Exam 2 - Module 6 - Lesson Answers Flashcards
three muscle tissue types
skeletal, cardiac, and smooth
which of the muscle types is/are striated
skeletal and cardiac
which of the muscle types is under strict voluntary control
skeletal muscle is under the control of the voluntary nervous system
why is elasticity an important quality of muscle tissue
it allows muscle to return to its original length during relaxation after contraction
perimysium
connective tissue later surrounding an individual fascicle
largest unit of organization in skeletal muscle tissue
fascicle
smallest unit of organization in skeletal muscle tissue
myofilament (or filament)
muscle fiber vs muscle cell
they mean the same thing
myofibril
contains many myofilaments
muscle fiber > myofibril
how do tendons facilitate body movement
when a muscle contracts, the force of movement is transmitted through the tendon, which pulls on the bone to produce skeletal movement
acetylcholine (ACh)
molecule released by a neuron at the neuromuscular junction (NMJ)
what causes the depolarization of the muscle cell membrane
influx of positively charged sodium (Na+) ions into the muscle cell via voltage-gated channels on the muscle cell membrane
at rest, what molecule blocks the myosin-binding sites on actin
tropomyosin
what causes the exposure of the myosin-binding sites on actin
binding of calcium (Ca++) to troponin moves the tropomyosin such that the binding sites become exposed
what must attach to the myosin heads in order for them to be able to detach from the actin (thus breaking the cross-bridges for the onset of muscle relaxation)
for muscle relaxation to occur, ATP must attach to the myosin head; a lack of ATP in the body, such as occurs upon death, leads to an extended contracted state called rigor mortis
what causes the striated appearance of skeletal muscle tissue
dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell cause the entire cell to appear striated.
how would muscle contractions be affected if ATP was completely depleted in a muscle fiber
without ATP, the myosin heads cannot detach from their binding sites on activ. all of the “stuck” cross-bridges result in muscle stiffness. in live people that is “writer’s cramps” - recently dead person it is rigo mortis
name the three types of skeletal muscle fibers and abbreviations
slow oxidative (SO), slow glycolytic (SG), and fast glycolytic (FG)
which skeletal muscle fiber fatigues the fastest
fast glycotic
which skeletal muscle fiber fatigues the slowest
slow oxidative
why do muscle cells use creatine phophate instead of glycolysis to supply ATP for the first few seconds of muscle contraction
creatine phosphate is used because that and ADP are converted very quickly into ATP by creatine kinase. glycolysis cannot generate ATP as quickly as creatine phosphate
what changes occur at the cellular level in response to endurance training
endurance training modifies slow fibers to make them more efficient by producing more mitochondria to enable more aeroib metabolism and more ATP production. endurance exercise can also increase the amount of myoglobin in a cell and formation of more extensive capillary networks around the fiber
what changes occur at the cellular level in response to resistance training
resistance exercises affect muscles by causing the formation of more actin and myosin, thus increasing the number of myofibrils and sarcomeres in the muscle fibers. this increases the thickness of the muscle fibers and the overall bulk of the muscle
how many nuclei in each muscle type
skeletal = multinucleated / cardiac = uni or binucleate / smooth = uninucleate
