There are 5 methods on how the energy is used in the human body like
1. Physical exertion
2. Mental exertion
3. Physiological functions of the body
4. metabolic reactions.
5. The energy lost by heat dissipation.
Energy is a critical requirement for the body that it doesn’t survive even a minute without it.
Hence, the cyanide pill used for suicide is so effective in causing death. It causes rapid energy failure (by mitochondrial enzyme arrest), leading to immediate death.
Even during sleep, huge amounts of energy are consumed by the body.
But unlike animals, the human body requires more energy as its needs and activities are more.
Before we detail how energy is used in the human body, You need to see how the body’s energy is produced in the human body.
There are four methods by which energy in the body is spent.
1. Mechanical energy
2. Electrical energy (nerves and muscles)
3. Heat energy.
4. Radiation energy.
These four types of energies are mostly spent as chemical energy derived from food as adenosine triphosphate (ATP).
It is produced by the biological oxidation of carbohydrates in the presence of oxygen.
See→ How food is converted to energy in the body.
From this chemical energy, electric energy is formed in nerves to conduct signals with electric speed.
And also, heat energy is formed in the muscles to maintain body temperature.
Radiation energy is the one we feel as an aura around us. Even you can notice someone when they stand very close to you due to this radiation energy.
How is Energy Used in the Human Body
Physical exertion
This is how most of the body’s energy is spent in living animals and humans beings.
This is done due to the intention to move, perform, or work. This may not be seen in plants as they do not move.
The body energy is also consumed for muscle contractions and relaxation.
We see this during walking, running, lifting, jumping, talking, shouting, etc.
Further body language also consumes energy.
So you can notice that when you are hungry, your body language will be low and ineffective.
Mental exertion
This is the next way how energy is used in higher animals like humans.
A good amount of energy is consumed for thinking, learning, memorizing.
Hence during the heartbeat, at least 20% of the blood pumped from the heart goes directly into the brain.
This brain is a high-energy-demanding organ, so it requires more glucose and oxygen from the blood.
Besides, anxiety and other behavior-related functions need energy.
Hence under stress, you can notice eating more will reduce stress.
So the Body first tries to fill up this energy need more than other energy needs.
Even animals do some brain and behavioral activity but low, unlike humans.
Physiological functions
- All the physiological functions in the body need energy.
- These include heartbeat, blood flow, breath (inspiration & expiration), digestion, intestinal contractions, etc. require a constant supply of energy.
- These are involuntary in nature without the intention of the animals.
- But are always active and energy demanding.
- The body energy is mostly used up due to smooth muscle contractions in the gut, blood vessels, lungs.
- The cardiac muscle in the heart is even more active and high energy is demanding.
Also, blood vessels carry blood to the corners of the body and are brought back by veins by contractions and relaxations.
Body metabolic and synthetic reactions
- Most of the body cell reactions like the formation of proteins (translation), multiplication of genes, the formation of genes demand energy.
- Also, transport of salts, nutrients across the cell membrane, degradation of toxic waste (metabolism) require energy.
- Further enzymes are the key factors involved in the above reactions.
- These enzymes perform only at body temperature.
So the body tries to maintain heat at a constant by heat generation.
Energy wastage
- The body energy formed is quite valuable, but still, it is lost.
- Here the energy is dissipated from the body in the form of heat.
- The body tries to maintain a constant fixed temperature to keep up the physiology.
- This temperature is generated by burning calories in muscles.
- During cold weather or atmospheric temperature, the body loses heat.
- So you can remember during winter you will feel more hungry and crave food.
- Also, energy is lost when the material goes out of the body.
- This we prominently see during breathing, hot air goes out and fresh air comes in.
- Also to some extent heat is lost due to urination, bowel evacuation.
So the energy formed is thus used up in four ways and lost in one way.
