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Physiology for Engineers > Lecture 3: Diving 3 > Flashcards

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
Q

What is thermal radiation in terms of animals and the environment?

A

receives heat from sun and surrounding objects
* Animal also emits heat by thermal radiation to surrounding objects

26
Q

What is the pilomotor response?

A

contraction or relaxation of muscle at base of hair causes erection or compression of hairs to trap or release air, affecting heat transfer

27
Q

What is vasomotor response in blood vessels?

A

constriction of arterioles to preserve heat; vasodilation of superficial veins to release heat

28
Q

What are a few thermoregulation adaptations important for diving homeotherms?

A
  • Integument modifications
  • Restriction of body surface area
  • Circulatory adjustments
  • Metabolism
  • Respiratory modifications
29
Q

Explain how cetaceans have improved insulation.

A

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
Q

Explain how pinnipeds have improved insulation.

A

fur and thick layer of
subcutaneous fat
- e.g. sea otter has thick fur coat that traps air

30
Q

Explain how cetaceans have improved body surface area.

A
  • 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
Q

Explain the circulatory adaptations of cetaceans.

A

-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
Q

Why are circulatory adjustments important for cetaceans?

A

Important in heat conservation because most
ocean water (even in tropics) is colder at depth

32
Q

How do mammals keep appendage tissues cool?

A

countercurrent heat exchange

32
Q

How do the arteries in dolphins react to heat?

A

Venous blood returns to heart via superficial veins which lose heat to environment

33
Q

How do the arteries in dolphins react to the cold?

A

Venous blood returns to heart via vessels that are wrapped around arteries, transferring heat from artery to vein, conserving body heat

34
Q

True/False: Cetaceans can also overheat during prolonged
fast swimming, in warm water or if the animal is
out of water

A

True

35
Q

What does overheating do to the body of cetaceans?

A

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
Q

True/False: A cetacean’s metabolism decreases during dive

A

True

37
Q

True/False: In general, marine mammals have higher
metabolic rates than land animals of similar size

A

True

38
Q

Why do marine mammals have higher metabolic rates than land animals of similar size?

A
  • High protein diet (dolphins eat few carbs)
  • Thermoregulation  increased heat production
39
Q

Explain the respiratory modifications of marine mammals.

A

Marine mammals breathe less frequently which
conserves considerable heat
 Land animals lose 10-30% body heat in pulmonary
ventilation

40
Q
A

Physiology for Engineers (15 decks)

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