Muscles--Skeletal Flashcards
(95 cards)
1
Q
what are the functional properties of muscle?
A
contractility, excitability, elasticity, extensibility
2
Q
skele muscles made up of ___ that are multinucleated and have a ___ appearance
A
myofibrils; striated
3
Q
cardiac muscle have ___ nucleus(nuclei)
A
single
4
Q
purpose of smooth muscle?
A
mech. control of: digestive, urinary, repro tract, blood vessels, airways
5
Q
smooth muscle is ___ shaped
A
spindle
6
Q
skel muscles attached to bones by ___
A
tendons
7
Q
___ is closest to trunk/more stationary bone; ___ is more mobile attachment
A
origin; insertion
8
Q
skel. muscle is ___% body weight, ____% daily energy expenditure (not include BMR)
A
40; 15-60
9
Q
skel muscle makes up ____% of BMR
A
20
10
Q
bundle of muscle fibres
A
fascicle
11
Q
cell membrane of muscle called:
A
sarcolemma
12
Q
back bone of thin fil, db stranded alpha helical polymer, has binding site
A
actin
13
Q
two identical alpha helicies coil around each other and sit in actin grooves, regulating myosin binding
A
tropomyosin
14
Q
what is the troponin complex?
A
trop T, trop C, trop I (every 7 actin cules)
15
Q
thick fil consist of ___ myosin cules, ___ intertwined heavy chains w/ globular heads
A
250; 2
16
Q
myosin head contains :
A
region bind ATP and region for actin binding
17
Q
_____ regulates ATPase activity
A
regulatory light chain
18
Q
____ stabilizes myosin head
A
alkali light chain (more important in smooth muscle)
19
Q
largest protein extending from M band to Z disk, involved w/ elastic recoil
A
titin
20
Q
large potein wraps around thin fil, reg. lenth and stability of thin fil
A
nebulin
21
Q
endings of sarcomeres, zigzag, attachment place for thin fil
A
Z disk
22
Q
____ are lightest bands of sarcomere, Z disk is in centre
A
I bands
23
Q
____ is darkest band, including entire length of thick and some overlap
A
A band
24
Q
central region of A band only consist of thick fil
A
H zone
25
equivalent to Z disk but for thick fil
M line
26
path of initiation of skel muscle contract?
lower motor neuron-->alpha motor neuron-->ventral horn-->muscle fibres
27
what is a motor unit?
single motor neuron and all fibres it innervates
28
what is the neuromusc junction?
area where motor neuron makes synaptic contact w/ muscle fibre
29
what are brain regions involved in voluntary mvmt?
premotor, basal ganglia, thalamus, midbrain, cerebellum
30
upper motor neuron (brain-->spinal cord) and lower motor neuron (spinal --> muscle) referred to collectively as:
corticospinal tract
31
neurodegenerative motor neuron disease
amyotrophic lateral sclerosis
32
____% ALS genetically inherited, ___% of these due to mutation in ___
10; 25; SOD
33
3 coponents of neuromusc junction:
1) presynaptic motor neuron terminal
2) synaptic cleft
3) postsynaptic membrane of skel muscle
34
motor neuron vesicles contain ____, muscle mem contain _____
Ach; nicotinic ACh receptor (need two ACh to open)
35
acetylcholine is broken down by ____
acetylcholinesterase (in cleft)
36
what happens to broken down choline?
transport back to motor neuron and combined w/ Acetyl CoA by cholin acetyltrasferase-->make ACh again-->ACh-H exchanger move ACh into synaptic vesicles
37
disorder of neuromusc transmission, common in cranial muscles
myasthenia gravis
38
myasthenia gravis mainly ____ thru production of antibodies, but can be ____
autoimmune; congenital (# receptors, v size of folds, ^ synaptic cleft)
39
how to treat myasthenia gravis?
AChesterase inhibitors
40
sarcolemma penetrate into muscle fibre in form of ___ that contain Ca storage organelles called ___
T tubules ; sarco reticulum
41
how does Ca enter cyto?
voltage gated Ca channels or from sarco reticulum
42
process by which electrical excitation of surface mem trigger ^ in [Ca]
excitation-contraction coupling
43
T tubules surround myofibrils at ___ and ___ bands; tubules associated w/ 2 ___to form a "triad"
A; I; cisternae
44
___Type channels and ___ are mechanically coupled
L; RyR
45
Ca induced Ca release is more important in ____ muscle
cardiac
46
release of ____ initiates power stroke
inorganic phosphate
47
how does Ca cause contraction?
bind trop C-->conformation change-->trop complex and tropomyosin move to reveal myosin binding site
48
what is cross bridge cycling?
myo attach to actin-->ATP bind to release it-->hydrolyze to ADP to cock and form cross bridge-->inorganic P release to power stroke
49
during muscle contraction, ___ zone and ___ band shoten, while ____ band remains constant
H; I; A
50
how is Ca removed to xtracell space?
Na-Ca-xchanger or Ca ATPase
51
Ca reuptake into SR mediated by:
SERCA type pump
52
___ in SR inhibits SERCA pumps; ___ exists to delay this inhibition
^ Ca; calsequestrin (triad region, 50 Ca binding sites/cule)
53
how does calsequestrin work?
form complex with RyR, buffer Ca and unload Ca near RYR to facilitate EC coupling
54
why does rigor mortis occur?
Ca leak into sarco, bind troponin-->stuck in latch state cuz ATP production stops (can't release), and Ca can't be removed
55
delay between muscle fibre AP and contraction
latent period (Ca being released and binding troponin)
56
most readily available back up to ATP is ____
phosphocreatine (10 seconds)
57
muscle has a lot of this enzyme
creatine kinase
58
why ATP needed in muscles?
sodium postassium pump, remove Ca, activate x bridge cycle
59
primary mech for long term regen of ATP
aerobic metabolism
60
___ fatigue precedes ___ fatigue
central (feeling); physiological
61
why muscle fatigue?
low pH from acid production during ATP hydrolysis
62
why periipheral fatigue?
1) ACh synth can't keep up with neuron firing rate-->fail reach threshold,
2) probs w/ excitation contraction coupling (NaK pump can't keep up)
3) buil up of inorganic P and ADP
63
how does inorganic P/ADP cause fatigue?
slow down cycling, reduce Ca reuptake, prevent RyR release Ca , v sensitivity to trop C
64
type one is ___fibres; two is __
slow; fast
65
type 2a is:
fast-ox-glycolytic
66
type 2x is:
fast-glyco
67
tension directly proportional to ______
number of crossbridges formed (overlap)
68
max contraction known as ____, which is subdivided into ___ and ___
tetanus; unfused, fused
69
group of all motor neurons innervating single muscle called:
motor neuron pool
70
during submaximal contraction, CNS mod. firing rates of motor neurons to allow diff units maintain contraction to prevent fatigue. THis is called:
asynchronous recruitment
71
force tending to pull attachment points of muscle towards one another
tension
72
creating force w/out moving load called ___, creating force to gen. mvmt called ___
isometric; isotonic
73
this type of contraction is best for muscle building
eccentric
74
how do sarco shorten during isometric w/out muscle change length?
elastic elements (tissues, tendons in series)-->ALWAYS start with isometric contract
75
4 examples of muscle adaptation?
1) ^ ATP-synth capacty (increase mito, glycolytic enzymes, cap. density)
2) muscle cross section (hypertrophy)
3) muscle fibre type transition (some endurance convert fast glyco to fast ox. glyco)
4) ^ strength w/out hypertrophy (motor learning)
76
where does hyperplasia occur?
in cats; when myosatellite cells involved in muscle repair form new myofibrils in development , split when become too large
77
how does resistance training cause hypertrophy
satellite cells donate nuclei to injury sites (chemotaxis) --> more myosin and actin , express myogenic reg. factors that aid repair, regen and growth; overload stim cause ^ # sarcomeres in muscle length and glycogen
78
why does atrophy occur?
immobilization, bed rest, unloading (space), food deprive cause ^ myostatin, age, cachexia, musc. dystrophy, denervation
79
___ send info about stretch to CNS, found among extrafusal fibres, arranged parallel to muscle fibres
muscle spindles
80
found in capsules and ligaments around joints, stim by mech distortion accompany changes in pos. of bones
joint receptors
81
muscle spindles aare ___ active, lack ___ in central region, responsible for____, made up of ___ neuron wrapped around ___ fibres
tonically; myofibrils; normal resting muscle tone; sensory; intrafusal
82
____ maintains spindle function when muscle conracts
alpha-gamma coactivation
83
sensory neuron interwoven among collagen in tendon, only active when high amounts fo tension, originally proposed to control ___
golgi tendon organ; inhibitory reflexes prevent damage
84
____ inhibition controls mvmt around joint
reciprocal
85
____ reflex pull limbs away from painful stim
flexion
86
complicated flexion reflex
crossed-extensor reflex
87
mvmts loosely classified into these 3 categories:
reflex, voluntary, rhythmic
88
___ is important for relaying/modifyig signals as pass from spinal cord/basal ganglia/cerebellum-->cerebral cort
thalamus
89
what are 3 levels nervous sys control mvmt?
1) spinal cord (integrate spinal reflex, central pattern generators for rhythmic)
2) brainstem/cerebellum (postural reflex, hand/eye)
3) cortex+basal ganglia (voluntary)
90
phases of vol. mvmt?
plan-->initiate-->execute
91
corticospinal tract cross to opp. side at ____ located in ____
pyramids; medulla
92
this disease reflects basal ganglia dysfunction; loss of ___ containing neurons in _____
Parkinson's; dopamine; substantia nigra
93
parkinson's is characterized by:
bradykinesia, akinesia, rigidity, tremors, cog. dysfunction
94
___ cause parkinson's as a byproduct of synthetic heroine
MPTP
95
how to treat parkinson's?
MAO inhibitors, dopamine precursors
