Phys: Muscle Phys. Flashcards

1
Q

where is the sarcolemma?

A

cell membrane found in skeletal & cardiac muscle

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2
Q

what does the sarcoplasmic reticulum do?

A

stores Ca++ to be released by skeletal muscle

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3
Q

T-tubules function?

A

“telephone” line to send the AP into th emuscle to cause Ca++ release from sarcoplasmic ret.

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4
Q

what are the 2 types of myofibril? ratio?

A

Actin- thin
Myosin- thick
2:1

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5
Q

where is the Myosin?

A
H zone- thick
cross bridges (ATPase attach to the myosin head)
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6
Q

Where is Actin? types?

A

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

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7
Q

what does smooth muscle have?

A

actin
myosin
sarcoplasmic reticulum

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8
Q

__ is needed for smooth muscle contraction?

A

calmodulin

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9
Q

what is the organization of a sarcomere?

A
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
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10
Q

what does eccentric mean?

A

muscle lengthens while it contracts

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11
Q

what does concentric mean?

A

muscle shortens while it contracts

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12
Q

what does isometric mean?

A

muscle contracts w/o joint movement or muscle lengthening (push a wall)

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13
Q

what is iostonic?

A

load remains the same

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14
Q

what is ioskinetic?

A

speed of contraction remains the same throughout the contraction

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15
Q

what is the motor unit?

A

single motor neuron & all the muscle fibers it innervates

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16
Q

what do fast twitch muscle fibers do?

A

split the ATP rapidly

17
Q

ventral root fibers are considered?

A

Alpha-extrafusal

Gamma- Intrafusal

18
Q

how is the strength of a muscle determined?

A

by the number of muscle fibers recruited

19
Q

what is the sequence for an AP?

A

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.

20
Q

what happens to the i-band when a muscle contracts?

A

the i-band will get smaller; whereas the A-band will stay the same

21
Q

how does rigor mortis happen?

A

it takes place after death bc crossbridges will form (myosin), but then are unable to release bc Actin is not activated by the AP

22
Q

Slow twitch fiber characteristics:

A
type 1
RED fibers
LOng distance runners
Smaller fiber size
uses LESS glycogen
Many MITOchondria
MORE myoglobulin
23
Q

Fast twitch fiber characteristics:

A
Type 2
WHITE fibers
Sprinters
Large fiber size (for greater contraction)
uses MORE glycogen
less mitochondria
LESS myoglobin
24
Q

what is the smooth muscle actin:myosin ration?

A

20:1

25
Q

what is the flexor withdrawal reflex?

A

a painful stimulus causes a flexor muscle to withdraw the affected limb on side of stimulus

26
Q

what is the crossed extensor reflex?

A

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

27
Q

what is the deep tendon reflex?

A

striking a muscle with a reflex hammer causes the muscle spindle in the muscle to be suddenly stretched

28
Q

how is an UMN lesion characterized:

A
Spastic paralysis
hyperreflxia
babinski sign
no atrophy
no fasciculations
29
Q

what will result with repetitive stimulation without relaxation?

A

tetany of the skeletal muscle