Unit 1 Flashcards
epimysium
the outer layer that surrounds a muscle
perimysium
surrounds a singular fasciculus
endomysium
surrounds an individual muscle fiber
two main myofilaments
actin and myosin
sarcomere
the functional unit of myofibril, z-line to z-line
A-band
contains both actin and myosin
unchanged with length
I-band
contains only actin
H-zone
contains only myosin
steps of the neuromuscular junction
1) motor neuron AP travels to the synaptic terminal
2) AP opens Ca+2 channels, Ca+2 enters voltage-gated channels
3) ACh is released into the synaptic cleft and binds to Na+ ligand channels
4) Na+ depolarizes the motor endplate and the sarcolemma (more +)
5) muscle fiber AP initiation, opens voltage-gated Na+ channels
6) depolarization continues down the t-tubules and opens Ca+2 channels in SR
7) Ca+2 released from SR into the cytosol, Ca+2 is low at rest, and myosin is not bound to actin
8) Ca+2 binds to troponin causing conformational change to tropomyosin and exposed binding sites
cross-bridge formation
1) cross-bridge binds to actin, depolarization, Ca+2 binds to troponin and sites exposed, myosin heads energized binds actin
2) ADP + Pi released from cross-bridge, results in a Powerstroke
3) ATP binds to myosin cross-bridge, detach actin
4) Hydrolysis of ATP energizes cross-bridge, myosin re-energized, myosin heads ATPase break down ATP
type I fibers
slow-twitch, slow oxidative
weak in strength
highly resistant to fatigue
type IIa
fast oxidative glycolytic (FOG)
type IIx
fast glycolytic (FG)
strongest
least resistant to fatigue
Size Principle
as force requirements increase, there is orderly recruitment of progressively larger motor units
Force-Velocity
increase force = decrease velocity
max force development decreases at higher speeds during concentric muscle contraction
Length-Tension
optimal sarcomere length = optimal overlap
isometric
no change in muscle length
concentric
muscle shortens
eccentric
muscle lengthens
goal of bioenergetics
produce ATP from fuel sources using energy systems
food to ATP to power all biological work
metabolism
all chemical reactions in the body
anabolism
small to large; build
amino acids to protein
catabolism
large to small; break down
glucose to CO2 + H2O
fat stored as
triglycerides
carbohydrates stored as
glycogen
percent of ATP production from protein at rest
2% at rest and up to 10% with prolonged exercise
how do enzymes influence the activation energy of a reaction
lowers activation energy to catalyze the reaction
what factors influence enzyme activity
body temperature and pH
the rank of systems with power
1) ATP-PCr
2) Glycolysis
3) Aerobic Carbs
4) Aerobic Fat
the rank of systems with capacity
1) Aerobic Fat
2) Aerobic Carbs
3) Glycolysis
4) ATP-PCr
how much ATP produced from 1 glucose
2 ATP
how much ATP produced from 1 glycogen
3 ATP
energy system used for the exercise of 10-15 seconds
ATP-PCr
energy system used for the exercise of 20sec-3min
glycolysis
energy system used for the exercise of 3min to fatigue
oxidative of carbs and fats
pathways involved in aerobic metabolism of carbs
1) glycolysis
2) Krebs cycle
3) ETC
pathways involved in aerobic metabolism of fats
1) beta-oxidation
2) Krebs cycle
3) ETC
what pathway produces NADH and FADH2 and CO2
Krebs cycle
what pathway uses NADH, FADH2, and O2
ETC
how much ATP is produced from the aerobic metabolism of a single molecule of glucose
32 ATP
how much ATP is produced from the aerobic metabolism of a single molecule of glycogen
33 ATP
what branch of the nervous system innervates skeletal muscle
somatic
motor cortex
voluntary muscle contraction to plan and execute muscle movements
sympathetic
fight or flight
increase HR
parasympathetic
rest and digest
decrease HR
what is RER
the respiratory exchange ratio, estimates exchanged gases
RER = VCO2 / VO2
RER value for fat
0.7
RER value for carbs
1.0
absolute value for RER
L/min
the relative value for RER
mL/kg/min
what does the O2 deficit indicate
O2 demand higher than O2 consumption
ATP produced anaerobically
what does EPOC indicate
O2 consumed greater than O2 demand ATP demand is low increase intensity = increase EPOC convert lactate to glycogen restore any low O2 stores in hemoglobin and myoglobin
lactate threshold
the point at which blood lactate is accumulated
interaction of aerobic and anaerobic systems
disproportion of blood lactate
exercise intensities below lactate threshold fueled by
aerobic metabolism
exercise intensities above lactate threshold fueled by
anaerobic metabolism
what causes DOMS
eccentric contractions
microtears within the sarcolemma which causes an inflammatory response
muscle damage stimulates hypertrophy
byproducts associated with fatigue
H+ and Pi
four major causes of fatigue
1) PCr and glycogen depletion
2) accumulation of byproducts (lactate, H+, Pi)
3) failure of contractile mechanisms of muscle fibers
4) altered neural control of muscle contraction
what molecule inhibits actin/myosin-binding at rest
tropomyosin
motor unit
beta motor unit and all the muscle fibers it innervates
muscle fiber type best at producing ATP aerobically
type I (SO)
two general mechanisms the nervous system used for force generation
motor unit recruitment and stimulation frequency
primary macronutrient to fuel high-intensity exercise
carbohydrates
primary macronutrient to fuel long-duration exercise
fat
the end product of anaerobic glycolysis
lactate
the end product of aerobic glycolysis
pyruvate
number of pyruvates produced from 1 molecule of glucose
2
the metabolic pathway that converts FFAs into acetyl-CoA
beta-oxidation
the metabolic pathway that starts with acetyl-CoA
Krebs cycle
the liver can convert lactate back into what and release it back into the bloodstream
glucose
how many molecules of acetyl-CoA can be produced from an FFA with 14 carbons
7
amount of substrate energy in metabolism that is lost as heat
60%
the single best measurement of aerobic fitness
VO2 max
two locations of glycogen storage
liver and skeletal muscle
the total amount of glycogen storage
600g
all steps of an action potential
1) neurons fire within the motor cortex initiating skeletal muscle contraction
2) AP from the motor cortex stimulate alpha motor neurons in the spinal cord
3) AP within alpha motor neuron depolarizes the synaptic terminal
4) Ca+2 enters the synaptic terminal
5) ACh binds receptors on the motor endplate
6) depolarization of the sarcolemma
7) depolarization of t-tubule
8) Ca+2 releases by SR
9) Ca+2 binds troponin
10) conformational change in tropomyosin exposes binding sites on actin
11) myosin cross-bridges bind the actin molecule
12) ADP +Pi release from the cross-bridge
13) Powerstroke of the myosin cross-bridge
14) fresh ATP molecule binds the myosin cross-bridge
15) myosin cross-bridge releases from the actin molecule