1. The point of contact between the nerve ending and the muscle fiber is called a neuromuscular junction.
2. At the synapse, there is a very small gap called a synaptic cleft. Neurotransmitters are released by the motor neuron in response to a nerve impulse.
3. What causes the muscle to relax is when the stimulation of the nerve stops.
4. Muscle fatigue occurs due to the accumulation of lactic acid in muscles during strenuous activity. Symptoms of muscle fatigue include weakness, soreness, and a decreased ability to generate force.
5. When Jim feels a burning sensation in his muscles while running, it is due to the buildup of lactic acid as a byproduct of anaerobic metabolism. This occurs when oxygen supply to the muscles is insufficient to meet the demands of the exercise, leading to the production of lactic acid.
6a. His breathing remains deep and fast even after slowing down because his body needs to replenish oxygen levels and remove carbon dioxide produced during the exercise. The increased breathing rate helps to supply oxygen to the muscles and remove waste products efficiently.
6b. The burning sensation occurs due to the accumulation of lactic acid, which is a result of anaerobic metabolism when oxygen supply is insufficient. Lactic acid buildup contributes to muscle fatigue and discomfort, signaling the need for the body to slow down and recover.
