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what are the layers of connective tissue?
epimysium, perimysium, endomysium
what are the 4 functions of connective tissue?
- 1. perimysium provides a conduit for blood vessels and nerves
- 2. resist passive stretching
- 3. distribution of contractile forces
- 4. elasticity enables the muscle belly to regain shape when forces are removed
where is most of the calcium stored?
satellite cells are responsible for what?
replacing damaged fiber/muscle
what are myotubes?
immature muscle fibers
what is proliferation?
satellite cells are activated resulting in the formation of myoblasts
what is differentiation?
myoblasts fuse together to form a multi-nucleated cell type called a myotube
what is maturation?
myotubes grow to form myofiber
what are the stages of myogenesis?
satellite cells - proliferation - myoblasts - differentiation - myotubes - maturation - myofibers
name 3 cytoskeletal proteins
contractile (actin and myosin), regulatory (troponin and tropomyosin) and structural
where are troponin and tropomyosin found?
actin (thin filament)
what are the 4 functions of exosarcomeric proteins?
- 1. link sarcomeres to the sarcolemma
- 2. transmission of contractile force to the sarcolemma
- 3. spatial arrangement of the myofibrils
- 4. anchor for organelles
what is dystrophin?
cytoseletal filaments that cross together combined with actin and spectrin
what is the function of endosarcomeric proteins?
- 1. transmission of contractile forces to the Z lines
- 2. spatial arrangement of the actin and myosin filaments
what are considered endosarcomeric proteins?
nebulin (helps align actin), titin (provides elasticity and stability to myosin expanding from one Z disk to the M line)
explain the steps to a power stroke
- 1. myosin head engergized before attaching to actin
- 2. cross bridge to actin
- 3. releasing of Pi causes change in myosin
- 4. power stroke causes fliaments to slide, ADP is released
- 5. new binding of ATP to myosin allows the release of actin
- 6. ATP is hydrolyzed causing cross bridge to return to its original orientation
what provides the energy for cross bridge formation?
hydrolysis of ATP
what does calcium do for the myosin?
exposes the binding site by binding to the troponin complex
2 types of ion channels and what they respond to
- 1. voltage - membrane potentials
- 2. chemically - neurotransmitters
where are voltage ion channels found?
axon of motor neurons and sarcolemma
where are chemically regualted ion chennels found?
dendrite and motor end plate
what is the axon hillock?
region of a neuron capable of generating an action potential
how does the action potential travel?
always from axon hillock to axon terminal
what is a refractory period?
degree of readiness of an axon to generate an action potential
what is absolute refractory period?
portion is incapable of generating an action potential
what is relative refractory period?
portion is capable of generating an action potential provided that the stimulus is strong enough
what part of the motor neuron is exposed to extracellular fluid?
the axon at the node of ranvier
what are the components of the neuromuscular junction?
axon terminal, synaptic cleft, motor end plate
what happens to ACH at a NMJ?
released from axon terminal, binds to receptor on motor end plate resulting in entry of Na, then degraded by acetylcnolinesterase which is found on the endomyosium
T-tubules contain what receptor?
what is the channel called that is connected from the T-tubule to the SR?
when Ca is released from the ryanodine channel, what happens?
type 1 muscle fiber
type 2a muscle fiber
fast twitch (anaerobic/aerobic)
type 2b muscle fiber
fast twitch (anaerobic)
small motor unit innervates what muscle fiber?
fast fatigue resistant innervates what muscle fiber?
fast fatigable innervates what muscle fiber?
what muscle type has a high glycogen content?
why are there differences in twitch contraction times?
motor neuron conduction velocity, myosin ATPase activity
which muscle fiber generates the fastest twitch tension? why?
type 1 - smaller motor units
what are the anaerobic capacity differences in the fatigue index?
creatine phosphate and glycolytic enzymes activity
what are the aerobic capacity differences in the fatigue index?
oxidative enzymes, myoglobin content, number of mitochondria, capillaries
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