digestion and metabolic rate

Question 1

metabolic rate

Answer 1

sum of all reactions taking place within an organism; very high in birds due to high blood pressure, muscle mass, and body temperature

Question 2

energy acquisition

Answer 2

must meet the demands of the body, done via foraging adaptations and rapid food breakdown (30 min to 24 hrs)

Question 3

foraging adaptations

Answer 3

frequent foraging, adapted bills and tongues, adapted feet

Question 4

digestive tract

Answer 4

mouth > tongue > esophagus > crop > stomach: proventriculus and gizzard > small intestine and pancreas > large intestine and ceca > cloaca; lack teeth and saliva

Question 5

crop

Answer 5

storage location in the upper chest to collect more food than they can consume at a given moment, often collected and taken to a safe location to eat; smaller in birds eating soft foods; acts as a fermentation chamber in hoatzin; produces pigeon milk

Question 6

proventriculus

Answer 6

anterior stomach with secretions to quickly break food down, storage of digestive oil by products

Question 7

gizzard

Answer 7

keratinized posterior stomach; stiff and muscular, used for grinding food since birds lack teeth to chew, consume some kind of grit to use for grinding such as rocks, sometimes requires a filter to protect the intestines

Question 8

ceca

Answer 8

enlarged hindgut portions to finalize breakdown, used for compaction and secretion; similar to the rumen aiding primarily in plant digestion and when some birds eat wax

Question 9

pigeon milk

Answer 9

fat and proteins from the esophagus lining to be fed to hatchlings

Question 10

esophagus

Answer 10

expandable for feeding on large prey, used for sound and display in some species

Question 11

2 chambered stomach

Answer 11

variable in size depending on diet, smallest in nectar eaters

Question 12

intestinal tract

Answer 12

varies in length from 3-20x the body, avg of 8.6; shorter in meat and insect eaters and longer in seed plant and fish eaters

Question 13

kidneys

Answer 13

differ from mammals in that excrete can be reabsorbed in the large intestine to retain as much water as possible; excrete uric acid

Question 14

uric acid

Answer 14

nitrogenous waste product in birds; Highly concentrated up to 3000x that of the blood requiring high energy input

Question 15

salt glands

Answer 15

found in marine birds to allow them to drink salt water; concentrates waste using countercurrent flow to excrete half the volume with double the salt concentration leaving the bird with half the volume of freshwater

Question 16

woodpecker tongues

Answer 16

very long to plunge into holes, and wraps around the skull which has very little extra space around the brain, this along with spongey bone behind the beak act as shock absorbers

Question 17

basal metabolism

Answer 17

resting metabolic rate which must be measured when fasted, at rest, and in the thermoneutral zone; lower in larger birds

Question 18

aerobic capacity

Answer 18

capacity for exercise, high in birds to allow for energetically expensive flight; can exercise at high levels for a long duration

Question 19

countercurrent heat exchange

Answer 19

transfer of heat from outgoing arteries to incoming veins to maintain both heat in the body and blood flow to the extremities; commonly used in the legs which can be tucked into apteria if too cold

Question 20

thermal neutral zone

Answer 20

range of temperatures in which no heating or cooling is required

Question 21

lower critical temperature (LCT)

Answer 21

temperature at which shivering thermogenesis begins to be needed; many birds can withstand up to -20 degrees C

Question 22

upper critical temperature (UCT)

Answer 22

temperature at which metabolic cooling becomes necessary; evaporative cooling or gular fluttering

Question 23

summit metabolic rate

Answer 23

coldest temperature at which a bird can operate without going hypothermic

Question 24

torper

Answer 24

a brief version of hibernation in which metabolic rate and body temperature are dropped to conserve energy; used exclusively in small birds because energy of reanimation is low; body temp drops until reaching near hypothermia at which that lower body temp is maintained and closely monitored