Question

During rest, the metabolic needs of the body are at their minimum. Which of the following is indicative of this situation? (a) Rate of breathing (b) \(0_{2}\) intake and \(\mathrm{CO}_{2}\) output (c) Pulse rate (d) All of these

Short answer

(d) All of these

Step-by-step solution

Understanding the Concept of Basal Metabolic Rate

The basal metabolic rate (BMR) is the rate at which the body uses energy while at rest to maintain vital functions such as breathing, circulating blood, and regulating body temperature. Look for factors that are typically minimal during rest when the metabolic needs of the body are minimum.

Assessing Each Option

Evaluate each option separately: (a) During rest, the rate of breathing is reduced. (b) Oxygen intake and carbon dioxide output are at lower levels because fewer metabolic reactions are occurring. (c) Pulse rate decreases during rest as the demand for blood and oxygen by muscles is lower.

Determining the Correct Option

Since all the provided options, including rate of breathing, oxygen intake and carbon dioxide output, and pulse rate, reflect the body's minimal metabolic needs during rest, the answer that indicates rest is the one that combines all of these factors.

Key concepts

Rate of Breathing

The rate of breathing is a clear indicator of the body's metabolic activity. During periods of rest, the body's demand for energy is at its lowest, which is reflected in a slower breathing rate.

When we’re actively involved in physical activities, our muscles demand more oxygen to produce energy, causing us to breathe more rapidly. Conversely, in a relaxed state, our body conserves energy, resulting in slower and deeper breaths. This reduced rate of breathing helps to maintain ideal levels of oxygen and carbon dioxide in the bloodstream while minimizing energy expenditure, aligning perfectly with the basal metabolic rate (BMR) during rest.

Oxygen (O2) Intake and Carbon Dioxide (CO2) Output

The balance of oxygen intake and carbon dioxide output is another essential element that mirrors the basal metabolic rate. Oxygen plays a crucial role in the process of cellular respiration, where it is used to break down nutrients, providing energy for the body.

In the tranquil state of rest, the body's metabolic reactions occur at a slower pace, conforming to the minimal energy requirements. Hence, oxygen consumption decreases, subsequently leading to a reduction in the production of carbon dioxide, the by-product of cellular respiration. This decrease in the exchange of gases is a direct correspondence with the body's decreased metabolic necessities and is a valuable indicator of BMR.

Pulse Rate

Pulse rate, or the number of heartbeats per minute, is intimately connected with the body's metabolic needs and energy expenditure. At rest, our body needs less oxygen and nutrients, which is reflected in a slower pulse rate.

Each heartbeat pumps a specific amount of blood, transporting oxygen and nutrients to the tissues and organs. When the demand for these resources drops during restful periods, the heart can work less strenuously, reducing not only the frequency of beats but also the body's overall energy demands. This relaxation of the cardiovascular system is indicative of a low basal metabolic rate and is key for preserving the body's energy reserves for times when they are more urgently needed.