What are the types of muscle tissue
skeletal, smooth, cardiac
Which type of muscle tissue are attached to bone and skin, are striated, voluntary, contract rapidly, and require nervous system stimulation?
skeletal muscle
What type of muscle tissue is only in the heart, striated, can contract without nervous system stimulation, and is involuntary?
cardiac muscle
What type of muscle tissue is also called visceral, is not striated, can contract without nervous system stimulation, is involuntary, and found in the walls of hollow organs?
smooth muscle
What type of muscle tissue is multinucleated?
skeletal muscle
What special characteristic of muscle tissue is the ability to receive and respond to stimuli?
excitability
What special characteristic of muscle tissue is the ability to shorten forcibly when stimulated?
contractility
What special characteristic of muscle tissue is the ability to be stretched?
extensibility
What special characteristic of muscle tissue is the ability to recoil to resting length?
elasticity
What are the important functions of muscle?
movement of fluid or bones; maintain posture and body position; stabilizing joints; heat generation
What are the additional functions of muscles?
protect organs; form valves; control pupil size; causes goosebumps
Each muscle is served by what?
one artery, one nerve, and one or more veins
What is the most external part of skeletal muscle - a dense, irregular connective tissue that surrounds the entire muscle?
epimysium
What is the fibrous connective tissue that surrounds fascicles (groups of muscle fibers) in skeletal muscle?
perimysium
What is the fine areolar connective tissue surrounding each individual muscle fiber/cell?
endomysium
Skeletal muscle attaches in at least what two places?
origin and insertion
What type of attachment in skeletal muscle occurs when the epimysium is fused to the periosteum of bone or the perichondrium of cartilage?
direct
What type of attachment in skeletal muscle occurs when connective tissue wrappings extend beyond the muscle as rope-like tendon or sheetlike aponeurosis?
indirect
What is the plasma membrane of a skeletal muscle fiber/cell called?
sarcolemma
What is the cytoplasm called in a skeletal muscle fiber?
sarcoplasm
What are the modified structures called in a skeletal muscle fiber?
myofibrils, sarcoplasmic reticulum, and T tubules
In skeletal muscle, what is the lighter region in the middle of the dark A band, where filaments do not overlap?
H zone
In skeletal muscle, what is the line of protein myomesin that bisects the H zone?
M line
In skeletal muscle, what is the coin shaped sheet of proteins on the midline of the light I band that anchors thin filaments and connects myofibrils to one another?
Z disc (line)
Which filaments run the entire length of the A band?
thick filaments
Which filaments run the length of the I band and partway into the A band?
thin filaments
What is the region between two successive Z discs called?
sarcomere
What is the smallest contractile unit (functional unit) of muscle fiber?
sarcomere
What are the thin filaments called that extend across the I band and partway into A band, and are anchored to Z discs?
Actin
What are the thick filaments called that extend the length of the A band and connect at the M line?
Myosin
Myosin heads contain 2 smaller, light polypeptide chains that act as ______ _______ during contraction.
cross bridges
What are the regulatory proteins that bind to actin?
tropomyosin and troponin
What links thin filaments to proteins of the sarcolemma; and are mutated in someone with muscular distrophy?
Dystrophin
What functions in regulation of intracellular calcium levels, stores and releases calcium to allow muscles to contract?
sarcoplasmic reticulum
What are continuations of the sarcolemma, increase the muscle fiber's surface area, penetrate the cell's interior at each A band-I band junction, and associate with paired terminal cisterns to form triads that encircle each sarcomere?
T tubules
In the triad, what conducts impulses deep into the muscle fiber?
T tubules
During contraction, thin filaments slide past thick filaments, and actin and myosin overlap more. This is called?
sliding filament model of contraction
What occurs when myosin heads bind to actin?
cross bridges
What forms and breaks several times, ratcheting thin filaments towards the center of the sarcomere?
cross bridges
What must happen for skeletal muscle to contract?
activation (must generate action potential in the sarcolemma) and excitation-contraction coupling (action potential is propagated along the sarcolemma and calcium levels rise briefly)
What does the sarcoplasmic reticulum release to bind to troponin?
calcium
What happens when calcium/potassium enter/leave the cell?
It becomes depolarized
When calcium binds to troponin, what is exposed?
myosin-binding sites on actin
What binds to actin, causing contraction to begin?
myosin heads
Action potential travels along what, causing the sarcoplasmic reticulum to release calcium?
T tubules