Seals can dive deep for a long time because their peripheral airways are very strong that allows their lungs to collapse in the depth. Also, their heart rate decreases during diving that reduces the energy consumption as well.
Peripheral airways are very small in size with an average diameter of 2 mm. They comprise of the non-cartilaginous bronchioles and the alveolar duct.
Heart rate in simple words is defined as the number of time heart beats in a minute. The number varies from organism to organism. Every time the heart beats, it means that blood in pumped from the heart to the complete body. Heart rate can change according to the activity body performs. For example, during workout the body needs huge amount of oxygen hence the heart rate is higher.
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