Muscular System Flashcards
The forces that help the body perform physical activity are supplied by the ________.
Muscular system.
What are muscle cells also known as?
Fibers
Muscle cells, also known as fibers, are _________ and connected in __________.
Muscle cells, also known as fibers, are multinucleated and connected in cylindrical bundles or individual cells.
What is a single muscle built from?
Many bundles of muscle fibers called fascicule.
Connective tissues run from one end of the muscle to the other to what?
To bind cells together and giving rise to muscle fiber bundles.
Muscle tissues are categorized into three types according to what? And what are they?
Function and structure.
Cardiac, smooth and skeletal.
Where is cardiac muscle found?
In the walls of the heart.
What does the smooth muscle compose?
Composes the epithelial of other hollow organs.
What do the cardiac muscle and smooth muscle have in common?
They are both under involuntary control.
Skeletal muscle is attached to what? Is it under voluntary or involuntary control?
Skeletal muscle is attached to the skeleton and is under voluntary control.
Skeletal muscle is composed of many what?
Many thread-like striations.
What is the basic unit of the myofibril?
The sarcomere.
How does the sarcomere expand?
Expands from z Z line to the next closest Z line.
What are sarcomeres composed of?
Alternating large myosin and thin actin strands made of protein.
Where does myosin develop?
In the middle of every M line.
What is the M line?
It is a line that runs the length of myofibrils.
What do the actin strands develop? How is it characterized?
A Z shaped pattern down the points that are anchored, which is characterized by having a darker color than other areas.
What happens when stimulation occurs and an action potential is received?
The skeletal muscles carry out a contraction by decreasing every sarcomere.
Actin and myosin fibers overlap in a _______.
Contractile motion toward each other.
How would you describe myosin filaments? Where do they project?
Club-shaped heads that project toward the actin filaments.
In relation to myosin filaments, what are the larger structures called? Where are they found? And what do they do?
Myosin heads. Found along the myosin filament and give attachment points on binding sites for the actin filaments.
How and where do myosin heads move? What do they do when they get there? What is this process called? And what happens as a result?
Myosin heads move in a synchronized manner toward the center of the sarcomere. They then detach and reattach to the closest active site of the actin filament. This is known as a “ratchet type drive system.” As a result, this process uses up large quantities of adenosine triphosphate (ATP).
Where does the energy for contraction come from?
It comes directly from ATP.
What is the energy source of a cell?
ATP.
What is the job of ATP?
To link the cross bridges among myosin heads and actin filaments.
What powers the twisting of the myosin head?
Energy.
What happens when ATP is used up?
ATP converts to adenosine diphosphate (ADP).
A person’s muscles accumulate a small amount of ATP by __________.
Constantly reusing the ADP and converting it back into ATP quickly.
Inside muscle tissues there is a what? What does this assist?
There is a storage supply of a high-speed recharge chemical called creatine phosphate. This assists in producing the fast renewal of ADP into ATP.
When is a muscle stimulated to contract?
When calcium is released.
A muscle is stimulated to contract when calcium is released from the ___________.
Sarcosplasmic reticulum into the sarcomere.
What is needed for every cycle of the sarcomere?
Calcium ions.
What does calcium reveal?
The actin binding sites.
What happens when a muscle does not need to contract?
Calcium ions are drawn out from the sarcomere and are stored back in the sarcoplasmic reticulum.
As a whole unit, skeletal muscles produce movement by ______.
Pulling on the skeleton in a nervous system-controlled manner.
What happens when a muscle shortens?
It moves a bone by pulling on the tendons which attack the muscle to the bones.
What do the integration of bones, skeletal muscles and joints create?
The apparent movements like running and walking.
Skeletal muscles and joints can generate movements that are more subtle like _____.
Respiration, eye movements and facial expressions.
The number of skeletal muscles used during a workout depends entirely on
which exercises are chosen and the
methods used during their implementation.
The skeletal muscles are grouped together, though this does not mean
that they function together.
Skeletal muscles can either function _____.
They can either function separately
or in groups along with other muscles.
What is formed by the action of skeletal muscles?
Power and muscle force.
Muscle contraction movement can fulfill several other vital functions in the human body like what? (3)
Heat production, posture and joint stability.
Sitting and standing with posture can be accomplished by
Contraction of muscles.
As soon as the nervous system triggers movement in the body, the entire muscle does not respond, why?
Because a muscle has several motor units (a motor neuron and the muscle fibers it innervates) and the movement may require just a small part of the muscle.
All of the fibers contract when
A motor unit is stimulated.
Clusters of motor units work in unison to
manage the contractions of a muscle.
