iv. Increased enzymatic capacities for substrate catabolism
v. Higher degree of clustering of subsarcolemmal mitochondria adjacent to capillaries-> higher O2 flux rates vi. Mitochondrial volume densities and surface areas per unit mitochondrial volume are near maximum theoretical limits in hummingbirds and higher than mammals-> achieved due to higher oxygen delivery capacities and substrate catabolism (Suarez et al. 1991)
5. Metabolic Substrate Turnover
a. Questions
i. Do hummingbirds metabolize sugars that they are readily taking in or that have been previously stored? ii. What is the turn over time of carbon?
b. Conclusion
i. Hummingbirds that have recently eaten fuel their metabolism by recently digested sugars ii. Hummingbirds that have …show more content…
Very brief period from stimulus to peak contraction (8ms)
f. Narrow relaxation period of 15ms
g. Hummingbirds only change wing beat frequencies slightly and majority by wing stroke amplitude (2 ways to change muscle power during flight)(inverse relationship if speed is held constant)
h. Electromyogram intensity is highest during the slowest and the fastest speeds
i. Wing stroke is initiated by 1-3 highly synchronous bursts of motoneuron action potentials ->spiking muscle action potentials in the pectoral muscles
j. Increased demand-> increase wing amplitude and wing beat frequencies -> increase number of motor units activated on each cycle
k. Peak lifting-more spikes per EMG burst->burst duration increases->overall cycle length decreases
l. Recruit additional motor units when regulating wing stroke amplitude and temporal recruitment is required when maintaining maximum stroke amplitude at highest wingbeat frequency
m. Muscles are innervated by a large motor pool spanning several spinal segments
n. High degree of synchrony in arriving motoneuron action potentials (synchronizing hundreds of motoneurons)
o. Unique pattern of two curvilinear bands of motor endplates(compared to other birds with a regular grid-like spacing) in the middle of the muscle(Donovan et al. …show more content…
The activities of key enzymes of carbohydrate, fat, and amino acid catabolism in flight muscle and heart were measured as well as the required energy demand. It was determined that the high ATP requirement of short term hoovering can only be supported by the oxidation of carbohydrate. Muscles also have the capability of fat oxidation, which can support a lower rate of ATP turnover for migratory flight. Mitochondria in flight muscles oxidize pyruvate and palmitoyl-CoA equally well (Suarez et al. 1986).
3. Digestive physiology is a determinant of forging bout frequency in hummingbirds This research explored the mechanism behind sugar absorption in the hummingbird. They provided the first measurement of nutrient absorption by the hummingbird’s intestine and measured crop emptying times. It was determined that hummingbird intestine has the highest active glucose transport rate and the lowest passive glucose permeability reported in vertebrates (Diamond et al. 1986).
4. Wing-pitching mechanism of hovering Ruby-throated
v. Higher degree of clustering of subsarcolemmal mitochondria adjacent to capillaries-> higher O2 flux rates vi. Mitochondrial volume densities and surface areas per unit mitochondrial volume are near maximum theoretical limits in hummingbirds and higher than mammals-> achieved due to higher oxygen delivery capacities and substrate catabolism (Suarez et al. 1991)
5. Metabolic Substrate Turnover
a. Questions
i. Do hummingbirds metabolize sugars that they are readily taking in or that have been previously stored? ii. What is the turn over time of carbon?
b. Conclusion
i. Hummingbirds that have recently eaten fuel their metabolism by recently digested sugars ii. Hummingbirds that have …show more content…
Very brief period from stimulus to peak contraction (8ms)
f. Narrow relaxation period of 15ms
g. Hummingbirds only change wing beat frequencies slightly and majority by wing stroke amplitude (2 ways to change muscle power during flight)(inverse relationship if speed is held constant)
h. Electromyogram intensity is highest during the slowest and the fastest speeds
i. Wing stroke is initiated by 1-3 highly synchronous bursts of motoneuron action potentials ->spiking muscle action potentials in the pectoral muscles
j. Increased demand-> increase wing amplitude and wing beat frequencies -> increase number of motor units activated on each cycle
k. Peak lifting-more spikes per EMG burst->burst duration increases->overall cycle length decreases
l. Recruit additional motor units when regulating wing stroke amplitude and temporal recruitment is required when maintaining maximum stroke amplitude at highest wingbeat frequency
m. Muscles are innervated by a large motor pool spanning several spinal segments
n. High degree of synchrony in arriving motoneuron action potentials (synchronizing hundreds of motoneurons)
o. Unique pattern of two curvilinear bands of motor endplates(compared to other birds with a regular grid-like spacing) in the middle of the muscle(Donovan et al. …show more content…
The activities of key enzymes of carbohydrate, fat, and amino acid catabolism in flight muscle and heart were measured as well as the required energy demand. It was determined that the high ATP requirement of short term hoovering can only be supported by the oxidation of carbohydrate. Muscles also have the capability of fat oxidation, which can support a lower rate of ATP turnover for migratory flight. Mitochondria in flight muscles oxidize pyruvate and palmitoyl-CoA equally well (Suarez et al. 1986).
3. Digestive physiology is a determinant of forging bout frequency in hummingbirds This research explored the mechanism behind sugar absorption in the hummingbird. They provided the first measurement of nutrient absorption by the hummingbird’s intestine and measured crop emptying times. It was determined that hummingbird intestine has the highest active glucose transport rate and the lowest passive glucose permeability reported in vertebrates (Diamond et al. 1986).
4. Wing-pitching mechanism of hovering Ruby-throated