The upper motor neuron impairment produces the following change of muscles tone:

Correct Answer: B

Rationale: Spasticity is the correct answer because upper motor neuron lesions typically result in increased muscle tone due to the loss of inhibitory signals from the brain. This leads to hyperreflexia, clonus, and rigidity, which are hallmark signs of spasticity. The condition arises from damage to the corticospinal tract, which disrupts the balance of excitatory and inhibitory inputs to the motor neurons.

Correct Answer: C

Rationale: Cerebellar is the correct answer because dysdiadochokinesis, or the inability to perform rapid alternating movements, is a hallmark sign of cerebellar dysfunction. The cerebellum is responsible for coordinating voluntary movements, and damage to this area disrupts the timing and precision of motor actions.

Correct Answer: B

Rationale: Deuterium oxide distributes throughout total body water (TBW), while inulin distributes only in extracellular fluid (ECF). The intracellular fluid (ICF) volume is calculated as TBW - ECF. Here, TBW = 42 L and ECF = 14 L, so ICF = 42 - 14 = 28 L. This calculation is based on the principle that deuterium oxide measures all body water, while inulin is restricted to the extracellular compartment.

Correct Answer: D

Rationale: The lateral spinothalamic tract carries second-order neurons transmitting pain and temperature information to the thalamus. It is a critical pathway for sensory perception and is involved in relaying these sensations to higher brain centers.

Correct Answer: C

Rationale: Acetylcholine is the primary neurotransmitter in autonomic ganglia, where it mediates synaptic transmission between pre- and post-ganglionic neurons. GABA, noradrenaline, and 5-HT are not involved in ganglionic transmission.