How do sweat glands help regulate body temperature?

Correct Answer: C

Rationale: Sweat glands play a vital role in regulating body temperature by releasing a watery fluid that evaporates from the skin's surface. This evaporation process helps cool the body down by dissipating heat, which is essential for maintaining a stable internal temperature. Choice A is incorrect because sweat glands do not produce sebum but rather a watery fluid. Choice B is incorrect because sweating itself does not involve the constriction of blood vessels; instead, it promotes heat loss through evaporation. Choice D is incorrect as sweat glands do not thicken the epidermis for insulation but rather facilitate the cooling process through sweat evaporation.

Correct Answer: C

Rationale: The correct answer is C: Flat bone. The kneecap (patella) is classified as a flat bone. Flat bones are thin, flattened bones that provide protection and offer a broad surface for muscle attachment. The patella fits this description as it is a flat, triangular bone located in front of the knee joint, protecting the knee and providing attachment points for muscles like the quadriceps. Choice A, long bone, is incorrect as long bones are typically found in the arms and legs, not in the knee area. Choice B, short bone, is incorrect as short bones are cube-shaped and are not characteristic of the patella. Choice D, irregular bone, is incorrect as irregular bones have complex shapes and do not apply to the flat, triangular structure of the patella.

Correct Answer: B

Rationale: The periosteum, the tough outer layer of bone, serves the purpose of providing protection to the bone and nourishing it through the blood vessels it contains. It acts as a protective layer for the bone structures. Choices A, C, and D are incorrect because the periosteum does not produce red blood cells (which is the function of bone marrow), form joint surfaces (which is typically the role of articular cartilage), or store minerals (which is primarily done by bone tissue itself and not the periosteum).

Correct Answer: B

Rationale: Regular exercise is beneficial for the muscular system by improving muscle strength and endurance. Exercise helps to build and maintain muscle mass, increase muscle strength, and enhance muscle endurance. It does not decrease muscle mass, make muscles less flexible, or increase the risk of muscle tears when done properly. Therefore, the correct answer is improving muscle strength and endurance, as it aligns with the positive effects of regular exercise on the muscular system.

Correct Answer: B

Rationale: The myelin sheath is a fatty substance that insulates some nerve fibers. It is made up of specialized cells that wrap around the axons of neurons, providing insulation and speeding up the transmission of nerve impulses. Choice A is incorrect as the myelin sheath is not a group of nerve cells but rather a substance that surrounds nerve fibers. Choice C is incorrect as the myelin sheath is not a fluid-filled cavity within the brain. Choice D is incorrect as the myelin sheath is not the junction between two neurons.