Ch 10 Muscles Flashcards
fascicles
bundle of muscle fibers or axons
muscle fibers
muscle cells
tendon
cord of dense regular connective tissue that connects muscle to bone
deep fascia
dense sheet of dense irregular connective tissue, separates muscles, binds together muscles with similar functions, fills spaces between muscles
epimysium
a layer of dense, irregular connective tissue surrounding a skeletal muscle
perimysium
fibrous sheath enveloping each of the fascicles of skeletal muscle fibers
endomysium
areolar connective tissue layer surrounding a muscle cell or fiber
a. Z disc
b. M line
c. I band
d. A band
e. myosin (thick filament
f. actin (thin filament)
a. tropomyosin
b. myosin binding site
c. troponin
d. Ca binding site
explain a twitch
electrical impulse travels from brain down axons to neuromuscular junction to activate muscle. changes to a chemical impulse at the synaptic knob in form of acetylcholene. ACh binds to receptors on sarcolemma, which triggers electrical pulse. this travels down the T-tubes and opens Ca gated voltage channels bringing Ca into cell
explain crossbridge cycling
- Ca bind to troponin on thin filament, causing tropomyosin to move and change and expose myosin binding cites on actin
- myosin heads in cocked position bind to exposed myosin binding site on actin, forming a crossbridge between myosin and actin
- myosin head swivels toward center of sarcomere, pulling attached thin filament, called power stroke. ADP is released
- ATP binds to ATP binding site on myosin head, which causes release of myosin head from the binding site on actin
- ATP is turned to ADP by myosin and provides energy to reset myosin head
sarcoplasmic reticulum
stores calcium, wraps around myofibrils (made of myofilaments) and contains Ca pumps to pump Ca into muscle
two ways muscles use ATP
crossbridge cycling and Ca pump
three ways to generate ATP in skeletal muscle
immediate phosphate transfer, short term supply via glycolysis, long term supply via aerobic cellular respiration
lactic acid
made from pyruvic acid when O2 not available
regenerates NAD+ to feed back through glycolysis (forming NADH)
aerobic excercise
cycling, walking, jogging, swimming
increase in number of mitochondria, surrounding capillaries, myoglobin synthesis (stores little bit of O2)
no noticeable muscle hypertrophy
resistance exercises
weightlifting, isometric exercise
increase in muscle fiber size, number of mitochondria, myofilaments, and myofibrils
store more glycogen
hypertrophy