CHapter 6: part 2

Question 1

What is the purpose of bursa of Fabricus?

Answer 1

• manufactures B-lymphocytes in birds
• lymphocytes are antibodies

Question 2

Describe importance of myoglobin

Answer 2

• offers oxygen in muscles for aerobic respiration
• allows certain animals to stay under water longer(aquatic birds)

Question 3

metabolic rate

Answer 3

Rate at which energy (ATP) is produced and used (because very little ATP is stored) from ingested or stored substrates

Usually measured (in the laboratory) as oxygen consumption

Question 4

basal metabolic rate

Answer 4

the amount of energy per unit of time needed to keep the body functioning at rest

Question 5

Mass-specific metabolic rate

Answer 5

the resting energy expenditure per unit body mass per day

Question 6

Describe the differences between basal and mass-specific metabolic rate

Answer 6

As body mass increases, the basal metabolic rate also increases

As a bird gains body mass, its mass‐specific metabolic rate decreases

Question 7

Describe daily energy budget in birds

Answer 7

• varies from existence metabolism, reproduction, and migration
• can have less energy during months before migration, has spike in metabolism and energy use in migration
• Metabolism and daily energy expenditures typically increase with body size

Question 8

Describe daily energy expenditures with body size

Answer 8

• flight metabolism varies from two to 25 times as high as basal metabolic rate
• Total daily energy expenditures do not increase as fast with increasing body size as does basal metabolism

Small birds are more active than large birds

Question 9

Describe aerobic scope of birds

Answer 9

Most birds have a greater aerobic scope, (ratio of active to resting metabolism) than do most mammals
- running birds are the exception, in most cases, not all, to fall under mammals

Question 10

What is the thermoneutral zone?

Answer 10

• a range of temperatures where a bird can maintain its normal expected body temperature without using energy above basal metabolic rate

Question 11

What are the upper and lower critical temperatures?

Answer 11

• lower is where shivering begins, pectoralis muscles produce heat this way
• upper is where evaporative cooling is used, big on heat loss

Question 12

When bird is below/above thermoneutral zone…

Answer 12

• below: increase heat production and/or decrease heat loss
• above: decrease heat production and/or increase heat loss

Question 13

How do birds insulate themselves

Answer 13

• plumage generally thicker in winter
• contour feathers can be thicker in colder habitats
• thick layer of down
• subcutaneous fat forms insulator layer only in few birds (penguins)

Question 14

Peripheral Vasoconstriction

Answer 14

• can create regional hypothermia: Regions of the body are maintained at temperatures lower than the body core
• restricts blood flow through certain areas of body, lets them become cold

Question 15

How do countercurrent heat exchangers conserve core temperature?

Answer 15

• Birds that swim in cold water or stand on ice minimize heat loss by allowing temperatures inside their feet to drop, nearly to ambient levels
• Cools blood flowing to the feet (artery),
  Heats blood as it returns to the body (vein)
• Steep temperature gradient reduces heat loss and saves a tremendous amount of energy

Question 16

Acclimatization

Answer 16

Changes in a bird’s physiology after it has been in a new environment for several days or weeks that allow it to function better in the new conditions

Question 17

Facultative Hypothermia

Answer 17

• body temp drops below normal

Daily cycles of hypothermia (mild or pronounced) may be tied to internal clocks

Also triggered on a day-to-day basis by food deprivation and low energy stores

Saves critical energy supplies

Question 18

Torpor

Answer 18

• A resting state in which the body temperature drops, metabolic processes slow, and reactions to external stimuli are slow or lacking
  (allows body temp. to reach closer to ambient(outside body temp.)
  More pronounced than facultative hypothermia
• example: purple throated warbler, common poorwill

Question 19

postural changes to deal with cold temps.

Answer 19

Ptiloerection: erecting feathers to trap heat

Question 20

Microclimate selection

Answer 20

• bushes, trees, under snow to stay warm in cold temps.

Question 21

Huddling

Answer 21

• provides thermoregulation, cycle of huddling in middle vs. outwards
• ex: penguins

Question 22

Food caching

Answer 22

• food storage for when the body needs it in the cold, have to remember location and access

Question 23

Adaptations to heat in body size/location

Answer 23

• smaller struggle to stay warm, bigger struggle to stay cool
• Body size (which is directly proportional to wing length) increases to the north, but individual birds in the warm, humid Mississippi Valley and coastal areas are small compared with those at other localities at similar latitudes

Question 24

Peripheral vasodilation

Answer 24

• Allows heated blood from core to get to the surface and be dissipated
• change from restricted to normal blood flow
• heat to leave body

Question 25

Controlled hyperthermia

Answer 25

• controlled elevation of body temp
• store heat
• birds have rete mirable opthalium, blood vessels in eyes that pull up heat and dissapate it
• birds throat flutter to get rid of heat

Question 26

Evaporative heat loss

Answer 26

• Metabolism increases above the UCT because of panting and other efforts that facilitate heat loss
• major source of water loss to environment

Question 27

Describe importance of the toucan bill

Answer 27

• it is not insulated, therefore making it easier to produce heat loss and cooling of the bird in its environment (huge thermal window for blood flow)

Question 28

Cutaneous water loss

Answer 28

• Evaporate water directly through the skin (without sweat glands)

Question 29

Describe the heat adaptations of birds in pstural adjustment, microclimate, and urohydrolysis

Answer 29

• these are basically the opposite of adjustments in cold temps!!!

Question 30

Urohidrosis

Answer 30

Defecating onto the scaly portions of the legs as a cooling mechanism, using evaporative cooling of the fluids.