muscle 1 Flashcards

1
Q

voluntary muscles

A

connected to bones and present in sphincters with some exceptions
skeletal muscles.
striated
elongated cell
multiple peripheral nuclei
parallell musvle fibre (cell)
sarcoplastic reticulum (modified ER) and terminal cristernae contaiing Ca
t tubule
myofibrils

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2
Q

involuntary muscle- cardiac

A

branching cell
single central nucleus
straited
present within the heart

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3
Q

invountary muscle- smooth muscle

A

present in visceral organs, blood vessels, eye (vision accomodation pilorecetor)
non striated
spindle shaped cell
single central nucelus

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4
Q

what are coluntary muscles covered by

A

dense connective tissue

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5
Q

t tubeule

A

axon like fibre that transmits action potential into muscle

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6
Q

bands of myofibril

A

alternating dark (A bands) and light bands (i bands) giving appearance of straiations. regular arrangement of thick and think fillaments which slide against each other changing muscle length

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7
Q

functional unit of striated muscle

A

sarcomere that is found between two Z lines

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8
Q

z lines

A

connects thin fillaments of two adjoining sarcomeres

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9
Q

a band

A

made up of thick fillaments along with portions of thin fillaments that overlap on both ends of thick fillaments

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10
Q

i band

A

constis of remiaing portion of think fillaments that do not project into a band

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11
Q

h zone

A

lighter area within middle of a band where thin fillaments do not reach

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12
Q

m line

A

extends vertically down middle of a band within centre of h zone

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13
Q

where do motor neurons project from and thier endings

A

the spinal chord and the axons divide into multiple endings. each ending synapses with one muscle fibre cell to form one end place per cell

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14
Q

action potentials and what they contract

A

each action potential transmitted through each motor neuron can contract multiple muscle fibre cells within the muscle bundle

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15
Q

how many types of muscle fibres innervate the same muscle

A

two
slow twitch- innervated by a2 small diameter low threshold motor neurons
fast twitch- innervated by a1 large diameter high threshold motor neurons

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16
Q

what is released after motor neuron action potential reaches end

A

achetylcholine into the space between the nerve and the muscle- motor endplate

17
Q

what receptors does acetylcholine bind to

what happens when acetylcholine binds to its receptor

A

nicotinic receptors on muscle plasma membrane which opens a channel that it is linked to leading to a lot of na into muscle with small amount of k leaving depolarizing the cell to threshold that activates fast na channels to produce AP.

AP is transmitted along plasma membrane through t tubule system casuing release of ca from the sarcoplasmic reticulum

18
Q

what can cause increased contratcion

A

increasing firing frequency of each motor neuron
recruiting more motor neurons to fire APs
recruiting a greater proportion of fast twitch muscle contraction which can develop greater contractile forces than slow twitch fibers