Phys: Muscle Phys. Flashcards
where is the sarcolemma?
cell membrane found in skeletal & cardiac muscle
what does the sarcoplasmic reticulum do?
stores Ca++ to be released by skeletal muscle
T-tubules function?
“telephone” line to send the AP into th emuscle to cause Ca++ release from sarcoplasmic ret.
what are the 2 types of myofibril? ratio?
Actin- thin
Myosin- thick
2:1
where is the Myosin?
H zone- thick cross bridges (ATPase attach to the myosin head)
Where is Actin? types?
i bands- thin
F-actin filament- contains the binding sites
Tropomyosin “mom”- covers the f-actin binding sites
Troponin “Dad”- binds Ca++ and moves tropomysosin off the binding sites- found in both sk. & cardiac
what does smooth muscle have?
actin
myosin
sarcoplasmic reticulum
__ is needed for smooth muscle contraction?
calmodulin
what is the organization of a sarcomere?
sarc.- Z line approximates to Z line A- band- contains both actin & myosin H- band- myosin only I band- actin only Z-H-IZI-A-Z
what does eccentric mean?
muscle lengthens while it contracts
what does concentric mean?
muscle shortens while it contracts
what does isometric mean?
muscle contracts w/o joint movement or muscle lengthening (push a wall)
what is iostonic?
load remains the same
what is ioskinetic?
speed of contraction remains the same throughout the contraction
what is the motor unit?
single motor neuron & all the muscle fibers it innervates
what do fast twitch muscle fibers do?
split the ATP rapidly
ventral root fibers are considered?
Alpha-extrafusal
Gamma- Intrafusal
how is the strength of a muscle determined?
by the number of muscle fibers recruited
what is the sequence for an AP?
AP by T-tubules> SR becomes more permeable to Ca++ ions & diffuse into sarcoplasm around myofibril> Ca++ binds to troponin> troponin- tropomyosin complex moves to expose active sites.
what happens to the i-band when a muscle contracts?
the i-band will get smaller; whereas the A-band will stay the same
how does rigor mortis happen?
it takes place after death bc crossbridges will form (myosin), but then are unable to release bc Actin is not activated by the AP
Slow twitch fiber characteristics:
type 1 RED fibers LOng distance runners Smaller fiber size uses LESS glycogen Many MITOchondria MORE myoglobulin
Fast twitch fiber characteristics:
Type 2 WHITE fibers Sprinters Large fiber size (for greater contraction) uses MORE glycogen less mitochondria LESS myoglobin
what is the smooth muscle actin:myosin ration?
20:1
what is the flexor withdrawal reflex?
a painful stimulus causes a flexor muscle to withdraw the affected limb on side of stimulus
what is the crossed extensor reflex?
is activated by a noxious stimulus to the skin
causes extensors to be activated on opposite side of stimulus
it provides support of the body during withdrawal of the affected limb as a righting reflex
what is the deep tendon reflex?
striking a muscle with a reflex hammer causes the muscle spindle in the muscle to be suddenly stretched
how is an UMN lesion characterized:
Spastic paralysis hyperreflxia babinski sign no atrophy no fasciculations
what will result with repetitive stimulation without relaxation?
tetany of the skeletal muscle
