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Final Exam - Muscle Overview
N/A
67
Anatomy
Undergraduate 3
12/10/2012

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Term
What are the three types of muscle?
Definition
skeletal, cardiac and smooth.
Term
What are the functional characteristics of muscle tissue?
Definition
1.)Excitability or irritability - ability to receive and respond to stimuli.
2.)Contractility - the ability to shorten forcibly.
3.)Extensibility - the ability to be stretched or extended.
4.)Elasticity - the ability to recoil and resume original resting length.
Term
How are skeletal and smooth muscles cells similar?
Definition
they are elongated and called muscle fibers.
Term
What 2 myofilaments does contraction depend on?
Definition
Actin and myosin.
Term
What is sarcolemma?
Definition
Muscle plasma membrane.
Term
What is sarcoplasm?
Definition
Cytoplasm of a muscle cell.
Term
What are skeletal muscles responsible for?
Definition
All locomotion.
Term
What is cardiac muscle responsible for?
Definition
Coursing blood through the body.
Term
What is smooth muscle responsible for?
Definition
Maintain blood pressure, squeezes/propels substances through organs.
Term
What are some miscellaneous muscle functions?
Definition
Maintaining posture, stabilizing joints, generating heat.
Term
What is skeletal muscle packaged in and attach to?
Definition
Skeletal muscle tissue and attach to and cover the bony skeleton.
Term
What are the obvious stripes in skeletal muscle and what are they composed of?
Definition
Striations made of proteins.
Term
Are skeletal muscles voluntary or involuntary?
Definition
Voluntary.
Term
How do skeletal muscles contract? Do they tire easily?
Definition
Rapidly and yes.
Term
Skeletal muscle is extremely _________ and can exert forces ranging from a fraction of an ounce to over 70 lbs.
Definition
Adaptable.
Term
Is cardiac muscle voluntary?
Definition
No.
Term
What is the frequency of it's contractions and is set by what?
Definition
Fairly steady and set by heart's pacemaker.
Term
______ _______ allow the heart to respond to changes in bodly needs.
Definition
Neural controls.
Term
Is smooth muscle striated, involuntary or voluntary?
Definition
No and involuntary.
Term
What are the three connective sheaths of skeletal muscle?
Definition
Endomysium - surrounds each muscle fiber
Perimysium - surrounds fascicles
Epimysium - surrounds entire muscle
Term
Most skeletal muscles span joints and are attached to bone in at least ____ spaces.
Definition
2.
Term
The insertion moves ______ the ______.
Definition
towards/origin
Term
Muscles attach ______ & _______.
Definition
directly & indirectly.
Term
What is a direct attachment?
Definition
Epimysium of the muscle is fused to the periosteum of a bone.
Term
What is an indirect attachment?
Definition
Connective tissue wrappings extend beyond the muscle as a tendon or aponeurosis.
Term
Each muscle is served by _____ nerve, _____ and ______.
Definition
one nerve, one artery, one or more veins.
Term
Each skeletal muscle fiber is supplied with a _____ _____ that controls contraction.
Definition
nerve ending
Term
Contracting fibers require _____ ______ __ ________ and _______.
Definition
continuous delivery of oxygen/nutrients
Term
Wastes are removed via ______.
Definition
veins.
Term
Skeletal muscles are stimulated by ____ _____ of the ______ nervous system.
Definition
motor neurons/somatic.
Term
Axons of these neurons travel in ______ to ______ cells.
Definition
Nerves/muscle
Term
Axons of motor neurons ______ as they enter muscles.
Definition
Branch.
Term
Each axonal branch forms a __________ ______ with a single muscle fiber.
Definition
neuromuscular junction.
Term
Neuromuscular junction is formed from _____ ______& ____ _____ ______ of a muscle.
Definition
Axonal endings/ motor end plate.
Term
Skeletal muscle fibers are short, cuboidal cells with 1 nucleus on top of the sarcolemma. TRUE OR FALSE?
Definition
FALSE! Long, cylindrical, multinucleated cells beneath the sarcolemma.
Term
Are fibers wider than they are long or vice versa?
Definition
Fibers are 10-100 mm in width and up to hundreds of centimeters long.
Term
What is the syncytium?
Definition
Produced by the fusion of embryonic cells. Multinucleated.
Term
What are the glycosomes and myoglobin in sarcoplasm?
Definition
Glycosomes - associated with cell metabolism. Forms organelles.

Myoglobin - monomeric heme protein found in muscle tissue and is used as a storage site for oxygen.
Term
What are myofibrils?
Definition
densely packed, rodlike, contractile elements. Make up most of muscle volume.
Term
What are sacromeres and where are the found?
Definition
Smallest contractile unit of a muscle. Region of a myofibril between two successive Z discs.
Term
What are the two types of microfilaments?
Definition
thick and thin.
Term
What is the difference between thick and thin filaments?
Definition
Thick - extend the entire length of A band.
Thin - extend across the I band and partway into the A band.
Term
What is a Z disc?
Definition
coin shaped sheet of proteins that anchors the thin filaments and connects myofibrils to one another.
Term
Do thin filaments overlap thick filaments in the lighter H zone?
Definition
NO!
Term
Why do M lines appear darker?
Definition
Desmin.
Term
What are thick filaments composed of?
Definition
myosin.
Term
What does each myosin molecule contain?
Definition
A rod-like tail and two globular heads.
Term
What are the tails of a myosin molecule made of?
Definition
Two interwoven, heavy polypeptide chains.
Term
What are the heads of a myosin molecule made of?
Definition
Two smaller, light polypeptide chains called cross-bridges.
Term
What are thin filaments made of?
Definition
Actin.
Term
What is actin made of?
Definition
Helical polymer of globular subunits called G actin.
Term
What are the subunits of actin?
Definition
They contain active sites to which myosin heads attach to during contraction.
Term
What are regulatory subunits bound to actin?
Definition
Tropomyosin and troponin.
Term
What is the sarcoplasmic reticulum?
Definition
An elaborate, smooth endoplasmic reticulum that most runs longitudinally and surrounds each myofibril.
Term
What forms perpendicular cross channels?
Definition
Paired terminal cisternae
Term
What is the function of the SR?
Definition
Regulation of intracellular calcium levels.
Term
What are T tubules and their function?
Definition
Elongated tubes that penetrate into the cell's interior at each A band I band junction.
Term
what forms triads?
Definition
T tubules associated with paired terminal cisternae
Term
What do t tubules conduct?
Definition
Impulses to the deepest regions of the muscle.
Term
What do t tubules signal for?
Definition
The release of Ca2+ from adjacent terminal cisternae.
Term
In order to contract, a skeletal muscle must:
Definition
1.)Be stimulated by a nerve ending.
2.)Propogate an electrical current, or action potential, along its sarcolemma.
3.)Have a rise in intracellular Ca2+ levels, the final trigger for contraction.
4.) Linking the electrical signal to the contraction is excitation-contraction coupling.
Term
What is the role of Ach?
Definition
Binds its receptors at the motor end plate which opens chemically gated channels, Na+ and K+ diffuse out and the interior becomes less negative and becomes DEPOLARIZED.
Term
What enzyme destroys Ach?
Definition
Acetylcholinesterase.
Term
What does the destruction prevent?
Definition
Continued muscle fiber contraction in the absence of additional stimuli.
Term
What are the 4 things that happens once an action potential is generated?
Definition
1.)Propogated along sarcolemma
2.)travels down t tubules
3.)triggers ca+2 release from terminal cisternae
4.)Ca2+ binds to troponin
Term
Once Ca2+ is bound to troponin, what does this cause?
Definition
The blocking action of tropomyosin to cease and actin active binding sites are exposed.
Term
Myosin cross bridges alternately attach and detach. Then what?
Definition
Thin filaments move towards the center of the sarcomere. Hydrolysis of ATP powers this cycling process. Ca2+ is removed into the SR, tropomyosin blockage is restored and the muscle fiber relaxes.
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