Lecture 2: Diving 2 Flashcards
What are the 4 adaptions that aquatic animals (cetaceans) have for deep diving?
- Flexible thorax (chest)
- Large distensible veins, venous sinuses, rete mirabile
- Large Lungs
- Resilient trachea (windpipe) and bronchi
Explain what happens when a cetacean dives deep (anatomically)?
as pressure increases during a dive, the lungs are compressed to collapsing point, and air escapes into rigid air spaces (bronchi and trachea)
What is the role of lungs for cetaceans during a dive (how do they work: 3)?
Provides stretch on inspiration (sponge-like rubber band)
They almost completely empty lungs using elastic recoil of
inflated lungs and diaphragm
On expiration, allow lungs to become atelectatic without
pulling from the thoracic wall
What does atelectatic mean?
collapsed alveoli (collapsed lung)
What is the function of Alveoli?
The site of gas exchange in the lungs
What is the general comparison between the lung mass as a percent of body mass of a terrestrial mammal vs a Phocoenidae?
Terrestrial Mammals is around 1% while Phocoenidae is around 3%
What is apnea in cetaceans?
– temporary cessation of breathing during dive
What does explosive ventilation in cetaceans do?
allows for greater total lung
volume exchange
What is the role of the distensible veins, venous sinuses and rete mirabile in a cetacean?
They are larger and Fill with blood as respiratory air is compressed during a dive and as the thorax (chest) collapses
“At the same time, blood squeezed out of the thorax is mostly shifted to the huge rete mirabiles of the vertebral column and spinal cord, from where originate the vertebral vessels that supply the brain”
What is the Rete Mirabilia?
a networks of arteriovenous shunts in the head and thorax
What does the Rete Mirabilia do for cetaceans?
Store blood while diving
Fill space in head and thorax as air is compressed during a dive
How do larger lungs affect cetaceans ability to dive compared to humans?
“Dolphins can replace as much as 95 percent of the air in their lungs in a single breath” “For comparison, humans are capable of replacing only as much as 65 percent”
What are chuffs?
When dolphins breath really hard
What is the comparison of dolphins vs humans moving air?
Dolphins move air two to three times faster than humans could
What is the role of a resilient trachea (windpipe) and bronchi (airways) for cetaceans (3)?
Allow lower respiratory passages to collapse
Cartilage lines trachea and upper airway (stiff)
Dead space (no gas exchange), holds air during dive
What the common name from trachea?
windpipe
What is the common name for bronchi?
airway
Overall, what do the 4 adaptations that cetaceans have do for them when diving to avoid the bends?
Allows air to be compressed away from alveoli in the lungs during increased pressure during a dive. It also prevents gas exchange and nitrogen from entering blood