How the Body Obtains and Uses Energy

Copyright 2010. PEER.tamu.edu

Discuss:

Are you an energetic person?

When do you have the most energy?

What do you do when you need to get more energy?

Energy

Energy is all around you!

You can hear energy as sound.

You can see energy as light.

And you can feel it as wind.

When do you use energy?

You use energy when you:

hit a softball.

lift your book bag.

grow.

study.

do any activity.

Why is energy important to our

bodies?Living organisms need energy

for their bodies’ daily activities and processes.

Try to Recall the

Six Forms of Energy

The six main forms of energy are:

Heat or Thermal

Chemical

Electromagnetic

Nuclear

Mechanical

Electrical

Our bodies use Chemical Energy

States of Energy

Potential Energy

Stored energy.

Energy that could be used.

Kinetic Energy

Energy of Action or Motion.

Energy that is being used.

There are two states in which energy can exist:

Energy Conversions or Transformations

Energy can be changed from one form or state into another. Changes in the forms or states of energy are called energy conversions or transformations.

Chemical Energy Mechanical and

Heat Energy

An Essential Energy Conversion

• Our body converts starches, sugars, fats and even proteins (chemical energy) that we eat into energy for our bodies’ daily functions (mechanical and heat or thermal energy).

How the Body Obtains Energy

First, you consume energy in the form of foods. Foods are made of organic molecules.

The organic compounds in foods that can be used for energy are:

Carbohydrates

Fats

Proteins

A Glucose (sugar)

Molecule

Molecules are held together by an energy force. Breaking the bonds between atoms in the molecules releases that energy.

Whether or not that bond energy does anything depends on whether it can be captured and "put to work."

The body's job is to break food down so that cells can break down some of the chemical bonds. Then that energy can be used to do things.

Any left-over energy escapes as heat.

Bond between atoms in the molecule.

C6H12O6

During the digestion process, how does the body

breaks down foods into smaller organic compounds?

Proteins are broken down chemically by pepsin in the stomach into amino acids.

Fats are broken down into fatty acids by bile from the liver in the small intestines.

Carbohydrates are broken down chemically into sugars (monosaccharides) by enzymes found in saliva in the mouth and by enzymes in the small intestine.

The teeth first break down the food physically into smaller pieces. The movement of the stomach and intestines also help physically break the food.

•These smaller molecules are transported into body cells and then go through several chemical processes that break the molecular bonds to produce ATP, a primary storage form and source of energy in the body.

•These chemical processes occur in the cytoplasm and mitochondria in the cells.

For more on energy use in the body please click here

Mitochondria

Cytoplasm

A mitochondrion is an oval bag that is filled with membranes.

Mitochondria are so small that you can only see them with the

high-power magnification of an electron micrograph.

An electron micrograph of a mitochondrion

Mitochondria, plural for mitochondrion, are the organelles that

cells use as their energy factories. Think of them as the cell's

way of recharging its battery.

An artist’s representation of a mitochondrion

Stop and Think:

What is an energy conversion or transformation?

What energy conversion is essential for the human body?

Summarize how humans get their energy from food. Be sure to include the structures in the body that are responsible for this process.

Calories

Calories are a unit of measurement of food energy. They measure the amount of potential heat energy contained in the chemical bonds of a food.

People need a certain amount of calories per day.

For the average teenage girl, the recommended daily allowance is 2200 calories. The average teenage boy

needs 2500-3000 calories.

Calories add up fast!

A large cheeseburger, fries, and a soda can add up to more than 1,390 calories.

That’s more than half of the calories that most teens need in one day! This is not a good deal for your body because this meal does not contain many of the other nutrients your body needs besides calories.

Our Energy Use Must be Balanced! The amount of energy that comes into

our body should be equal to the amount of energy that we use.

If it is not, we STORE the extra energy that is not used.

The main way the body stores excesss energy is in the form of fat.

Did I eat ALL of that?

Energy Imbalance Causes Problems

Obesity

A person has traditionally been considered to be obese if they are more than 20 percent over their ideal weight. That ideal weight must take into account the person's height, age, sex, and build.

If their Body Mass Index (BMI) is between 25 and 29.9 a person is considered overweight. If their BMI is 30 or over the person is considered obese.BMI Calculator

Obesity is a problem in

people and pets!

Childhood obesity has more than tripled in the past 30 years. The prevalence of obesity among adolescents aged 12 to 19 years increased from 5.0% to 18.1%.

An estimated 51.5% of dogs and cats in the United States are overweight or obese.

Common Health Risks of Obesity

Osteoarthritis

Type 2 Diabetes

Respiratory disorders

Hypertension (high blood pressure)

Heart Disease

Many Forms of Cancer

How to keep Energy Balanced:

The best way to balance your energy is to find out how much energy is used by the body each day and…..

Eat only enough calories to equal that amount of energy.

Energy Used in a Day

Energy Consumedin a Day

Special Considerations for Teens

Teens have a little higher energy requirement than adults.

Can you guess why?

The answer is that they are growing!

Growth requires energy and healthy nutrients from foods.

As a teen, you must choose wisely so you can reach your potential!

Can you recall?

What are calories?

How is extra energy stored in our bodies?

What are some risks associated with obesity?

What is meant by “energy balance” in the body?