A&p Ch. 6 Muscle

Front 1

The branch of motor system that controls skeletal muscle.

Back 1

somatic

Front 2

Consists of thin filaments composed of polymerized actin and thick filaments composed of aggregations of myosin.

Back 2

contractile machinery

Front 3

Protein component of the sarcomere. The thin polymerized filaments in the contractile machinery of all muscle.

Back 3

actin

Front 4

Protein component of the sarcomere. Aggregations of filaments in the contractile machinery of all muscle.

Back 4

myosin

Front 5

The basic functional unit of the contractile machinery of
striated muscle.

Back 5

sarcomere

Front 6

Contained within heart muscle that are spontaneously active and can serve as pacemakers for the entire heart.

Back 6

nodal fibers

Front 7

Some heart muscle fibers that are spontaneously active.

Back 7

pacemakers

Front 8

Muscle not connected by gap junctions and typically is not
spontaneously active. Such muscle is found in the iris of the eye and in the arrector pili muscles attached to individual hairs.

Back 8

multiunit smooth muscle

Front 9

A type of smooth muscle that contains extensive gap junction
connections, making it possible for a large number of neighboring cells to contract simultaneously as if they were one unit. Such muscle is found in the GI tract and in blood
vessels.

Back 9

single-unit smooth muscle

Front 10

Stem cells that fuse to form skeletal muscle during embryonic development, with the result that the mature cells are long cylinders with multiple nuclei.

Back 10

myoblasts

Front 11

A layer of connective tissue that wraps each individual muscle fiber.

Back 11

endomysium

Front 12

Bundles of fibers enclosed in connective tissue sheaths of perimysium.

Back 12

fascicles

Front 13

A covering that surrounds all of the fascicles.

Back 13

epimysium

Front 14

The attachment of muscle to bone may be direct, or the connective tissue may extend beyond the muscle to form a cord-like tendon or a sheet-like _________..

Back 14

aponeurosis

Front 15

When the arrangement of the fascicles converge from a broad origin toward a tendon so that the muscle has a fan shape.

Back 15

convergent

Front 16

The arrangement of the muscle looks like a feather with the
fascicles (the barbs of the feather) projecting at an angle from a tendon (the shaft of the feather) that runs the whole length of the muscle.

Back 16

pennate

Front 17

The central principle of leverage is: effort × length of effort arm= load × length of load arm.

Back 17

leverage

Front 18

Leverage using a small force operating over a large distance to move a heavy load a short distance.

Back 18

mechanical advantage

Front 19

Leverage allowing a strong force to move a light load rapidly through distance.

Back 19

mechanical disadvantage

Front 20

The fulcrum lies between the effort and the load so that moving the effort arm in one direction moves the load in the
other direction.

Back 20

first class lever

Front 21

The load is attached between the effort and the fulcrum. The closer the load is to the fulcrum relative to the position of the effort, the greater the mechanical advantage.

Back 21

second class lever

Front 22

Effort is applied between the load and the fulcrum. The load is moved rapidly, but with a mechanical disadvantage—the disadvantage increases with the length of the load arm.

Back 22

third class lever

Front 23

Muscles that are responsible for a particular movement.

Back 23

agonists

Front 24

Muscles that oppose or reverse a movement.

Back 24

antagonist

Front 25

A motor neuron, together with its muscle fibers.

Back 25

motor unit

Front 26

The connection between a motor neuron and a skeletal muscle fiber.

Back 26

neuromuscular junction

Front 27

A neurotransmitter. When _________ interacts with receptors on the muscle fiber, an action potential is initiated in
the muscle fiber membrane.

Back 27

acetylcholine

Front 28

Rapid, brief (several msec in duration) changes in the membrane potential of a neuron or muscle cell.

Back 28

action potential

Front 29

Each skeletal muscle fiber either contracts maximally or not at all.

Back 29

all-or-nothing principle

Front 30

A process that will result in a detectable mechanical response
of the muscle, as the action potential sweeps across the muscle cell surface.

Back 30

excitation-contraction coupling

Front 31

A measurable delay between muscle excitation and the onset of tension development or shortening in the muscle.

Back 31

latent period

Front 32

Follows each action potential.

Back 32

refractory period

Front 33

Early in the refractory period a period restimulation is effectively impossible.

Back 33

absolute refractory period

Front 34

A period during which it is more difficult to restimulate the muscle.

Back 34

relative refractory period

Front 35

The force summation in muscle generated by the newly added motor units to increase force production summates with the
force produced by the units already active.

Back 35

spatial summation

Front 36

The force delivered by a muscle may increase in proportion to
the intensity of the stimulus delivered to its motor nerve, even
though each motor neuron and each muscle fiber obeys the allor-
nothing rule.

Back 36

graded strength principle

Front 37

The muscle is not allowed to shorten, although tension does develop in the muscle.

Back 37

isometric contraction

Front 38

The muscle is allowed to shorten and lift a load.

Back 38

isotonic contraction

Front 39

Part of the contractile machinery of the muscle to which thin filaments are attached.

Back 39

Z discs

Front 40

Double strands of polymerized actin.

Back 40

thin filaments

Front 41

A theory of muscle contraction that states that each thick filament has one end overlapping slightly with the thin filaments of one Z disc and the other end among the thin filaments of the other Z disc. Shortening of the distance
between the hairbrushes occurs as the thick filaments pull both
sets of thin filaments toward the center.

Back 41

sliding filament theory

Front 42

Structural proteins associated with thin filaments; serves as a molecular yardstick that limits the length of thin filaments.

Back 42

nebulin

Front 43

Connects the ends of thick filaments to Z disc to prevent
sarcomeres from falling apart; believed to be largely responsible for the series elastic properties of muscle

Back 43

titin

Front 44

Forms the Z discs.

Back 44

CapZ

Front 45

Attaches thin filaments to Z disc and determines their spacing.

Back 45

alpha actinin

Front 46

Attachments made by myosin heads to actin binding sites that generate force during muscle contraction.

Back 46

crossbridges

Front 47

A rotation of the head that applies force to the thin filament.

Back 47

power stroke

Front 48

Can be determined by subtracting the predetermined passive tension curve from the total tension curve.

Back 48

active tension

Front 49

Skeletal muscles that are removed from the body assume a standard length.

Back 49

rest length

Front 50

The curve of ____________ of a muscle has a value of zero at
rest length and rises as the length is made greater than rest length.

Back 50

passive tension

Front 51

Can be determined by subtracting the predetermined passive tension curve from the total tension curve.

Back 51

active tension

Front 52

The curve shows that the active tension is maximal when the muscle is near its rest length.

Back 52

length-tension curve

Front 53

The optimal range of contractile performance created by the leverage arrangements imposed by the skeleton that restricts muscle lengths.

Back 53

operating range

Front 54

The site within the cell where Ca++ is stored.

Back 54

sarcoplasmic reticulum (SR)

Front 55

A vessel formed by the SR, near the Z disc of each sarcomere.

Back 55

terminal cisterna

Front 56

Finger-like projections of plasma membrane (T tubules) that project into the interior of the muscle fiber and pass close to each terminal cisterna.

Back 56

transverse tubules

Front 57

Formed by T tubules lying between two terminal cisternae.

Back 57

muscle triad

Front 58

The protein components of the endfeet that sense the action potential passing along the T tubule.

Back 58

voltage sensors

Front 59

Stretch components that are part of the contractile machinery.

Back 59

series elastic elements

Front 60

A form of summation in muscle contraction: If the muscle is
restimulated within a few tens of msec, the force or shortening
generated in the second twitch can summate, or add on top of, the initial one, making a stepwise increase in tension or decrease in length.

Back 60

temporal summation

Front 61

A smooth rise in muscle tension or decrease in length resulting
from the further reduction of the interval between successive
impulses.

Back 61

tetanus

Front 62

A tetanic contraction of all of the fibers of a muscle—almost never occurs

Back 62

complete tetanus

Front 63

An incomplete tetanus that does not involve all of the fibers of the muscle at any one time.

Back 63

a typical contraction

Front 64

The force summation in muscle generated by the newly added
motor units to increase force production summates with the
force produced by the units already active.

Back 64

spatial summation

Front 65

Muscle activity requires _______ ?

Back 65

ATP

Front 66

The enzyme that catalyzes the transfer of phosphate groups
from CrP to ADP and from ATP to Cr.

Back 66

creatine phosphokinase

Front 67

ATP + Cr =

Back 67

ADP + CrP

Front 68

Skeletal muscle fibers can be divided into two major categories:

Back 68

slow twitch (Type I) and fast twitch (Type II).

Front 69

Type I muscle expresses a myosin that cycles less rapidly than that expressed by Type II fibers.

Back 69

slow twitch (Type I)

Front 70

Type II muscle expresses a myosin that cycles more rapidly than that expressed by Type I fibers.

Back 70

fast twitch (Type II) Skeletal muscle fibers.

Front 71

An intracellular oxygen carrier.

Back 71

myoglobin

Front 72

Type I fibers that are a red color due to myoglobin.

Back 72

red fibers

Front 73

Slowly fatiguing Type IIa fibers that contain some myoglobin

Back 73

pink fibers

Front 74

Rapidly fatiguing Type IIb fibers contain some myoglobin.

Back 74

white fibers

Front 75

A sustained increase in oxygen uptake that follows exercise.
In order to incur an oxygen debt, the exercise must be of such
intensity that it demands significant recruitment of Type IIb
fibers.

Back 75

oxygen debt

Front 76

Involuntary contractions of skeletal muscles initiated when the
core body temperature falls below its central setpoint, resulting
in an increase in heat production.

Back 76

shivering

Front 77

Defined as the mass of the load multiplied by the distance it is moved.

Back 77

Work

Front 78

Defined as a set of adaptive changes that occurs in response to exercise

Back 78

Conditioning

Front 79

With conditioning skeletal muscles undergo adaptive changes
that are visible mainly as an increase in the size of the cells.

Back 79

hypertrophy

Front 80

An increase in the number of muscle cells.

Back 80

hyperplasia

Front 81

A dramatic loss of muscle mass due to long-term immobilization of a muscle.

Back 81

disuse atrophy

Front 82

Structures that make durable end-to-end connections between
the plasma membranes of adjacent fibers in cardiac muscle.

Back 82

intercalated discs

Front 83

Attaches some of the network of actin thin filaments within the
interior of smooth muscle cells. These bodies are the functional equivalent of the Z disc in striated muscle.

Back 83

dense bodies

Front 84

Electrical excitation results in the opening of plasma membrane Ca++ channels that induce Ca++ release from the SR.

Back 84

elecromechanical route,

Front 85

The second messages set in motion by autonomic transmitters
may control release of Ca++ from the intracellular stores without involvement of a change in membrane potential

Back 85

pharmacomechanical route

Front 86

An enzyme that phosphorylates a portion of the myosin head.

Back 86

myosin light-chain kinase (MLCK)

Front 87

Removal of the phosphate by an enzyme called ___________ serves as a turn-off pathway that can be initiated by an inhibitory autonomic signal

Back 87

myosin light chain phosphatase

Front 88

A type of smooth muscle that contains extensive gap junction
connections, making it possible for a large number of neighboring cells to contract simultaneously as if they were one unit. Such muscle is found in the GI tract and in blood
vessels.

Back 88

single-unit smooth muscle

Front 89

Muscle not connected by gap junctions and typically is not
spontaneously active. Such muscle is found in the iris of the eye and in the arrector pili muscles attached to individual hairs.

Back 89

multiunit smooth muscle