Diving Physiology

Question 1

What contributes to buoyancy in seabirds?

Answer 1

Body density and trapped air

Question 2

How do diving birds overcome buoyancy

Answer 2

Birds fluctuate from positive to neutral to negative buoyancy

Question 3

What are some challenges that diving birds face?

Answer 3

• The viscosity and density of water compared to air
• Fueling activity with oxygen while not breathing

Question 4

How are penguins morphologically adapted for diving?

Answer 4

• Streamlined body shape
• Dense bones (not pneumatic)
• Webbed feet
• Specialized feathers
• Stiff wings with fused bones

Question 5

What happens to the diving duration of seabirds when body size increases?

Answer 5

The dive duration will increase (more oxygen capacity)

Question 6

Apnea

Answer 6

Holding your breath

Question 7

How do seabirds conserve oxygen during Apnea?

Answer 7

1. Increase their oxygen storage capacity
2. Bradycardia
3. Peripheral ischemia

Question 8

Bradycardia

Answer 8

Decrease in heart rate

Question 9

What are the affects of bradycardia

Answer 9

• Increased amount of oxygen storage capacity
• Decreased amount of oxygen consumption

Question 10

Peripheral ischemia

Answer 10

Reduced blood flow to the extremities

Question 11

Why are bird lungs more efficient than mammalian lungs?

Answer 11

There is no mixing of oxygen rich air and oxygen poor air (gas exchange is more efficient)

Question 12

What happens to the solubility of gasses as underwater pressures increase?

Answer 12

Solubility will increase

Question 13

Describe “the bends”

Answer 13

• As dive depths increase solubility of gases increase
• On Acension gas solubility decreases as pressure decreases
• Gasses dissolved in cells release in the form of bubbles
• End result is “the bends”

Question 14

What do marine mammals do to prevent “the bends”

Answer 14

• As pressure increases, the lungs will collapse
• Air moves into rigid structures
• Gasses do not get dissolved in the blood

Question 15

How do shallow diving seabirds deal with increased dive pressures?

Answer 15

1. The do not dive deep
   - Shallow dives = not enough dissolved gasses to cause “the bends”

Question 16

How do deep diving seabirds deal with increased dive pressures?

Answer 16

1. Severe bradycardia: reduction of cardiac output and gas uptake
2. Pressure induced reduction of gas
3. Increased capillary volumes: capillaries engorge in order to prevent gas exchange
4. Reduced respiratory air volume (take short breath of air before diving)

Question 17

Aerobic Dive Limit (ADL)

Answer 17

The maximum amount of breath that can be held without an increase in blood lactic acid concentration during or after a dive

Question 18

What affects ADL

Answer 18

• Stored oxygen reserves
• Oxygen consumption rates
• Degree of peripheral ischemia
• Rate of lactic acid production and consumption