The motor cortex is essential for monitoring and controlling body movements. Where is the motor cortex located within the brain?

Correct Answer: C

Rationale: The motor cortex is located in the frontal portion of the brain, specifically in the precentral gyrus of the frontal lobe. It plays a crucial role in planning, controlling, and executing voluntary movements. Choice A, 'Top, middle portion of the parietal lobe,' is incorrect because the motor cortex is not located in the parietal lobe but rather in the frontal lobe. Choice B, 'Back of the head,' is incorrect as it refers to the occipital lobe, not where the motor cortex is situated. Choice D, 'Around the auditory cortex,' is incorrect as the motor cortex is not located around the auditory cortex but in the frontal lobe, as mentioned earlier.

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: A

Rationale: Insulin is secreted by the pancreas to lower blood glucose levels by facilitating the uptake of glucose into cells. It promotes the storage of glucose as glycogen in the liver and muscles, reducing blood sugar levels. Glucagon, on the other hand, works to raise blood glucose levels by stimulating the breakdown of glycogen into glucose and releasing it into the bloodstream. Somatostatin regulates the endocrine system and inhibits the release of insulin and glucagon. Cortisol is a hormone produced by the adrenal glands, not the pancreas, and it plays a role in stress response and metabolism, but it does not directly lower blood glucose levels.

Correct Answer: B

Rationale: The correct answer is a hinge joint. The knee is a hinge joint that allows for flexion and extension movements, enabling the leg to bend and straighten. This type of joint is designed for movement along one plane, similar to a door hinge. Choice A, ball and socket joint, is incorrect as this type of joint allows for a wider range of motion in multiple directions, unlike the knee joint. Choice C, pivot joint, and Choice D, saddle joint, are also incorrect as they do not accurately describe the type of joint found in the knee.

Correct Answer: A

Rationale: The pituitary gland, known as the 'master gland,' plays a crucial role in regulating various physiological processes by secreting hormones that control other endocrine glands. This includes the regulation of metabolism, growth, reproduction, stress response, and more. Therefore, the correct function of the pituitary gland is regulating metabolism, making choice A the correct answer. Choices B, C, and D are incorrect as the pituitary gland is not involved in producing bile, filtering blood, or controlling muscle movement.

Correct Answer: A

Rationale: The correct answer is the pancreas. The pancreas is responsible for producing insulin, a hormone crucial for regulating blood glucose levels. Insulin plays a key role in allowing cells to take in glucose, thereby helping to keep blood sugar levels in check. The liver (choice B), gallbladder (choice C), and kidneys (choice D) do not produce insulin. The liver is involved in glycogen storage and glucose regulation, the gallbladder stores bile, and the kidneys filter blood and regulate fluid balance.

Correct Answer: A

Rationale: The correct answer is the left ventricle. The left ventricle is the largest and strongest chamber of the heart. It pumps oxygenated blood to the entire body, making it a vital component of the circulatory system. The left atrium receives oxygen-rich blood from the lungs, the right ventricle pumps deoxygenated blood to the lungs for oxygenation, and the right atrium receives deoxygenated blood from the body.

Correct Answer: C

Rationale: The pituitary gland, often referred to as the 'master gland,' controls the release of hormones from other endocrine glands in the body. It secretes various hormones that regulate many bodily functions, making it a central and vital component of the endocrine system. The thyroid gland (Choice A) regulates metabolism, the adrenal gland (Choice B) produces hormones like adrenaline, and the pineal gland (Choice D) secretes melatonin, but none of these glands are considered the 'master gland' that controls the functions of other endocrine glands.

Correct Answer: B

Rationale: The gallbladder's main function is to store and concentrate bile produced by the liver. Bile is essential for the digestion and absorption of fats in the small intestine. Therefore, the correct answer is B, as the gallbladder acts as a reservoir for bile rather than producing it. Choices A, C, and D are incorrect because the gallbladder does not produce bile, detoxify harmful substances, or regulate blood sugar in the digestive system.