Energy, Work, and Power of the Body

Flashcards covering key vocabulary and concepts related to energy, work, and power in the human body.

Energy Converter

The body is considered to be an energy converter, where activities like thinking involve energy changes.

Body's Energy Source

Food is the body’s basic energy source, converted chemically into molecules to operate organs and maintain temperature.

Conservation of Energy

The conservation of energy in the body can be described as: Change in stored energy = Heat lost from the body + Work done

First Law of Thermodynamics

The first law of thermodynamics equation is: ΔU = ΔQ + ΔW, where ΔU is the change in stored energy, ΔQ is the heat lost or gained, and ΔW is the work done by the body.

Units of Energy

The units of energy changes in the body are joule or calorie.

Metabolic Rate

The rate of oxidation within the body is called the metabolic rate.

Respiratory Quotient (R)

The ratio of moles of CO2 produced to moles of O2 used.

Basal Metabolic Rate (BMR)

The lowest rate of energy consumption when the body is completely at rest.

Factors Affecting BMR

BMR is affected by factors that increase metabolic activity, such as fever and muscular activity.

Kilocalorie in Metabolism

In metabolism, the heat unit used is the kilocalorie (kcal), which equals 1000 calories.

Typical Metabolic Rate

The metabolic rate for most people is typically between 50 and 70 kcal/h.

Energy Expenditure

Energy expenditure includes basal metabolism, the energy of food ingestion, and muscular activity.

Work Output

Work output is zero when forces within the body do not cause displacement of the body or external objects.

Body Efficiency

The maximum body efficiency is about 20%, similar to that of a petrol engine.

Heat Losses in the Body

The body loses heat through radiation, conduction, convection, and evaporation.

Temperature Difference in Heat Loss

The rate of heat loss in the body is roughly proportional to the temperature difference between the body and the environment.

Evaporation as a Cooling Mechanism

Evaporation of perspiration is a crucial cooling mechanism, especially at high temperatures.