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PHYSIOLOGY > ME02 - Muscle Physiology > Flashcards

ME02 - Muscle Physiology Flashcards

1
Q

[Skeletal Muscle]
Intrafusal:
Extrafusal:

A

Gamma/Intrafusal: Muscle Spindle

Alpha/Extrafusal: Muscle Contraction

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2
Q

Types of Extrafusal

A

Type I: Slow Oxidative (Red)
Type IIb: Fast Glycolytic (White)
Type IIa: Fast Oxidative (Red to Pink)

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3
Q

Complete table
Type I Type IIb Type IIa
Contraction/
ATPase activity

ATP synthesis
Rate of fatigue
Fiber diameter
Activities
Location
A

Complete table
Type I Type IIb Type IIa
Contraction/ Slow Fast Fast/Intermediate
ATPase activity

ATP synthesis Oxidative Glycolytic Oxidative
Rate of fatigue Slow Fast Intermediate
Fiber diameter Small Larger Intermediate
Activities Endurance Quick, Power Uncommon
Posture
Location Soleus, EOMs, abundant SRCA
Antigracity muscles
of back

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4
Q

One SLOW RED OX with a Perfect Posture

A

Mnemonic yes

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5
Q

Types of Cardiac Muscle Fibers

A

Atrial Muscle Fibers
Ventricular Muscle Fibers
Conductive Muscle Fibers

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6
Q

Types of Smooth Muscle

A

Multi-unit Smooth Muscle Unitary Smooth Muscle
Act on their own Act together as one
Controlled by ACh, NE Controlled by hormones, stretch
- Gap Junctions + Gap Junctions
No true AP, Electronic cond. Pacemaker waves, Spike pot.
- Spontaneous contractions Exhibit spontaneous contractions
Ciliary eye muscle, iris Intestines, Bile Ducts, Ureters
piloerector muscle, vas deferens

Fine Motor Control Gross/Movement

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7
Q

Smooth Muscle

Phasic vs Tonic

A

Phasic Smooth Muscle Tonic Smooth Muscle
Rhythmic, Intermittent Continuously active
Walls of GI, Urogenital Sphincters, Respiratory sm. ms

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8
Q

Component of Skeletal Muscle

A

Sarcomere&raquo_space; Myofibril&raquo_space; Muscle Fiber&raquo_space; Muscle Fascicle&raquo_space; Skeletal Muscle

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9
Q

Endomysium surrounds _______________
Perimysium surrounds _________________
Epimysium surrounds _________________

A

Endomysium surrounds Muscle Fiber
Perimysium surrounds Muscle Fascicle
Epimysium surrounds Skeletal Muscle

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10
Q

Plasma membrane that surrounds muscle fiber

A

Sarcolemma

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11
Q

Invaginations of sarcolemma in close proximity to the terminal cisternae of SR, in 90 degrees

A

Transverse Tubules

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12
Q

Endoplasmic Reticulum surrounds myofibril

Contains Calcium for muscle contraction

A

Sarcoplasmic Reticulum

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13
Q

Functional unit of muscle
Between two Z lines
Thick and Thin Filaments

A

Sarcomere

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14
Q

Thick vs Thin Filaments

A 
THICK 
Myosin Tail - 2 heavy chains
Myosin Head - free ends of heavy chain + light chain
Body: Tails bundled together
Cross Bridges : Arms and Myosin Heads
Hinges : Arm-Body and Arm Head
THIN
Actin, Tropomyosin, Troponin
Troponin T - attach troponin complex to tropomyosin
Troponin I - inhibits actin-myosin
Troponin C - calcium binding protein
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15
Q

Muscle Proteins

A

Titin - scaffolding | Tethers Myosin to Z lines, Binds Z to M lines
Dystrophin - Attach and Stabilize to Plasmalemma, Prevent contraction induced rupture

Actinin and Capz Protein - Binds Actin to Z lines
Desmin - Binds Z lines to plasma membrane

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16
Q

Muscle protein related to Duchenne’s and Dilated Cardiomyopathy

A

Dystrophin

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17
Q

What happens if Troponin Opens

A

Muscle contracture happens

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18
Q

Structure

A 
Z line - middle of I band
I band
A band - everything between I band
H band - Thick Filament includes M line
M line - Middle line in the Thick Filament
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19
Q

Skeletal Muscle Contraction

A

Sliding Filament Model
- thin filament slide against thick filament toward center of sarcomere
Z-discs meets the myosin filaments

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20
Q

Steps in Muscle Contraction

A

Discharge of motor neuron
Release of ACh at MPE
Binding of ACh to Nicotinic ACh receptor
Increased Na and K conductance in MPE
Endplate potential
AP in muscle fibers
Inward spread of depolarization along T tubules
Release of Ca from terminal cisterns of SR
Diffusion to thick and thin filaments
Binding of Ca to troponin C&raquo_space; uncovering myosin binding sites
Formation of cross-linkages between actin and myosnin
Sliding of thin on thick filaments&raquo_space; SHORTENING

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21
Q

Steps in Muscle Relaxation

A

Ca2+ pumped back into the SR
Release of Ca2+ from troponin
Cessation of interaction between actin and myosin

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22
Q

What is the distance achieved in each cross bridge cycle

A

10 nanometers

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23
Q

Brief muscular contraction followed by relaxation due to a single action potential

A

Muscle Twitch

24
Q

All muscle fibers are innervated by single motor nerve fiber

25
Q

Components of Motor Unit

A

Alpha motor neuron - Final common pathway,
lower motor neuron
Axon
Muscle Fibers it supplies

26
Q

What kind of motor unit is used in movements that require rapid and exact control

A

One motor nerve fiber innervate few muscles

27
Q

Multiple Fiber Summation :

Frequency Summation :

A

Multiple Fiber Summation : Spatial Summation

Frequency Summation : Temporal Summation

28
Q

Considerations for Spatial Summation

A

Size Principle
Smaller motor units are recruited first since they are exciteable than large ones

Graded muscle force
Driven Asynchronously

29
Q

Higher the stimulus, Higher the tension

30
Q

Any increase in stimulus, it doesn’t increase anymore

A

Maximum contraction

31
Q

Each contraction occurs after complete relaxation
Due to Ca accumulation, INC in temp, pH change
WARM UP EXERCISE

A

STAIRCASE (TREPPE) EFFECT

32
Q

Complete relaxation not given,
Subsequent stimuli done
Results in progressive increase in total contraction strenght

A

Wave Summation

33
Q

All Ca2+ from SR are used up

A

Saturation

34
Q

Incomplete - doesn’t complete or meet the relaxation

A

Incomplete Tetany

35
Q

Fibers that tetanizes at lower stimulus frequency

A

Slow-Twitch Fibers

36
Q

Fibers that has larger maximal force during tetany

A

FAST Twitch Fibers because of bigger diameter

37
Q

Tension and Initial Length

A

Passive tension - stretching of muscle to diff lengths
Active tension - muscle is stimulate to contract at diff lengths
Total Tension = Active Tension + Passive Tension

38
Q

Reflects work done at each load
Max rate of work done at submaximal load
When force of contraction is 30% of Max tetatnic tension

A

Power-Stress Curve

39
Q

Isometric Vs Isotonic

A

ISOMETRIC ISOTONIC
Length is constant Load is constant
No muscle shortening With muscle shortening - CONCENTRIC
> pulling a weight up
With muscle lengthening - ECCENTRIC
> lowering a weight down

Holding Ipad in midair
TENSION IS MEASURED LENGTH IS MEASURED

40
Q

Remaining contractile activity of muscle at rest

Maintain posture

A

Muscle Tone

41
Q

Protective mechanism to prevent muscle injury

Directly proportional to rate of depletion of muscle glycogen and creatine phosphate

A

Muscle Fatigue

42
Q

CLINICAL CONDITIONS

A

Muscle Denervation - Muscle Fasciculation, Fibrillation
Polio - nerve fibers sprout new axons, stronger muscles less control

Rigor Mortis - Start 3-6 hours, end after 15-25 hours
Myasthenia Gravis - Anti ACh receptor antibodies

43
Q

CARDIAC MUSCLE CONTRACTION

A

Exhibit atrial and ventricular Syncitium

Use Extra and Intra cellular Calcium

44
Q

Phases in Cardiac Muscle Action Potential

A

Phase 0 - Rapid Depolarization
Phase 1 - Rapid Repolarization minute K efflux
Phase 2 - Plateau influx of Ca2+
Phase 3 - Final Repolarization complete efflux of K
Phase 4 - Resting efflux is slightly more than influx

45
Q

Conductive System

A

SA node > Atrium > AV node > Bundle of His > Purkinje Fibers

46
Q

Cardiac Muscle Contraction

A

More developed T-tubule, Less developed SR compared to skeletal muscles
Ca2+ regulation

47
Q

CARDIAC VS SKELETAL

A

CARDIAC SKELETAL
Electrochemical coupling Electromechanical coupling
Ca 2+ induced interaction bet DHPR and RYR
T-tubules in Z lines T-tubules at ends of I bands
No tetany Recruitment, undergo tetany
Long refractory period
secondary to voltage -gated
L-type Calcium channels

48
Q

SMOOTH MUSCLE CONTRACTION

A

No Troponin
Components: MLCK -Myosin Light Chain Kinase “activation”
Calmodulin, Caldesmon, Calponin

49
Q

Components if Smooth Muscle

A

Dense Bodies - similar to z discs
SR - Rudimentary&raquo_space; Smooth ms rely on extracellular Ca
Caveoli - contains voltage gated L type Ca Channel and 3Na1Ca antiporter

Intermediate Filaments:
Desmin and Vimentin - Connect dense bodies to cytoskeletal network

50
Q

Many Ca -voltage channels, and few Na-gated channels

A

InsP3-gated Ca channel - open slowly remain open | Hormones
cAMP & cGMP mechanism - relaxation vascular smooth muscles | NO, Adenosine, drugs, hormones

Ca++ sparks - spontaneous elevation in intracellular calcium levels

51
Q

Slow acting calcium pumps that excrete Ca in smooth muscles

A

Ca++ ATPase

3Na1Ca antiporter

52
Q

External Characteristics

SKELETAL CARDIAC SMOOTH

A

SKELETAL CARDIAC SMOOTH
10-100um 10um 2-5um
Up to

53
Q

Structural Characteristics

SKELETAL CARDIAC SMOOTH

A

SKELETAL CARDIAC SMOOTH
Myofibril REGULAR IRREGULAR
Mitochondria Few Many Less
Syncytium Functional
Sarcomere ABSENT
Actin Z-line Dense bodies
Ca binding CHON Troponin Calmodulin

54
Q

Functional Characteristics

SKELETAL CARDIAC SMOOTH

A

SKELETAL CARDIAC SMOOTH
Stimulus Graded All-or-none Change in tone
Excitability Nerve Supply Self Self/induced
Electrical Absent Intercalated disc Gap junction
coupling
Extracellular NO YES
Ca

55
Q

BEHAVIORAL CHARACTERISTICS

SKELETAL CARDIAC SMOOTH

A

SKELETAL CARDIAC SMOOTH
Pacemaker None PRESENT
Energy cost Max High Low
Plasticity ABSENT Present
Tetanus NO
Force-Velocity Directly related
relationship
Refractory SHORT
Period

56
Q

Function and Types of Muscles

A 
Function: Movement, Energy Storage
Types:
Skeletal - Voluntary
Cardiac - Involuntary
Smooth - Involuntary

PHYSIOLOGY (13 decks)

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