Muscles generate what three things?
motion, force, and heat
Skeletal muscles are controlled by..
somatic motor neurons
Cardiac and smooth muscle are controlled by..
autonomic innervation, paracrines, and hormones
___ is the more distal or mobile attachment.
Insertion
___ bring bones closer together
flexors
___ move bones further apart
extensors
Flexor-extensor pairs are examples of..
antagonistic muscle groups
___ allow action potentials to move rapidly into the interior of the fiber and release calcium from the sarcoplasmic reticulum.
T-tubules
___ are intracellular bundles of contractile and elastic proteins.
Myofibrils
___ are made of myosin.
Thick filaments
___ are made of mostly actin
thin filaments
___ and ___ hold thick and thin filaments in position.
Titin, nebulin
Myosin binds to actin, creating ___ between thick and thin filaments
crossbridges
One ____ is composed of two Z-disks and the filaments between them.
Sarcomere
A sarcomeere is divided into ___ (thin filaments only).
I bands
An ____ runs the length of a thick filament.
A band
_____ is occupied of thick filaments only.
H zone
M line is an attachment site for...
myosin
Z disks are attachment sites for...
actin
The force created by contracting muscle is called
muscle tension
The ____ states that during contraction, overlapping thick and think filaments slide past each other in an energy dependent manner as a result of acin-myosin crossbridge movement.
Sliding filament theory of contraction
In a relaxed muscle, ____ partially blocks the myosin-binding site on actin.
Tropomyosin
To initiate contraction, Ca2+ binds to ___, unblocking the myosin-binding sites and allows myosin to complete its power stroke
troponin
During relaxation, the sarcoplasmic reticulum uses a _____ to pump Ca2+ back into its lumen.
Ca2+-ATPase
Myosin converts energy from ATP into motion, ____ hydrolyzes ATP to ADP and P.
Myosin ATPase
When myosin releases P, the myosin head moves in the _____.
power stroke
At the end of the power stroke, myosin releases ADP. The cycle ends in the ____, with myosin tightly bound to actin.
Rigor state
In _____, a somatic motor neuron releases ACh, which initiates a skeletal muscle action potential that leads to contraction.
excitation-contraction coupling
Voltage-sensing Ca2+ channels called ____ in the t-tubules open RyR Ca2+ release channels in the sarcoplasmic reticulum
DHP receptors
___ occurs when Ca2+ is pumped back into the SR by a Ca2+-ATPase
Relaxation
Single contraction-relaxation cycle is known as a ___.
twitch
The ___ between the end of the muscle action potential and the beginning of muscle tension development represents the time required for Ca2+ release and binding to troponin
latent period
Muscle fibers store energy for contraction in ____.
Phosphocreatine
____ is a reversible condition in which a muscle is no longer able to generate or sustain the expected power output.
Muscle fatigue
Skeletal muscle fibers can be classified on the basis of their speed of contraction and resistance to fatigue into what three fibers?
fast-twitch glycolytic, fast-twitch oxidative-glycolytic, and slow-twitch (oxidative)
___ is an oxygen binding pigment that transfers oxygen to the interior of the muscle fiber.
Myoglobin
the tension is of a skeletal muscle contraction is determined by the ____ before contraction begins.
length of the sarcomeres
Maximal contraction
tetanus
____ are of the same fiber type.
motor units
The force of contraction within a skeletal muscle can be increased by ___ of additional motor units.
recruitment
An ____ creates force as the muscle shortens and moves a load.
isotonic contraction
An ____ creates force without moving a load
isometric contraction
Isometric contractions occur because ____ allow the fibers to maintain constant length even though the sarcomeres are shortening and creating tension.
series elastic elements
Contraction is fastest when the load on the muscle is..
zero
___ can sustain contractions longer than skeletal muscle without fatiguing
smooth muscle
___ are relaxed, ___ are usually contracted. (smooth muscle)
Phasic muscles, tonic smooth muscle
Smooth muscle has less ___ than skeletal muscle
myosin
____ contracts as a single unit when depolarizations pass form cell to cell through gab junctions
single-unit smooth muscle
In ___, individual muscle fibers are stimulated independently
multi-unit smooth muscle
Smooth muscle sarcoplasmic reticulum has both RyR Ca2+ release channels and ____.
IP3-receptor channels
MLCK phosphorylates ______ which activates myosin ATPase. THis allows corssbridge power strokes
myosin light protein chains
During relaxation Calcium is pumped out of the cytosol, and myosin light chains are dephosphorylated by ___
myosin phosphatase
In ____, stretch on the cell depolarizes it and opens membrane Ca2+ channels
myogenic contraction
Unstable membrane potentials in smooth muscle take the form of either ____ or pacemaker potentials.
slow wave potentials
In ____, smooth muscle contraction initiated by chemical signals can take place without a significant change in membrane potential.
pharmacomechanical coupling