What are the five functions of skeletal movement?
1. Produce Movement
2. Maintain posture and body position
3. Support soft tissue
4. Guard entrances and exits
5. Maintain body temperature
What is skeletal muscle?
organs that contain connective tissue, nerves and blood vessels.
What does perimysium do?
divides the muscles into bundles of fascicles
What does endomysium do?
envelopes individual muscle cells.
What is fascicle?
bundle of muscle fibers
dense connective tissue
What is a tendon?
collagen fibers of all 3 layers come together to form a bundle.
What is sarcolemma?
the plasma membrane
What is sarcoplasm?
What is transverse tubules?
tube that intersects adjacent sarcoplasmic reticula.
-they play a role in calcium transportation
What is myofilaments?
protein filaments consisting primarily of proteins actin and mysoin
a cylindrical cord of protein in the sarcoplasm
What is thin filaments?
actin molecules found here
protein molecules that make up the myofibril
What is sarcoplasmic reticulum?
similar to ER, sac like organ that stores calcium ions
What is a sarcomere?
a segment of the myofibril whose thick and thin filaments are divided into regions
What is the Z-line?
boundaries of each sarcomere.
What is the M-line?
made up of proteins that connect the central portions of each thick filament to its neighbors
What is an A band?
where thick and thin filaments overlap (dark)
What is an I band?
where only thin filaments occur (light)
What is tropomyosin?
the active sites along the thin filaments are covered by strands of protein.
What is troponin?
tropomyosin strands are held in position by molecules of troponin that are bound in the actin strand.
What is the synpatic terminal?
a single axon branches within the perimyosium to form the ST
What is synaptic cleft?
a narrow space that separates the synaptic terminal from sarcolemma
a recessed pocket of the scarolemma that receives the motor neuron
What is the motor end plate?
region of sarcolemma at the synaptic cleft
What is acetycholinesterase?
breaks down molecules of ACh.
What is aponeurosis?
board flat sheet of connective tissue
Muscle is composed of
skeletal muscle tissue
What are the 4 properties that muscle tissue exhibits?
The muscle system is composed mainly of?
Superficial fascia is where?
beneath the skin
Deep fascia is where?
around the organs(including muscle)
What 3 layers is connective tissue found?
The epimysium, permysium and endomysium are continuous with?
fibrous tissue that extends from the muscle as a tendon
What is a tendon?
a strong touch cord that connects at its other end with the fibrous periosteum covering a bone
Skeletal muscle is highly specialized to?
A motor neuron provides stimulates to what?
What is motor unit?
one motor neuron with the muscle fiber it innervates
What is neuromuscular junction?
The region between the motor neuron
Neuromuscular junction contains?
a. synaptic cleft
b. motor end plate
c. synaptic vesicles
What are synaptic vesticles?
small sacs within the terminal end of the motor neuron that contain actycholine, a neurotransmitter.
Acetylchnline is released when?
action potential reaches the neuron terminal end
The nerve supply diffuses across the synaptic cleft until?
it contacts the motor end plate.
A muscle contracts when?
the thin filaments slide across the thick filaments toward the center of sarcomere.
Physiology of the Skeletal Muscle Contraction
1. Fiber at Rest
2. Role of Stimulus
3. Muscle Contraction
4. Return to Rest
When the muscle is at Rest, Calcium ions are stored within the
When the muscle is at Rest, ATP molecules are bound to?
thick filaments and thin filaments are intact
What happens when action potential is stimulated in the sarcolemma?
it passes along the membrane until reaching the SR
After the action potential is stimulated, the action potential causes?
SR to release its calcium ions
During muscle contraction, calcium ions are diffused into the?
sarcoplasm, where they bind to think filaments
Cross Bridge Connections are formed?
the heads of myosin thick filaments attach to the exposed binding sites on the actin thin filaments
What happens when the cross bridge shift their angle?
the thin filaments slide over the think filaments
Once shifting is complete, what does the another ATP molecule provide?
the energy to break the bond between the thick filaments cross bridge and the think filaments.
The shifting in the cross bridge requires?
ATP which is bound to myosin
WHen the muscle returns to rest, the ATP provides the energy for?
the enzymes to return calcium ions to SR
The lack of calcium ions in the rest causes?
the thin filaments to return to their original shape, closing off the binding site to the Cross Bridge.
What releases additional ATP after the metabolic conversion?
Why is oxygen required for contraction?
to synthesize ATP
What is muscle fatigue?
when the muscle becomes unable to contract?
The muscle become unable to contract during muscle fatigue because?
of accumulation of lactic acid and unavailability of ATP