Muscular Tissues Part 2 Flashcards
outer layer, encircling the entire muscle
epimysium
surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles called fascicles
perimysium
surrounds and separates individual muscle fibers from one another
endomysium
three kinds of proteins:
contractile proteins
regulatory proteins
structure proteins
generate force during contraction
contractile protein
help switch the contraction process on and off
regulatory proteins
keep thick and thin filaments of myofibrils in proper alignment, give myofibrils elasticity and extensibility, and link myofibrils to sarcolemma and extracellular matrix
structural proteins
two types of contractile proteins
myosin
actin
makes up thick filament; a molecule consists of a tail and two myosin heads, which bind to myosin-binding sites on actin molecules of thin filament during muscle contraction
myosin
these two both functions as a motor protein in all three types of muscle tissue
myosin and actin
main component of thin filament; each one of this molecule has a myosin-binding site where myosin head of thick filament binds during muscle contraction
actin
two types of regulatory proteins
tropomyosin
troponin
component of thin filament; when skeletal muscle fiber is relaxed, this covers myosin/binding sites in actin molecules, thereby preventing myosin from binding to actin
tropomyosin
makes up thick filament; molecule consists of a tail and two myosin heads, which bind to myosin-binding sites in actin molecules of thin filament during muscle contraction
troponin
five types of structural proteins
Titin
a-Actinin
Myomesin
Nebulin
Dystrophin
connects z disc to M line of sarcomere, thereby helping to stabilize thick filament position; can stretch and then spring back unharmed, and thus accounts for much of the elasticity and extensibility of myofibrils
titin
structural protein of z discs that attaches to actin molecules of thin filaments and to titin molecules
a-actinin
forms m line of sarcomere; binds to titin molecules and connects adjacent thick filaments to one another
myomesin
wraps around entire length of each thin filament; helps anchor thin filaments to z discs and regulates length of thin filaments during development
nebulin
links thin filaments of sarcomere to integral membrane proteins in sarcolemma, which are attached in turn to proteins in connective tissue matrix that surrounds muscle fibers; thought to help reinforce sarcolemma and help transmit tension generated by sarcomeres to tendons
dystrophin
skeletal muscle fibers are classified into three main types:
slow oxidative fibers
fast oxidative-glycolytic fibers
fast glycolytic fibers
two fibers that appear dark red bcs of large amounts of myoglobin and many blood capillaries
slow oxidative fiber
fast oxidative-glycolytic fiber
both contains large mitochondria therefore generate ATP mainly by aerobic respiration
slow oxidative fiber
fast oxidative-glycolytic fiber
ATPase in the myosin heads hydrolysis ATP relatively slow
slow oxidative fibers
ATPase in the myosin heads hydrolyzes ATP 3-5x faster than myosin ATPase in SO fibers
fast oxidative-glycolytic fibers
both can also generate ATP by anaerobic glycolysis due to high levels of intracellular glycogen level
fast oxidative-glycolytic fibers
fast glycolytic fibers
very resistant to fatigue
slow oxidative fibers
moderately resistance to fatigue
fast oxidative-glycolytic fiber
adapted fro maintains posture and for aerobic, endurance-tyoe activities
slow oxidative fibers
twitches of this reach tension more quickly than those of SO fibers but are briefer in duration
fast oxidative-glycolytic fibers
contribute to activities like walking and sprinting
fast oxidative-glycolytic fibers
low myoglobin content, few blood capillaries, few mitochondria, and appear white in color
fast glycolytic fibers
this contract strongly and quickly due to ability to hydrolyze ATP rapidly
fast glycolytic fibers
adopted for intense anaerobic movements of short duration
fast glycolytic fibers
fatigued quickly
fast glycolytic fibers
type of muscle tissue that is located in heart and large vessels attached to heart
cardiac muscle tissue
branched cylindrical fiber with one centrally located nucleus; striated
cardiac muscle tissue
develop from mesodermal cells that migrate to and envelope the developing heart while it is still in the form of endocardial heart tubes
cardiac muscle tissue
length of cardiac muscle fiber
long (50-100um)
diameter of cardiac muscle fiber
large (10-20um)
T/F: t tubules located at z lines are smaller than in skeletal muscle
FALSE
T/F: sarcoplasmic reticulum in cardiac muscle is less well developed
TRUE
found in walls of hollow viscera, airways, blood vessels etc
smooth muscle tissue
fibers are in fusiform in shape (thickest jn middle, tapered at each end)
smooth muscle
contain one centrally positioned nucleus and not striated
smooth muscle tissue
develop from mesodermal cells that migrate or and envelop the developing gastrointestinal tract and viscera
smooth muscle
length of smooth muscle fiber
intermediate (30-200um)
diameter of smooth muscle fiber
small (3-8um)
actin and myosin form ______ network and insert into dense bodies in the sarcoplasm
lattice (criss-cross)
it has gap junctions couple muscle and allow ionic communication between all fibers
smooth muscle fiber
T/F: t Tubules are PRESENT in smooth muscle fiber
FALSE
short membrane invaginations, called _____, are often frequent at the smooth muscle cell structure
caveolae
T/F: smooth muscle fiber has very little sarcoplasmic reticulum
TRUE
regulatory proteins of smooth muscle fiber:
myosin light-chain kinase (MLCK)
calmodulin
regulatory proteins of cardiac muscle fiber:
tropomyosin and troponin
