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55 Cards in this Set

  • Front
  • Back
Mucle arrises from what type of tissue organ (endoderm, mesoderm, or ectoderm?)
Mesoderm
Four ways to classify muscle include
type: skeletal, cardiac, smooth
voluntary vs involuntary
striated vs smooth
contractile components/ myofilaments
Skeletal muscle cells (one fiber) is a cylindrical _____with _______nuclei
Syncytium
-multiple, peripherally located
Syncytium definition
a cell divides without undergoing cytokinesis
In skeletal muscle the fibers are_____packed, (organized/disorganized), (striated or smooth)
tightly packed, organized cytoplasmic protein filaments and striated
Connective tissues assocated with skeletal muscle include three layers
epimysium, perimysium, endomysium
Epimysium
Connective tissue around entire muscle
Perimysium
Connective tissue around groups of myofibers
Endomysium
Connective tissue around individuals myofibers
Is there an extensive or lacking capillary network in skeletal muscle
an extensive capillary network to meet the high energy requirement of skeletal muscle demands
Connective tissue type on skeletal muscle
cross-sectional view of muscle: A. epimysium B. perimysium C. endomysium D. myofibrils E. sarcolemma of one muscle fiber F. collagen fibers
How do you distinguish the I band from the A band on skeletal muscle?
Dark = A band
Light = I band
dArk vs lIght
A Sarcomere is a _____unit that runs from __line to ___line
single contraction unit that runs from z line to z line
The Sarcolema of a muscle fiber can be thought of the
plasma membrane of the cell
The Sarcoplasmic reticulum of a muscle fiber can be compared to the ____ of a generic cell
Endoplasmic reticulum
where Ca++ is released for contraction
Differences in the myofilament of the I and A bands
I band has no myosin included and the A band has both myosin and actin
Distinguish between the A, H, and A band
I band is actin, troponin, and tropomysin (stains light -more eosinophilic)
H band is thick and myosin only
A nad is both actin and myosin with a darker stain
Which band changes in lenght during a contraction/ shortening of the sarcomere?
The H band width becomes shorter and there is no changein teh A band
Name the most superficial connective tissue around a microfiber?
Endomyosin
What are the three thin filaments/ muscle proteins
actin (2 strands of fibrous actin in 2xhelix)
tropomyosin (fibrous, located b/w strands of actin 2x helix)
Troponin (regulatory components, located along actin 2x helix and attached to tropomyosin) Troponin C is associated with Ca++
What is the thick filaments/ muscle protein
myosin- has ATP-ase activity within strand and 2 heavy chain tails connected together
How does a muscle contraction take place?
acetylcholine released from a motor nerve binds to its receptors on the muscle cell,
a wave of depolarization spreads along the sarcolemma into the transverse tubules (these extend
into the interior, so the depolarization wave goes deep into the myofiber), a calcium channel called
DHPR is activated, opening a calcium channel on the SER called the ryanodine receptor, Ca++ is
released from the sarcoplasmic reticulum, Ca++ binds to a protein called ‘troponin’ and allows
myosin to interact with actin, which is necessary for energy + ADP to be formed from ATP; the
energy causes the myosin head to bend, pulling actin along the myosin filament.
What is the difference between a ‘motor endplate’ and a ‘motor unit?’
motor endplate is the myoneural junction: the synapse between the motor axon and
the skeletal fiber; the neurotransmitter is acetylcholine, and there is an enzyme,
acetylcholinesterase, in the synaptic space that inactivates acetylcholine. The ‘motor unit’ is one
alpha (lower) motor neuron in the spinal cord ventral horn and all the myofibers it innervates
What is the neurotransmither that initiates depolarization which spreads via t-tubules
Acetylcholine (ACh)
What are the t-tubules?
Transverse tubules are invaginations of the cel membrane that extend b/w myofibrils
What are the terminal cisternae?
Expansions of the SER and located adjacent to T-tubules
Depolarization of sarcolemma is conducted down T-tubule to the triad junction where the _____ activates the_______ on the sarcoplasmic reticulum
DHPR- dihydropyridine receptor activating the RyR (ryanodine receptor)
An actin-myosin complex forms when _____binds to Calcium and the thick and thin filaments "slide" across one another as the myosin changes conformation when it______
Troponin C
Hydrolyzes ATP
Muscle Fibers can be classified by fnxts and colors including ___-
Red fibers(Type 1= endurance)
White fibers (Type II = sprint)
Intermdt fibers (type IIa)
What is the difference between ‘red’ (type I) myofibers and ‘white’ (type II) myofibers?
Red fibers (type I) are slow twitch but long-endurance, look more ‘red’ because they have
a higher content of myoglobin and cytochromes, more mitochondria and have aerobic metabolism.
White fibers (type IIb) are fast twitch but of short duration – they tire rapidly, have anaerobic
metabolism, low content of myoglobin and cytochromes and have fewer mitochondria. There are
actually fibers intermediate between these two called type IIa.
True or False: The red:white fiber ratio in muscle can be modified
yes by training and use
Muscle Spindle is located_______and serves to _______
b/w endomysium and perimysium and is part of the regulation mechanism of muscle contraction
What is a muscle spindle?
stretch receptors found usually in the c.t. of muscle. They contain miniature
versions of skeletal muscle called “intrafusal fibers” (hence, regular fibers are called “extrafusal
fibers”). They are innvervated by gamma motor neurons (not alpha motor neurons like those
going to extrafusal fibers). They send sensory information to the spinal cord
The sensory nerves in the muscle spindle can ____
sense if the muscle is straight or contracted and detect the degree of the stretch of the intrafusal fibers
The gamma efferent (motor) nerves in muscle spindle maintain ___
tension in the intrfusal fibers
Cardiac muscle is (smooth/ striated ) and (voluntary/voluntary)
striated and involunatry
Distinguishing characteristics of cardiac vs skeletal muscle include
smaller, branched cells, only one centrally located nucleus per cell (some have 2) and intercalated discs (joining cells for end-end communication)
What are ‘satellite’ cells?
Spindle-shaped cells that lie within the basal lamina but outside the sarcolemma.They retain the ability to divide (remember,
the nuclei of the myofiber cannot divide). Thus after injury, especially in young animals, satellite
cells can form some new myofibers
What are the cardiac intercalated discs?
an electron dense junctional comples that contains gap junctions and desmosomes that transmit contractile stimuli and create the functional syncytium
What are the three types of junctions within the intercalted disks?
Fascia adherens
Desmosomes
Gap Junctions
What are the differnt functions of the three types of junctions of the intercalated disks?
Fascia adherens- provide intercellular adhesion, anchors actin filaments
Desmosomes- provide interacellular adhesion (prevent separation during contraction)
Gap Junctions- allow for rapid communication of electric and chemcial signals
For the cardiac muscle contraction the intrinsic conduction system is carried out by_________
Purkinje Fibers and low electrical reistance of gap jnxts
What are the purkinje fibers?
modified cardiac myocytes that are specializaed for orchestrated contraction
Purkinje Fibers
Modified cardiac myocytes specialized for the orchestrated contraction
Distinguishing characteristics of smooth muscle
non-striated
involuntary
cells are spindle-shaped
One nucleus per cell (elongated and oval)
scant CT separated them
unorganized myofilaments
The analogous structure in smooth muscle for T-tubules is the
caveoli
The analogous structure in smooth muscle that holds filaments in register is the
dense bodies
Smooth muscle contraction also involves the myosin and actin interaction but is also regulated by different types of ___
surface receptors that activate diff second messenger systems. this involves phosphorylation of myosin light chains
How do the three types of muscles regenerate themselves?
skeletal muscle-uses satellite cells and connective tissue scars
Cardiac-very little regeneration (transplating stem cells)
Smooth muscle (normal cell division)
smooth muscle
smooth muscle
TEM skeletal muscle
TEM skeletal muscle
comparison chart
chart
does smooth muscle contain gap jnxts?
yes
What is the morphology of smooth muscle cells?
They are long, spindle-like cells (you usually can’t see this on H&E because they blend
together and form a smooth mass); they have one centrally-positioned, elongated nucleus, (which
may appear folded due to contraction after death). Smooth muscle is non-striated and involuntary
muscle spindle
muscle spindle= stretch receptors found usually in the c.t. of muscle. They contain miniature
versions of skeletal muscle called “intrafusal fibers” (hence, regular fibers are called “extrafusal
fibers”). They are innvervated by gamma motor neurons (not alpha motor neurons like those
going to extrafusal fibers). They send sensory information to the spinal cord