Why Do We Shiver?

Why Do We Shiver

Have you ever wondered why we shiver in cold weather? Not just the sensation of shivering but also the chattering of teeth and your body’s twitching state after every little while?

Primarily, this happens due to the sudden drop in temperature in your external environment. Just like our bodies sweat in summers to cool off and maintain their temperature, they tend to shiver and constrict their blood vessels in winters to warm up a little.

Sounds simple, doesn’t it? But do you know what exactly goes on in your body while you are shivering? And what is the real cause behind this whole process?

In simpler words, shivering is an adaptation that our bodies undergo to increase their temperature in case of drastic temperature changes in your external environment.

There are mainly two types of organisms – one that we know as the endotherms or the warm-blooded animals and cold-blooded ectotherms.

Do you know why endotherms are warm-blooded animals?

 It is because endotherms can constantly regulate their body temperature within a narrow limit. Hence, their body temperature stays steady throughout.

On the other hand, if we talk about ectotherms, they have a vast range of fluctuating body temperature, which changes accordingly with the varying temperature of the external environment.

Endotherms mainly consist of human beings that have their body temperatures maintained within the range of 95-104 degrees Fahrenheit or 35-40 degrees Celsius. In summers, when your body temperature rises above 37 degrees celsius, you usually sweat to bring your body temperature back within its normal limits. Apart from sweating, vasodilation occurs as well to dissipate heat instead of accumulating it.

In contrast, your body temperature drops down in winters and becomes much lower than the required temperature range. In response, your body activates its homeostatic mechanism to bring the temperature back to its normal range.

 The regulatory mechanisms that help our body accumulate heat in winters are shivering, vasoconstriction, and brown fat burning. This fatty tissue produces heat to maintain the internal temperature, alongside the hormone Adrenaline.

When the temperature of your body drops or rises, some physiological changes are induced instantly to counteract it. These physiological changes are influenced by certain stimuli like an increase or decrease in the temperature of the external environment.

Did you know that maintaining your body temperature is integral to sustaining your normal body functions?  But how does the mechanism of maintaining temperature work in our bodies?

This process of maintaining the temperature of our body is known as thermoregulation. It allows the body to maintain its internal environment regardless of the external temperature.

There are several processes that our body undergoes for its thermoregulation. But firstly, let’s talk about the part of our body that is primarily responsible for the mechanism to occur.

This vital function of maintaining an optimum internal environment is controlled by a small part of your brain, known as the hypothalamus.

Now let’s look into all the factors which assist in shivering thermogenesis.

Shivering thermogenesis undoubtedly minimizes heat loss from our body by trapping the heat and accumulating it in cold weather. Shivering is most importantly a function that happens to maintain homeostasis in our internal environment. It generates heat and increases the metabolic rate up to 5-6x times more than the regular metabolic rate. Shivering is a muscular activity performed by your skeletal muscles.

Skeletal muscles are attached to our bones, and they help us generate heat. The heat generated increases your internal temperature and warms you up. During shivering thermogenesis, skeletal muscles contract and relax to produce movements which in turn increases metabolic rate.

Contraction of muscles is always initiated by a stimulus. In winters, the stimulus is a sudden drop in temperature in the environment. Stimulus is a sensation that prepares us for a particular reaction.

Although our body mainly uses the shivering mechanism to produce heat and combat the cold weather, the second process that further assists shivering thermogenesis is vasoconstriction.

Vasoconstriction is the decrease in the size of blood vessels. Less blood flows to the skin’s surface, and the heat, in turn, remains trapped in the body, increasing the body temperature.

Lastly, let’s look into the hormonal activity assisting in shivering thermogenesis!

It’s the hormone Adrenaline which deals with the fight and flight responses of our body. As the temperature of the external environment drops, Adrenaline is released. It burns the fatty tissues known as brown fat, therefore increasing our body’s temperature so that homeostasis is maintained.

However, it has to be carefully monitored by the hypothalamus since it is an involuntary action. A sudden increase in shivering thermogenesis can cause hyperthermia, which is an uncontrollable rise in the temperature that causes hormones to denature and can turn into a medical emergency.

Hyperthermia occurs due to the increased activity of skeletal muscles in our body, which stimulates overheating to the point that enzymes break down and the body’s normal metabolic function is interrupted.

Until Next Time,

Team Doctor ASKY!