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Anatomy > Skeletal Muscle sys > Flashcards

Skeletal Muscle sys Flashcards

1
Q

What are the 3 concentric layers of connective tissue in the muscle in order from outermost to innermost?

A

Epimysium
- dense irregular
-separates muscles from other tissues

Perimysium
- divides muscles into compartments called fascicles
- collagen, elastic fibers, blood vessels and nerves go to each fascicle

Endomysium
- surrounds each individual fiber
-connects fibers together and to blood vessels

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2
Q

what is a fascicle?

A

a bundle of fibers

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3
Q

what are myosatelite cells?

A

stem cells. Considered totipotent: unlocked DNA

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4
Q

what are tendons? what is an aponeurosis

A

connect muscle to bone. flat tendon sheet.

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5
Q

where do nerves and blood vessels reside?

A

in the connective tissues

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6
Q

nerves are?

A

bundles of axons

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7
Q

what do nerves form with muscles?

A

neuromuscular junctions

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8
Q

embryonic myoblasts

A

muscle progenitor cells that proliferate and fuse together to form muscle fibers during embryonic development

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9
Q

What are transverse (t) tubules

A

deep indentations in sarcolemma that conduct electrical impulse to sarcoplasmic reticulum

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10
Q

myofibrils and myofilaments

A

give muscle striated appearance
hundreds/thousands of myofibrils per muscle

myofibrils:
myofilaments - thick and thin
myosin and actin
regulatory proteins: tropomyosin and troponin
accessory proteins: titin and nebulin

abundant mitochondria

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11
Q

What is the sarcoplasmic reticulum

A

storage site for Ca ions
t-tubules enlarge, fuse, and form expanded chambers

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12
Q

Different bands of the sarcomere?

A

A band: dark band (myosin concentrated)
I band: light band (actin concentrated)
M line: where the myosin meets and makes a straight line
z lines: ends of sarcomeres that move closer together when contraction
H band: lighter zone in A band

HAMIZ: initial of every band

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13
Q

thin filaments?

A

f-actin, nebulin, tropomyosin, troponin

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14
Q

what does nebulin do?

A

supports actin and maintains its form

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15
Q

thick filaments?

A

bundles of myosin
twisting tail binds to other myosin molecules
myosin heads project towards thin filaments

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16
Q

what does titin do?

A

structural component of myosin
loose when myosin is relaxed
tight when stretched

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17
Q

describe steps for a muscle contraction

A

…

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18
Q

motor units?

A

individual neurons and the muscle fibers they control
can be 1:1 or 1:100
smaller the ratio finer the movement

19
Q

what produces tension?

A

frequency of stimulation
number of motor units recruited

20
Q

what are singular contractions called?

A

muscle twitches

21
Q

all or none principles

A

muscle fibers contract completely or not at all
all muscles in a motor unit contract at the same time
number of motor units recruited increases gradually
peak tension occurs at max rate of stimulation

22
Q

Describe a t-tubule… how is it continuous? What role does it play in the activation of contraction?

A

…

23
Q

What releases ACh? what does acetylcholine bind to on the muscle? what does it cause?

A

voltage gated Ca channel on neuron opens due to AP. nicotinic receptor. Opens Na channel on muscle causing an AP which allows calcium to be released by sarcoplasmic reticulum

24
Q

what else can happen to acetylcholine

A

acetylcholinesterase breaks it up into acetyl and choline and choline gets reused

25
Q

How does calcium affect muscle contractions at high and low concentrations?

A

…

26
Q

What is troponin?

A

calcium activated troponin binds to 2 additional calcium (4Ca) which causes the troponin to change shape and move tropomyosin off of the myosin binding site.

27
Q

What are the 3 methods for calcium clearance?

A

Ca-H+ exchangers which require ATP found on sarcolemma and sarcoplasmic reticulum
Na-Ca exchangers which are passive on sarcolemma
calsequestrin and calreticulin bind Ca to them and store them in reticulum

28
Q

How do muscles respond to exercise?

A

increasing the amount of intracellular contractile proteins

29
Q

what causes a muscle pump?

A

increased myofibrils and mitochondria

30
Q

what causes the degeneration of muscle? characteristics?

A

lack of stimulation
is initially reversible, dying muscle fibers not replaced

31
Q

skeletal muscle fiber types? how are they classified

A

by how they obtain atp
fast (white) fibers
- densely packed w myofibrils
-large glycogen storage, little mitochondria
-contract quickly and powerfully, energy sinks (anaerobic)

slow (red) fibers
-smaller and take 3x the time to contract
-extended contraction
-aerobic metabolism
-many mitochondria

intermediate fibers
-in between both

32
Q

what are the 2 types of motor neurons?

A

slow-twitch fiber neurons
-small diameter
-conduction velocity is low

fast-twitch fiber neurons
-conduction velocity is high
-large diameter

33
Q

Muscle fiber organization

A

parallel
-run whole length
- can be banded (abs) or wrap (supinator)

Convergent
-cover broad area and attach at same site
-pecs

pennate medicine
- pull at an angle
-unipennate (finger flexors)
-bipennate (quads)
-multipennate deltoids

circular
-asshole

34
Q

smooth muscle?

A

involuntary
contractile filaments that connect at focal densities
cell is pulled inward from all angles

35
Q

multiunit vs unitary

A

multiunit: each one has their own autonomic neurons

unitary: gap junctions permit coordinated contraction

36
Q

Muscle twitch? 3 phases?

A

single, brief stimulus

latent: first few milliseconds, contraction coupling
contraction: cross bridging shortens
relaxation: calcium restoration

37
Q

how long do muscles store atp for?

A

6 seconds of work

38
Q

modes of ATP synthesis in muscles

A

hydrolysis in creatine phosphate (15s)
glycolysis (40s)
TCA and ETC (long term)

39
Q

creatine phosphate hydrolysis

A

phosphate from creatine + ADP = ATP
fast
limited, rapidly depleted

40
Q

glycolysis and sources of glucose

A

sources: blood, glycogen

glycolysis is aerobic or anaerobic
fairly fast, not long acting

fermentation

purpose: regen NADH and ATP

41
Q

Citric acid cycle and ETC

A

long term energy, krebs cycle first then ETC
fats can be sent into krebs in long term exercise

42
Q

Both fiber types use what metabolism? Specific?

A

creatine phosphate

glycolysis: fast twitch

etc and krebs: slow twitch

over time they use fats from adipocytes

43
Q

Muscle fatigue? occurs when? what produces rapid fatigue? what restores ionic balance? what gets damaged, in turn what regulation is disrupted?

A

physiological inability to contract. Intense exercise? Na/K pumps. Sarcoplasmic reticulum gets damaged, regulation of Ca is disrupted.

44
Q

What is oxygen debt? what causes dramatic changes in muscle chemistry? to return to a resting state:

A

amount of extra O2 needed for restorative processes

exercise

o2 reserves must be replenished
lactic acid conversion
glycogen regen
ATP and CP reserves

Anatomy (7 decks)

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