Part 2.2 Flashcards
Type I vs. Type II muscle fibers
Type I: red, slow and oxidative
- rich in mitochondria and myoglobin
- light activity and endurance athletes
Type II: white, fast and anaerobic
- short, high-intensity activity and fatigues easily
- high energy demand during exercise
- Subtypes:
1) IIa - more mitochondria and more oxidative
2) IIb - more glycolytic and tire easily
Fuel for type II muscle during vigorous exercise vs light activity
Vigorous fuels: muscle glycogen, blood glucose and phosphocreatine –> creatine
Light activity fuels: FA, lactate, ketone bodies, AA
The Cori Cycle explained
In exercising muscle or erythrocytes:
1) 1 Glucose –> 2 Pyruvate –> 2 Lactate
Liver:
2) 2 Lactate –> 2 pyruvate –> 1 glucose
ATP used: 2 by pyruvate carboxylase and 2 by phosphoglycerate kinase (4 ATP total)
GTP used: PEP carboxykinase (2 GTP total)
Considered carbon sharing between liver and muscle
Type II muscle is more involved
Phosphocreatine system in muscle
Muscles at rest/low ATP demands:
Plasma:
1) excess plasma Cr transported into muscle cells by CrT
Cytoplasm:
2) Excess plasma Cr –> PCr to store excess ATP by CK(c)
High ATP demands:
3) CK(c) catalyzes ADP + PCr –> Cr + ATP which is used for energy
Muscle cells:
4) CK(m) converts Cr –> PCr with ATP from ETC
5) CK(c) converts PCr –> Cr + ATP to provide more energy to muscles
Increased [creatine] effects
1) stored energy as PCr
2) increased cell osmolarity, size, and anabolic stimulus (with resistance training)
3) Transduction of oxidative energy in muscle cells converting Cr/PCr back and forth
PCr is more concentrated in which muscle fiber type?
Fast twitch type II fibers
Carbohydrate as fuel: glucose vs glycogen
Respiratory and ATP/O2 quotients
Glucose proceeds full oxidation: 1 glucose + 6 O2 –> 6 CO2 + 6 H2O (30 ATP)
Glycogen oxidation: 1 G6P (C6H10O5) + 6 O2 –> 6 CO2 + 5 H2O (31 ATP)
Respiratory quotient: 1 (mol CO2/mol O2)
ATP/O2 glycogen quotient: 31/6 = 5.2
ATP/O2 glucose quotient: 30/6 = 5
Palmitic acid as fuel
Respiratory and ATP/O2 quotients
Palmitic acid + 23 O2 –> 16 CO2 + 16 H2O (108 ATP)
Respiratory quotient: 16 CO2/23 O2 = .7
ATP/O2 quotient: 108/23 = 4.7
Carbo-loading protocol
Why use?
Method for increasing glycogen stores by increasing carbohydrate intake and decreasing exercise 3 days before an event
Increases glycogen stores by 70% and extends glycogen use during the race
Fat is not as good a source of fuel as carbohydrates (especially glycogen) when oxygen becomes the limiting factor (ie. during endurance events)
What is compensated left ventricular hypertrophy?
Decompensated?
Enlarged left ventricle of the heart to ensure increased O2 delivery
Decompensated left ventricular hypertrophy can lead to heart failure
Fuel preferences for type I and type II muscle fibers
Type I: variety like fats, ketone bodies, lactate, and amino acids
Type II: glucose and glycogen reserves (and PCr)
∆G differences in glycolysis vs full glucose oxidation?
Glycolysis: -146 kJ/mol
Full ox: -2840 kJ/mol
Entry into intermembrane space of mitochondria
Outer membrane is permeable and porins allow anything less than 2 kDa into the intermembrane space
Intermembrane space is low pH - important to power the proton motive force
- ETC complexes I, III and IV pump H+ into intermembrane space
- as a form of energy release H+ flows into matrix with UCP-1 (heat) and ATP synthase
Mitochondrial inner membrane permeability
Impermeable to everything but gases
Rich in transport proteins and respiratory complexes and UCP-1
Mitochondrial matrix pH and enzymes
High pH (low H+)
TCA cycle enzymes (excluding succinate dehydrogenase in inner membrane), B-ox enzymes, and parts of urea cycle
Mitochondrial pyruvate carrier
PDH
Inner membrane symport H+/pyruvate transport protein
- H+ going down concentration, pyruvate against gradient
Pyruvate dehydrogenase (PDH):
pyruvate NAD+ + CoASH –> acetyl coA + NADH + CO2
Krebs Cycle main info
Metabolic intersection believed to be the first evolved in organisms: transformation and oxidation
Metabolic pathway converge on Krebs cycle adding carbon to produce energy or generate precursor molecules for biosynthesis pathways
Itaconate
product of citrate synthase utilized in cancer growth
What is the total redox change from NADH-ubiquinone to O2?
The total redox change from NADH-UQ oxidoreductase to O2 is 1.15 V
