final lecture 1 Flashcards
(120 cards)
1
Q
what are the 3 muscle types?
A
skeletal, cardiac, smooth
2
Q
skeletal muscle
A
- attaches to bones
- moves bones
- multinucleated and striated
- voluntary contraction
3
Q
cardiac muscle
A
- found in the heart
- pumps blood
- one nucleus, striated, and intercalated discs
- involuntary contraction (SA node)
4
Q
visceral smooth muscle
A
- various organs (ex: GI tract)
- various functions (ex: peristalsis)
- one nucleus and no striations
- involuntary contraction
5
Q
learn skeletal muscle diagram
A
fig 18.1
6
Q
skeletal muscle ultrastructure
A
- single multinucleated muscle fiber contains myofibrils that lie parallel to the fiber’s long axis (myofibrils contain small subunits called myofilaments that lie parallel to the long axis of the myofibril)
- myofilaments consists of actin and myosin that account for approx 85% of myofibrillar complex
- other proteins either serve structural function or affect protein filament interactions during muscle action (tropomyosin, troponin, alpha actinin, beta actinin, M protein, and C protein
7
Q
we have relatively lesser muscle when we are younger and it builds up over time as we grow
true or false?
A
false, we are born with as many muscle fibers as we will have our whole lives, the muscle fibers expand as they are used but we actually begin to destroy muscle fiber later on in life
8
Q
sarcomere
A
consists of basic repeating unit between two Z lines; comprises the functional unit of a muscle fiber
- lie in a series and their filaments have a parallel configuration within a given fiber
- length determines the muscle’s functional properties
9
Q
which muscle fiber type has the greatest rate of fatigue? which has greatest endurance?
A
type 2x has the greatest rate of fatigue, type 1 has the greatest endurance
10
Q
contractile proteins
A
- “molecular motors”
- myosin and actin are examples
11
Q
regulatory proteins
A
- “on and off’s” of muscle contraction
- troponin and myosin light chain are examples
12
Q
structural proteins
A
nebulin and titin are examples
13
Q
what are the 3 types of protein found in muscle?
A
1) contractile proteins
2) regulatory proteins
3) structural proteins
14
Q
thin filament is to _____whereas thick filament is to _____
A
actin, myosin
15
Q
sliding filament model
A
proposes that muscle shortens or lengthens because thick and thin filaments slide past each other without changing length
16
Q
the ___ band decreases as the ____ bands are pulled toward the center of the sarcomere
A
I, Z
17
Q
what are the 4 steps in cross bridging?
A
1) activation: ADP + Pi bind to myosin, energy from ATP hydrolysis is used to activate the hear
2) binding: activated myosin head binds to actin in the presence of Ca++, ADP + Pi remain bound to myosin
3) power stroke: Pi released from myosin, head swivels causing displacement of actin
- rigor complex - tight binding: ADP is released from myosin - the head is bound
4) dissociation: ATP binds to myosin, actin and myosin dissociate
18
Q
when does muscle relaxation occur?
A
- when actin and myosin return to their original states
- when muscle stimulation ceases, Ca++ activity stops and troponin frees up to inhibit actin-myosin interaction (recovery involves active pumping of Ca++ back into SR by Ca++/ATPase pumps)
19
Q
what are the two purposes of muscle “deactivation”
A
1) prevents any mechanical link between myosin crossbridges and actin filaments
2) inhibits myosin ATPase activity to curtail ATP splitting
20
Q
what equation describes the dissociation of actomyosin complex?
A
actomyosin + ATP — actin + myosin - ATP
myosin ATPase splits ATP to yield energy for muscle action
21
Q
excitation contraction coupling - def.
A
represents physiologic mechanism whereby an electrical discharge at muscle initiates chemical events at cell surface to release intracellular Ca++ and produce muscle action
22
Q
___ discs get closer to each other when a muscle contracts
A
Z
23
Q
which zones of the muscle fiber shorten as a result of contraction?
A
H band and I band
24
Q
the A band shortens when muscles contract
true or false?
A
false
25
the inside of the cell is ___ relative to the outside
negative
26
there is ____ Na+ outside the cell relative to the inside
more
27
there is ____ K+ inside the cell than the inside
more
28
______ create myelin in the peripheral NS, whereas ______ create myelin in the CNS
Schwann cells, oligodendrocytes
29
how do endurance and resistance training alter the NMJ?
- it expands on pre and post synaptic sides (size)
| - it increases its quantal content - more ACh (reinforce signal)
30
how does the lack of exercise affect the NMJ?
-decreases the end-plate size - related to muscle fiber type
31
explain how differences in sarcomere alignment and length affect a muscle's force and power generating capacity?
1) fusiform muscles: fibers run straight down the length
2) pennate muscles: fibers come down on an angle
pennate muscles transmit more force because of the arrangement, there are more muscle fibers present (parking lot)
- more fibers = more force
- shorter fibers can generate more force than longer fibers, but longer fibers have a greater range of motion
32
motor unit
one motor neuron and all the muscle fibers it innervates
33
gives 4 reasons as to why pennate muscles differ from fusiform muscles
1) contain shorter fibers
2) possess more individual fibers
3) exhibit less range of motion
4) lie at oblique pennation (unipennate, bipennate, multipennate)
- allows individual muscle fibers to remain short while overall muscle attains considerable strength
34
fusiform fibers (spindle shaped fibers) run ____ to muscle's long axis and taper at its tendinous attachment
parallel
35
in fusiform muscles, fiber length = muscle length
true or false?
true
36
complex fusiform arrangement
- features individual fibers that run parallel to muscle's line of pull
- arrangement features muscle fibers that terminate in muscle's midbelly, and taper to interact with connective tissue matrix and/or adjacent fibers
- enables parallel packing of relatively short fibers within a long muscle
-structural specialization creates lateral tension at various points along the fiber's surface
37
which produce more force, longer or shorter muscles?
shorter
38
which produce force faster, longer or shorter muscles?
longer
39
the slower the muscle, the less force it can produce
true or false?
false, the faster the muscle, the less force it can produce
40
the optimal sarcomere length for maximal contraction is between ____ and ____ micro meters
2, 2.2
41
according to research, all power athletes have over ___% fast twitch fibers
60
42
according to research, all endurance athletes have less than ___% fast twitch fibers
40
43
skeletal muscle contains two main types of fibers that differ in three characteristics, what are they?
1) primary mechanism used to produce ATP (oxidative vs glycolytic)
2) type of motor neuron innervation (slow type 1 or fast type 2)
3) type of myosin heavy chain expressed
44
look at chart on muscle fiber types
first set of slides
45
what are the 4 characteristics of fast twitch fibers? (type 2)
1) high capability for electrochemical transmission of action potentials
2) high myosin ATPase activity
3) rapid Ca++ release and uptake by efficient SR
4) high rate of crossbridge turnover
-these factors contribute to this fiber's rapid energy generation for quick, powerful muscle action
46
the speed of shortening and tension development of fast twitch (type 2) muscle fibers is from ____ to ____ times faster than slow twitch fibers
3, 5
47
how do type 2 muscle fibers mainly generate ATP?
short-term glycolytic system
48
when does activation of type 2 muscle fiber dominate?
in anaerobic type sprint activities and other forceful muscle actions that rely entirely on anaerobic energy transfer
49
what type of sports are type 2 muscle fibers mostly useful?
-stop and go or change of pace sports such as basketball, soccer, lacrosse, or field hockey
50
what are the 3 primary subtypes of type 2 muscle fibers?
1) type IIa: represents fast-oxidative-glycolytic fibers (FOG)
2) type IIx: midway between a and b types in physiolgic and metabolic characteristics
3) type IIb: possesses greatest anaerobic potential and most rapid shortening velocity; represents "true" fast glycolytic fiber (humans do not have many of these)
51
how do slow twitch (type 1) muscle fibers generate ATP?
through aerobic system
52
what are the four distinguishing characteristics of slow twitch (type 1) muscle fibers?
1) low myosin ATPase activity
2) slow Ca++ handling ability and shortening speed
3) less well-developed glycolytic capacity than fast twitch fibers (lactate dehydrogenase tends to take lactate and make it pyruvate)
4) large and numerous mitochondria
53
which type of muscle fiber is highly fatigue resistant?
slow twitch
-ideally suited for prolonged aerobic exercise
54
both slow and fast twitch muscle fiber types contribute during near maximum aerobic and anaerobic exercise
true or false?
true
55
in muscle biopsy, which part of the muscle fiber is "stained"?
parts associated with myosin
56
what are the fiber type difference among athletic group individuals?
- large individual difference in fiber type distribution
- endurance athletes are very high in type 1 muscle fibers (some as high as 90-95% in gastrocnemius)
- speed and power athletes have lots of type 2 fibers
- middle distance athletes have a more even fiber distribution
57
which muscle fiber type has the greatest power loss?
-type 2a and 2x (along with ATP loss)
58
men, women, and children on average possess ___ to -___% slow twitch fibers in arm and leg muscles
45, 55
59
fast twitch fibers distribute evenly between type 2a and 2x subdivisions
true or false?
true
60
there are significant gender differences when it comes to the distribution of muscle fiber types
true or false?
false, there are no gender differences, the only differences exist in interindividuals (nothing to do with gender)
61
trends in muscle fiber type distribution varies significantly among the body's major muscle groups
true or false?
false, they are fairly constant
62
what are the 4 different independent chemical signalling pathways that regulate skeletal muscle fiber types?
1) Ras/mitogen-activated protein kinase (MAPK)
2) calcineurin
3) calcium/calmodulin-dependent protein kinase IV
4) coactivator peroxisome proliferator g coactivator 1 (PGC-1 sigma)
- promotes mitochondrial biogenesis
- mitochondrial fatty acid oxidation
- hepatic gluconeogenesis
63
by weight, a muscle fiber consists of ____% water, ____% protein, and the remainder other substances
75, 20
64
muscle's VO2 during vigorous exercise increases up to ___ times resting level
70
65
the ____ represents the functional unit of a muscle fiber, it contains the contractile proteins actin and myosin
sarcomere
66
______ serve as structural links between thick and thin protein filaments
myosin crossbridges
67
_____ inhibits actin and myosin interaction
tropomyosin
68
_______ function as a micro transportation network to spread the action potential from the fiber's outer membrane
the triad and T tubule system
69
hypertrophy - def.
involves an increase in size of skeletal muscle through a growth in size of its component cells
- sarcoplasmic hypertrophy: focuses more on increased muscle glycogen storage
- myofibrillar hypertrophy: focuses more on increased myofibril size
70
which starts first when talking about muscle gains? the neural or the hypertrophic aspect?
neural starts earlier, then comes hypertrophic (increase in size due to protein)
71
muscle mass is affected by which 6 things?
1) PA (stimulates hormones that stimulate an increase in muscle mass)
2) genetics
3) nervous system activation
4) nutritional status
5) endocrine influence (human growth hormone, testosterone, etc)
6) environmental factors
72
smaller motor neurons tend to innervate muscles for _______ activities whereas longer motor neurons tend to innervate muscles for _____ activities
endurance, power
73
before protein is put down inside sarcomeres, what contributes to increase in muscle strength in the first two weeks of training?
increased functioning of the CNS
74
insulin growth factor 1, testosterone are both hormones that promote muscle growth
true or false?
true
75
adaptations to resistance training: muscle fibers
- increase in size
| - increase in strength
76
adaptations to resistance training: mitochondria
decrease in volume, decrease in density
77
adaptations to resistance training: enzymes
creatine phosphokinase: increase
| myokinase: increase
78
adaptations to resistance training:; intramuscular stores
- ATP: increase
- PCr: increase
- glycogen: increase
- TG: maybe
79
adaptations to resistance training: basal metabolism
increased functioning
80
adaptations to resistance training: aerobic capacity
-circuit training: increased capability
81
adaptations to resistance training: body comp
- % body fat: decreased
| - lean body mass: increase
82
adaptations to resistance training: connective tissue
- ligament strength increases
| - tendon strength increases
83
adaptations to resistance training: bone
- mineral content and density increases
- cross sectional area increases
- twitch time decreases (mostly due to recruitment of fast twitch fibers)
84
grey matter
unmyelinated axons and or cell bodies
85
white matter
myelinated axons
86
which is more likely to have less motor neurons innervate it by muscle fiber? muscles of the eye or muscles of the leg?
muscles of the eye
- muscles that requires a lot of control are innervated by motor neurons that innervate less muscle fibers as opposed to muscles that don't require high amounts of control which have one motor neuron innervating more muscle fibers
- these motor neurons also sometimes connect directly to the muscle that have fine control rather than going through an interneuron
87
what are the three types of neurons?
1) motor
2) sensory
3) interneuron
88
which is a better insulator? fat or muscle?
fat is a better insulator because it contains less water than muscle
-this is why fat or myelin surrounds axons
89
saltatory conduction
propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials
90
what is the neural end plate?
communication area where ACh is released from motor neurons
| -ACh binds to NICOTINIC receptors - ligand operated
91
what is the enzyme that breaks down ACh? what would happen if we didn't have this?
acetylcholinesterase
| -ACh would forever be floating in the synapse and binding to nicotinic receptors, and our muscles would never relax
92
excitatory post synaptic potential (EPSP)
postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential
- these can be summed and when the charge reaches the threshold, an action potential fires
- sum in space and in time
- strength of excitement determines its amplitude (unlike action potentials
- they also decrease in amplitude with time
93
hyperpolarizations are always more _______ and depolarizations are always more ______
negative, positive
94
motor neuron pool
every motor neuron that innervates a muscle as a whole
| -ex: every motor neuron that innervates the bicep
95
one single motor neuron is less likely to innervate multiple muscle fibers in which type of muscle?
- one motor neuron will innervate multiple fast fatigueable muscle fibers
- one motor neuron will only innervate a couple slow twitch muscle fibers
96
what are the two ways we can modulate muscle force?
- increase the rate of firing
- recruit more motor units
ex: slow twitch fibres are recruited first, and as intensity of the exercise increases, the fast twitch oxidative glycolytic and the fast twitch glycolytic are recruit as needed
97
what is the size principle?
with increased muscle force, motor neurons with larger axons are recruited
- orderly recruitment of specific motor units to produce a smooth muscle action; allows the CNS to fine tune skeletal muscle activity to meet motor task demands
- differential control of motor unit firing patterns represents major factor distinguishing skilled from unskilled performance
98
fatigue - def.
decline in force capacity with repeated stimulation or during a given time period
99
what are the 4 components that impact voluntary muscle action?
1) CNS: when everything is working well peripherally but the CNS loses motivation to keep the task going at the same intensity
2) PNS: decrease in ATP stores, glycogen stores in the liver, etc.
3) NMJ: can't keep up with the rate of msucle contraction - decrease in available ACh in synaptic cleft
- branch point failure: failure of AP to go past the NMJ
4) muscle fiber: build up of H+ ions, acidic environment, which inhibits enzymes
- ionic imbalances - there a certain [] of ions is optimal to allow depolarization (Cl-, K+, Na+)
100
fatigue occurs from the disruption in the chain of events between the ____ and the muscle fiber
CNS
101
how do we modulate motor signals?
1) feedback through reflex loops at the spinal cord - these don't need to reach the brain to operate
2) feedback or descending control from supraspinal centres
- basic control comes from medulla and pons - M1 (motor control centre) is able to override brain stem to a certain extent
102
what are the two parts of the nervous system
1) CNS - brain and spinal cord
| 2) PNS - nerves that transmit information to and from the CNS (voluntary control for the most part)
103
CNS function
- brain and spinal cord
| - integrative/control centers
104
PNS function
- cranial nerves III-XII
| - spinal nerves
105
afferent division of the CNS - function
- sensory component
- somatic and visceral neurons
- conducts impulses from receptors to CNS
106
efferent division of the PNS - function
- motor neurons
| - conducts impulses from the CNS to effectors
107
autonomic NS - function
- involuntary
| - conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands
108
somatic nervous system - function
- voluntary
| - conducts impulses from the CNS to skeletal muscles
109
proprioceptors - def.
muscles and tendons contain specialized sensory receptors sensitive to stretch, tension, and pressure, which relay info about muscular dynamics and limb movement to conscious and subconscious portions of the CNS
110
muscle spindle - def.
the functional significance of the muscle spindle lies in its ability to detect, respond to, and modulate changes in the lengths of the extrafusal fibers
-has to do with proprioception
111
muscle spindle - fusimotor system
- these are parallel to muscle fibers
- sensitive to length and rate of change of muscle fibers
- associated with gamma motor neurons
- the primary and secondary fibers give info to CNS, tells us how our limbs are in space
- every time one of our muscles changes length, these are activated, the degree of pressure on these fibers determines how excited they become
112
what is reciprocal inhibition?
process of muscles on one side of a joint relaxing to accommodate contraction on the other side of that joint
113
what is the function of the golgi tendon organ?
function of the GTO can be considered opposite of the muscle spindle, which serves to produce muscle contraction
114
golgi tendon organ 1b
- tendon organ
- connective tissue capsule penetrated by 1b afferent nerve
- branching axon - tension produces stretch which causes 1b activation
-1b inhibitory interneuron receives info from 1b and inhibit aelpha motor neuron - decreases firing rate
115
what is the name of the cell that causes recurrent inhibition or "self inhibition" in motor neuron discharge?
Renshaw cell
116
pacinian corpuscle
- small ellipsoidal bodies located close to GTOs and embedded in a single, unmyelinated nerve fiber
- respond to quick movement and deep pressure
- detect changes in movement or pressure
- act as fast adapting mechanical sensors that discharge a few impulses at the onset of a steady stimulus, and then remain electrically silent or discharge a second volley of impulses when the stimulus ceases
117
free nerve endings - group III
```
Polymodal response (multiple synapses involved - greater than 3 or 4) - i.e. chemical and mechanical stimuli
Respond to intensity of contraction
-intermittent or maintained (vigorous response at onset of contraction; increased response during tetanic contraction as tension increases to peak)
Chemicals
-K+, lactate, arachidonic acid, histamine
```
118
free nerve endings - IV
Group IV (C fibers)
-polymodal
-respond to contraction (respond with latencies of 5 to 30 seconds; amplified during ischemia)
Chemicals
-similar to Group III; except for arachidonic acid
119
increasing activation of muscle group III and IV afferent with lead to motor neuron _____
inhibition
-to decrease force
120
what are the 6 main brain regions?
1) medulla oblongata
2) pons
3) midbrain (locomotion)
4) cerebellum (postural)
5) diencephalon
6) telencephalon
