Muscular System Flashcards
Three basic muscle types
Skeletal
Cardiac
Smooth
What is different about muscle cells?
They’re elongated
Muscle cells are known as
Muscle fibers
Contraction of muscles is due to the movement of
Microfilaments
Prefix myo refers to
Muscle
Prefix mys refers to
Muscle
Prefix sarco refers to
Flesh
Skeletal muscles are attached to bones by?
Tendons
How many nucleus do skeletal muscle cells have?
They are multinucleate
Are skeletal muscles straited?
Yes
What does it mean to be straited?
To have visible banding
Are skeletal muscles voluntary?
Yes
What does it mean when a muscle is voluntary?
It is subject to conscious control
What are skeletal muscle cells surrounded and bundled by?
Connective tissue
What is the connective tissue which wraps around a single skeletal muscle fiber?
Endomysium
What is the connective tissue which wraps are a fascicle (bundle) of skeletal muscle fibers?
Perimysium
What is the connective tissue which covers the entire skeletal muscle?
Epimysium
The connective tissue on the outside of the epimysium
Fascia
What connective tissue wrapping blends into a connective tissue attachment
Epimysium
Cord-like structure
Connective tissue attachment
Tendon
Sheet-like structure
Connective tissue attachment
Aponeuroses
Sites of muscle attachments
Bones
Cartilages
Connective tissue coverings
How much striation to smooth muscles exhibit?
None
What is the cell shape of smooth muscles?
Spindle-shaped
How many nucleus do cells of smooth muscle contain?
One
Are smooth muscles voluntary or involuntary?
Involuntary
A muscle with no conscious control is
Involuntary
Where are smooth muscles mainly found?
The walls of hollow organs
Do cardiac muscles have striations?
Yes
How many nucleus do cardiac muscles have?
Usually one
Where are cardiac muscle cells joined?
Intercalated disc
Cardiac muscles are involuntary or voluntary?
Involuntary
Where are cardiac muscles found?
The heart only
Functions of muscles
Produce movement
Maintain posture
Stabilize joints
Generate heat
Where are nuclei located in skeletal muscle cells?
Sacrolemma
Specialized plasma membrane
Sacrolemma
Specialized smooth endoplasmic reticulum
Sacroplasmic reticulum
Bundles of myofilaments
Myofibrils
What is aligned to give muscles distinct bands?
Myofibrils
The light band of striated muscle is the
I band
The dark band of striated muscles is the
A band
Contractile unit of a muscle fiber
Sarcomere
Thick filaments =
Myosin filaments
What are myosin filaments composed of?
The protein myosin
What do myosin fibrils contain?
ATPase enzymes
Thin filaments =
Actin filaments
What are actin filaments composed of?
The protein actin
Which filaments have heads?
Myosin
Examples of myosin filament heads
Extensions
Cross bridges
Do myosin and actin overlap?
Somewhat
What types of body movements are muscles responsible for?
All of them
At rest, what does the bare zone lack?
Actin filaments
What does the sacroplasmic reticulum (SR) store?
Calcium
Ability to receive and respond to stimulus
Irritability
Ability to shorten when an adequate stimulus is received
Contractility
What needs to stimulate skeletal muscles in order for them to contract?
Nerves
A motor unit is composed of
One neuron
The muscle cells stimulated by that neuron
Association sure of nerve and muscle
Neuromuscular junctions
Gap between nerve and muscle
Synaptic cleft
How much contact is there in a synaptic cleft?
None
In a synaptic cleft, what is the area between the nerve and muscle filled with?
Interstitial fluid
Chemical released by nerve upon arrival of nerve impulse
Neurotransmitter
The neurotransmitter for skeletal muscle is
Acetylcholine
Neurotransmitter attaches to receptors of the
Sacrolemma
During transmission of nerve impulses the sacrolemma becomes permeable to
Sodium
What does sodium rushing into a cell generate?
Actin potential
Can muscle contraction be stopped after being started?
No
In the sliding filament theory of muscle contraction activation by nerve causes ____ to attach to binding site on the ____
Myosin heads
Thin filaments
In the sliding filament theory of muscle contraction, a continuation of action causes what of myosin along the actin?
Sliding
What is the result of the sliding filament theory?
The muscle is shortened/contracted
Muscle fiber contraction is
“All or none”
Not all skeletal muscle fibers may be ____ durning the same ____
Stimulated
Interval
What muscle fiber contractions five different responses?
Different combinations
Different degrees of skeletal muscle shortening
Graded responses
Single, brief contraction
Not a normal muscle function
Twitch
One contraction is immediately followed by another
Tetanus
The muscle does not completely return to a resting state
Tetanus
Summing of contractions
Tetanus
Incomplete tetanus
Unfused
Some relaxations occurs between contractions
Unfused
Results are summed
Unfused
Complete tetanus
Fused
No evidence of relaxation before the following contractions
Fused
The result is a sustained muscle contraction
Fused
Muscle force depends on
Number of fibers stimulated
More fibers contracting results in
Greater muscle tension
Muscles can continue to contract unless
They run out of energy
What do muscles initially use for energy?
Stored ATP
How is energy from ATP released?
Bonds are broken
How much ATP is stored by muscles?
About 4-6 seconds worth
After the initial use of ATP, what must be utilized to produce ATP?
Other pathways
Energy for muscle contraction comes from what?
Direct phosphorylation
Muscle cells contain
Creatine phosphate
Aerobic respiration
Anaerobic glycolysis
High-energy molecule
CP
After ATP is depleted, what is left?
ADP
CP transfers energy to
ADP
Why does CP transfer energy to ADP?
To regenerate ATP
Series of metabolic pathways that occur in the
Mitochondria
What is broken down to CO2 and H2O, to release energy?
Glucose
Anaerobic glycolysis reactions breakdown glucose without
Oxygen
During anaerobic glycolysis, glucose is broken down to ____ to produce some ____
Pyruvic acid
ATP
Which energy reaction is efficient but not fast?
Anaerobic glycolysis
In anaerobic glycolysis, huge amounts of what are needed?
Glucose
Lactic acid produces
Muscle fatigue
When a muscle is fatigued, it is unable to
Contract
What is the most common reason for muscle fatigue?
Oxygen debt
How can oxygen debt be removed?
Oxygen must be “repaid”
Oxygen is required to get rid of
Lactic acid
Increasing acidity and lack of ATP causes muscles to contract
Less
