NT

Dietary Energy and Cellular Respiration Summary

Energy Use in the Body

  • The body utilizes energy from food through biochemical processes, primarily aerobic respiration, which extracts energy in the presence of oxygen.

  • Fermentation occurs in the absence of oxygen, but it cannot support human life long-term due to lower ATP yield.

Obesity

  • Defined as an unhealthy amount of body fat, with nearly 40% of U.S. adults classified as obese as of 2019.

  • Caused by chronic energy imbalance: excess energy intake compared to expenditure.

Measuring Energy

  • Food energy is measured in calories (lowercase) and Calories (uppercase, equivalent to 1 kilocalorie).

  • Different macromolecules provide varying energy: fats (9 C/g), proteins & carbohydrates (4 C/g).

Energy Use and Balance

  • A balanced intake and expenditure of calories is crucial for maintaining healthy weight.

  • Factors affecting energy expenditure include genetics, muscle mass, and gender.

Nonexercise Activity Thermogenesis (NEAT)

  • NEAT encompasses movement during daily activities. Increasing NEAT can mitigate weight gain from excess calorie intake.

Cellular Energy Extraction

  • Energy from food is converted into ATP, the cell's energy currency, during aerobic respiration.

  • This process consists of glycolysis, the citric acid cycle, and the electron transport chain.

Aerobic vs. Anaerobic Respiration

  • Aerobic respiration requires oxygen and produces substantial ATP, while anaerobic respiration (fermentation) occurs without oxygen and yields less.

Storage of Excess Energy

  • Excess calories are stored as glycogen (short-term) in muscles/liver or triglycerides (long-term) in fat cells.

Cycle of Photosynthesis and Respiration

  • Photosynthesis produces glucose and oxygen, utilized in aerobic respiration, creating a cyclical flow of energy.