Muscle Physiology Flashcards
Muscle
Comprises ____ group of tissues in body
Three types of muscle (reflective of function)
Skeletal muscle Makes up____t of the muscular system
Cardiac muscle Found only in the ___t About the size of the___
Smooth muscle Appears throughout the body systems as components of__ __ and tubes
Classified in two different ways
Striated or unstriated( __) Striated: Cardiac and Skeletal
Voluntary or involuntary(____) Voluntary: Skeletal Involuntary: Cardiac, Smooth ANS
Muscle Comprises largest group of tissues in body Three types of muscle (reflective of function) Skeletal muscle Makes up most of the muscular system Cardiac muscle Found only in the heart About the size of the fist Smooth muscle Appears throughout the body systems as components of hollow organs and tubes Classified in two different ways Striated or unstriated (form) Striated: Cardiac and Skeletal Voluntary or involuntary (function) Voluntary: Skeletal Involuntary: Cardiac, Smooth ANS
Categorization of Muscle
_______: “Sliding Filament”
Categorization of Muscle Cardiac and Skeletal: “Sliding Filament”
Muscle
Controlled muscle contraction allows
_____ movement of the whole body or parts of the body
We think about it as being voluntary but frequently there are ____ that occur at lower brain or spinal cord
Very rapid reflexes that provide ____ benefit
Never really reach our ___ ____
Hand withdrawn from flame before we even think about it
There are other fcns that occur thru the ____
Not something that we concentrate on→ the way we walk
“withdrawal”, “crossed extension”
Manipulation of ___ ____
Primarily_____
Sometimes involves extremely __ motor control
A __ ____ nerves supplying a ____ number of muscle fibers
____ of contents through various ____ internal organs
We think of this as ____ but if you have digestive upset you probably have thought about it
____ activity,___ ____
___ of contents of certain organs to ___ environment
Most ____ but voluntary ____
Voluntary control is learned thru use of sphincter
When propulsion is too great, then no amount of mental activity will stop what is going to happen
Muscle Controlled muscle contraction allows Purposeful movement of the whole body or parts of the body We think about it as being voluntary but frequently there are reflexes that occur at lower brain or spinal cord Very rapid reflexes that provide protective benefit Never really reach our cerebral levels. Hand withdrawn from flame before we even think about it There are other fcns that occur thru the cerebellum Not something that we concentrate on→ the way we walk “withdrawal”, “crossed extension” Manipulation of external objects Primarily voluntary Sometimes involves extremely fine motor control A lot more nerves supplying a smaller number of muscle fibers Propulsion of contents through various hollow internal organs We think of this as involuntary but if you have digestive upset you probably have thought about it Glandular activity, gut motility Emptying of contents of certain organs to external environment Most involuntary but voluntary sphincter Voluntary control is learned thru use of sphincter When propulsion is too great, then no amount of mental activity will stop what is going to happen
Myosin
Component of____ filament
___ molecule consisting of __ ____subunits shaped somewhat like a ___ ___
Tail ends are ____d around each other
Globular heads ____ out at one end In____ directions
Tails oriented toward____r of filament and globular heads protrude____ at regular intervals
Heads form ___ ___ between ___ and ___ ____.
Cross bridge has two important sites critical to contraction
An__ ___ site
A___ ___ (____ ___ ) site
Myosin Component of thick filament Protein molecule consisting of two identical subunits shaped somewhat like a golf club Tail ends are intertwined around each other Globular heads project out at one end In different directions Tails oriented toward center of filament and globular heads protrude outward at regular intervals Heads form cross bridges between thick and thin filaments Cross bridge has two important sites critical to contraction An actin-binding site A myosin ATPase (ATP-splitting) site
Actin
Primary structural component of ___ filaments
____ l in shape
Thin filament also has___ other proteins
____ and ____
Determine level of____ to see amt of ____e that has been done
Eac____ molecule has special binding site for attachment with___ ___ ___
Binding results in____ of muscle fiber
Actin Primary structural component of thin filaments Spherical in shape Thin filament also has two other proteins Tropomyosin and troponin Determine level of troponin to see amt of damage that has been done Each actin molecule has special binding site for attachment with myosin cross bridge Binding results in contraction of muscle fiber
Comment! Actin and myosin are often called ___ ___s …but neither actually ___
Actin and myosin are __ ___to muscle cells, but are more___ and more highly ___d in muscle cells.
Comment! Actin and myosin are often called contractile proteins …but neither actually contracts. Actin and myosin are not unique to muscle cells, but are more abundant and more highly organized in muscle cells.
Tropomyosin and Troponin Often called___ proteins
Tropomyosin
___-like molecules that lie __ to ___ alongside___ of ___ ___
In this position, it ___ ___ ___ blocking interaction that would lead to muscle contraction
Troponin
Made of ____polypeptide units
One binds to ___ One binds to___ One can bind wit___
Tropomyosin and Troponin Often called regulatory proteins Tropomyosin Thread-like molecules that lie end-to-end alongside groove of actin spiral In this position, it covers actin sites blocking interaction that would lead to muscle contraction Troponin Made of three polypeptide units One binds to tropomyosin One binds to actin One can bind with Ca2+
Troponin
When not bound to Ca2+, troponin stabilizes tropomyosin in a “___ ____” over actin’s cross-bridge binding sites
When Ca2+ binds to troponin, then____ moves away from ___ ___
With tropomyosin out of way___ and ___ bind, interact at cross-bridges to cause___ ____
Troponin When not bound to Ca2+, troponin stabilizes tropomyosin in a “blocking position” over actin’s cross-bridge binding sites When Ca2+ binds to troponin, then tropomyosin moves away from blocking position With tropomyosin out of way, actin and myosin bind, interact at cross-bridges to cause muscle contraction
Role of Calcium in Cross-Bridge Formation
Relaxed State: • Muscle Fiber relaxed • ___ cross bridge binding bc binding site on actin covered by ___________n complex
Excited State • Muscle Fiber Excited • ___ Ca binds with t_____n, pulling troponin-tropomyosin complex aside to ____ cross bridge binding site • Cross bridge binding occurs • Binding of actin and myosin at cross bridge triggers ___ _____ that pulls ____filament inward during contraction
Role of Calcium in Cross-Bridge Formation Relaxed State: • Muscle Fiber relaxed • No cross bridge binding bc binding site on actin covered by troponin/tropomyosin complex Excited State • Muscle Fiber Excited • Released Ca binds with troponin, pulling troponin-tropomyosin complex aside to expose cross bridge binding site • Cross bridge binding occurs • Binding of actin and myosin at cross bridge triggers power stroke that pulls thin filament inward during contraction
The Theory & Mechanism
___ ___ ____ between actin and myosin brings about muscle contraction by means of the “___ ____” mechanism.
The Theory & Mechanism Cross-bridge interaction between actin and myosin brings about muscle contraction by means of the “Sliding Filament” mechanism.
“Sliding Filament Mechanism”
____ in ___ initiates filament sliding
____ in _____ turns off sliding process
____ filaments on each side of ____ slide ____ over____ ____filaments toward center of ___ band during contraction
As thin filaments slide inward, they pull __ ___ closer together …thus causing the sarcomere to ____
Sarcomere is measured from__ to ___
“Sliding Filament Mechanism” Increase in Ca2+ initiates filament sliding Decrease in Ca2+ turns off sliding process Thin filaments on each side of sarcomere slide inward over stationary thick filaments toward center of A band during contraction As thin filaments slide inward, they pull Z lines closer together …thus causing the sarcomere to shorten Sarcomere is measured from Z to Z
“Sliding Filament Mechanism”
All sarcomeres throughout muscle fiber’s length___ ____
We have excitation going over the____
Contraction is accomplished by___ ___ s from___ ___s of each sarcomere sliding____r together ____ thick filaments
“Sliding Filament Mechanism” All sarcomeres throughout muscle fiber’s length shorten simultaneously We have excitation going over the membrane Contraction is accomplished by thin filaments from opposite sides of each sarcomere sliding closer together between thick filaments
The Steps toward the “Power Stroke”
____ cross bridge___ twd ___ of ____ flilament, “___” in ___ filament to which it is attached
___ ____ releases Ca into ____
____ ___ bind to actin
Myosin heads swivel toward center of sarcomere (the “power stroke”)
____ binds to myosin head and detaches it from ____
The Steps toward the “Power Stroke” Activated cross bridge bends toward center of thick filament, “rowing” in thin filament to which it is attached Sarcoplasmic reticulum releases Ca2+ into sarcoplasm Myosin heads bind to actin Myosin heads swivel toward center of sarcomere (the “power stroke”) ATP binds to myosin head and detaches it from actin
Key Determinants of The Power Stroke
____ of ___ transfers ____ to myosin head and____ it
Contraction continues IF (1) ___ is available and (2) ___ level in ____ is high
Key Determinants of The Power Stroke Hydrolysis of ATP transfers energy to myosin head and reorients it Contraction continues IF (1) ATP is available and (2) Ca2+ level in sarcoplasm is high
Determinants of “Relaxation”
Depends on____ of Ca2+ into___ ____
_____e breaks down ___ at ___ ____
Muscle fiber action potential stops and when th____ action potential is no longer present, Ca2+ moves back into sarcoplasmic reticulum to wait for next depolarization
Determinants of “Relaxation” Depends on reuptake of Ca2+ into sarcoplasmic reticulum (SR) Acetylcholinesterase breaks down ACh at neuromuscular junction Muscle fiber action potential stops and when the local action potential is no longer present, Ca2+ moves back into sarcoplasmic reticulum to wait for next depolarization