Describe the role of energy in the body and the physiology of three named body systems in relation to energy metabolism

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Michaela O’Connor                                                                                                                  unit 5 P4, M1

Describe the role of energy in the body and the physiology of three named body systems in relation to energy metabolism (p4)

Explain the physiology of three named body systems in relation to energy metabolism (m1)


In this assignment I will describe how energy works in the body and why we need energy. I will also link this to the three body systems relating to energy. The three body systems I will be discussing:

  1. Respiratory
  2. Digestive
  3. Cardiovascular

What is Energy?

Energy is made up of glucose + oxygen, ATP and ADP (adenosine triphosphate). Energy is measured in kilojoules or calories.

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There are three sources of  (ATP), the body's main energy source on the cellular level.

  1. ATP-PC system (phosphogen system) this system is used for very short durations of up to 10 seconds. The ATP system doesn’t use oxygen and doesn’t produce lactic acid. This is the primary system behind very short, powerful movements. For example power lifting, golf swing.
  2. Anaerobic system (lactic acid system) the anaerobic supplies energy for exercise lasting less than 2 minutes. This system is also known as the glycolytic system. This system would be used for activities such as a 400m sprint.

  1. Aerobic system- this is a long duration of energy system. Doing 5 minutes of exercise the O² system is the main functioning system. For example a 1km run, the system will be providing half the energy.

“Glycolysis - The first stage is known as glycolysis, which produces 2 ATP molecules, a reduced molecule of NAD (NADH), and 2 private molecules which move on to the next stage - the Krebs cycle. Glycolysis takes place in the cytoplasm of normal body cells, or the sarcoplasm of muscle cells.

The Krebs Cycle - This is the second stage, and the products of this stage of the aerobic system are a net production of 1 ATP, 1  Molecule, three reduced NAD molecules, 1 reduced FAD molecule (The molecules of NAD and FAD mentioned here are electron carriers, and if they are said to be reduced, this means that they have had a H+ ion added to them). The things produced here are for each turn of the Krebs cycle. The Krebs cycle turns twice for each molecule of glucose that passes through the aerobic system - as 2  molecules enter the Krebs cycle. In order for the Private molecules to enter the Krebs cycle they must be converted to Acetyl Coenzyme A. During this link reaction, for each molecule of private that gets converted to Acetyl Coenzyme A, an NAD is also reduced. This stage of the aerobic system takes place in the matrix of the cells' mitochondria.

Oxidative Phosphorylation - This is the last stage of the aerobic system and produces the largest yield of ATP out of all the stages - a total of 34 ATP molecules. It is called 'Oxidative Phosphorylation' because oxygen is the final acceptor of the  and  that leave this stage of aerobic respiration (hence oxidative) and ADP gets phosphorylated (an extra phosphate gets added) to form ATP (hence phosphorylation).”

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Types of energy:

  • Chemical
  • Radiant
  • Sound
  • Nuclear
  • Electro-magnet

The role of energy

Our body requires energy for all functions, movement, reproduction and respiration. Energy assists us in everyday life by helping us to exercise, cook and clean.

How we get/ make the energy metabolism

The human body consumes energy through food. The food is measured in units either kilojoules or calories. Energy is used in the body in three different ways:

  • Basal metabolism- energy required to keep the body functioning at a reasonable level.
  • Physical activity
  • Thermogenesis- ...

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The essay sets out to explain the role of energy in the human body - where the body obtains its energy supply from and what activities the energy is required for. The writer partially succeeds in this aim, giving insights into respiration - the process which supplies energy in the form of ATP. The essay explains the role of three body systems in enabling all cells in the body to carry out respiration. However, the title of the essay specifies 'energy metabolism'. This encompasses not only the release of energy from glucose (respiration) but also the roles of ATP in the body, i.e. for what purposes does the body need energy? Little mention was made of work - those cellular activities which require energy (ATP). The writer tends to provide the reader with too much information on the three selected systems, much of which is not relevant to energy metabolism. This topic needed a sequential approach to the energy 'story', starting with a clear definition of energy metabolism (both anabolism and catabolism); then looking at how cells acquire their oxygen and glucose to respire; and finally, an account of work in the body, i.e. the uses of ATP to run energy-requiring processes.