Muscles Flashcards
detail traits of smooth muscle cells
single nucleus spindle shaped not striated simple around blood vessels and intestines involved in blood flow, emptying bladder, and digestion
detail traits of cardiac muscles
branches striated only in heart connected via gap junctions can self depolarize/beat spont
detail traits of skeletal muscles
striated
control voluntary movements
large, multinucleated
can’t extend muscles…can only relax or contract
a muscle fiber equates to a cell
each fiber is packed w/ bundles of myofibrils
each myofibril has sarcomeres
functions of diff sarcomere things
Z lines are the boundaries; anchor actin
A band is band of myosin in the middle (w. overlapping actin)
M band has proteins that support myosin filaments
H, I bands are non overlapping actin and myosin
H band is just myosin
I band is just actin
how are bundles of myosin held together?
in register by titin that runs all along through sarcomere, Z line to Z line though myosin
which bands elongate or narrow in contraction
A band elongates….eh kinda
I band narrows
anatomy of myosin molecule
2 polypep chains coiled together, each w a globular head
what properties do the mysosin heads exhibit
ATPase. hydrolyzing
anatomy of actin molecule
2 chains of f actin twisted
troponin- a 3 subunit molecule that binds to Ca+2, tropomyosin, and actin; sim to calmodulin
tropomyosin wraps around actin and masks myosin binding sites
what energy conformatin does myosin bind to actin w
high energy, releases at low energy
what constitutes a motor unit
a motor neuron and all the muscle fibers it branches to and synapses w
function of SR?
Ca+2 store, intracellular
T/F: muscle cells are excitable
T
detail muscle contraction
AP down axon that releases ACh in neuromuscular junction…AP propagated down muscle fiber and T tubule which are next to SR…conformational change of Ca+2 channels–> open –> influx into cytoplasm–> binds to troponin which pushes tropomyosin off myosin binding sites–> When myosin bound to ATP, low energy–> hydrolyze and high energy, bind to actin–> release hydrolyzed ATP and slides–> ATP binds and releases actin–> start all voer
Explain rigor mortis
dec ATP = Ca+2 pumps not working, so excess Ca+2 in cytoplasm–> cross bridges form, can’t unform–> muscle rigidity due to contraction of muscles on both sides of joints
3 major factors for determining TOD for forensics
body temp, rigor mortis, blood settling
what happens after rigor mortis?
proteases chew up actin and myosin, no more cross bridges so limp
What is tetanus? and how is it diff from RM
max muscle contraction
doesnt occur n both sides of joint
what are the 2 major groups of muscle fibers
oxidative (Type I red) and glycolytic (Type IIb white)
what are the traits of oxidative muscle fibers
many mito and myoglobin; long term aerobics like swimming and running
what are the traits of glycolytic fibers
fewer mito and myoglobin, myosin has high ATPase but can’t replenish aTP fast enough to sustain; sudden and max strength, sprinting
effect of weightlifting on myosin and actin?
increases number, DOESNT inc number of muscle cells
effect of aerobic exercise?
inc capillary density in muscles, inc myoglobin and mito
if occurs in fast twitch fibers, can convert from glycolytic fast twitch type IIb to oxidative fast type IIa
what are the 2 types of oxidative fibers
Type 1 Red: slow oxidative, lots of myoglobin, slow contraction, fatigue resistant, many mito, split ATP slowly
Type IIa Red: fast oxidative, lots of myoglobin, faster contraction, fatigue resistant, many mito, split ATP quickly
