Muscle Flashcards
(119 cards)
1
Q
3 types of muscle
A
skeletal, cardiac, smooth
2
Q
skeletal is the only one that is?
A
voluntary one
3
Q
cell membrane is the
A
sarcolemma
4
Q
skeletal muscle
A
attached to bones by tendons
5
Q
flexor
A
brings bones togeher- biceps
6
Q
extensor
A
moves bones away- triceps
7
Q
when do skeletal muscles contract
A
only when response from a motor neuron
8
Q
epi, peri, ende -mysium
A
epi- around the whole thing
peri- binding fascicles (bundles) together
endo-covers individual muscle fibres
9
Q
t-tubules
A
are formed from inward extensions of the sarcolemma
- allow electrical signals to go deeper into the cell
10
Q
triad
A
formed from a triplet ( one T-tubual and 2 terminal cristae) of tubules made of the sarcoplasmic reticulum which surrounds the T-tubule
11
Q
I band
A
only thin filaments
12
Q
H zone
A
only thick filaments
13
Q
A band
A
both thick and thin
14
Q
myosin
A
thick filament
15
Q
actin
A
thin filament
- globular protein that forms wo strands that twist together
16
Q
troponin
A
holds tropomyosin molecules in place
17
Q
tropomyosin
A
protein that blocks the active sites on the actin molecule
18
Q
titin
A
provides elasticity and stabilizes myosin
19
Q
nebulin
A
helps to align the actin
20
Q
muscle fibres contain lots of?
A
mitochondria and several nuclei
21
Q
what are myofilaments?
A
the microfilaments- thick and thin in myofibrils
22
Q
segment of myofibril between 2 successive Z lines?
A
sacromere
23
Q
conratile unit of muscle fibres?
A
sacromere
24
Q
each myofibril consist of many contractile units called
A
sacromeres
25
Z line
anchor for myofibriles
| - thiner striation than the A band
26
A band
wide dark stripe
27
what band gives muscles their striation look?
A band
28
4 things muscle fibres contain?
sarcolemma
t-tubules
sarcoplasm ( which has myofibrils, mito, SR)
multiple nuclei
29
6 types off myofibriles
actin, troponin, tropomyosin (thin)
myosin (thick)
titin and nebulin
30
sarcolemma
muscle cell plasm
31
SR stores?
Ca2+
32
4 types of protein that make up the myofilament?
myosin, actin, tropomyosin and troponin
33
______ filaments DO NOT attach to z lines
thick (myosin)
| - just in the centre A band area
34
Actin
globular protein that forms two fibrous strands that twist around each other to form bulk of the thin filaments
35
tropomyosin
protein that blocks the active sites (for myosin to bind to actin) on the actin molecules
36
troponin
protein that holds tropomyosin molecules in place
37
titin and nebulan are____ proteins
regulatory
38
nebulin helps to ?
align actin
39
titan provides?
elasticity and stabilizes myosin
40
motor neurons connect to sarcolemma at _____
motor endplate
| this is a neuromuscular junction
41
neuromuscular junction
is a synapse where neurotransmitter molecules transmit signals
42
motor neuron releases at the motor endplate
acetylcholine (ACH) which binds with receptors on the muscle fibre and depolarizes the cytoplasmic membrane of the muscle fibre
43
what happens when the fibre is stimulated by ACH
net entry of Na2+ into the muscle through ACH channel receptors ( they open to let Na inside) which creates an
electrical impulse which travels from the sarcolemma and down t-tubules where the voltage change triggers the opening of voltage gated Ca2+ channels----> which allows Ca2+ to diffuse out of the SR and this is what causes contraction --. Ca2+ interacts with troponin, allowing actin-myosin binding
44
RyR
ryanodine receptor channel- it is in the ER membrane, when the action potenical travels down the t-tubuleit alters the conformation of DHP receptor which then opens RyR channel and Ca2+ can flow out of SR
45
DHP-
calcium channel that is in t-tubules and when triggered by an action poetical will open up RyR to allow Ca2+ to flow out of the SR
46
ca2+ binds to __________, which allows _________ to shift and expose the actin site
ca binds to troponin
| allowing tropomyosin to shift and expose the active site for mason heads to bind to actin
47
the binding of myosin heads triggers?
the hydrolysis of ATP into ADP and P
48
when calcium is absent the active _____ binding sites on actin are??
myosin binding sites
| covered by tropomyosin
49
describe relaxation?
immediately after Ca ions are released, SR begins to actively pump them back into sacs
50
resting muscles store _____ in the high energy bonds or ______
ATP,
phosophocreatine
(ATP + creatine--> ADP + phosphocreatine)
51
working muscles break down _______ into _____ + _____
phosphocreatine + ADP--> creatine + ATP
52
muscles store very limited _______, but can store _______ used to make ___ on creatine
very little ATP reserves, but can store phosphate used to make ATP on creatine as PHOSPHOCREATINE
53
three types of muscle fibres?
slow twitch oxidative (SO), fast twitch oxidative (FOG),, fast twitch glycolytic (FG)
54
slow oxidative
use aerobic metabolism and oxidative phosphorylation to produce low power contractions over a long period of time and do not fatigue as fast
- red in colour and lots of mito
55
Fast oxidative
oxidative phosphorylation to produce higher tensoion contractions
56
fast glycolytic
rely on anaerobic glycolysis to produce ATP and powerful contractions but fatigue very quickly
57
describe the look of the cardiac muscle
branched, and forms junctions called intercalated disks with adjacent cardiac fibres
- not as highly organized as skeletal muscles
- contain SR and T-tubules
58
cardiac muscle fibers form a ____________ around the heart chambers that conducts a single impulse across a virtually continuous sarcolemma
contractile band
59
compare the T-tubules of cardia vs skeletal
cardiac- T-Tubules are larger and form dads ( not triads) with a rather sparse SR
60
other important aspects about cardiac muscle
self-stimulating
does not run low on ATP
no fatigue
sustains each impulse for longer than skeletal muscles
61
Smooth muscles
small tapered cells with a single nuclei
- no T-tubules and only a loosely organized SR
no striations, bc thick and thin oil are arranged differently
- myofilaments are NOT organized into sarcomeres!
62
do Smoot muscles have sarcomeres?
no
63
if the SR in smooth muscles is loosely organixized where does the Ca2+ come from? does it still store Ca2+?
no the calcium comes from outside of the cell and binds to calmodulin instead of troponin to trigger a contraction
SR can still hold some but not a lot
64
Ca in smooth muscle binds to ______ instead of ______ to trigger a contraction?
Calmodulin instead of troponin
65
Contraction in smooth muscles can be described as?
"balling up"
66
2 types of smooth muscle include
```
single unit (visceral)
Multiunit
```
67
single-unit smooth muscle tissue
- many cells contract as a unit
- impulses are passed to adjacent muscle cells through gap junctions
gap junctions join smooth muscles fibres into large, continuous sheets
this is the most common type, forms a muscular layer in the walls of hollow structures such as digestive, urinary and reproductive tracts
-exhibits autorythmicity- for peristalsis
68
multiunit smooth muscle tissues
each cell stimulated independently
does not act as a single unit bu tis composed of many independent cell units
each fibre responds only to nervous input
69
Smooth muscle contraction steps/proccess
-Ca concentration increase as Ca moves in from SR and outside the cell
-ca binds to calmodium
ca-calmodium activates myosin light chain kinase (MLCK)
- MLCK phosphorylates light chaos in myosin heads and increases myosin ATPase activity
- active myosin crossbrisges slide along actin
70
smooth muscle relaxation
- ca actively pumped back out of cell or into SR
71
smooth muscle contracts ______ and is _______
slowly and is prolonged
72
smooth muscle characteristics
much smaller than skeletal,
has longer actin and myosin filaments, myosin light chain plays regulatory role, no sarcomeres, less SR, controlled by hormones and paracrine, variable electrical responses
73
smooth muscle cells contain ___________ calcium channels, that open when ________
stretch-activated
- ops when press or other force distorts cell membrane
- known as myogenic contraction
74
myogenic contraction is?
when stretch -activated calcium channels open due to pressure to force distorting cel membrane
75
atria
are the two upper chambers that receive blood from systemic veins (right) and the pulmonary veins (left atrium)
76
ventrilces
two lower chamber that pump blood out of heart
77
the inter ventricular septum separates the low-oxygen blood on the ____ side of the heart from the high-oxygen blood on the ___ side of the heart
low= right
| high=left
78
the right atrium receives blood from the ?
systemic viens (low O2)
79
the left atrium receives blood from the?
pulmonary veins (which are the only veins that are high o2 bc just coming from the lungs)
80
the heart wall consists of three layers
endocardium
myocardium
epicardium
81
endocardium
inner thin layer of the heart
82
myocardium
middle layer of the heart
| thick and intestine looking
83
epicardium
external membrane of the heart
84
heart is composed of mostly?
myocardium
85
pericardium
fluid filled sac that encases the heart
86
blood returning from the systemic circulation enters the _____ through the _____
right atrium
| vena cava
87
blood leaving the right ventricle through _______ goes to the ______ and is oxygen ______
pulmonary arteries
lungs
poor
88
venae cava
blood from systemic system to right atrium
89
pulmonary circulation is ____ pressure while systemic is _____ pressure
low pressure, Hugh pressure
90
what can increase blood viscosity?
```
high hematocrit ( % RBC)
high plasma protein concentration
```
91
which side of the heart does more work?
left side ( has to pump into a longer high resistance system )
92
chordae tendinae
heart strings that play a role in holding the AV (atrioventricular) valves in place- prevent them from being inverted
93
which AV valve is bicuspid? which is tricuspid?
bi- left
| tai-right
94
semilunar valves separate?
major arterial trucks from ventricles
| aorta and pulmonary parties
95
semilunar valves open when?
the pressure in the ventricles are higher than the pressure in the aorta
96
how does the heart contract?
as a result of an AP that it produces itself
97
what are the 2 specialized types of cardiac muscle cells?
contractile and autorhythmic
98
contractile cells in the heart functin
99% of the cells- do the pumping- they do not initiate!
99
autorhythmic cells of the heart
initiate and conduct action potencial- they do not contract!
100
what is the hearts pacemaker?
the sinoatrial node
101
where is the sinoatrial node located? why?
the arteria wall
| - because the ratio need to contract first
102
how is the rythm maintained?
specialized cells inside the node possess an intrinsic rythm
103
what happens if the SA node gets "derailed"
it gets passed to the next node ( AV node) and the AV node will now set pace
- will be abnormal rate
- how does it get derailed?
104
what is ectopic focus?
occasionally a different area of the heart gets overly excited and depolarizes faster than the SA node
- as a result of anxiety, lack of sleep, caffeine, nicotine or heart disease
- results in the whole heart being driven faster)
105
describe the route of contraction
SA node- in artia initiates AP
- -> traves to AV node--> conduction slows to allow complete contraction of the artia before the contraction reaches the ventricles
- after the AV node, contraction velocity increases,
- impulse travels to right and left branches of the bundle fibres and Purkinje fibres- this tells ventricles to contract! (simultaneously)
106
cardiac autorythmic cells do not have a?
resting potencial
| - instead they have pacemaker activity
107
describe pacemaker activity
the membrane potential's slow drift to threshold is caused by cyclical decrease in passive outward flux of K+ and constant inward leak of NA+ and inward Ca2+
108
within the intercalated disc what 2 types of junctions are there?
gap and desmosomes
109
gap junctions in intercalated discs function
areas of low electrical resistance and allow or electrical impulses to spread from cardiac cell to the next
110
how is the threshold reached in cardiac contractile cells?
activation of voltage gated Na+ channels (same as other cells)
- unlike other cells the plate phase is prolonged
111
cardiac troponins
are indicators of heart damage
- they are released when the heart muscle has been damages
- determined in blood test
- high levels say that a heart attack has occured
112
do cardiac muscle cells have a RP?
yes and a refractory period
| - the resting potenicail of cardiac muscle cells is -90 (not -60 as in ARC) and the threshold is -70
113
parasympathetic control of heart rate
various autonomic nervous system input can change the rate of the heartbeat
- the parasympathetic nerve is the vagus nerve which primarily affects the atrium and the SA node
- decrease it by releasing acetylcholine which increases the permeability of the K+ channels ( more K+ out of cell) which has a hyper polarization effect
114
parasympathetic nerve is the
vagus nerve
115
parasympathetic mechanism to
releases acetylcholine which increase K+ out of cell- hyper polarization effect on cell
116
sympathetic control of heart rate
stimulates SA node by releasing norepinephrine by accelerating inactivation of K+ channel--> K+ stays in the cell
cell becomes less negative
swifter drift to AP
117
what are baroreceptors
receptors sensitive to changes in pressure
- they send nerve fibres to the cardia control centre in the medullar oblongata
-stretch receptors
-
118
what are the two baroreceptors in the heart
carotid and aortic
119
what do baroreceptors do
coordinate with the integators in the cardiac control centre in negative feedback loops to oppose changes in blood pressure by adjusting the heart rate
