At the start:
Question 1: Since the race has not actually started, the anticipation of the race is activating the sympathetic division of the autonomic nervous system, which is stimulating these changes.
Question 2: The thought of the race creates enough stress to activate the sympathetic division of the autonomic system.
Question 3: The sympathetic division stimulates the fight or flight organs. This means that blood and nutrients are being delivered to areas that might be needed for a fight for your life, or to run for your life. This means that organs needed for non-life saving actions, such as the bladder and digestive systems, will be inhibited so that the heart, limbs, and brain can receive more blood and nutrients for quick decision making and to support fight or flight scenarios. Sympathetic stimulation also increases ADH release which will preserve blood volume and insure greater blood flow to large muscle groups and other tissues.
Question 4: Sympathetic stimulation of the liver will stimulate glycogenolysis, which puts more glucose into the bloodstream.
Question 5: Sympathetic stimulation decreases the production of saliva.
One Minute In:
Question 1: With any sort of extreme exertion, such as intense rowing, muscles will have an immediate increase in their demand for ATP. ATP is produced by aerobic cellular respiration, which is the most efficient method. This creates demand for oxygen from the muscles as well. The body responds by increasing heart rate and respiratory rate to meet the body’s needs.
Question 2: When acidity and temperature increase, the bond between hemoglobin and oxygen decrease. The acidity in a working muscle increases because of the production of CO^2 and lactic acid. As a muscle works, friction is created which will increase temperature as well.
Question 3: Jim’s muscles feel like they are burning because of the presence and build up of lactic acid.
Question 4: Jim’s body is trying to maintain homeostasis. As his body temperature rises above a safe threshold, the response will be to try to cool his body off. His body does that by stimulating the sweat glands to sweat and help with evaporative cooling. At the same time, the kidneys, although inhibited, are working on removing waste from his body. This is the reason Jim, and other athletes, hydrate well before a big event. They have to be prepared for the increased water loss.
At the halfway mark
Question 1: Jim wants to ensure the stamina of the muscles so that he would not be too tired to row before the race ends, so he intentionally slows down the strokes a bit after the start. Also, the muscles now cannot exert full force to row as fatigue builds up, and the fight-or-flight response operated by the sympathetic division cannot last too long.
Question 2: The stroke rate has decreased from 39 strokes to 34 strokes per minute, allowing the heartbeat to slow down, and he is sweating more to release extra heat.
At the Finish
Question 1: After the sympathetic division finished its part, the parasympathetic division must act to release chemicals to redo the flight-or-flight response. But this process takes time for the chemicals to get the heart and breathing rates back to normal.
Question 2: With his temperature at 102 F, sweating is the body's way of cooling down.
Question 3: Glucose levels rise, pH levels fall (more acidic), lactate levels rise, creatinine levels rise, and temperature rises, too!
Back at the Dock
Question 1: At this point the parasympathetic division has probably kicked in, he is resting and is at rest allowing the heart rate and respirations to come back to normal.
Question 2: Since the human body is mainly made of water, profuse sweating during intense exercise/activities will result in losing water weight, plus removal of waste and toxins, all factors in losing so much weight so quickly.
Question 3: The ADH is in full effect, the kidneys are trying to retain as much water as possible. Conserving the fluid volume of your body by reducing the amount of water passed out in the urine. Also, any water absorbed from the digestive tract will be retained also, to prevent the body from becoming dehydrated.
Question 4: Cells in Jim’s body need to replenish water slowly, and a sudden large intake of water would be unbearable for the cells.
