Because the cells of skeletal muscle are relatively large and cylindrical in shape, they are also known as ____.
fibers
Over each Z disc, the SR forms the thickened areas called the __________.
terminal cisternae
the force generated by whole muscle reflects the # of active ______ at a given time
motor units
Name parts #4-6
4: Z-disc
5: H Zone
6: Z-disc
What type of force is produced by the physiological contraction of a muscle rather than by elastic recoil?
active
a process that when the # of active motor units increases, there is a steady increase in muscle force produced
motor unit recruitment
Name parts #10-12
10: triad
11: mitochondria
12: myofibrils
Name parts #13-16
13: tubules of sarcoplasmic reticulum
14: terminal cisterna of the sarcoplasmic reticulum
15: T tubule
16: myofibril
Name parts #1-3
1: sarcolemma
2: mitochondrion
3: myofibril
Name parts #4-6
4: bone
5: perimysium
6: fascicle (wrapped by perimysium)
The movable attachment site of a muscle is called ___.
insertion
The junction between an axon and a muscle fiber is called a ____.
neuromuscular junction
Fascicles are covered by a connective tissue sheath called the ___________.
perimysium
If we place a muscle under more load than it can lift and stimulate it, what type of contraction will we produce?
isometric
contractile of unit of muscle
sacromere
isolated skeletal muscle resulting in an increase in force produced by the whole muscle
stimulus frequency
actin- or myosin-containing structure
myofilament
Identify the indicated region of the sarcomere.
H-zone
Motor neurons release the neurotransmitter ________ onto the sarcolemma.
acetylcholine
Name parts #10-12
10:
11:
12:
Name parts #4-6
4: I band
5: Z disc
6: H zone
as the ______ to a muscle is increased beyond the threshold voltage, the amount of force produced by the whole muscle also increases
stimulus voltage
superficial sheath that covers the entire muscle
epimysium
If we place a muscle under a load than it can lift and stimulate it, what type of contraction will we produce?
isotonic
sum of passive and active forces
total force
when muscle fibers that are developing tension are stimulated again before the fibers have relaxed
wave summation
The three phases of a muscle twitch are the contraction period, the relaxation period, and the:
latent phase
The endoplasmic reticulum of a muscle cell is called
sarcoplasmic reticulum (SR)
plasma membrane of the muscle fiber
sarcolemma
From what cellular organelle is calcium released during the latent period of a muscle twitch?
sarcoplasmic reticulum
Each muscle fiber is surrounded by thin connective tissue called the ____.
endomysium
Identify the indicated structure.
sarcoplasmic reticulum
What type of force is produced by the elastic recoil of a stretched muscle?
passive
In what way is the stimulation of a muscle to produce treppe different from stimulation to produce summation?
treppe
Membrane potential changes from the _______ travel along the T tubules to the _____ and signals the release of calcium from the SR, which initiates _______.
sarcolemma; triads; contraction
The absence of what molecule is involved in the phenomenon of rigor mortis?
ATP
a skeletal muscle produces what when nervous or electrical stimulation is applied
tension (a.k.a. muscle force)
bundle of muscle fibers
fascicle
if the muscle shortens as the load moves, the contraction is called
isotonic concentric contraction
* failure of a muscle fiber to produce tension because of previous contractile activity;
* a decline in the muscle’s ability to maintain a constant force of contraction after prolonged, repetitive stimulation
fatigue
when stimuli frequency reaches a value beyond which no further increases in forces are generated by the muscle
maximal tetanic tension
In sarcomeres, what corresponds to the light striations?
I band
Identify the indicated region of the sarcomere.
A-band
What experimental factor do we increase to produce tetany rather than simple wave summation?
frequency of stimulation
In sarcomeres, what corresponds to the dark striations?
A band
Immovable attachment site of a muscle is called the _____
origin
a long organelle with a banded appearance found within muscle fibers
myofibril
maximal tension in the whole muscle occurs when all the muscle fibers have been activated by a sufficiently strong stimulus
maximal voltage
What phenomenon is considered an extreme form of wave summation in which a steady, sustained contraction is achieved?
tetanus, tetany
Flat sheets of the tendon are called _________.
aponeuroses
isometric
same length
Identify the indicated layer of connective tissue.
endomysium
Identify the indicated structure.
muscle fiber
rise in muscle tension but no observable movement of the weight
latent period
maximum possible from each stimulus will eventually reach a plateau
unfused tetanus
a single stimulated contraction of the whole skeletal muscle
muscle twitch
In skeletal muscle, the signal that initiates contraction is always ________, meaning it comes from the _______.
neurogenic; motor neuron
the mechanical response to a single action potential
muscle twitch
In sarcomeres, what anchors to the proteins of the Z disc on one end?
thin filaments
a graph relating the three forces generated and the fixed length of the muscle
isometric length-tension relationship
Muscles contain ______________ and ___________ tissues.
skeletal muscle; regular connective
Name parts #1-3
1: Part of skeletal muscle fiber (cell)
Left image 2: sarcolemma
Right image 2: I band
3: A band
a process where the end-plate potential triggers a series of events that results in the contraction of the muscle cell
excitation-contraction coupling
What type of force is produced by the elastic recoil of a stretched muscle?
passive
The SR surrounds each _____ so that calcium can reach the ___________.
myofibril; contractile machinery
Name parts #1-3
1: Z disc
2: M line
3: Z disc
cord of collagen fibers that attaches a muscle to a bone
tendon
What type of force is produced by the physiological contraction of a muscle rather than by elastic recoil?
active
Name parts #7-9
7: blood vessel
8: endomysium
9: muscle fiber (cell)
A cordlike structure that connects a muscle to another muscle or bone is _____.
a tendon
Individual muscles are ______.
Organs
Name parts #4-6
4: thin (actin) filament
5: elastic (titin) filaments
6: thick (myosin) filament
thin aerolar connecive tissue surrounding each muscle fiber
endomysium
Name parts #1-3
1: tendon
2: epimysium
3: endomysium (between fibers)
Name parts #7-9
7: M line
8: Z disc
9: sarcolemma
Name parts #7-9
7: thin (actin) filament
8: thick (myosin) filament
9: I band
skeletal muscle length changes and load moves a measurable distance
isotonic contraction
Identify the indicated structure.
fascicle
the rate of stimulus delivery to the muscle
stimulus frequency
stimuli applied with greater frequency which have twitches beginning to twitch and fuse so peaks and valleys of each twitch become indistinguishable from one another
complete (fused) tetanus
A ___________, which is continuous with the sarcolemma, also runs along each myofibril at the Z disc.
transverse tubule (T tubule)
The SR stores ______ and release them whenever a change in the membrane potential signals the start of a muscle contraction.
calcium ions
If we place a muscle under a load than it can lift and stimulate it, what type of contraction will we produce?
isotonic
In sarcomeres, what forms the thin filaments that overlap the thick filaments?
actin
Name parts #10-12
10: A band
11: I band
12: sarcomere
Identify the indicated region of the sarcomere.
A-band
Blood vessels and nerves travel through the ________.
perimysium
The contractile unit of muscle is ______.
sacromere
Name #13-15.
13: dark A band
14: Light I band
15: nucleus
the smallest stimulus required to induce an action potential in a muscle fiber’s plasma membrane
threshold voltage
connective tissue covering a bundle of muscle fibers
perimysium
List two of the seven criteria listed in your lab manual that are used to name muscles?
direction of muscle fibers
relative size
location
number of origins
location of origin and insertion
shape
action
Identify the type of muscle tissue shown?
Smooth
What neurotransmitter do motor neurons use to stimulate muscle cells?
acetylcholine
If a muscle contracts against a load that it is able to lift, what type of contraction is the muscle demonstrating?
isotonic
If we stimulate a muscle, and then stimulate it again immediately after it has been allowed to relax, we observe that the second contraction of the muscle is slightly greater than the first. What do we call this phenomenon?
treppe
If a muscle contracts against a load that is too heavy for the muscle to lift, what type of contraction is the muscle demonstrating?
isometric
What do we call muscles that oppose or reverse a particular movement?
antagonists
If we stimulate a muscle, and then stimulate it again immediately after it has been allowed to relax, we observe that the second contraction of the muscle is slightly greater than the first. What do we call this phenomenon?
treppe
What do we call muscles that immobilize the origin of another muscle so that all of the tension is exerted at the insertion?
fixators
Name one action of the semitendinosus muscle.
extension of thigh
flexion of leg
medial rotation of leg
Name one action of the trapezius muscle.
extension of head
elevation of scapula
rotation of scapula
adduction of scapula
Name one action of the biceps brachii muscle.
flexion of forearm
supination of forearm
Name one insertion of the supraspinatus muscle.
greater tubercle of humerus
Name one insertion of the biceps brachii muscle.
radial tuberosity
Name one insertion of the orbicularis oculi muscle.
eyelid
Name one insertion of the flexor carpi radialis muscle.
base of metacarpals II and III
Name one origin of the gastrocnemius muscle.
medial and lateral condyles of femur
Name one origin of the supraspinatus muscle. Name one origin of the supraspinatus muscle.
supraspinous fossa of scapula
Identify the indicated muscle.
semimembranosus
Identify the indicated muscle.
extensor digitorum longus
peroneus