Which structure in the ear is responsible for detecting sound?

Correct Answer: A

Rationale: The cochlea, situated in the inner ear, is responsible for detecting sound waves and converting them into neural signals that are transmitted to the brain for processing. The cochlea contains specialized sensory cells that respond to different frequencies of sound, allowing us to hear a wide range of sounds. The other structures listed, such as the eustachian tube, ossicles, and semicircular canals, play roles in functions like equalizing pressure, transmitting vibrations, and maintaining balance, respectively, but they are not directly involved in the detection of sound.

Correct Answer: B

Rationale: The pinna, also known as the auricle, is the most visible part of the ear. It is responsible for capturing sound waves and directing them into the ear canal, where the process of hearing begins. The other structures mentioned, such as the cochlea, ear canal, and organ of Corti, play crucial roles in the auditory system but are not the most visible parts of the ear. The cochlea is a spiral-shaped cavity responsible for converting sound vibrations into neural signals. The ear canal is a tube that connects the outer ear to the eardrum. The organ of Corti is the actual sensory organ of hearing located in the cochlea.

Correct Answer: B

Rationale: Parathyroid hormone, produced by the parathyroid glands, is responsible for regulating calcium levels in the blood. It achieves this by increasing calcium absorption in the intestines and kidneys, thus maintaining appropriate calcium levels in the bloodstream. Insulin is involved in glucose metabolism, not calcium regulation. Cortisol is a stress hormone that affects various body functions but not calcium levels. Melatonin is responsible for regulating the sleep-wake cycle, not calcium levels.

Correct Answer: B

Rationale: The correct answer is the Glomerulus. The glomerulus is a network of tiny blood vessels located within the Bowman's capsule. It acts as the initial filtering component in the nephron, filtering blood and allowing waste products and excess substances to pass through to form urine. Choice A, Nephron, is incorrect as the nephron is the structural and functional unit of the kidney composed of several parts, including the glomerulus. Choice C, Bowman's capsule, is where the glomerulus is located, but it is not the structure responsible for filtering blood. Choice D, Loop of Henle, plays a role in reabsorption of water and electrolytes but is not the primary structure for blood filtration in the kidney.

Correct Answer: B

Rationale: The thyroid gland is responsible for producing hormones, such as thyroxine, that play a crucial role in regulating metabolism, energy production, and overall growth and development in the body. The pituitary gland, while important for hormone regulation, does not primarily regulate metabolism. The adrenal gland is responsible for producing hormones like cortisol and adrenaline, which are more related to stress response than direct metabolism regulation. The pineal gland mainly produces melatonin, which regulates sleep-wake cycles and not metabolism. Therefore, the correct answer is the thyroid gland.

Correct Answer: B

Rationale: The skin is the largest organ in the human body. It serves as a protective barrier against the environment, regulates temperature, and provides sensory information. The liver, brain, and heart are vital organs, but they are not as extensive as the skin. The liver is primarily responsible for detoxification and metabolism. The brain is the control center of the body, coordinating various functions. The heart is a crucial organ that pumps blood throughout the body. However, in terms of size, the skin surpasses all of these organs.

Correct Answer: C

Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata, situated in the brainstem, plays a crucial role in regulating vital functions such as heart rate, breathing, and blood pressure. It serves as the control center for involuntary actions, ensuring the body's automatic functions work properly. Choices A, B, and D are incorrect because the cerebrum is primarily responsible for functions such as thinking, voluntary movements, and sensory processing; the cerebellum is involved in coordination, balance, and muscle control; and the hypothalamus regulates body temperature, thirst, hunger, and some aspects of the autonomic nervous system but not specifically heart rate and breathing.

Correct Answer: B

Rationale: The correct answer is B: Support and protection. The primary functions of the skeletal system include providing structural support to the body and protecting internal organs. While the skeletal system also plays a role in hematopoiesis (production of blood cells) and stores minerals, its main function is to support the body's framework and protect vital organs. Choices A, C, and D are incorrect as they do not directly relate to the primary functions of the skeletal system.

Correct Answer: B

Rationale: Thyroxine, produced by the thyroid gland, is the hormone responsible for regulating metabolism. It plays a fundamental role in controlling the body's metabolic rate, affecting processes such as energy production and utilization. Thyroxine also influences growth and development in the body. Choice A, Insulin, is involved in regulating blood sugar levels and promoting the storage of glucose. While insulin has an impact on metabolism, it is not primarily responsible for regulating overall metabolic rate. Choice C, Glucagon, acts in opposition to insulin, stimulating the release of glucose from the liver to increase blood sugar levels. Glucagon primarily targets glucose regulation rather than overall metabolism. Choice D, Cortisol, is known as the stress hormone and plays a role in the body's response to stress, regulation of blood pressure, immune function, and anti-inflammatory actions. While cortisol can have some effects on metabolism during stress responses, it is not the primary hormone responsible for regulating overall metabolic rate.