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Block 1: Physiology > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

Muscle Types?

A

-Skeletal
-Smooth
-Cardiac

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2
Q

Skeletal Muscle is Not Uniform?

A

True

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3
Q

Skeletal is Striated, thus it?

A

Appears to have stripes
(myocyte –> myofibril –> sarcomere –> actin/myosin)

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4
Q

Large Bundles of muscle are composed of individual muscle cells that each contain many?

A

Myofibrils

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5
Q

Myofibrils each contain many?

A

Sarcomeres that are arranged end-to-end in series

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6
Q

Each Sarcomere is composed of?

A

(smallest functioning unit of muscle)
Actin, Myosin, and other molecular machinery

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7
Q

Actin?

A

Thin

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8
Q

Myosin?

A

Thick

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9
Q

Thin Filaments?

A

Actin helix with tropomyosin and troponin complex attached

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10
Q

Thick Filaments?

A

Myosin II = ATPase because breakdown ATP for energy

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11
Q

Thin and Thick filaments interact to produce?

A

Force

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12
Q

AChR causes?

A

Depolarization in skeletal muscle cells

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13
Q

Neuromuscular Junction?

A

1) Nerve axon innervating each muscle fiber
2) Release actylcholine (ACh)
3) ACh binds to AChR which is permeable to Na+, K+, and Ca2+

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14
Q

Each Muscle Cell innervated by?

A

1 Nerve

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15
Q

Initiation of Skeletal Muscle Contraction?

A

1) Ca2+ release from SR
2) Ca2+ binds to Troponin C and initiates a conformational change
3) Tropomyosin slides into groove between actin strands
4) Myosin can now bind actin

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16
Q

Muscle Relaxed?

A

-Z-bands become wider
-I-bands widen
-A-bands remain the same
-H-bands widen

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17
Q

Muscle Contraction?

A

-Z-bands move closer together
-I-bands narrow
-A-bands remain the same
-H-bands narrow

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18
Q

(Skeletal Muscle Relaxation) SERCA?

A

(Sarcoplasmic Endoplasmic Reticulum ATPase)
-A calcium pump that sequesters myoplasmic Ca2+ into SR
-Pumps 2 Ca2+ into lumen/ATP while extruding 2 H+

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19
Q

(Skeletal Muscle Relaxation) Calsequestrin?

A

Ca2+ binding protein near RyR (holds Ca2+ into SR in preparation for next contraction)

20
Q

(Skeletal Muscle Relaxation) Sarcalumenin?

A

Transfers Ca2+ from uptake sites to release sites (transport of Ca2+ from SERCA to RyR)

21
Q

(Initiation of Smooth Muscle Contraction) Ca2+ initiates smooth muscle contraction by?
Myosin light chain kinase (MLCK) is required to?

A

-Binding to calmodulin (can bind 4 molecules of Ca2+)

22
Q

Skeletal Muscle: T-tubules carry charge to SR to stimulate?

A

Ca2+ release from internal stores

23
Q

Smooth Muscle: Caveolae bring?

A

External Ca2+ to the SR (when refills SR)

24
Q

Factors Affecting Force Production in Skeletal Muscle?

A

1) Initial Length of Muscle Fiber
2) Fiber Type
3) Motor Unit Recruitment
4) Speed of Contraction
5) Muscle Fiber Arrangement

25
Q

Dynamic Actions?

A

-Concentric
-Eccentric

26
Q

Concentric?

A

-Muscle develops Tension and Muscle shortens and pulls weight up
-Muscle Force > External Force

27
Q

Eccentric?

A

-Muscle develops Tension and Muscle lengthens lowering weight gently
-Braking Action= hiking downhill, spring-like storage of energy
-Muscle Force < External Force

28
Q

Static Action - Isometric?

A

-Muscle develops Tension with no change in Length
-Muscle Force = External Force

29
Q

Passive Force is Mediated by Titin?

A

(largest known protein)
-Elastic protein that runs from Z line to M line of the sarcomere (halfway)
-Acts as a molecular spring that is responsible for producing passive force in muscle

30
Q

Increased O2?

A

Increased ATP

31
Q

Motor Unit?

A

All Muscle Fibers Innervated by a Single Motor Neuron, all move together when AP fires

32
Q

Summation?

A

How muscle increases force

33
Q

Temporal Summation?

A

-Increased frequency of stimulation
-Increased AP firing rate
-Single AP releases Ca2+ for a short duration to cause a twitch
(Tetany)

34
Q

Spatial Summation in Skeletal Muscle?

A

-All muscle fibers in a motor unit are activated simultaneously
-All or None
-Not all motor units are available at same time

35
Q

Recruitment?

A

Not all muscle fibers are participating all the time; some are inactive

36
Q

Tetany?

A

-Maximum force
-Spasmic Muscles
-Stimulating a muscle with an AP before muscle has had time to totally relax leads to

37
Q

Tonic?

A

-Continuously active to maintain a level of tone
-Ex. blood vessels, respiratory tract, some sphincters
-Multiunit

38
Q

Phasic?

A

-Rhythmic or intermittent contractions
-Ex. GI tract, urogenital, lymphatic
-Single unit

39
Q

1 Sarcomere is bounded by 2?

A

Z-lines

40
Q

I-Band decreases?

A

Increased overlap
(I-Band has only actin)

41
Q

H-Zone decreases?

A

Increased overlap
(H-Zone has only myosin)

42
Q

Sarcoplasmic Reticulum in Myocytes is?

A

Ca2+ storage cell

43
Q

T-tubules maximize SA of cell membrane contact with SR to couple?

A

Electrical activity from nerve with Ca2+ release

44
Q

Intermediate filaments desmin or vimentin form a?

A

Cytoskeleton network connecting dense bodies (dense bodies also contain a-actinin, which binds actin)

45
Q

Smooth Muscle Relaxation?

A

-Similar to skeletal Muscle, Ca2+ must be resequestered in SR and can also pump Ca2+ out of cell
-Additional Step: MLCP (to remove phosphate from myosin to inactivate)

46
Q

Muscle Energy Sources During Exercise?

A

1) ATP (small but replenishable pool)
2) Creatine Phosphate (ATP buffer system that keeps ATP constant)
3) Glycogen (from muscle cells)
4) Plasma glucose + glycogen
5) Plasma Free Fatty Acids

Block 1: Physiology (10 decks)

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