Study sets, textbooks, questions
Upgrade to remove ads
Exercise Physiology: Neuromuscular Physiology (Matt Silvers Fall 2015)
Terms in this set (74)
can generate tension
responds to stimulation
can return to original length
Thin filaments (actin, troponin, tropomyosin) & Thick filament (myosin, which includes heavy and light chains) (NOTE: For every ONE thick filament, there are SIX thin filaments surrounding it.) includes: collagen, elastin, titin, and nebulin
bundle of myofilaments - The "sarcomere" is the functional unit of the myofibril - NOTE: Each sarcomere contains multiple thick and thin filaments.
the edges of the sarcomere
the center "anchor" of the sarcomere
area where only actin filaments are present (no overlap with myosin)
area where only myosin filaments are present (no overlap with actin)
area that spans the length of actin filaments (includes areas of myosin and actin overlap)
bundle of myofibrils
(regulate growth & adaptation)
(fluid part; contains ATP-CrP, glycogen, fats, mitochondria)
Transverse tubules (T-tubules;)
(propagate action potentials inward from sarcolemma to myofibrils)
Sarcoplasmic reticulum (SR)
(network of longitudinal tubules that surround myofibrils for Ca2+ storage and release)
(enlarged portion of SR for Ca2+ storage and release)
(aerobic factories that produce ATP)
(control centers for the muscle fiber)
(negatively regulates muscle growth)
(links cytoskeleton of muscle fiber to the extracellular matrix)
bundle of muscle fibers
bundle of fascicles
(surrounds whole muscle)
(the "architecture" of a muscle)
long fibers arranged in parallel along the length of a muscle to produce large ranges of motion: Flat, Fusiform, Strap, Radiate, & Sphincter
fibers arranged obliquely to the central tendon to maximize cross-sectional area and force: Unipennate, Bipennate, & Multipennate
Type IIx (Fast Glycolytic): Anatomical properties
Little myoglobin, mitochondria, and blood capillaries & A lot of glycogen and CrP in sarcoplasm & Fast form of myosin ATPase enzyme
Type IIx (Fast Glycolytic): Physiological/functional properties
Can anaerobically generate and hydrolize ATP at a high rate & Fatigue easily & Speed of contraction is 5-6x faster than Type I fibers & Contraction force is much higher than Type I fibers & Great for speed/power activities
Type IIa (Fast Oxidative Glycolytic): Anatomical properties
Moderate amounts of myoglobin, mitochondria, and blood capillaries & A lot of glycogen and CrP in sarcoplasm & Fast form of myosin ATPase enzyme
Type IIa (Fast Oxidative Glycolytic): Physiological/functional properties
Decent capacity for generating ATP via anaerobic AND aerobic metabolism, therefore these fibers can hydrolyze ATP at a high rate (slower than Type IIx, but still fast) & Faster contraction velocity than Type I, but slower than IIx & Higher contraction force than Type I, but less than IIx & More resistant to fatigue than Type IIx, but less resistant than Type I & Good compromise for all activities
Type I (Slow Oxidative): Anatomical properties
A LOT of myoglobin, mitochondria, and blood capillaries & Slow form of myosin ATPase enzyme
Type I (Slow Oxidative): Physiological/functional properties
Can aerobically generate loads of ATP, but at a slow rate & Most resistant to fatigue & Slowest contraction velocity & Lowest contraction force & Great for endurance activities
1. Provide feedback on muscle length and rate of change in length to the CNS 2. These are known as intrafusal muscle fibers, which are innervated by gamma (γ) motor neurons 3. Rapid lengthening of whole muscle (feedback sent to CNS) elicits the "stretch (myotatic) reflex" (response)...
What is the "stretch (myotatic) reflex" (response)?
a. Lengthening of the intrafusal fibers (muscle spindles) stimulates Ia afferent (sensory) neurons. b. Sensory feedback is received in the CNS and stimulates α-motor neuron for the agonist muscle and inhibits α-motor neuron for the antagonist muscle (reciprocal inhibition) c. Motor feedback from α-motor neuron stimulates extrafusal muscle fiber contraction in the agonist muscle
Golgi Tendon Organs (GTO's):
1. Provide feedback on muscle tension and rate of change in tension to the CNS 2. Located in tendinous connective tissue at ends of skeletal muscle 3. Tension placed on several motor units within a muscle (feedback sent to CNS) elicits the "autogenic inhibition reflex" (response)...
What is the the "autogenic inhibition reflex" (response)?
a. Deformation of 10-20 motor units (due to tension) within the GTO stimulates 1b afferent (sensory) neurons b. Sensory feedback is received in the CNS and inhibits α-motor neuron for the agonist muscle and excites α-motor neuron for the antagonist muscle (reciprocal excitation) c. Inhibited motor feedback from α-motor neuron for agonist muscle inhibits or reduces extrafusal muscle fiber contraction. NOTE: Autogenic inhibition and reciprocal excitation play critical roles in the timing of muscle activation during locomotion.
1. Nervous stimulus in the form of an action potential (AP) is delivered to muscle via α-motor neuron 2. At the neuromuscular junction, acetylcholine (Ach) is released from the pre-synaptic membrane of the α-motor neuron into the synaptic cleft 3. Ach binds to nicotinic receptors on the post-synaptic membrane of the muscle fiber 4. An AP is generated across the sarcolemma of the muscle fiber and down the T tubules 5. The AP activates DHP receptors, which transmit electrical signal through triadic feet to ryanodine receptors located in the SR 6. Ryanodine receptors signal Ca2+ release from the SR into the muscle sarcoplasm
Sliding filament theory
1. Ca2+ binds to troponin, pushing tropomyosin off from active binding sites on actin 2. Myosin heads bind to actin at a 45o angle 3. ATP binds to myosin heads causing myosin to dissociate from actin 4. ATP is hydrolyzed into ADP and Pi by myosin ATPase, which cocks the myosin heads 5. Myosin binds weakly to actin again, this time at 90o 6. Pi is released from myosin heads, which initiates the power stroke 7. Myosin heads rotate back to a 45o position relative to actin, dragging actin closer to the M-line 8. ADP is released after the power stroke and myosin remains bound to actin 9. Repeat a bajillion times...the resultant ratcheting movement of myosin head and repeated coupling and uncoupling with actin produces muscle shortening/lengthening under tension. NOTE: When muscular contraction is no longer desired, Ca2+ is resequestered into the SR, tropomyosin covers binding sites, and actin slides back to original resting position.
Excitation-contraction coupling step 1.
Nervous stimulus in the form of an action potential (AP) is delivered to muscle via α-motor neuron
Excitation-contraction coupling step 2.
At the neuromuscular junction, acetylcholine (Ach) is released from the pre-synaptic membrane of the α-motor neuron into the synaptic cleft
Excitation-contraction coupling step 3.
Ach binds to nicotinic receptors on the post-synaptic membrane of the muscle fiber
Excitation-contraction coupling step 4.
An AP is generated across the sarcolemma of the muscle fiber and down the T tubules
Excitation-contraction coupling step 5.
The AP activates DHP receptors, which transmit electrical signal through triadic feet to ryanodine receptors located in the SR
Excitation-contraction coupling step 6.
Ryanodine receptors signal Ca2+ release from the SR into the muscle sarcoplasm
Sliding filament theory step 1.
Ca2+ binds to troponin, pushing tropomyosin off from active binding sites on actin
Sliding filament theory step 2.
Myosin heads bind to actin at a 45o angle
Sliding filament theory step 3.
ATP binds to myosin heads causing myosin to dissociate from actin
Sliding filament theory step 4.
ATP is hydrolyzed into ADP and Pi by myosin ATPase, which cocks the myosin heads
Sliding filament theory step 5.
Myosin binds weakly to actin again, this time at 90o
Sliding filament theory step 6.
Pi is released from myosin heads, which initiates the power stroke
Sliding filament theory step 7.
Myosin heads rotate back to a 45o position relative to actin, dragging actin closer to the M-line
Sliding filament theory step 8.
ADP is released after the power stroke and myosin remains bound to actin
Sliding filament theory step 9.
Repeat a bajillion times...the resultant ratcheting movement of myosin head and repeated coupling and uncoupling with actin produces muscle shortening/lengthening under tension
muscle produces force while moving at any velocity
muscle produces force while shortening
muscle produces force while lengthening
muscle produces force statically (no movement)
muscle produces maximal force at a fixed velocity
an α-motor neuron and all the muscle fibers it innervates
Gross movement =
single neuron innervating several fibers
Fine movement =
single neuron innervating a few fibers
All or None Principle:
When a motor unit is recruited, all innervated fibers contract to their full potential. So, when...1. Few motor units are recruited, little force is produced 2. Lots of motor units are recruited lots of force is produced.
low threshold motor units recruited first and higher threshold motor units are recruited as more force is needed. 1. Type I motor units are easier to recruit, so they are recruited first 2. Type II motor units are recruited later
a motor unit can exert varying levels of force dependent on the frequency at which it is stimulated. 1. Single stimulus = twitch (little force) 2. Repeated, rapid stimuli = summation (more force) 3. Continued stimulation = tetanus (max force)
What are some additional factors that influence muscle force output
a. Fiber cross-sectional area (CSA) b. Muscle pennation c. Muscle receptor sensitivity & feedback d. Velocity of muscle contraction e. Muscle length f. Muscle elasticity g. There is an elastic component of force output that can be augmented when a muscle is stretched (think of a rubber band) h. Type of muscle action i. Concurrent-activation potentiation (CAP) j. Remote voluntary contractions or the H-reflex may induce a motor overflow that excites target motor units, which in turn increases force output. k. Post-activation potentiation (PAP) l. 30-sec to a few minutes after a high intensity muscle contraction, the activated motor units may be more easily excitable and, therefore, more easily recruited for greater force production.
The faster a muscle fiber contracts,
the less force it can produce
i. When the sarcomere is too short or too long, the number of actin-myosin cross-bridges decreases, so force output is limited. ii. The ideal sarcomere length maximizes the number of actin-myosin cross-bridges for maximum force output.
is typically the weakest due to dynamic cross-bridging and actin-myosin overlap at shorter muscle lengths
action can produce more force than concentric action probably because of static cross-bridges.
(strongest) action can produce the most force because of the additional contribution of stored elastic energy.
Sets with similar terms
Chapter 8 : Skeletal Muscle: Structure a…
Physiology of Exercise: Chapter 1
KIN 275 Chapter 1, Exercising Muscle
Muscles ch 12
Sets found in the same folder
QUIZ QUESTIONS MIDTERM
Ex Phys Q7 (midterm 2)
Exercise Physiology: Acute Responses (Matt Silvers…
Other sets by this creator
BIO 140 Unit 2 Quizzes
Biology 140 Exam 2 Key Terms
BIO 140 Unit 1 Quiz and Review Questions
Biology 140 Exam 1 Review
Which of the following is a positive result of conflict? (a) Improved problem-solving skills, (b) Stress, (c) Damaged relationships, (d) Violence.
Should companies be required to give parents a leave of absence upon the birth of a child? Should this benefit apply to fathers as well as mothers? Explain your answers.
Use complete sentences to answer the following questions. How can you help someone who is mourning?
Which of the following is true about malignant tumors? (a) They are inconvenient but harmless. (b) They stay in their original location. (c) They travel to other parts of the body via the blood or lymph. (d) They occur only in older adults.
Recommended textbook solutions
Clinical Reasoning Cases in Nursing
Julie S Snyder, Mariann M Harding
Essentials of Strength Training and Conditioning
G Haff, N Triplett
Sports Medicine Essentials: Core Concepts in Athletic Training and Fitness Instruction
Law and Ethics for Health Professions
Carlene Harrison, Karen Judson
Other Quizlet sets
Chapter 7, circulatory, lymphatic, and immune syst…
Why did the witch-hunt come to an end in 1647?
Green Light Cards!!!