Lecture 10 Flashcards
Kreb’s Cycle Net (For each (blank)) 3 NADH + H+ 1 FADH2 2 CO2 1 ATP X2 for glucose or Glycogen
acetyl CoA
32 to 33 molecules ATP for every glucose molecule
-about 35-40% (blank)
efficiency
Oxidation of Fat
•(blank): major fat energy source
– Broken down to 1 glycerol + 3 FFAs
– Lipolysis, carried out by lipases
• Rate of FFA entry into muscle depends on (blank)
• Yields ~3 to 4 times (blank) ATP than glucose
• Slower than glucose oxidation
triglycerides
concentration gradient
more
Fatty Acid (FA) Metabolism • Break down of FFA to form reducing equivalents and (blank) • 2 sources of FFA – Adipose cell triacylglycerides – Intramuscular triacylglycerides
acetyl CoA
(blank) is the process by which fatty acids, in the form of Acyl-CoA molecules, are
broken down in mitochondria to generate Acetyl Co-A, the entry molecule for the Kreb’s Cycle.
• It occurs in many tissues including liver, sk.ms and heart.
• Fatty acid oxidation doesn’t occur in the (blank), as fatty acid can’t be taken up by that organ.
beta-oxidization
brain
The beta oxidation of fatty acids involve three stages:
- Activation of (blank) in the cytosol
- Transport of activated fatty acids into mitochondria (carnitine shuttle)
- Beta oxidation proper in the mitochondrial (blank)
fatty acids
matrix
Fatty Acids must be linked to Coenzyme A Before They Are (blank) in the mitochondria
oxidized
• Entry of FA into mitochondria regulated by (blank)
• CPT1 is believed to be rate determining for FA
oxidation
CPT1
β-Oxidation of Fat
• Process of converting (blank) to acetyl-CoA before entering Krebs cycle (fatty acid activation)
• Requires up-front expenditure of 2 ATP
• Number of steps depends on number of carbons on FFA
– 16-carbon FFA yields 8 acetyl-CoA
– Compare: 1 glucose yields 2 acetyl-CoA
– Fat oxidation requires more O2 now, yields
far more ATP later
FFA’s
Oxidation of Fat:
Krebs Cycle, Electron Transport Chain
• Acetyl-CoA enters Krebs cycle
• From there, same path as (blank)
• Different FFAs have different number of (blank)
– Will yield different number of acetyl-CoA molecules
– ATP yield will be different for different FFAs
– Example: for palmitic acid (16 C): 106 ATP
net yield
glucose oxidization
carbons
The β oxidation pathway is (blank). The product, 2 C shorter, is the input to another round of the pathway.
If the fatty acid contains an even number of Catoms, the final reaction cycle (for which the substrate is butyryl-CoA) yields 2 copies of acetyl CoA
cyclic
(blank) is converted to the Glycolysis intermediate glyceraldehyde 3- Phosphate, by reactions catalyzed by:
glycerol
- Once FFA reach the muscle they must be actively transported into the mitochondria
- FFA cannot cross mitochondrial (blank)
- A series of reactions allow FFA to be transported
membrane
Beta-oxidization
Each “Turn” – (blank) 2C – 1 Acetyl CoA – 1 NADH – 1 FADH2 • This process repeats until FA CoA has been totally broken into 2C acetyl CoA molecules
removes
Substrate metabolism efficiency
– 40% of substrate energy = (blank)
– 60% of substrate energy = (blank)
ATP
heat
(blank) Calorimetry • Pros – Accurate over time – Good for resting metabolic measurements • Cons – Expensive, slow – Exercise equipment adds extra heat – Sweat creates errors in measurements – Not practical or accurate for exercise
direct
(blank) Calorimetry
• Estimates total body energy expenditure based on O2
used, CO2 produced
– Measures respiratory gas concentrations
– Only accurate for steady-state oxidative metabolism
• Older methods of analysis accurate but slow
• New methods faster but expensive
indirect
V•O2: volume of O2 (blank) per minute
– Rate of O2 consumption
– Volume of inspired O2 −volume of expired O2
V•CO2: volume of CO2 (blank) per minute
– Rate of CO2 production
– Volume of expired CO2 −volume of inspired CO2
consumed
produced
(blank) Exchange Ratio
• O2 usage during metabolism depends on type of fuel being oxidized
– More carbon atoms in molecule = more O2 needed
– Glucose (C6H12O6) < palmitic acid (C16H32O2)
• Respiratory exchange ratio (RER)
– Ratio between rates of CO2 production, O2 usage
– RER = V
• CO2/V• O2
respiratory
Indirect Calorimetry (blank)
• CO2 production may not = CO2 exhalation
• RER inaccurate for protein oxidation
• RER near 1.0 may be inaccurate when lactate buildup is higher than CO2 exhalation
• Gluconeogenesis produces RER <0.70
limitations
Isotopic Measurements
• Isotope: element with (blank) atomic weight
– Can be radioactive or nonradioactive
– Can be (blank) throughout body
• 13C, 2H (deuterium) common isotopes for studying energy metabolism
– Easy, accurate, low-risk study of CO2 production
– Ideal for long-term measurements (weeks)
atypical
traced
Basal Metabolic Rate
• Basal metabolic rate (BMR): rate of energy expenditure at (blank)
– In supine position
– Thermo(blank) environment
– After 8 h sleep and 12 h fasting
• Minimum energy requirement for living
– Related to fat-free mass (kcal kg FFM-1 min-1)
– Also affected by body surface area, age, stress, hormones, body temperature
rest
neutral
Resting metabolic rate (RMR)= Resting Energy Expenditure (REE)
– Similar to BMR (within 5-10% of BMR) but easier
– Doesn’t require stringent standardized (blank)
– 1,200 to 2,400 kcal/day
• Total daily metabolic activity
– Includes normal daily (blank)
– Normal range: 1,800 to 3,000 kcal/day
– Competitive athletes: up to 10,000 kcal/day
conditions
activites
RER – gives us an idea of the type of food substrate being oxidized
Based on indirect calorimetry which measures the CO2 released and
the O2 consumed. RER = VCO2/VO2
BMR – basal metabolic rate reflects the minimum amount of energy
required (i.e. energy expenditure) to carry out essential physiological
function. Also measured by indirect calorimetry but
must be measured under strict conditions.
RMR – resting metabolic rate doesn’t require the stringent conditions.
(it is very close – within (blank)% of the BMR- with BMR being slightly
Lower)
5-10
