why can humans hold their breath longer underwater than above water?
In: Biology
You can fit a bit more air in your lungs since your chest is under water when you’re floating at the surface. What’s more, you can hyper inflate your lungs slightly, which normally would cause chest discomfort, but if you immediately dive down to higher water pressure, it will compress your chest and relieve that discomfort.
mammals have a thing called the mammalian dive reflex. when specific places on our face detect being cold and wet (like how they would be if your face was under water, your body enters dive mode.
one of the side effects is a reduced urge to breathe
Because you’ll die if you don’t. Your body has an amazing ability to keep you alive, and will give you an extra boost when it needs to.
It’s like Fight or Flight.
The Mammalian Dive Reflex diverts oxygen flow away from certain non-essential organs, giving priority to the brain and heart. Your spleen holds a reserve of extra red blood cells, normally to slowly replace cells as they get worn out or in case of blood loss. During the dive reflex, your spleen releases those extra red cells to more efficiently carry around the oxygen you’re holding in your lungs. Your heart rate slows down and your blood vessels restrict flow. Altogether, your body uses less oxygen and moves oxygen more efficiently.
When we’re underwater, a reflex called the mammalian dive response is triggered, which slows our heart rate and directs blood flow to vital organs. This conserves oxygen, allowing us to hold our breath longer than on land. On land, we don’t trigger that same reflex, so our body’s urge to breathe kicks in sooner.
I’m a surfer, I think I’ve got like 58 years in the water? If I can’t hold my breath underwater I’m going to die. I’m smart enough not to put myself in those situations anymore but Jesus christ, I could tell you some stories.
We tested the dive reflex in our university marine biology class. Took base line BP/pulse and then submerged our heads in buckets of ice water and recorded how our BP/pulse changed.
Is this really a universal thing? I’m pretty sure I can hold my breath above water for quite a bit longer than underwater.
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