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PHYS: UNIT 2 > Muscular System > Flashcards

Muscular System Flashcards

1
Q

3 types

A

Skeletal, Smooth, Cardiac

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2
Q

Striations are in _____ muscle

A

Skeletal and Cardiac

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3
Q

Intercalated disks are in the _______ muscle

A

Cardiac

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4
Q

Skeletal muscle fiber traits

A

Multinucleated, mitochondria, transverse(t) tubules

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5
Q

Sarcolemma

A

Plasma membrane in skeletal muscle

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6
Q

Sarcoplasm

A

Cytoplasm in skeletal muscle

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7
Q

Smooth e.r in skeletal muscle

A

Sarcoplasm reticulum

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8
Q

T tubules

A

Channels made up of membrane that send action potential from sarcolemma to Sarcoplasm reticulum

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9
Q

Traits of skeletal muscle

A

Sarcomeres, myofibrils, striations

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10
Q

Sarcomeres

A

Form myofibril, smallest contractile unit of muscle

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11
Q

Myofibrils

A

Contractile organelles, cause striations

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12
Q

Striations

A

Caused by myofibrils, thick and thin filaments

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13
Q

Contraction

A

Activation of force generating sites within muscle fibers (cross bridges)

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14
Q

Motor unit

A

Motor neuron and skeletal muscle fibers it innervates

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15
Q

Steps of muscle contraction

A
  1. ATP binds to myosin head
  2. ATP broken down into ATP+ phosphate
  3. Myosin head extends and binds to actin filament
  4. ADP and phosphate detach from myosin head
  5. M.H returns to compact formation and pulls actin filament as it does
  6. Myosin head detaches from actin filament when ATP binds again
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16
Q

Cardiac Muscle

A

Striated, use sliding filament method to contract
1-2 central nuclei
Branched w intercalated disks
Desmosomes and gap junctions
Absolute refractory period is 250 milli, prevent tetanic contractions

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17
Q

Nodal cells

A

Stimulate own action potentials in the heart (automaticity) for the heart

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18
Q

Single unit smooth muscle

A

Respond to stimuli as single unit bc cells are connected by gap junctions

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19
Q

Multi unit smooth muscle

A

Respond to stimuli independently, few gap junctions

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20
Q

Response (excitatory or inhibitory) depends on ________________

A

Receptors the chemical receptors bind to and what mechanism they activate

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21
Q

A single motor neuron connects to _______ muscle fiber

A

Many

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22
Q

Each muscle fiber is connected to more than one motor neuron.

A

False

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23
Q

When an action potential occurs in a _______ all the _________ contract

A

Motor neuron, muscle fibers (the muscle fibers are the h*es that copy)

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24
Q

There’s are many motor units within a muscle

A

True

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25
Skeletal muscle are only activated by action potentials from neurons.
True
26
Alpha motor neurons
Neurons whose axons activate skeletal muscle fibers
27
Where are the cell bodies of (alpha) motor neurons located?
Brain stem and spinal cord
28
The axons of the motor neurons are ________ to allow ________
Myelinated, signals to travel fast
29
Neuromuscular junction
Junction between axon terminal and muscle cell, transport vesicles with acetylcholine
30
Events at N.M junction
Action potential flys down axon, voltage gated calcium channel open and calcium rushes into cell, The change in potential releases ACh from terminals into NMJ, ACh binds to receptors on muscle cells, Sodium channels open, sodium rushes into cell, change in potential causes muscle cell to depolarize, action potential started in muscle cell, down the m. Fiber, excess acetylcholine in NMJ is broken down to prevent over excitation
31
All neuromuscular junctions are ______
Excitatory
32
Acetylcholineesterase
Enzyme that breaks down ACh
33
Botulinum toxin (Cosmetic BOTOX)
Potent poison that blocks the release of ACh from axon terminals (disrupts proteins necessary for ACh vesicles to bind)
34
What makes up a Sarcomeres?
Skeletal muscle made up of actin and myosin filaments
35
Protein composition of thin filaments
Actin, troponin, tropomyosin that regulate contraction
36
Each actin molecule contains…
A binding site for myosin
37
Tropomyosin
Rod shaped Two intertwined polypeptides Held in position by troponin
38
Troponin
Holds tropomyosin down to actin When calcium binds to troponin, it releases and allows tropomyosin to binds to actin
39
Sliding Filament Mechanism
Force causes shortening of muscle, overlapping thick and thin filaments in each Sarcomeres move past each other, propelled by movement of cross bridges
40
Shortening of Sarcomeres causes shortening of filaments
False; it changes the amount of overlap
41
Single Fiber Contraction
Muscle tension, load, twitch
42
Muscle tension
Forces exerted on object by contracting muscle
43
Load
Force exerted on muscle by object
44
Twitch
Mechanical response of muscle fiber to a single action potential
45
Isometric Twitch
Length of muscle stays the same of tension changes
46
Isotonic Twitch
Tension stays the same but muscle length changes
47
Summation
Increase in muscle tension from successive action
48
Tetanus
Maintained contraction in response to repetitive simulation
49
Titin
Protein responsible for passive elastic properties of relaxed muscle fibers (stetching increases passive tension)
50
Muscle fatigue
Decline in muscle tension as result of previous contractile activity, (slower rate of relaxation and ⬇️ shortening velocity)
51
Acute fatigue from excessive involves
⬇️ ATP concentration, ⬆️in ADP, Pi, Mg, H and O2 free radicals
52
Types of skeletal muscle fibers
Oxidative and glycolytic, slow and fast
53
Oxidation skeletal fibers
Numerous mitochondria for E, long term contraction
54
Glycolytic skeletal fibers
Few mitochondria but lots of glycolytic enzymes and stores, produce E quickly
55
Type 1 Skeletal Fibers
Slow oxidative, combine low myosin - ATPase activity w high oxidative capacity Rate of fatigue: slow Small fiber diameter
56
Type 2A Skeletal Fibers
Rate of fatigue: intermediate
57
Type 2X Skeletal Fibers
Rate of fatigue: Fast
58
Each muscle fiber only contains one of each fiber
False; it contains a mixture of all
59
Tension a muscle can develop depends on…
Amt of tension developed from each fiber, number of fibers contracting at once
60
Motor Unit Size Varies
Small motor units are in small intricate places
61
Shortening velocity…
62
M. Adaptation to Excersize
Increase size of muscle fibers (hypertrophy) Changes capacity for ATP production Changes myosin they express USE IT OR LOSE IT
63
Disuse atrophy
Arm in a cast
64
Denervation Atrophu
Nerve damage = loss of function
65
Muscle cramps
Involuntary tetanic contraction of skeletal muscle A.P fire are highhh rates Caused by electrolyte imbalance in extra cellular fluid (persistent dehydration or over excersize
66
Smooth muscle fibers are ______ than skeletal muscles
Smaller
67
Smooth muscle cells
Single nucleus Divide throughout life DO NOT have troponin DO NOT have Sarcomeres (no banding pattern, hence smooth)
68
Smooth muscle contraction occurs by…
Sliding filament mechanism
69
Pacemaker Potential
70
Varicosities

PHYS: UNIT 2 (4 decks)

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