Lecture 3: Diving 3 Flashcards

1
Q

How does blood redistribute during a dive?

A
  1. Diving Apnea (breath hold)
  2. Diving Bradycardia (slow HR) begins with a dive
  3. Peripheral vasoconstriction (resistance) occurs
    (blood vessels in non-vital areas constrict down)
  4. Dilatation in ascending aorta in cetaceans and
    pinnipeds (“Natural aneurysm”)
  5. Helps circulate blood during prolonged diastole (relaxation of heart) due to slow heart rate , maintaining blood pressure and distributing oxygenated blood during a dive
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2
Q

What is apnea?

A

breath hold

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3
Q

What is Bradycardia?

A

slow HR

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4
Q

What is peripheral vasoconstriction (general)?

A

blood vessels in non-vital areas constrict down

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5
Q

Explain what happens during peripheral vasoconstriction?

A
  • Appendages will have less blood circulation, while
    blood shunts to vital organs (e.g. brain, heart)
  • Decreased blood flow to muscles
  • Increased blood flow to brain and heart (vital organs)
  • Brain needs certain amount of glucose (sugar) and
    blood flow to survive
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6
Q

Explain some of the differences between an artery and a vein.

A

An artery has a thick outer wall, small lumen (tube), and thick media (smooth muscle).
A vein has a thin outer wall, large lumen, and thin media.

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7
Q

What are the different layers of skin going from inner to outer?

A

Muscle, subcutaneous tissue, dermis, epidermis

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8
Q

True/False: Plasma takes up the most volume in blood?

A

True

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9
Q

Explain how muscle myoglobin in marine mammals affects their metabolism.

A
  • Normally muscle has O2 supply for aerobic metabolism
  • Lack of O2 causes anaerobic metabolism
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10
Q

Are the muscles during a dive aerobic or anaerobic?

A

Not entirely anaerobic

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11
Q

What is an aerobic system?

A

Oxidation of foodstuffs in the mitochondria to provide energy; Glucose (sugar, carbs), Amino Acids (protein), Fatty Acids (fat) combine with oxygen to release ATP

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12
Q

What is an anaerobic system?

A

Energy from food without utilization of oxygen; Carbs are metabolized (stored glycogen in cells breaks down into pyruvic acid and ATP (E) ->lactic acid which diffuses out of cells – makes muscles burn – stay hydrated, good cool down

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13
Q

What are examples of aerobic excercise?

A

running, biking, swimming

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14
Q

What are examples of anaerobic excercise?

A

sprints, weightlifting, and HIT workouts

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15
Q

Explain what happens during the period of a dive (aerobic/anaerobic).

A

Most dives are aerobic, but throughout the latter
part (e.g. >20 minutes) of a prolonged dive, the
animal is in an almost completely anaerobic state

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16
Q

Explain how the brain can operate anaerobically.

A

Brain must operate with at least a partial decrease in
O2 consumption (brain can function anaerobically
for a period of time if enough glucose is available)

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17
Q

Why can diving mammals go longer anaerobically?

A

Healthy diving mammals have relatively high blood
glucose level and blood circulation is maintained
during latter part of dive, bringing glucose to brain

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18
Q

Explains what happens during a “natural aneurysm”?

A

Dilatation in ascending aorta in cetaceans and pinnipeds

19
Q

What is diastole?

A

relaxation of heart

20
Q

What is the function of the large posterior vena cava and venous sinuses during a dive?

A
  • Fill with blood, offering a large blood reservoir
  • May prevent fluid overload of heart during diving
  • Caval sphincter in vena cava at diaphragm interrupts
    blood flow through vena cava
  • May open periodically to allow bolus of blood to travel to
    heart
21
Q

What are the 4 methods of heat transfer between animal and environment?

A

Conduction, convection, evaporation, and thermal radiation

22
Q

What is conduction in terms of animals and the environment?

A

heat transfer through material that is macroscopically
motionless (e.g. ground)

23
Q

What is convection in terms of animals and the environment?

A

heat transfer through material by flow of the substance (e.g.
wind, water)

24
Q

What is evaporation in terms of animals and the environment?

A

lose heat/cool by evaporation
* Evaporation of sweat (if animal has sweat glands)
* Evaporation of water from respiratory tract (e.g. panting dog)

25
What is thermal radiation in terms of animals and the environment?
receives heat from sun and surrounding objects * Animal also emits heat by thermal radiation to surrounding objects
26
What is the pilomotor response?
contraction or relaxation of muscle at base of hair causes erection or compression of hairs to trap or release air, affecting heat transfer
27
What is vasomotor response in blood vessels?
constriction of arterioles to preserve heat; vasodilation of superficial veins to release heat
28
What are a few thermoregulation adaptations important for diving homeotherms?
- Integument modifications - Restriction of body surface area - Circulatory adjustments - Metabolism - Respiratory modifications
29
Explain how cetaceans have improved insulation.
Thick blubber layer (hypodermis) with fibrous tissue interspersed with a lot of fat - Reduces heat loss which saves energy - An energy reservoir during long periods without food
29
Explain how pinnipeds have improved insulation.
fur and thick layer of subcutaneous fat - e.g. sea otter has thick fur coat that traps air
30
Explain how cetaceans have improved body surface area.
- Decreased appendages and spindle-shaped body - Reduce total surface area to mass ratio - Decrease amount of exterior area to which blood is exposed - Therefore, both reduce heat radiation
30
Explain the circulatory adaptations of cetaceans.
-Countercurrent heat exchange in flipper, dorsal fin and flukes of cetaceans -Peripheral artery surrounded by many veins which returns heat to body core - Restriction of peripheral circulation keeps blood away from surface and conserves heat
31
Why are circulatory adjustments important for cetaceans?
Important in heat conservation because most ocean water (even in tropics) is colder at depth
32
How do mammals keep appendage tissues cool?
countercurrent heat exchange
32
How do the arteries in dolphins react to heat?
Venous blood returns to heart via superficial veins which lose heat to environment
33
How do the arteries in dolphins react to the cold?
Venous blood returns to heart via vessels that are wrapped around arteries, transferring heat from artery to vein, conserving body heat
34
True/False: Cetaceans can also overheat during prolonged fast swimming, in warm water or if the animal is out of water
True
35
What does overheating do to the body of cetaceans?
Overheating increases blood pressure and size of central artery in countercurrent heat exchange, closing peripheral veins, forcing blood to flow to superficial veins and dissipates heat - Example: for a beached marine mammal, apply water and sunscreen
36
True/False: A cetacean's metabolism decreases during dive
True
37
True/False: In general, marine mammals have higher metabolic rates than land animals of similar size
True
38
Why do marine mammals have higher metabolic rates than land animals of similar size?
- High protein diet (dolphins eat few carbs) - Thermoregulation  increased heat production
39
Explain the respiratory modifications of marine mammals.
Marine mammals breathe less frequently which conserves considerable heat  Land animals lose 10-30% body heat in pulmonary ventilation
40