-
Most skeletal muscles cross one or more joints to bring about movements in those joints. Which attach of a muscle usually remains stationary when a muscle contracts?
the origin
-
Most skeletal muscles cross one or more joints to bring about movements in those joints. Which attach of a muscle usually moves when a muscle contracts?
the insertion
-
What portion of a whole muscle produces the force?
the belly
-
What is a muscle producing a particular movement called?
agonist
-
What is a muscle that assists the prime mover in its action?
Synergist (examples: Triceps & anconeus)
-
What is a muscle whose actions oppose those of the prime mover?
antagonist
-
Because of the tissue composition of an individual skeletal muscle what level of organization is a muscle such as the biceps brachii or pectoralis major classified within?
An organ
-
What is the study of muscle?
Myology
-
List the four characteristics of muscle tissue.
- excitability
- contractility
- elasticity
- extensibility
-
In some situations, as when you lay an object on a table, a muscle is actually getting longer while doing what you want. One of the characteristics of muscle that most authors list is contractility. Yet a muscle allowing you to extend your elbow in a controlled fashion is not getting shorter. What is it
doing?
Producing force
-
What is another term for skeletal muscle cell?
Muscle fibers
-
What are five functions of muscle tissue. Be aware of how smooth and cardiac muscle as well as skeletal muscle might be involved in these functions.
- body movement
- maintenance of posture
- temperature regulation
- storage and movement of materials
- support
-
What are cordlike structures that attach muscle to bone, skin, or other structures?
tendons
-
What are sheets of tissue that connect muscle to bone, skin, or other structures?
Aponeuroses
-
What is another term for the plasma membrane of a muscle fiber?
sarcolemma
-
What histological term refers to the stripes seen in cardiac and skeletal muscle fibers?
striations
-
What is histological term for the functional connection between a muscle fiber and a motor neuron?
the neuromuscular junction
-
What is the specialized region of the sarcolemma at the neuromuscular junction?
motor end plate
-
What are all of the muscle fibers innervated by a single motor neuron?
a motor unit
-
What is the functional unit of a whole skeletal muscle?
the motor unit
-
How are contractions of varying strengths produced within a skeletal muscle?
by recruiting varying numbers of motor units
-
What is the number of muscle fibers innervated by a single motor neuron?
the innervation ratio
-
What is the relative innervation ratio for muscles involved in fine skeletal movements?
low (1:10 is the low end)
-
What is the relative innervation ratio for muscles involved in gross skeletal movements?
high (1:2000 is the high end)
-
What is the process of activating motor units?
recruitment
-
What are the longitudinal, parallel subunits within a muscle cell?
myofibrils
-
What are the long, thin strands of contractile proteins within a muscle fiber?
myofilaments
-
What are the two types of myofilaments within a muscle fiber?
thick and thin filaments
-
What protein makes up the thick filaments of a muscle fiber?
myosin
-
What protein makes up the thin filaments of a muscle fiber?
actin
-
What is the functional unit of a muscle fiber?
a sarcomere
-
What structure are thin filaments attached to proximally and distally within a sarcomere?
the Z-lines
-
What structure makes up the proximal and distal borders of a sarcomere?
the Z-lines
-
What structure attaches a thick filament to the Z-line?
a titin filament
-
Shortening of a sarcomere occurs due to what action?
sliding of the myofilaments over one another
-
What part of myosin changes configuration to bring about contraction?
the cross bridge (myosin head)
-
What part of a sarcomere functions to split ATP to ADP and Pi and thus release energy for contractions? What is a second name for this part?
the myosin head acts as myosin ATPase
-
What term describes the change in configuration of a cross bridge that is attached to actin?
power stroke
-
What two chemicals are attached to a cross bridge that is cocked but not attached to actin?
ADP + Pi
-
What chemical must be released from a cross bridge in order for the power stroke to occur?
Pi
-
What chemical is released from the cross bridge after the power stroke?
ADP
-
What chemical must attach to the cross bridge in order for it to release from actin after the power stroke?
ATP
-
What is the immediate source of energy for muscle contractions?
ATP
-
What is the result of the hydrolysis of ATP to ADP and Pi after the power stroke?
the energy is used to cock the cross bridge
-
What molecule covers the active sites on actin when a muscle is relaxed?
tropomyosin
-
What molecule is attached to tropomyosin to allow its regulation?
troponin
-
What ion binds to troponin to change it configuration?
Ca++
-
What organelle stores calcium within a muscle fiber?
the sarcoplasmic reticulum
-
What neurotransmitter occurs at the neuromuscular junction?
acetylcholine
-
What structures open to the extracellular environment outside of a muscle fiber and conduct action potentials through the cell?
transverse tubules
-
Action potentials within a muscle fiber are not graded. What is this effect called?
the all-or-none law
-
What type of structure opens within the t-tubules in response to depolarization?
voltage-gated Ca2+ channels
-
What type of mechanism regulates the release of Ca2+ from the sarcoplasmic reticulum?
Ca2+-induced Ca2+ release mechanism
-
What structures remove Ca2+ from the sarcoplasm once a muscle fiber is no longer depolarizing?
Ca2+-ATPase pumps
-
What type of contraction occurs as a muscle actually gets shorter when producing force?
isotonic or concentric
-
What type of contraction occurs when a muscle does not change its length as it produces force?
isometric
-
What type of contraction occurs when a muscle is elongated as it produces force?
eccentric or lengthening
-
What is the general relationship between the length of a muscle and the tension it is able to produce?
There is an ideal length (2-2.25 m) at which the fiber produces maximum force. Any increase or decrease in this length lessens the force produced.
-
Skeletal muscles at rest obtain most of their energy from what?
aerobic respiration of fatty acids
-
What is the main source of energy for skeletal muscle during heavy exercise?
muscle glycogen
-
Exercise increases the what carrier molecule in the plasma membranes of muscle fibers?
GLUT 4 (the carrier protein for glucose)
-
What source of energy usually makes up the largest percentage of that used by a muscle?
free fatty acids from the plasma
-
What is the maximum rate of oxygen consumption by the body?
VO2max (maximal oxygen uptake or aerobic capacity)
-
What units is V-O-2 max measured in?
ml of oxygen per minute per kilogram of body weight
-
What is the general range of V-O-2 max overall?
12 ml/min/kg in older, sedentary people to 84 ml/min/kg in young, elite, male athletes
-
What is the percentage of the maximal oxygen uptake at which a significant rise in blood lactate
levels occurs?
lactate threshold
-
Why does a person continue to breathe heavily after exercise?
to repay the oxygen debt
-
What is the cause of oxygen debt?
the use of oxygen stored in hemoglobin and myoglobin
-
What substance is used to make ATP when ATP is used faster than it can be produced through
cellular respiration?
creatine-phosphate (phosphocreatine)
-
What are the two categories of skeletal muscle fibers based on contraction time?
slow-titch (type I) and fast-twitch (type II)
-
Within muscles, what is the red pigment, similar to hemoglobin, that stores oxygen?
myoglobin
-
Based on metabolism, what other term may be used for slow-titch muscle fibers?
slow-oxidative
-
Based on the amount of myoglobin, what is another term for slow-twitch muscle fibers?
red fibers
-
Based on the amount of myoglobin, what is another term for fast-twitch fibers?
white fibers
-
Based on metabolism, what are the two types of fast-twitch fibers?
fast oxidative (type IIA) and fast glycolytic (type IIX)
-
What is exercised-induced reduction in the ability of a muscle to generate force?
muscle fatigue
-
What appears to be the cause of muscle fatigue during maximal contractions?
an accumulation of K+ outside of the cells
-
What are the two major components of muscle fatigue?
peripheral (within muscles) and central (in the CNS)
-
What is the general adaptation shown in muscles trained for endurance?
an increase in aerobic capacity through such changes as more mitochondria and capillaries
-
What is the general adaptation of muscles trained with high-intensity exercise?
hypertrophy from an increase in cross-sectional area of fibers and an increase in the number of fibers
-
How can damaged muscle fibers be replaced?
through the conversion of satellite cells into muscle fibers
-
What sensor responds to the tension put on tendons?
Golgi tendon organ
-
What sensor responds to changes in muscle length?
muscle spindle apparatus
-
What is a response to sensory input that does not depend on the activation of upper motor neurons?
a reflex
-
What is the neural pathway of a reflex?
a reflex arc
-
What type of reflex arc involves a single synapse within the CNS?
a monosynaptic reflex
-
What reflex occurs in all muscles in response to a rapid change in their length?
the stretch reflex
-
What type of reflex has two synapses within the CNS?
a disynaptic reflex
-
What is the effect of feedback from the Golgi tendon organs?
inhibition resulting in relaxation
-
Stretch reflexes involve dual innervation. The agonist is excited. The antagonist is inhibited. What is this dual innervation called?
reciprocal innervation
-
What is reciprocal innervation of both the side of the body sensing a reflex stimulus and the contralateral side?
double reciprocal innervation
-
What type of double reciprocal innervation occurs when a painful stimulus occurs on the sole of one
foot?
a crossed-extensor reflex
|
|
