What is the primary function of carbohydrates in the human body?

A. By regulating body temperature through sweat and blood flow:The skin (integument) plays a vital role in thermoregulation. When the body is hot, sweat glands release sweat (evaporative cooling) and blood vessels dilate (vasodilation) to release heat. When cold, vessels constrict (vasoconstriction) to retain heat.

B. By producing digestive enzymes:The production of digestive enzymes is the function of the digestive system organs, such as the stomach and pancreas.

C. By storing nutrients and minerals:While the skin synthesizes Vitamin D, the primary storage sites for nutrients and minerals are the liver (vitamins/glycogen) and bones (calcium/phosphorus).

D. By filtering blood to remove waste products:Filtration of blood to remove metabolic waste is the primary function of the urinary system (kidneys).

A. Bladder control:Voluntary bladder and bowel control is mediated by the sacral nerves (S2-S4). A C5 injury severs the connection between the brain and the lower spinal cord, typically resulting in neurogenic bladder (loss of voluntary control).

B. Full hand dexterity:The nerves controlling the hands and fingers originate from the C8 and T1 levels. A C5 injury usually leaves the patient with shoulder and partial biceps control, but paralysis of the wrists and hands.

C. Ability to breathe independently:The diaphragm is innervated by the phrenic nerve, which originates from spinal roots C3, C4, and C5("C3, 4, 5 keep the diaphragm alive"). While a C5 injury may weaken respiratory effort (due to loss of intercostal muscles), the diaphragm usually remains functional, allowing independent breathing.

D. Ability to walk unaided:The muscles for walking are controlled by the lumbar and sacral spinal nerves. A cervical injury (C5) results in quadriplegia (tetraplegia), involving paralysis of both the trunk and legs.