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Physiology Exam 2 > Muscles > Flashcards

Muscles Flashcards

(87 cards)

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1
Q

What are the 4 properties of muscles?

A

Contractility
Excitability
Extensibility
Elasticity

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2
Q

What is muscle contractility?

A

Ability of a muscle to shorten with force

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3
Q

What is muscle excitability?

A

Capacity of a muscle to respond to a stimulus

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4
Q

What is muscle extensibility?

A

Muscle can be stretched to its normal length and beyond to a limited degree

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5
Q

What is muscle elasticity?

A

Ability of muscle to recoil to original resting length after stretched

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6
Q

What three things are muscles organized into?

A

Location
Structure
Mode of control

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7
Q

What are the two modes of control of muscles?

A

Voluntary
Involuntary

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8
Q

What are the two types of muscle structure?

A

Striated
Smooth

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9
Q

What are the three types of muscle location?

A

Skeletal
Cardiac
Visceral (gut)

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10
Q

What are muscle cells

A

muscle fibers

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11
Q

What is a myofibril?

A

rod-like organelle of muscle cell

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12
Q

What are myofilaments?

A

Actin
Myosin

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13
Q

Where are myofilaments located?

A

Myofibrils

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14
Q

What myofilament is connected to z disks?

A

Actin

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15
Q

What is thick filament?

A

bundle of Myosin

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16
Q

What is thin filament?

A

Actin

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17
Q

Which myofilament slides?

A

Myosin slides along actin

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18
Q

What two binding sites exist on myosin head?

A

Actin binding site
ATPase site

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19
Q

What is the structure of an actin filament?

A

Actin monomer in 2-strand helix
Tropomysoin
Troponin

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20
Q

What are the steps of the power stroke?

A

Myosin binds to actin
Phosphate is released
Power stroke happens
ADP is released
ATP binds
Myosin unbinds from actin
ATP is hydrolyzed

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21
Q

How does myosin rotate during the power stroke?

A

Four sequential bonds, each stronger
ADP leaves and ATP binds

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22
Q

How is muscle contraction regulated?

A

Tropomysosin and Troponin

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23
Q

What is the role of tropomyosin and troponin in actin?

A

Tropomysoin blocks myosin binding sites
Calcium binds to troponin which moves tropomyosin, revealing myosin binding site

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24
Q

What concentration does calcium remove inhibition of cross bridges?

A

10^-7 M

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25
What is calcium concentration controlled by?
Sarcoplasmic reticulum
26
How is calcium released from the sarcoplasmic reticulum?
Muscle action potential
27
What is the funciton of T tubules?
allows action potentials to go inside cell
28
What is the structure of t tubules?
formed from sarcolemma (muscle plasma membrane) Open to extracellular environment
29
What are the steps of excitation-contraction coupling?
ACh release Na+ initiates action potential Action potential in T-tubes opens DHP receptor which opens calcium release channels in SR calcium enters cytoplasm Calcium binds to troponin Myosin-actin binding Power stroke Actin filament slides Calcium pumped back into SR Troponin returns to original position
30
Where and what releases ACh during excitation-contraction coupling?
Neuro-muscular junction Somatic motor neurons
31
Where does Na+ go to initiate a muscle action potential?
Entry into ACh recpetors
32
How do t-tubules open DHP receptor?
Action potential in t-tube alters conformation of receptor
33
What is titin?
Titin proteins stabilize myosin, located between actin and myosin, bound to myosin at various points
34
What is a motor unit?
All muscle fibers connected to one motor neuron
35
Are motor unit contractions all or nothing?
Yes
36
How do muscles vary contraction force and duration?
Recruitment of differet types and amount of motor units
37
What is tension control?
The more motor units recruited, the greater the force generated
38
What are the two types of movement control?
Fine and coarse
39
What is fine motor control?
1:1 nerve fiber
40
What is an example of fine motor control?
finger tips
41
What is coarse motor control?
1: 2000 nerve to fiber
42
What is an example of coarse motor control?
Leg muscles
43
What is isotonic muscle contraction?
Muscle changes length
44
What is isometric muscle contraction?
Constant muscle length
45
Does isotonic or isometric muscle contractions have more tension?
Isometric
46
What are two components of muscle elasticity?
Parallel Elastic Component Series Elastic Component
47
What is Parallel Elastic Component?
passive elasticity derived from muscle membranes
48
What is series Elastic Component?
passive elasticity derived from tendons when a tensed muscle is stretched
49
What is the difference between the series elastic components in isometric and isotonic contractions?
Isometric- SEC compensates for changes in contractile component- doesn't change length Isotonic- Not as much compensation, does change length
50
What is a twitch?
Brief increase in tension due to cross-bridge activity
51
What does the active state of muscles require?
Calcium
52
What is tetanus?
Activate state of muscle persists, many action potentials Maximal internal and external tension
53
What happens when Maximal internal and external tension is reached in muscles?
Tetanus
54
When is tension in the muscle the highest?
Relaxed muscle, a little bit of overlap, room for sliding
55
What are the three metabolic pathways that supply ATP for muscle activity?
Creatine phosphate Glycolysis Oxidative phosphorylation
56
Where does energy come from in the first 30 minutes of exercise?
Creatine phosphate Glycogen Glucose Fatty acids from bloodstream
57
Where does energy come from after 30 minutes of exercise?
Only fatty acids from blood stream
58
What type of fibers are red fibers?
Slow
59
What type of fibers are white fibers?
fast
60
What are slow fibers?
Small, dark, fatigue resistant
61
What are fast fibers?
Large, light, easily fatigued
62
Where are smooth muscles found in the body?
GI, lining of blood vessels
63
What is the role of smooth muscles?
Homestatic- Control fluids, sphincters Support tubes Move prodcuts
64
What type of contractions are used in smooth muscle?
Slow Little fatigue, low O2
65
What is multi unit smooth muscle?
Individual cells with several neuron
66
What is single unit smooth muscle?
Gap junctions between cells with fewer neurons
67
What are multi unit smooth muscles used for?
Fine control Respiratory airways, large arteries
68
What are single unit smooth muscles used for?
GI tract Uterus
69
Do action potentials spread from cell to cell in multi or single unit smooth muscle?
Single unit
70
What do some visceral muscles exhibit?
Autorhythmic contractions
71
What is true about smooth muscle tension?
Relatively constant tension
72
How does the amplitude of contraction change in smooth muscle?
Remains constant despite muscle length changes
73
What in smooth muscles is analogous to z-lines in striated muscle?
Dense bodies
74
What are dense bodies?
connect to actin in smooth muscles, analogous to z-lines
75
What is the mechanism of smooth muscle contraction?
Calcium increases from SR and from outside cell Calcium binds to calmodulin Activates MLCK in myosin head MLCK phosphorylates myosin heads and increases myosin ATPase activity Binds to actin Power stroke
76
What does calcium bind to in smooth muscle contraction?
Calmodulin
77
Is troponin present in smooth muscle?
No
78
Is tropomyosin present in smooth muscle?
Yes but function unknown
79
What is the mechanism of smooth muscle relaxation?
Calcium leaves cytoplasm into SR or out of cell Calcium unbinds calmodulin Myosin phosphotase inactivates myosin
80
What are unique characteristics of smooth muscle contraction?
Slow prolonged contractile activity Low energy requirements Response to stretch
81
What is phasic contraction?
Brief stimulation, quick calcium elevation, quick loss of phosphorylation
82
What is tonic contraction?
continued stimulation, continued calcium elevation, continued phosphorylation latch stage
83
What is a similar smooth muscle event to tetanus in skeletal muscle?
Tonic contraction
84
What smooth muscles are normally contracted?
Sphincters
85
What smooth muscles are normally partially contracted?
Blood vessels Airways
86
What smooth muscles are normally relaxed?
Esophagus Bladder
87
What smooth muscles are phasically active?
Stomach Intestines

Physiology Exam 2 (5 decks)

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