Lecture 1: Muscle Structure Flashcards

1
Q

each muscle consists of _____ to ______ of individual contractile fibers

A

hundreds to thousands

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2
Q

connective tissue:

A

mostly collagen some elastin

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3
Q

epimysium

A

tough coat of tightly woven bundles of collagen which surround entire muscle, separating it from other muscles and structures

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4
Q

myotendinous junction

A

ends of the muscle where epimysium connects with the sarcolemma

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5
Q

why does the myotendinous junction have extensive folding of the epimysium and sarcolemma

A

to increase surface area

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6
Q

perimysium

A
  • also tough and thick
  • divides muscle fibers into fascicles or bundles
  • provides pathways for arteries, veins and nerves
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7
Q

endomysium

A

surrounds each muscle fiber, connections to both the perimysium and the basement membrane

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8
Q

sarcolemma

A

consists of basement membrane and the plasmalemma

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9
Q

conduit arteries and veins

A

run in parallel along the surface of muscle

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10
Q

perforating arteries and veins

A

periodically branch and dive into belly of muscle in parallel, with several generations of branching

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11
Q

arterioles lead to capillaries which __________. note multiple branching within network

A

capillaries surround each fiber!!

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12
Q

nerves usually run in _____ with the arteries and veins

A

parallel

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13
Q

motor nerves make up ____% of the nervous innervation of skeletal muscle

A

60%

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14
Q

motor nerves represent ….

A

the final nerve in the path from the motor centers in the cerebrum to the target muscle

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15
Q

motor nerve impulses travel in an _____ direction

A

efferent (away from CNS)

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16
Q

due to the ________, impulses travel very fast along the axon

A

myelin sheath

17
Q

near muscle fibers, the myelin sheath ends and the axon splits sending a _______ to each fiber

A

terminal branch

18
Q

motor end plate

A

the region of muscle plasmalemma under the terminal axon

19
Q

sensory nerves represent ____% of the nerves in skeletal muscle

20
Q

sensory nerves impulses run in a ______ direction

A

afferent direction (toward the CNS)

21
Q

sensory nerve impulses rely on a variety of _____, ____, ____, ____

A

touch, pain, muscle tension, contraction information

22
Q

skeletal muscle cells appear ______.

23
Q

sarcolemma

A

the cell membrane surrounding each cell

24
Q

sarcoplasmic reticulum

A

membranous network that surrounds each myofibril

25
what is the primary role of the SR?
the release of Ca++ which initiates the contraction process
26
transverse tubules
membranous channels that extend inward from the sarcolemma and pass completely through the fiber
27
cisternae
enlarged portions of the SR that the t-tubules pass through
28
motor end plate is the site where the _____ ends and transmits depolarization signal to the muscle
alpha-motorneuron
29
does the alphamotorneuron touch the arcolemma?
no
30
neuromuscular or synaptic cleft
the space where the sarcolemma invaginates around the alpha-motorneuron synapse
31
steps in excitation contraction coupling
1 a-motorneuron depolarizes leads to release of ACh 2. ACh binds causing Na+ to enter the cell, leading to the depolarization of the muscle cell (end-plate potential) 3. depolarization wave on sarcolemma is transmitted down t-tubules 4. calcium released from SR 5. Ca++ binds to troponin initiating contraction process 6. Ca++ pumped back into SR by SR Ca++ ATPase 7. Ach is broken down by acetylcholinesterate
32
sliding filament theory steps
1. rest 2. excitation coupling 3. active contraction 4. recharging system 5. subsequent response dependent on presence of Ca++
33
why when animals or people die do their bodies go into rigor?
run out of ATP