Muscular system test Flashcards
What happens to your muscles when you don’t exercise regularly?
Atrophy:a decrease in total mass of a muscle
happens when muscles aren’t contracting frequently enough
What happens when multiple nerve impulses get sent to a muscle?
Stimulation of the muscle can occur before the relaxation phase is complete
This leads to increases overlap and greater muscle shortening causing greater force of contraction
Since the stimuli are being added together this process is called summation
If you have muscles that continually work without relaxation that’s called tetanus
How do the muscle filaments know when to move?
Skeletal muscles must be stimulated by a nerve to contract
Motor unit
One neuron
Muscle cells stimulated by that neuron
What are the functions of muscles?
1.Produce movement
2.Maintain posture
3.Stabilize joints
4.Generate heat
What are the three types of muscles and their characteristics?
Cardiac muscle – involuntary muscle found in heart control by autonomic nervous system
Smooth muscle – involuntary muscle found in lining of various organs
Ex) digestive system, uterus, blood vessels
Skeletal muscle – voluntary muscle found covering body, attached to bones using tendons
How do muscles attach to bone?
Muscles are attached to at least two points
Origin – attachment to a immovable bone
Insertion – attachment to an movable bone
What is the sliding filament theory?
This is a working model of what scientists believe happens during muscle contraction
The end of the fiber contains a Z line which is attached to the actin fibers
Ca binds the actin fibers to reveal binding sites that myosin will power stroke to attach to reducing the I band
When ATP interacts with the myosin, the club like head releases, resetting the I band
ATP is reduced to ADP until the next power stroke
What is an antagonistic pair?
Muscles working pairs are called antagonistic muscles
This means that when one contracts the other relaxes
EX) bicep contracts, tricep relaxes
The muscle that contracts to bend a joint is a flexor
The muscle that relaxes to bend a joint is a extensor
Explain how nerves stimulate muscle cells.
Skeletal muscles must be stimulated by a nerve to contract
Motor unit
One neuron
Muscle cells stimulated by that neuron
Explain muscle contraction.
Starts with a nerve impulse stimulating muscles cells
Muscle fiber contraction is “all or none”
The pause between impulse and contraction is called latent period
Contraction phase - The actin and myosin filaments contract causing the shortening of the muscle
Relaxation phase – the filaments relax and disengage returning the muscle to resting length
What are the different graded responses?
Twitch
Single, brief contraction
Not a normal muscle function
Tetanus (summing of contractions)
One contraction is immediately followed by another
The muscle does not completely return to a resting state
The effects are added
Unfused (incomplete) tetanus
Some relaxation occurs between contractions
The results are summed
Fused tetanus
No evidence of relaxation before the following contractions
The result is a sustained muscle contraction
What causes fast and slow twitch?
How do muscles get energy for contractions?
ATP
What is creatine phosphate?
Creatine phosphate, is naturally found in the muscle cells to ensure that ATP supplies remain high
Explain muscle fatigue and oxygen debt.
Under heavy exercise, the environment around muscles becomes acidic
This leads to a burning feeling and eventually muscle failure
The rapid breathing that follows is designed to repay the oxygen debt
