energy metabolism i - boston college...energy metabolism/unit time = metabolic rate kcal/hr...
TRANSCRIPT
Energy Metabolism I -measuring metabolic rate -factors influencing VO2
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DPG (2,4 diphosphoglycerate) has little effect
Fetal Hb
3
Q. Is RBC count always the same?
myoglobin
hyperbolic curve
sigmoid curve
6
Q. How are leaks plugged?
7
Leukocyte
Erythrocyte (RBC) platelet
Clotting
8
Haemophilia: loss of critical clotting factors leads to uncontrolled bleeding (rare recessive trait that most often affects males)
9
Sickle cell anemia
-1M deaths/yr-10% of population infected by malaria-90% of casesare in sub-Saharan Africa
Normal RBCs are particularly susceptible
Heterozygotes for Hb-SA (‘sickle-cell trait’) are less vulnerable.
Energy Metabolism
C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O + 38 ATP + ‘heat’ glucose (oxidative phosphorylation)
heat released from food/unit time
energy metabolism/unit time = metabolic rate kcal/hr kJoules/hr (1 kcal = 4.184 kJ) watts (1 watt = 1 Joule/sec) (weight specific) kcal/kg . hr kJ/kg . hr
basal metabolic rate (BMR) - endotherms at rest standard metabolic rate - ectotherms at rest (specify temperature)
How can we measure metabolic rate in a whole animal?
C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O + 38 ATP + ‘heat’ glucose
1) Calculate difference between energy content of food (Kcal) and energy content of waste products (material balance)
Q: Problems?
Antoine Lavoisier 1743-1794
calorimeter
ice
2) Measure total heat production (direct calorimetry)
1919
3) Respiratory gas exchange (indirect calorimetry)
C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O + 38 ATP + ‘heat’ glucose
. VO2
ml O2/g . hr
4.8 kcal released/ liter of O2 consumed
a) Measure rate of oxygen consumption
closed respirometry
aquatic animals
open respirometry
respiratory conformers respiratory regulators
air-breathing animals
closed respirometry
spirometer (closed system)
Antoine Lavoisier
spirometer
open respirometry (air breathers)
1784
Q: what is the problem with using O2 consumption as a measure of metabolism during exercise?
Q: what is the problem with using O2 consumption as a measure of metabolism during exercise?
b) Measure rate of CO2 production
C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O + 38 ATP + ‘heat’ glucose
2) exhaled [CO2] too variable; may not reflect metabolic rate
BUT: 1) amount of heat produced per unit of CO2 released varies more with diet
RQ = 1
obtain metabolic rates of whole animals in the field??
doubly labeled water technique:
a) inject tritium (3H) and oxygen 18 (18O)
b) wait several hours or days
c) collect blood sample, and measure depletion of 3H and 18O
--decline in [18O] relates to rate of CO2 and water loss --decline in [3H] relates to rate of water loss
What factors influence metabolic rate in whole animals??
ml O2/hr ?
ml O2/hr
ml O2/g . hr