7.2: The Need for Energy

• In this section you will:

• Learn about the metabolic requirements of your bodies in order to maintain homeostasis.

• Examine how individual internal temperature varies throughout the day.

• Consider factors that contribute to the rise and falls of temperature within their bodies.

• Compare energy release from the human body and the light bulb.

Homeostasis - any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival. 

In order for cells to function properly, conditions inside the cells must remain fairly constant. One example of how cells self-regulate is through regulation of body temperature. 

Mammal body temperatures are considerably higher than the environment around us. This higher temperature provides a higher metabolic rate, making it possible for high activity levels. These higher body temperatures are much easier to maintain then if it was lower than the surrounding environment. 

Have you ever wondered how cows could stay warm out in the middle of a field in the wintertime?

Cows have a layer of fat as well as hair that acts to insulate them from the weather. These layers prevent their bodies from allowing heat to escape. Another interesting fact about animals is they are able to shunt blood away from the blood vessels near the body surface. When they close these vessels, they are able to keep warm blood near the body core.

As we learned in the previous section cellular respiration increases thermal energy production. This explains why shivering is one way that the body tries to regulate the internal temperature. Shivering is an intense muscle activity that rapidly uses up ATP and thus stimulates more cellular respiration. When animals shunt blood away from the body surface and are able to shiver they are able to maintain their body temperatures better than humans. Unless we put a sweater on. 👘🤣 

When the body gets too warm, the body will sweat.  This water moves from the core to the surface of the skin and then evaporates.  The controlling of internal body temperature when hot can be different for other animals. For example, a dog will pant which allows the water to evaporate from their tongue, cooling the dog. Cold blooded animals do not have a fairly constant internal temperature. Instead, they get their heat from the outside environment. If it is 10°C outside, the cold-blooded animal will adjust to the outside environment by increasing or decreasing the temperature to be the same as its surroundings. 

How do bodies respond to extra thermal energy that is released by an increased number of chemical reactions occurring?

There is an increased breathing rate and sweat production. 

What happens when someone goes outside in the cold without a jacket on?

Arms and cheeks get red or pink as the body loses heat through the outer body parts. The body begins to shiver. 

Everyone has a unique basal metabolic rate. This means we all use energy at different rates and this changes throughout the day. We know that daily activities increase cells’ respiration rate. This includes both physical activity and stress. With this energy conversion, some energy is given off as thermal energy, thus increasing the internal temperature slightly. 

When there is a negative stimulus on our body’s temperature, our body will offset these large changes by inducing perspiration and the releasing of thermal energy from the capillaries close to the bodies surface. 

Have you noticed that we go to bed and we are generally warm, but in the morning, we are a bit cooler, even if the day is relatively warm. This is because our bodies have used the least amount of energy during our deep sleep periods, thus giving off less thermal energy from energy conversion. Our bodies internal core temperatures will drop slightly. 

Activity

1. Go to the Daily Temperature Changes assignment in Workspace. Work through each of the steps and questions. 

2. Submit when you have completed it. 

1. How do homeostasis and metabolism work together to keep an Organism alive?

2. List and explain four methods that an Organism, such as a cat, uses to stay warm on cooler days.

3. Many exercises on weight loss programs encourage speeding up an individual's metabolism. Explain how a person could lose weight by increasing their exercise routine.