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A&P Test 2
Muscular System
39
Anatomy
Professional
02/04/2010

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Term
space between the motor neuron and the motor end plate; also the space that Ach is released into
Definition
synaptic cleft
Term
by what method is is Ach released into the synaptic cleft?
Definition
exocytosis
Term
contains Ach receptors
Definition
motor end plate on the sarcolemma
Term
functions in movement, heat generation, posture, and joint stabilization
Definition
the muscular system
Term
the 3 muscle types all contain this
Definition
myofilaments
Term
all 3 muscle types have this common function
Definition
movement
Term
individual skeletal muscle cells(fibers) are wrapped in
Definition
endomysium
Term
when epimysium itself is fused to bone or cartilage the attachment is known as
Definition
direct attachment
Term
the attachment site at the movable bone is known as
Definition
insertion attachment
Term
specialized plasma membrane of skeletal muscle cells
Definition
sarcolemma
Term
invaginates into T-tubules at A band I band junction
Definition
sarcolemma
Term
cytosol of muscle cells
Definition
sarcoplasm
Term
rod like structures contained within skeletal muscle cells that are made of myofilaments and associated proteins
Definition
myofibrils (an organelle)
Term
made mostly of actin and regulatory proteins
Definition
thin filaments (a type of myofilament)
Term
what 4 banding patterns on the myofibrils are responsible for striations?
Definition
A band, I band, H zone, Z disk
Term
lighter region in center of each A band which lacks thin filaments when muscle fibers are relaxed
Definition
H zone
Term
cylindrical protein that blocks myosin binding sites on actin to prevent myosin binding
Definition
tropomyosin
Term
organelles that act as contractile elements in skeletal muscle cells
Definition
myofibrils
Term
smooth endoplasmic reticulum of muscle cells that forms a network for tubules around each myofibril in muscle cell
Definition
sarcoplasmic reticulum
Term
anchors actin (thin filaments)
Definition
nebulin (which makes up the Z disk)
Term
proposed mechanism of contraction that states that during contraction actin slides past myosin causing overlap, while myosin stays mostly still
Definition
sliding filament model/theory
Term
I bands do what during muscle contraction due to the sliding of actin?
Definition
shorten
Term
H zones do what during muscle contraction due to the sliding of actin?
Definition
disappear
Term
thin filament sliding is mediated by _____ attaching, ratcheting, and detaching from actin filaments
Definition
cross bridges(myosin heads)
Term
tropomyosin blocks myosin binding sites on actin when?
Definition
when intracellular Ca2+ levels are low
Term
What is it called when you have a junction between a motor neuron's branched axonal terminal and a skeletal/cardiac muscle cell?
Definition
a neuromuscular junction (nm junction)
Term
Describe the events at the nm junction leading to sarcolemma action potential and skeletal muscle contraction in 6 steps.
Definition
1. Action potential arrives at axon terminal of the motor neuron.
2. Voltage gated Ca2+ Channels open and Ca2+ enters the axon terminal.
3. Ca2+ entry causes synaptic vesicles to release Ach by way of exocytosis.
4. Ach diffuses across the synaptic cleft and binds to receptors in the sarcolemma.
5. Ach binding opens ion channels that allow simultaneous passage of Na+ into muscle cells and K+ out.
6. Ach effects are terminated by its enzymatic breakdown in the synaptic cleft by acetylcholine esterase.
Term
action potential is an electrical impulse generated by rapid influx of what?
Definition
Na+
Term
Rapid Na+ flow into the cell causes _____ of membrane above the threshold level.
Definition
depolarization
Term
At how many mV do Ach receptors open up to post synaptic membrane depolarization?
Definition
-70mV
Term
From the action potential on the sarcolemma, to the sliding myofilaments, to muscle contraction is all known as what process?
Definition
excitation contraction coupling
Term
small, spindle shaped cells with single nuclei, also called "muscle fibers", not striated
Definition
smooth muscle cells (fibers)
Term
junction with no motor end plate for neurotransmitters
Definition
diffuse junctions
Term
most hollow organs have how many sheets of smooth muscle?
Definition
2
Term
in cardiac muscle a signal from the autonomic nervous system causes excitation or inhibition?
Definition
either
Term
The arteries and the GI tract are examples of this
Definition
smooth muscle
Term
these display autorhythmicity
Definition
cardiomyocytes
Term
How does contraction speed of cardiac muscle compare to that of skeletal muscle?
Definition
it's slower
Term
this makes up wall of hollow organs
Definition
smooth muscle
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