Muscle Metabolism Flashcards
Name energy sources and order in fastest to slowest activation during exercise
1 ATP + creative phosphate
2 Anaerobic glycolysis: muscle glycogen
3 Aerobic oxidation: muscle glycogen, plasma glucose, liver glycogen
4 Aerobic oxidation: plasma FFA, adipose tissue triglycerides
How much stored ATP is in skeletal muscle fibres
Enough for 3 seconds of contraction
What is PCr and what is it used for
Creatine phosphate (PCr)- high energy compound
Quickly broken down to make ATP
How much energy is supplied by PCr
Creatine phosphate
Energy for 10 seconds of contraction
ATP + creatine breakdown equation for muscles at rest vs working muscles
Muscles at rest: ATP from metabolism + creatine -> ADP + phosphocreatine
Working muscles: phosphocreatine + ADP -> creatine + ATP
- Enzyme- creatine kinase
- High energy phosphate group of phosphocreatine is transferred to ADP to produce ATP
- Phosphocreatine is constant source of energy during muscle contraction
What is the order compounds are used for energy
Glucose
Glycogen
FFA
Amino acids
Ketone bodies
What body part can’t consume FFA for fuel
Brain
What energy sources can the brain use
Glucose
Ketones
What energy source do normal cells use
Glucose or FFA
What is the absorptive phase
Absorb nutrients to convert to ATP
Occurs after a meal and body digesting
What is the post absorptive state
Break down glycogen and FFA
Occur when sleep or fast- food has been digested, absorbed, stored
Example of effective stored energy (ATP is not stored)
Triglycerides
What allows cells to uptake glucose
Insulin
GLUT 4- protein transporter
Output fuel required % of resting metabolic rate and activity/movement
60-70% resting metabolic rate
25-30% movement/activity
What is resting metabolic rate
Amount of fuel required for daily business
What is homeostasis
The body’s tendency to maintain constant internal environment
Primary energy source at rest
Circulating FFA
Input and output of anaerobic glycolysis
Glucose (6C)
2 pyruvate (3C) + 2ATP
What adds glucose to liver
Glycogen synthases
How much glycogen can the liver store
100g
What removes glucose molecules from glycogen
Glycogen phosphorylase
What converts glucose-6-phosphate to glucose
Glucose-6-phosphatase IN LIVER NOT IN MUSCLE
Removes phosphate
What can contribute to blood/plasma glucose levels and why
Liver can
Not possible in muscles- no glucose-6-phosphatase
When is muscle glycogen used
During exercise
How much glycogen can muscles store
400g
What is glycogenolysis
Muscle glycogen broken down into glucose
What enzymes are in muscles relating to glucose
Glycogen phosphorylase
NO GLUCOSE-6-PHOSPHATASE
What is glycogen loading
Increasing carbohydrate intake before an endurance race to build up muscle glycogen
What do muscles use to produce ATP
Glucose-6-phosphate
How can we make ATP
Glucose
Amino acids
Free fatty acids
Glycolysis input and output and amount of contraction time provided
Anaerobic- no O2 required
Glucose
2 pyruvate + 2 ATP (lactic acid is byproduct)
90 seconds contraction
What does lactic acid cause
Perception of fatigue and muscle soreness
Aerobic respiration input and output and amount of contraction time provided
O2 required
Acetyl CoA
36 ATP
Slowest regeneration of ATP route
Occurs in mitochondria
Fatiguability of type 1 and type 2 motor units
Type 1- low (oxidative capacity high)
Type 2- high (glycolytic capacity high)
What is FATP
Fatty acid transport proteins
How can we go from FFA to acetyl CoA
Beta oxidation
How are fats broken down in adipose tissue
Lipolysis
How do FFA circulate in the blood
Bound to albumin
How do FFA enter muscle cells
Fatty acid transport proteins
What does glucokinase do
Convert glucose to glucose-6-phosphate
How do FFA cross mitochondria membrane
Carnitine palmityltransferases
What is produced after every beta oxidation cycle
2 carbons removed
Generate 1 acetyl CoA
What do the FFA products participate in after
Oxidative phosphorylation- Kreb Cycle
BYPASS GLYCOLYSIS
Products of FFA breakdown
17 ATP
1 FADH2
1 NADH
How much energy do you get from lipids, carbs, proteins
9 kcal/g lipids
4 kcal/g carbs/proteins
Get more energy from fats
What needs to happen before amino acids can be oxidized
Transamination
Transfer amino group to another molecule (get rid of NH3)
Amino group must be removed b/c it gives rise to ammonia (toxic)
How do amino acids get to the kreb cycle
Amino acids -> pyruvate -> Acetyl CoA
Bypasses glycolysis
Explain all energy related activities at rest
- Circulating fatty acids are primary energy source
- O2 is abundant = aerobic metabolism used
- glucose taken in is stored as glycogen
- phosphocreatine reserves are built up
Explain all energy related activities during moderate activity
- phosphocreatine reserves are used first (quickly used up)
- aerobic metabolism of fatty acids and glucose released from glycogen stores to make ATP
Explain all energy related activities for intense activity
- muscles lack O2 to support mitochondria
- rely on glycolysis for ATP
- pyruvic acid build up, is converted to lactic acid
How is mitochondrial DNA inherited
Maternal inheritance
What is mitochondrial DNA susceptible to
Mutation
Not protected like nuclear DNA
How have we been able to identity evolutionary relationships
mtDNA
What are mitochondrial diseases associated with
Lactic acidosis (lots of lactic acid build up)
Exercise related
Mitochondrial disease effects on skeletal muscle
Weakness
Fatigue
Exercise intolerance
Myopathy (dysfunction muscle fibres)
Hypotonia (decreased muscle tone)
Explain Mitochondrial donor process for embryo repair
Parent- nucleus removed
Donor- embryo and mitochondria stay while nucleus removed/destroyed
Result- parents nucleus in donors embryo
Explain mitochondrial donor process for egg repair
Mother- nucleus removed
Donor- egg and mitochondria stay. Nucleus removed/destroyed
Result- mothers nucleus in donor egg
