Question

Marty runs in marathons. Explain the functions of Marty's sympathetic and parasympathetic nervous systems during and after the race.

Short answer

During the marathon, Marty's sympathetic nervous system increases heart rate, blood pressure, and blood glucose levels, while constricting blood vessels in non-essential systems to meet the energy demands of the race. After the marathon, his parasympathetic nervous system takes over to conserve energy, slow heart rate, decrease blood pressure, and redirect blood back to the digestive system for recovery.

Step-by-step solution

Understanding the functions

Two major divisions of the autonomic nervous system are the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is involved with energy expenditure. It's often referred to as 'fight or flight' system that prepares the body for intense physical activity. The parasympathetic nervous system is known as the 'rest and digest' system, involved in conserving energy and enhancing body relaxation.

Function of Sympathetic Nervous system during the race

During the marathon, Marty's sympathetic nervous system is activated. It increases heart rate, blood pressure and blood glucose levels to deal with the increased energy needs. Constriction of blood vessels in non-essential systems like the digestive occurs to redirect blood towards muscles and the brain which are actively used during the marathon.

Function of Parasympathetic Nervous system after the race

After the race, his parasympathetic nervous system takes over. This is the body’s way of bringing all systems back to normal. It slows his heart rate, decreases blood pressure, and shunts blood back to the digestive system. This allows Marty to relax and recover after the race.

Key concepts

Sympathetic Nervous System

The sympathetic nervous system (SNS) is often likened to the gas pedal in a vehicle, revving up the body’s responses in times of stress or physical activity. During strenuous activities like running a marathon, the SNS jumps into action. It secretes adrenaline and other stress hormones, leading to a cascade of physiological effects.

• Heart rate increases to pump more blood to the muscles.
• Breathing becomes more rapid, enhancing oxygen intake.
• Energy stores are mobilized, releasing glucose into the bloodstream.
• Blood is diverted from the digestive system to the muscles and brain.

This transformation is crucial for athletes like Marty to perform optimally during the race, as it ensures that his muscles have the oxygen and nutrients needed to sustain the effort and prevent fatigue.

Parasympathetic Nervous System

Contrary to the SNS, the parasympathetic nervous system (PNS) acts like a brake. It conserves energy and facilitates non-emergency bodily functions. After Marty crosses the finish line, the PNS dials back the body’s heightened state. Here's how the PNS restores equilibrium:

• Heart rate is lowered as there is no longer a need for excessive blood flow to the muscles.
• Breathing slows down, reducing the intake of oxygen to resting levels.
• Digestive activity is promoted for the absorption and assimilation of nutrients.
• Overall energy consumption decreases as the body enters a state of recovery and repair.

This harmonizing system helps Marty's body to heal and recuperate post-marathon, ensuring that all systems return to their peaceful, resting state.

Fight or Flight Response

The fight or flight response is a survival mechanism primed by the SNS. When Marty's body senses the physical stress of the marathon, this response gears him up to face the 'threat'. Although running a marathon is not a danger, his body reacts in a similar way as if he were facing a predator:

• Adrenal glands pump out adrenaline.
• Muscles become ready for quick, powerful movements.
• Attention sharpens, improving reaction times.
• Non-essential processes like digestion are put on hold.

Understanding this natural reflex is vital for athletes, as it empowers them to harness their body's innate power to overcome challenges during intense physical competition.

Rest and Digest Response

On the flip side, the 'rest and digest' response, activated by the PNS, is all about maintenance and restoration. It is the calming counterbalance to the fight or flight response. After all the intense activity of the race, the rest and digest response helps Marty in several key ways:

• Muscles relax, which may prevent cramping and help in the prevention of injury.
• Enzyme production is increased to aid in digestion, allowing Marty to effectively turn his post-race meal into much-needed energy.
• Cellular repair processes are initiated to recover from the physical taxation of the marathon.

This response not only promotes relaxation but is also essential for bodily functions that support long-term health and vitality.