Which component of the neuron is responsible for transmitting signals to the next cell?

A. Parasympathetic nervous system: The parasympathetic system promotes “rest and digest” activities, slowing the heart rate, stimulating digestion, and conserving energy. It functions in opposition to the fight-or-flight response.

B. Central nervous system: The central nervous system, consisting of the brain and spinal cord, processes and integrates information but does not directly mediate the autonomic fight-or-flight response. It coordinates signals but relies on the sympathetic system to execute them.

C. Somatic nervous system: The somatic nervous system controls voluntary movements of skeletal muscles. It does not regulate involuntary responses such as increased heart rate, dilation of pupils, or bronchodilation associated with stress.

D. Sympathetic nervous system: The sympathetic nervous system activates the fight-or-flight response by increasing heart rate, dilating airways, redirecting blood flow to muscles, and releasing adrenaline. It prepares the body for rapid, intense physical activity during stress or danger.

A. Increased ATP levels: During exercise, ATP is consumed rapidly to fuel muscle contractions. Increased ATP levels are not a cause of fatigue; rather, ATP depletion can contribute to reduced muscle performance.

B. Depletion of oxygen: Oxygen depletion can limit aerobic metabolism, but muscles often continue generating energy anaerobically. Oxygen shortage alone is not the primary cause of fatigue in prolonged activity.

C. Lack of glycogen stores: Glycogen is a key energy source, and its depletion can reduce endurance. However, fatigue is more directly related to metabolic byproducts affecting muscle contraction.

D. Accumulation of lactic acid: During intense or prolonged exercise, anaerobic metabolism produces lactic acid, which lowers pH in muscle cells. This acidic environment interferes with enzyme activity and muscle contraction, leading to fatigue.