The "all-or-none" concept of skeletal muscle contraction means that
Muscle fibers contract completely.
Action potential frequency is best described as:
The number of action potentials produced per unit of time.
All of the following are true of muscle tone except
depends on multiple motor units contracting in phase with each other
Binding of acetylcholine with its receptor on muscle cells causes
opening of a ligand-gated sodium channel
A buildup of acetylcholine in the synaptic cleft without breakdown may cause . . .
A connective tissue on the surface of muscles (that extends onto the tendon and bone) is known as
The cytoplasm within the muscle fiber contains a molecule to distribute oxygen within the cell. This molecule is known as
During an action potential, calcium is released into the sarcoplasm, near the actin and myosin molecules. Which of the following is the best explanation of what the calcium does?
The calcium removes the tropomyosin block
An effect of aging on skeletal muscle is increased time for muscle to respond to stimuli, increased recovery time, loss of muscle fibers. What is not an effect of aging on skeletal muscle?
Explain why treppe takes place in muscle contractions?
increased calcium levels around the myofibrils
In a muscle twitch, what represents the time between application of a stimulus and the beginning of contraction?
The molecule within the cytoplasm of a muscle fiber that supplies quick energy for contraction is
Muscle fibers and neurons are called electrically excitable cells because
their plasma membranes exhibit voltage changes in response to stimulation
Muscle soreness can be produced by . . .
muscular fatigue, enzymes in the extracellular fluid commonly found within muscle, collagen in the extracellular fluid
Objects that move through organs that are surrounded by smooth muscle are often moved by means of
On the surface of the sarcolemma, the voltage may shift up and down rapidly. This change in electrical potential caused by shifts in ions across the membrane is known as a(n)
Once a signal molecule has left the neuron and binds to a receptor molecule on the surface of the muscle fiber, a sodium channel opens, allowing entry of sodium into the muscle fiber. Which substance is then released from the sarcoplasmic reticulum?
One of the characteristics of muscle tissue is that is has conductivity. Which of the following best describes this characteristic?
Muscles have local electrical charges that are capable of moving along the muscle fiber.
One of the characteristics of muscle tissue is that is has excitability. Which of the following best describes this characteristic?
Muscles contract when stimulated.
One of the characteristics of muscle tissue is that is has extensibility. Which of the following best describes this characteristic?
Muscles can stretch when needed
The properties of cardiac muscle cells are intercalated discs, involuntary, branching fibers. What is not a property?
shorter in duration of contraction than skeletal muscles.
Rapid contraction, break down ATP rapidly, fewer mitochondria than slow-twitch fibers are all true about fast-twitch fibers, which in not true?
high amount of myoglobin
The recovery stroke in muscle contraction involves what?
return of the myosin head to its original position after the cross bridge releases
Slow contraction, good blood supply, and many mitochondria are characteristics of slow-twitch fibers, what is not a characteristic?
Smooth body movements result from
both incomplete and complete titanic contractions of motor units contracting out of phase with each other.
The striations in striated muscle correspond with actual molecular structures. Which of the following is the H band?
a band where only myosin molecules are found
The striations in striated muscle correspond with actual molecular structures. Which of the following is the I band?
a band where only actin molecules are found
The striations in striated muscle correspond with actual molecular structures. Which of the following is the Z line?
an attachment point for actin molecules
Unitary smooth muscle is found in what location of the body?
Digestive tract, reproductive tract, urinary tract.
What assures quick removal of neurotransmitter at the junction between a nerve and a muscle?
What best describes a muscle motor unit?
one nerve fiber and all the muscle fibers innervated by that nerve
What best describes the use of muscle tone in the body?
It keeps our backs straight and our heads up
What determines the height of the peaks in multiple motor unit summation?
the amount of tension produced by the number of motor units responding
What is considered to be parts of the series-elastic components of muscle?
Endomysium, perimysium, epimysium, fascia, and tendons.
What is true about distribution of fast and slow-twitch fibers in the body?
Slow-twitch fibers are usually more resistant to fatigue
What is true about skeletal muscle fibers in aging people?
The number of fibers decreases, there is a decreased density of capillaries that supply muscle cells, the number of motor neurons that innervate skeletal muscle decreases.
What represents extreme muscular fatigue when the muscle is incapable of either contracting or relaxing?
What type of fatigue is caused by the release of more acetylcholine than can be produced to replace it?
When acetylcholine is broken down by acetylcholinesterase in the synaptic cleft, what happens to the choline?
It is reabsorbed at the presynaptic terminal and combined with more acetic acid to make acetylcholine.
When the myosin head (of the thick filament) flexes into a bend, while releasing ADP and inorganic phosphate, pulling the thin filament along with it, this is called the
When the neuron stimulates a muscle fiber, what molecule diffuses across the gap between them?
When the thick and the thin filaments pull together, which of the following is TRUE?
The sarcomere gets shorter.
Which effects of exercise elevate the body temperature?
elevated metabolism from the oxygen debt, vasodilation of blood vessels in the skin, skeletal muscle contractions.
Which energy storage source is most commonly used during the first 10 seconds of exercise?
Which is true about smooth muscle?
The resting membrane potential is less negative than in skeletal muscle
Which is true of an isometric muscle contraction?
The amount of tension increases during the contraction
Which myofilaments within the muscle fiber are composed of three integral items.
Myosin, actin, and elastic (titin) filament.
Which of the following best describes the function of the series-elastic component of muscle?
These are not excitable or contractile, but are extensible and elastic.
Which of the following is TRUE of cardiac tissue?
It has abundant glycogen and myoglobin and is aerobic
Which of the following muscle types contains peripherally located, multiple nuclei in its cells?
Which of the following muscles is involuntary and is the most widely found throughout the body?
Which represents the amount of oxygen that is necessary for the body to recover from anaerobic respiration?