eli5 (possible nsfw), but why do nipples get hard when people get cold?

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optionally, same thing of why the shrinkage happens in the cold. why do people shrink overall in the cold?

In: Biology

3 Answers

Anonymous 0 Comments

When we get cold, it starts a negative feedback loop in our bodies that tries to warm us back up. One of the big ways our body does this is through muscle contraction. Our muscles tighten, using energy to generate heat. It’s the same reason you shiver. When the muscles around the nipple contract, they also tighten their pull on the nipple, causing it to get harder.

To answer your second question, things seem to “shrink” on the body when it gets cold because they are again trying to gain heat. Your internal body temperature is ~98 degrees F (~37 degrees C), so the “shrinking” is really just trying to get more parts of you closer to this warmth. Evolutionarily, there’s not much reason to risk frostbite or other cold-related issues for the slim chance of reproduction while freezing, so we evolved to stay warmer at the small cost of “shrinkage” when cold.

Anonymous 0 Comments

Your nipples are made up of dense connective tissue that is surrounded by a cushion of blood. When you get cold, the blood vessels in your skin contract, which reduces blood flow to your skin – including to your nipples.

With less blood in your nipples, you lose that cushioning effect that the blood was providing. This causes your skin to shrink around the dense connective tissue and the nipple appears to both shrink and get harder. The reality is that connective tissue was always there, you just couldn’t feel it before because of all the blood around it.

Anonymous 0 Comments

Can you show a Pic of what you mean?