Energy. Flashcards
Why is energy needed in the body?
Every function and process in the body requires a source of energy.
All energy is initially supplied by food and is then what happens afterwards?
All energy is initially supplied by food, and released for use in the body after digestion and absorption.
What are the four uses of energy in the body?
- Mechanical energy.
- Chemical energy.
- Heat energy.
- Electrical energy.
Give an example of mechanical energy.
For the movement of muscles (voluntary and involuntary).
Give an example of chemical energy.
For all chemical and metabolic reactions.
Give an example of heat energy.
To maintain body temperature.
Give an example of electrical energy.
For the transmission of nervous impulses.
What are the three main nutrients that supply energy?
There are three primary nutrients that supply energy - protein, fat, and carbohydrates.
Of the three main nutrients that supply energy, which one provide the most concentrated source of energy?
Of these three fat provides the most concentrated source of energy.
Give examples of the most energy dense foods.
- Fats - lard, butter, margarine, suet.
- Oils - vegetable/plant, nut.
- Fatty foods - egg yolk, cheese, cream, bacon.
- Others - sugar, cereals, cereal products and starchy vegetables.
Energy is released in a reaction between glucose and oxygen which takes place in all body cells. The reaction produces energy, CO2, and H2O as by-products.
Give the equation of this statement.
Glucose + Oxygen → energy + carbon dioxide + water.
Glucose + Oxygen → energy + carbon dioxide + water. What does this reaction where energy is produced require?
This reaction where energy is produced requires B Vitamins; Phosphorus; and lodine.
What happens during energy release?
- Glucose from food is digested and goes into the bloodstream.
- Oxygen is breathed into the lungs, then goes into the bloodstream, then attaches to the hemoglobin in red blood cells.
- Hemoglobin contains iron which is important to transport oxygen and energy release.
Not all glucose is converted to energy. What
- Some are stored as GLYCOGEN in the liver and muscles (energy from glycogen can be released quickly e.g. to run a race).
- Some as fat in the adipose tissue under the skin (energy stored as fat is released slowly e.g. in times of famine).
Energy is measured in kilocalories (kcal) or kilojoules (kj). How many kilojoules in one kilocalorie?
1kcal = 4.2kj.
How many kilocalories and kilojoules in:
- 1 gram of protein.
- 1 gram of fat.
- 1 gram of carbohydrate.
- 1g of protein = 4kcal or 17kj.
- 1g of fat = 9kcal or 38 kj.
- 1g of carbohydrate = 3.75kcal or 16kj.
The amount of energy used by the body is called energy expenditure. This varies widely according to the: 5 reasons.
- Age.
- Sex.
- Occupation.
- Physical activity.
- State of the body e.g. pregnancy, illness.
Give one group which require more energy because of age and why?
Young children need more energy as they are growing rapidly and tend to be very active.
Which gender requires more energy and why?
Men tend to be larger in body size so they have a higher
metabolism.
Give examples and reasons of occupation that requires less energy and those that require more energy.
Office workers, pilots, and architects (sedentary) require less energy than manual workers, army workers, and athletes (moderately/very active) who require more energy.
Give three states of the body that require more energy.
extra energy is required in pregnancy for the growth of the baby, lactating mothers require extra energy for the production of milk. Those that are ill require less energy as their metabolism may be decreased.
At least half of the energy released in the body is used for basal metabolism (resting metabolism).
Define Basal Metabolic Rate (B.M.R).
This is the amount of energy that is required to keep the body alive when it is at complete rest and warm.
What is the basal metabolism used for?
It is used to keep the heart, lungs, and digestive system moving.
The rest of the energy is used by the muscles and to maintain posture.
In what case is excess energy stored in the body as fat?
If the energy intake of food exceeds the amount of energy required, then the excess is stored in the body as fat.
This is one of the major causes of obesity.
