The human spinal cord extends from the: MCQ with Answer and Explanation

Explanation:
Thermoregulation uses negative feedback mechanisms: when body temperature rises, sweating and vasodilation cool the body; when it falls, shivering and vasoconstriction generate and conserve heat. Negative feedback counteracts deviations from a set point. Positive feedback amplifies a change (e.g., labor contractions).

Explanation:
Vitamin D (specifically cholecalciferol, Vitamin D3) is unique because it can be synthesized endogenously in the human skin. When 7-dehydrocholesterol in the skin is exposed to ultraviolet B (UVB) radiation from sunlight, it is converted to previtamin D3, which then isomerizes to Vitamin D3. It is subsequently hydroxylated in the liver and kidneys to its active hormonal form, calcitriol, which regulates calcium and phosphorus metabolism.

Explanation:
Marasmus is a form of severe malnutrition caused by a deficiency of both calories and protein. It results in extreme wasting of muscle and subcutaneous fat, making the child look emaciated or 'wasted'. Unlike kwashiorkor, marasmus typically does not present with edema. The child is extremely weak, has a 'old man' face, and is highly susceptible to infections.