Practice Set 3B Flashcards
Which is a quick cycle of contraction in a whole muscle that occurs when a threshold level stimulus is reached?
Twitch
What does the latent period on a myogram indicate?
The time period between the stimulus and the twitch
On a myogram, how does the relaxation phase compare to the contraction phase?
The relaxation phase is longer.
Which affects the strength of a muscle twitch?
How stretched the muscle was before stimulation
True or false: A twitch is a sustained contraction in a whole muscle that occurs when a threshold level stimulus is reached.
False
On a myogram, the time between the stimulus and the twitch is known as the _____ period.
latent
The movement of an object or load results from the development of what kind of tension?
External
As the myosin head releases the thin filament, muscle tension declines during what is referred to as the ______ phase of a muscle twitch.
relaxation
Which affect twitch strength?
Stimulation frequency
Muscle fatigue
Temperature of the muscle
How stretched the muscle was just before it was stimulated
Which is a quick cycle of contraction in a whole muscle that occurs when a threshold level stimulus is reached?
Twitch
What type of tension develops during the latent period of muscle contraction?
Internal
A muscle fiber shortens and generates force during the ______ period of a muscle twitch.
contraction
A muscle fiber shortens and generates force during the ______ period of a muscle twitch.
contraction
Temporal summation leads to a state of fluttering contraction known as what?
Incomplete tetanus
Complete (fused) __________ is the continuous forceful contraction in a muscle with no relaxation between stimuli.
tetanus, tetany, or Tetanus
Stimulus frequency affects the sarcoplasmic concentration of which of the following?
Calcium
True or false: A twitch is a sustained contraction in a whole muscle that occurs when a threshold level stimulus is reached.
False
When lifting something heavy, which type of contraction occurs first?
Isometric
What produces incomplete tetanus?
Temporal summation
Which is not naturally seen in the muscles of the body?
Complete tetanus
Which type of contraction maintains joint stability and posture?
Isometric
In what type of contraction does the internal tension build until it overcomes resistance and the muscle moves the load?
Isotonic
Which describes slow-twitch fibers?
They have a rich blood supply.
Temporal summation leads to a state of fluttering contraction known as what?
Incomplete tetanus
Which fibers contain a fast-acting ATPase and phosphagen enzymes?
Fast-twitch
In which condition are stimuli are so frequent that the muscle cannot relax, and the muscle twitches fuse into a smooth prolonged contraction?
Tetanus
Skeletal muscles contain which of the following?
Both slow oxidative and fast glycolytic fibers
A muscle shortens as it maintains tension in a what type of contraction?
Concentric
Slow-twitch fibers are also known as ______ fibers.
red
Fast-twitch fibers are also known as ______ fibers.
white
Which fascicle arrangement produces the weakest muscle?
Circular
Fatigue resistance is improved by ______ exercise which enhances the delivery and use of oxygen.
endurance
What are muscles that contain mainly slow oxidative fibers called?
Red
Fibers that are well adapted to aerobic respiration are called ______ -twitch fibers.
slow
Which types of muscle tissue are considered involuntary?
Cardiac and smooth
Muscle that are larger can generate ______ strength than those that are smaller.
more
Which of the following is true of endurance exercise?
It increases oxygen transport in the blood.
The thighs of a chicken are composed mostly of ______ fibers.
slow-oxidative
Cardiac and smooth muscle are both considered which of the following?
Involuntary
Which describes cardiac muscle tissue?
Striated, usually uninucleate, branching
Intercalated discs contain which of the following that prevent cardiac cells from pulling apart during contraction?
Mechanical junctions
Resistance exercise causes muscle growth by stimulating which of the following?
An increase in myofibril size
Cardiac muscle tissue is autorhythmic but the ______ can increase or decrease the heart rate and contraction strength.
autonomic nervous system
Where is cardiac muscle found?
In the heart wall only
In the heart, what triggers the wave of electrical excitation that causes the heart to contract?
Pacemaker
The thickened notched ends of cardiac muscle cells which contain gap junctions are called __________ discs.
intercalated
Why are gap junctions important?
They allow the cells to contract in a coordinated fashion.
What does it mean that cardiac cells are autorhythmic?
They contract rhythmically and independent of nervous stimulation.
Choose all that are characteristics of cardiac muscle.
It uses aerobic respiration almost exclusively.
It has large stores of glycogen.
It is rich in myoglobin.
Which muscle type is resistant to fatigue, contracts with a regular rhythm, and functions 24 hours a day?
Cardiac
What is the function of the cardiac pacemaker?
It triggers contraction in the heart muscle.
Which muscle type is striated, uninucleate, and branched?
Cardiac
Cardiac muscle cells are considered ___________ because they contract rhythmically and independently.
autorhythmic or Autorhythmic
Which muscle tissue is rich in myoglobin, mitochondria, glycogen and uses aerobic respiration almost exclusively for its energy needs?
Cardiac
Which are the characteristics of cardiac muscle cells?
They are resistant to fatigue.
They contract with regular rhythm.
They contract nearly in unison.
The muscle tissue that is typically slow to contract and slow to relax is _________ muscle.
smooth
Which tissue can propel contents of a digestive organ?
Smooth muscle
Which describes cardiac muscle tissue?
Striated, usually uninucleate, branching
In smooth muscle cells, what binds the dense bodies to the membrane?
Intermediate filaments
What does it mean that cardiac cells are autorhythmic?
They contract rhythmically and independent of nervous stimulation.
What regulatory protein is associated with the thick filament of smooth muscle and activates myosin light-chain kinase?
Calmodulin
Which describes smooth muscle?
It is slow to contract and slow to relax.
What are the functions of smooth muscle?
To constrict or dilate blood vessels to control blood pressure
To move material through the digestive tract
To regulate pupil diameter
What is the function of intermediate filaments in smooth muscle cells?
They bind the dense bodies to the sarcolemma.
What is the immediate trigger for the contraction of smooth muscle?
Calcium ions
In smooth muscle, which protein does calcium bind to?
Myosin
The sarcolemma of smooth muscle cells has pockets called ______ that contain calcium channels.
caveolae
