pituitary gland.
Which of the following cardiac valves prevents blood from returning to the left ventricle of the heart?
- A. pulmonic
- B. mitral
- C. tricuspid
- D. aortic
Correct Answer: D
Rationale: The correct answer is the aortic valve. The aortic valve is located between the left ventricle and the aorta, preventing the backflow of blood into the left ventricle once it has been pumped out during systole. Choice A, pulmonic, is incorrect as it is associated with the right side of the heart. Choice B, mitral, is incorrect as it is the valve between the left atrium and ventricle. Choice C, tricuspid, is incorrect as it is located between the right atrium and ventricle.
Which of the following is a result of stimulation of the sympathetic nervous system?
- A. decreased blood flow to the skeletal muscles
- B. increased cardiac output
- C. decreased respiratory rate
- D. increased urinary output
Correct Answer: B
Rationale: Stimulation of the sympathetic nervous system leads to an increase in cardiac output. When the sympathetic nervous system is activated, it causes the heart to beat faster and with more force, leading to an increased cardiac output. Choices A, C, and D are incorrect because the sympathetic nervous system does not cause decreased blood flow to the skeletal muscles, decreased respiratory rate, or increased urinary output.
Which of the following may indicate hypersecretion of thyroid hormone?
- A. weight loss
- B. Bradycardia
- C. cold intolerance
- D. lethargy
Correct Answer: A
Rationale: Weight loss is a common symptom of hyperthyroidism, which is characterized by an excess secretion of thyroid hormone. This increased metabolic rate can lead to weight loss despite normal or increased appetite. Bradycardia (slow heart rate), cold intolerance, and lethargy are more commonly associated with hypothyroidism, where there is an insufficient production of thyroid hormone. Therefore, choices B, C, and D are incorrect in the context of hypersecretion of thyroid hormone.
Which part of the brain regulates heart rate, respiratory rate, and blood pressure?
- A. Corpus Callosum
- B. Medulla Oblongata
- C. Pituitary Glands
- D. Pineal Glands
Correct Answer: B
Rationale: The correct answer is the Medulla Oblongata. This part of the brain is responsible for regulating essential autonomic functions such as heart rate, respiratory rate, and blood pressure. The Corpus Callosum is responsible for connecting the left and right hemispheres of the brain, not for regulating these vital functions. The Pituitary Glands and Pineal Glands are part of the endocrine system and are not directly involved in regulating heart rate, respiratory rate, and blood pressure.