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Section 1

Terms in this set (74)

What is the muscle structural hierarchy?
1. Whole muscle
2. Fascicles
3. Muscle Fibers
4. Myofibrils
5. Sarcomeres
What are the 3 extracellular matrix and what do they enclose?
-Epimysium: Whole Muscle
-Perimysium: Fascicles
-Endomysium: Muscle Fibers
What makes up a muscle fiber?
Sarcolemma
What makes up a sarcolemma?
Basement membrane and plasmalemma
Where are Satellite Cells located and what is their function?
-In between the Basement Membrane and the Plasmalemma
-Produce proteins
What is inside the muscle fiber?
-Myofibril: Sarcomeres in series
Define myonuclei
Nucleus of muscle fiber
What is the smallest functional unit of a muscle?
Sarcomeres
What is the purpose of sarcomeres?
Bands and protein identification
What are the two types of myofilaments?
Thick and thin filaments
What are the 3 purposes of the Muscle Cytoskeleton?
-Structural integrity
-Force transmission
-Signal transduction
What is the largest protein in skeletal muscle?
Titin
What myofilament is associated with titin? Where does it span?
-Associated with myosin
-Spans z-disk to m-line
What myofilament is associated with nebulin? Where does it span?
-Associated with actin
-Extends from z-disk
What is the major protein in sarcolemma?
Dystrophin
What is a costameres associated with? What makes up a costamere?
-Costamere is associated with z-lines
-Complex of proteins
What would occur if dystrophin was not in the complex?
-Things won't work right and muscle would break down
Where is Desmin located and what does it attach to? What does Desmin connect? What is its function?
-Located at z-lines
-Attaches to subsarcolemmal proteins
-Connects myofibrils
-Function: force transmission
What type of protein is myosin?
Contractile protein: motor protein/force generation
What are the 2 types of actin?
Globular and Filamentous
Where is tropomyosin located? What is its function?
-Runs in groove of actin
-Covers binding sites on actin
What are the C.I.T roles of troponin?
-C: Calcium Binding Site
-I: Inhibatory Effect
-T: Tropomyosin
What type of arrangement are thick and thin filaments?
-Lattice arrangement
What is the effect of passive stretching?
-I band lengthening
-No change in A band
What is the effect of Isometric twitches?
No band changes
What is the effect of Isotonic contractions?
-I band narrowing
-A band constant
Define sliding filaments?
Interdigitation of myofilaments
What are the 5 steps of the cross bridge cycle?
1. Muscle fiber action
2. Actin/Myosin interaction
3. Role of Calcium and ATP
4. ATP and Myosin ATPase
5. Contractile function and MHC and ATPase isoforms
Skeletal muscle has what type of membrane?
Excitable
How do you get an Ach receptor to open?
2 acetylcholines need to bind
Where is the majority of calcium stored?
Terminal cisternae
What is the acronym for SERCA pumps?
Sarcoendoplasmic Reticulum Calcium Pump
What is inside the Transverse Tubules (T-Tubules)? What does it establish?
-Interstitial Fluid
-Establishes a concentration gradient
What does the protein DHP influence?
Integral part of t-tubules
What does the protein Ryanodine influence?
Receptor part of SR
What are the 5 steps to Excitation-Contraction Coupling?
1. Action Potential
2. Membrane Depolarization
3. Calcium Release
4. Actin-Myosin interaction and power stroke
5. Calcium uptake- repolarization-reaction
What causes muscles to relax?
The removal of calcium
What occurs if there is tension in a muscle?
-Actin and Myosin binding
-Calcium is present inside cytoplasm of cell
What are the biochemical properties of muscle fiber?
-Oxidative capacity (mitochondria, capillaries, myoglobin)
-Type of ATPase (slow or fast isoforms)
What are the contractile properties of muscle fiber?
-Maximal force production (peak tension, fiber CSA)
-Velocity of contraction (twitch characteristics, ATPase, and MHC isoforms)
What are the characteristics of Type 1 muscle fiber?
-Oxidative (mitochondrial) and slow twitch
What are the characteristics of Type 2a muscle fiber?
-Intermediate (oxidative and glcolytic)
What are the characteristics of Type 2x muscle fiber?
-Glycolytic enzymes, fast twitch
What are the predominant energy systems for Type 2x, Type 2a, Type 1?
-Type 2x: Anaerobic
-Type 2a: Combination
-Type 1: Aerobic
What is a hybrid muscle fiber?
Single muscle fibers expressing more than 1 MHC isoform
What is the muscle fiber type continuum?
I....I/IIa....IIa....IIa/IIx....IIx
Slow...............................Fast
What type of fiber types do power athletes, endurance athletes, and others have?
-Power: high percentage of fast fibers
-Endurance: high percentage of slow fibers
-Others: 50% slow 50% fast
What are the 4 General Nervous System Functions?
1. Control of the internal environment
2. Voluntary control of movement
3. Programming spinal cord reflexes
4. Assimilation of experiences necessary for memory and learning
What is included in the central nervous system?
-Brain
-Spinal cord
What is included in the peripheral nervous system?
-Nervous outside CNS
What is the structure of a neuron?
-Cell body
-Dendrites
-Axon
-Synapse
How do neurons communicate?
Neurons communicate across synapses using neurotransmitters
Where are neuron communications released from? Where do they bind?
-Released from presynaptic membrane
-Binds to receptor on post synaptic membrane
What does EPSP stand for? What does it cause?
-EPSP: Excitatory postsynaptic potentials
-Causes depolarization which may or may not reach threshold
What does IPSP stand for? What does it cause?
-IPSP: Inhibitory postsynaptic potentials
-Causes hyper polarization
What is spatial summation?
Summing from several different presynaptic neurons
What is a temporal summation?
Summing several EPSPs from one presynaptic neuron
Define motor unit
Neuron and associated muscle fibers
What are the 2 ways that motor units are distributed?
-Glycogen depletion method
-Distribution and motor unit type
What should you consider when classifying a motor unit?
-Physical size
-Number of fibers
-Force generation
-Rate of force production
-Fatigability
*Study graph of motor unit recruitment*
...
*Study graph of force generation x cross-sectional areas *
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How can you measure muscle strength?
-Force generation
-1 rep max
-Muscle size
What is the equation for power?
P=(Force x Distance)/time
What is the best measure of performance?
Power
Define endurance?
Sustained muscular contraction (not just aerobic exercise)
What is an isometric contraction?
-Postural muscles
-Static
What is an isotonic contraction?
-Concentric: shortening
-Eccentric: lengthening
What are are the characteristics of Muscle Force Production?
1. Muscle mass
2. Motor unit characteristics
a. Number
b. Type
3. Initial muscle length
4. Contraction velocity
What is the muscle force production relationship?
Length-tension relationship
When is the maximum velocity of shortening the greatest?
The maximum velocity of shortening is greatest at the lowest force
What are the principles of overload?
-Frequency
-Intensity
-Duration
What are the principles of specificity?
-Muscle
-Movement
-Metabolism
How can you make improvements in strength via progressive overloads?
Periodically increasing resistance (weight lifted) to continue to overload the muscle
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