Which hormone is released in response to low blood glucose levels?

Correct Answer: B

Rationale: Glucagon is the hormone released in response to low blood glucose levels. When blood glucose levels drop, the pancreas secretes glucagon to stimulate the liver to break down glycogen into glucose, increasing blood sugar levels. This helps to restore the body's glucose balance. Insulin, on the other hand, is released in response to high blood glucose levels to lower blood sugar by promoting glucose uptake by cells. Cortisol is a stress hormone, and adrenaline is released in response to stress or danger, not specifically to regulate blood glucose levels.

Correct Answer: C

Rationale: Mitochondria are commonly referred to as the powerhouses of the cell as they are primarily responsible for generating energy through cellular respiration. This process involves converting nutrients into adenosine triphosphate (ATP), which is the main energy currency of the cell. The nucleus is responsible for storing the cell's genetic material, the ribosome is involved in protein synthesis, and the Golgi apparatus is responsible for packaging and distributing molecules produced by the cell; therefore, they are not directly involved in energy generation.

Correct Answer: A

Rationale: Melatonin, produced by the pineal gland, is the hormone that regulates the sleep-wake cycle. Its secretion is influenced by light exposure, with levels typically rising in the evening to promote sleep and falling in the morning to encourage wakefulness. Insulin is involved in regulating blood sugar levels, not the sleep-wake cycle. Cortisol plays a role in the body's stress response and circadian rhythm but is not the primary hormone regulating sleep-wake cycles. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, not the sleep-wake cycle.

Correct Answer: B

Rationale: Arteries are blood vessels that carry oxygenated blood away from the heart to supply tissues and organs with oxygen and nutrients. Veins carry deoxygenated blood back to the heart. Capillaries facilitate the exchange of nutrients and gases between the blood and tissues. Lymphatic vessels are part of the lymphatic system responsible for returning interstitial fluid to the bloodstream. Therefore, the correct answer is arteries as they carry oxygenated blood away from the heart.

Correct Answer: A

Rationale: The correct answer is the Adrenal gland. The adrenal glands are located on top of the kidneys. They produce hormones such as adrenaline and cortisol, which play essential roles in regulating metabolism, immune response, and stress in the body. The Thyroid gland, Pineal gland, and Pancreas are not located on top of the kidneys. The Thyroid gland is located in the neck, the Pineal gland in the brain, and the Pancreas behind the stomach.

Correct Answer: B

Rationale: The correct answer is B: Pivot joint. A pivot joint, like the one found in the neck, allows for rotational movement, enabling the head to turn from side to side. Hinge joints (Choice A) allow movement in one plane like a door hinge and are not found in the neck. Ball and socket joints (Choice C) allow for a wide range of motion in multiple directions and are typically found in the hip and shoulder. Saddle joints (Choice D) allow for movement back and forth and side to side, like the thumb joint, but are not found in the neck.

Correct Answer: D

Rationale: The correct answer is D, the Hypothalamus. The hypothalamus is responsible for releasing key hormones like thyrotrophic-releasing hormone, growth hormone-releasing hormone, and gonadotropin-releasing hormone. These hormones play essential roles in regulating various body functions by influencing the activities of other endocrine glands. Choices A, B, and C are incorrect because the thymus is involved in immune function, the pituitary gland releases different hormones, and the pineal gland primarily produces melatonin, not the hormones mentioned in the question.

Correct Answer: A

Rationale: Hemoglobin, located in red blood cells, is responsible for binding to oxygen in the lungs and transporting it to tissues throughout the body. Red blood cells contain hemoglobin, making them the primary carrier of oxygen to cells. Hemoglobin is the correct answer because it is the protein within red blood cells that directly binds to oxygen for transport. Plasma is the liquid component of blood and does not carry oxygen. Platelets are responsible for blood clotting and have no role in oxygen transport. While red blood cells do carry oxygen, it is specifically the hemoglobin within them that performs this function.

Correct Answer: B

Rationale: The pituitary gland, often referred to as the 'master gland,' is the correct answer. It is responsible for regulating the release of hormones from other endocrine glands in the body. The pituitary gland controls various bodily functions and plays a crucial role in maintaining hormonal balance, making it a central and vital component of the endocrine system. The other options, such as the thyroid gland (A), adrenal gland (C), and pineal gland (D), have important functions in the endocrine system but are not specifically known as the 'master gland.'