Goosebumps

You get these little bumps on your skin when you’re cold or when you feel any strong emotion, such as fear. But how does our body produce these bumps and why? And why are they called goosebumps?

What are Goosebumps?

Goosebumps, also called cutis ancerina (which is the Latin translation of ‘the skin of the goose’), are the bumps that result from the erection of the hairs in our skin. It is an involuntary, or uncontrollable, response to cold temperatures or strong emotions.

How do we get them?

Last week, we talked about the four components of hair: the follicle, the shaft and the inner and outer sheaths. Each of  your hairs’ outer sheaths, which encompass the follicle and the inner sheath, are surrounded by fibrous layers that attach to smooth muscles known as erector pili. These muscle are stimulated by the autonomic nervous system, which is the division of our nervous system that works with our conscious effort. The involuntary muscle reflex that causes goosebumps is referred to as the pilomotor reflex.

When we’re in cold environments, our thermoreceptors signal to our brain that our body temperature is decreasing. This triggers the release of the hormone epinephrine (aka adrenaline), which targets these erector pili and causes them to contract. The contraction of these muscles causes our hairs to stand erect, which is also the cause of the bumps. In fact, erector pili literally translates to ‘a thing that erects hair’. See, scientific names aren’t that random at all!

If you recall from that first post I did about anxiety, epinephrine is also released when one feels anxious. When this feeling is so strong that it promotes the release of a large amount of epinephrine, it can trigger the contraction of the erector pili in our skin, causing goosebumps. The same can be said for when you’re frightened, since the body mechanisms for anxiety and fear are similar.

Okay… but why do we get goosebumps?

Goosebumps are more helpful to animals than they are for us. That being said, goosebumps aren’t a total waste of energy for our bodies.

It’s believed that the formation of goosebumps is a phenomenon that we inherited from our primal ancestors (for those who don’t believe in Evolution, their theory is still applicable to humans, don’t worry!).

You see, we’re hairy mammals and our hair allows us to retain some heat, somewhat like a natural blanket. There is also a layer of air that surrounds our bodies that can serve as an insulator for heat. Now, in the case of the evolutionist theory, our primal ancestors had a lot more hair than we do; thus, they had a better blanket and more warmth. So, when they were in cold environments, their hairs would stand up (much like ours). These raised hairs causes the insulating air layer to expand, allowing your body to retain more heat. In other words, the expansion of this layer of air due to your raised hairs decreases the amount of heat that you lose to the cold environment.

This theory can also be applied to us; however, we don’t have as much hair as the primal ancestors in the evolutionist theory. This means our ability to retain heat isn’t as efficient since the layer of insulating air wouldn’t be consistent due to the visible gaps between our hairs. But it can still be argued that goosebumps do try to help us stay warm!

A reason for animals to have goosebumps can also be related to their predator-prey relationships. If a prey were to experience goosebumps upon seeing their predator (due to fear usually), their fur would make them seem bigger than they actually are since the hairs would be standing out. This would give them a better chance at intimidating the predator, which in turn means that they have a slightly better chance at surviving the encounter.

Why are they called ‘Goosebumps’?

Have you ever plucked a goose? Or a duck? Or seen a frozen chicken in the grocery store with its skin still on? They all have bumps on their skin after having been plucked which look like the bumps we get! So that partially explains the name…

But why not call it ‘Duck-bumps’ or ‘Chicken-bumps’ (which would make sense in terms of fear)? It really all has to do with which bird has been domesticated at the time the term was coined. For the English, Germans, Polish, Russians and others, geese had been domesticated. For the Spanish, they coined the term ‘piel de gallina’ which translates to ‘the skin of the hen’. The Japanese term is torihada, which literally means ‘bird skin’. So really, the term varies for different languages and cultures.

So now you know what goosebumps are, how we get them, why we get them and why we call them goosebumps! And now you know that you can start calling them ‘duck-bumps’ without being wrong… That being said, I can’t promise you won’t get any strange looks.

Bubenik, G.A. 2003. Why do humans get “goosebumps” when they are cold, or under other circumstances? ScientificAmerican.com. <http://www.scientificamerican.com/article.cfm?id=why-do-humans-get-goosebu>. August 15th, 2013.

Parker, A. 2010. Five things you probably didn’t know about your body. TorontoSun.com. <http://blogs.canoe.ca/parker/general/five-things-you-probably-don%E2%80%99t-know-about-your-body/>. August 15th, 2013.

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Shivering

We’ve explored one of the things our bodies do when they experience high temperatures, but what about when we get cold? When we’re outside in the blistering cold, we tend to shiver without control. But why do we shiver and how does it work?

Why do we shiver?

Shivering is our body’s mechanism of returning the body temperature to 98.6° Fahrenheit/37° Celsius from a lower temperature. Shivering increases your body temperature and attempts to prevent you from going into a state of hypothermia.

Shivering is basically our muscles contracting rapidly to generate heat.

How do we shiver?

We have thermoreceptors, little structures in our skin that detect temperatures, that relay a signal via the nervous system to a part of our brain, called the hypothalamus. This sends a different signal, using the nervous system, to our skeletal muscles (especially those that surround our vital organs) and tell them to contract rapidly. This causes an increase in heat production (up to 18x greater than usual!).

Your teeth chatter when you’re really cold for this reason; the muscles in your jaw are contracting.

Seeley, R.R., Stevens, T.D., and Tate, P. 2008. Anatomy and Physiology (8th ed.). pp. 307, 1012. New York: McGraw-Hill.

Sweat

We start to sweat when we exercise, or when we’re anxious because we get really warm. But why and how do we sweat? And what’s in our sweat? As gross as we think sweating may be, it’s important for our bodies to maintain its regular temperature.

Why do we sweat?

Sweating is a mechanism that our bodies use in an attempt to cool us down when it feels too warms (when our body temperature goes over 98.6° Fahrenheit/37° Celsius). If we didn’t sweat, we wouldn’t be able to cope with high temperatures in the environment or created by our bodies.

The sweat that we release via our sweat glands when we’re warm spreads across the surface of our skin and evaporates, which in turn allows the skin to cool; the evaporation of sweat generates a breeze-like effect.

How do we sweat?

We have little structures in our skin called thermoreceptors that allow us to detect changes in temperature. These thermoreceptors are found at the end of nerves. These thermoreceptors will detect a change in the temperature of our bodies and convey this message to the hypothalamus, which is the part of the brain that controls the sweat glands. The hypothalamus then sends a signal to the sweat glands, via the nervous system, to produce sweat in an effort to bring the body temperature back to 98.6°F/37°C.

We have two different types of sweat glands in our bodies, eccrine (aka merocrine) and apocrine. Apocrine sweat glands don’t partake in the cooling of the body. Eccrine sweat glands are found in our skin, including our palms and the soles of our feet. They open directly onto our skin’s surface through sweat pores. These glands, in addition to releasing sweat, also produce the sweat when the hypothalamus sends a signal through the nervous system!

What’s in our sweat?

Sweat consists of a lot of water, some salts and extremely small amounts of waste products. These waste products, urea, uric acid & ammonia, are also components of our urine. Hence the justification to saying ‘Pee-You!’ when someone sweaty walks by; they literally have a tiny bit of pee on them.

Seeley, R.R., Stevens, T.D., and Tate, P. 2008. Anatomy and Physiology (8th ed.). pp. 162, 164-165, 1012. New York: McGraw-Hill.