Motor Physiology

Question 1

Skeletal muscle type: In muscle spindle

Answer 1

Intrafusal

Question 2

Skeletal muscle type: For muscle contraction

Answer 2

Extrafusal

Question 3

Extrafusal Skeletal Muscle: Larger (2x), faster, Glycolytic, more active (2-3x) enzymes in phosphagen & glycogen-lactic acid energy sytem, less active enzymes in aerobic sustem, high myosin ATPase, less mitochondria, in EOMs, fast contration velocity, short duration

Answer 3

Fast-Twitch/Fast Glycolytic/White muscle/Type II

Question 4

Extrafusal Skeletal Muscle: Smaller, slower, Oxidative, less active enzymes in phosphagen & glycogen-lactic acid energy sytem, more active enzymes in aerobic sustem, low myosin ATPase, more mitochondria, in Soleus, Anti-gravity muscles of the back, moderate contration velocity, prolonged duration

Answer 4

Slow-Twitch/Slow Oxidative/Red Muscle/Type I

Question 5

Smooth Muscle Type: Act on their own, no Gap junctions, no true Action Potential, Junctional Potential only, no spontaneous contractions (eg: ciliary eye muscle, iris, piloerector muscle, vas deferens)

Answer 5

Multi-unit Smooth Muscle

Question 6

Smooth Muscle Type: Act together as one, controlled by nerve signals, hormones, stretch, local factors, with Gap junctions, Slow waves, Spike Potentials & Plateau Potentials, exhibit spontaneous contractions (eg: intestines, bile ducts, ureters, uterus)

Answer 6

Unitary Smooth Muscle (aka Syncytial Smooth Muscle, Visceral Smooth Muscle)

Question 7

Rhythmic, Intermittent Smooth Muscle (eg: walls of the GI and Urogenital Tracts)

Answer 7

Phasic Smooth Muscle

Question 8

Continuously Active Smooth Muscle (eg: vascular smooth muscle, respiratory smooth muscle, sphincters)

Answer 8

Tonic Smooth Muscle

Question 9

Surrounds muscle fiber

Answer 9

Endomysium

Question 10

Surrounds muscle fascicle

Answer 10

Perimysium

Question 11

Surrounds skeletal muscle

Answer 11

Epimysium

Question 12

Plasma membrane that surrounds muscle fiber

Answer 12

Sarcolemma

Question 13

Invaginations of the sarcolemma in close proximity to the terminal cisternae of the Sarcoplasmic Reticulum

Answer 13

Transverse Tubules

Question 14

Endoplasmic reticulum surrounding myofibril that contains Calcium

Answer 14

Sarcoplasmic Reticulum

Question 15

Functional unit of the muscle; Area between 2 Z lines; Exhibited by skeletal and cardiac muscles; Has thick and thin filaments

Answer 15

Sarcomere

Question 16

Thick filaments

Answer 16

Myosin

Question 17

Thin filaments

Answer 17

ActinTropomyosinTroponin

Question 18

Attaches troponin complex to tropomyosin

Answer 18

Troponin T

Question 19

Inhibits Actin-Myosin binding

Answer 19

Troponin I

Question 20

Calcium binding protein

Answer 20

Troponin C

Question 21

Tethers Myosin to Z lines (scaffolding); Binds Z lines to M lines

Answer 21

Titin

Question 22

Stabilizes Sarcolemma & prevents contraction-induced rupture

Answer 22

Dystrophin

Question 23

Binds Actin to Z lines

Answer 23

Actinin, Capz Protein

Question 24

Binds Z lines to Sarcolemma

Answer 24

Desmin

Question 25

Act as a molecular ruler that sets the length of actin during assembly

Answer 25

Nebulin

Question 26

Involves motor neurons & extrafusal fibers; Demonstrated by the Sliding-Filament Model

Answer 26

Skeletal Muscle Contration

Question 27

Actin & Myosin Interaction

Answer 27

Cross-Bridge Formation

Question 28

Thin filaments "slides" against the thick filaments towards the center of the sarcomere

Answer 28

Sliding Filament Model

Question 29

What is the distance achieved in each cross-bridge cycle?

Answer 29

10 nanometers

Question 30

True or False: All muscle fibers innervated by a single motor nerve fiber

Answer 30

True

Question 31

"Final common pathway" or "Lower motor neuron"

Answer 31

Alpha motor neuron

Question 32

Small Motor Units are recruited first before Big Motor Units

Answer 32

Size Principle

Question 33

Multiple Fiber Summation

Answer 33

Spatial Summation

Question 34

Frequency Summation

Answer 34

Temporal Summation

Question 35

Each contraction occurs after complete relaxation producing stronger contraction each time

Answer 35

Staircase (Treppe) Effect

Question 36

Basic for Treppe Effect

Answer 36

Ca2+ accumulationpH changesIncrease temperature

Question 37

Complete fusion of individual muscle contraction when Ca2+ is all used up

Answer 37

Tetany

Question 38

Which tetanizes at lower stimulus frequency?

Answer 38

Slow twitch muscle

Question 39

Which has a larger maximal force during tetany?

Answer 39

Fast twitch muscle

Question 40

Tension developed when muscle is stretched INCREASES

Answer 40

Passive Tension

Question 41

Tension developed when muscle is stretched DECREASES

Answer 41

Active Tension

Question 42

Force of contraction developed when muscle is stretched

Answer 42

Increases

Question 43

Active Tension reflect what?

Answer 43

of cross-bridges that cycle

Question 44

Velocity of contraction reflect what?

Answer 44

Speed of cross-bridge cycling

Question 45

What happens to velocity of contraction if afterload is increased?

Answer 45

Velocity of contraction decreases

Question 46

Length is held constant; No muscle shortening or lengthening (eg: pushing against the wall)

Answer 46

Isometric Contraction

Question 47

Load is held constant; With muscle shortening/lengthening

Answer 47

Isotonic Contraction

Question 48

With muscle shortening (eg: pulling a weight up)

Answer 48

Concentric Contraction

Question 49

With muscle lengthening (eg: lowering a weight down)

Answer 49

Eccentric Contraction

Question 50

Protective mechanism to prevent muscle cell injury or death; Directly proportional to rate of depletion of muscle glycogen and creatine phosphate stores and accumulation of lactic acid

Answer 50

Muscle Fatigue

Question 51

Exhibits atrial and ventricular syncytium; Relies on both extra- & intra- cellular calcium

Answer 51

Cardiac Muscle Contraction

Question 52

Cardiac Action Potential: Due to Na+ influx

Answer 52

Phase 0

Question 53

Cardiac Action Potential: Brief period of repolarization; Due to K+ influx

Answer 53

Phase 1

Question 54

Cardiac Action Potential: Plateau of Action Potential; Due to Ca2+ influx

Answer 54

Phase 2

Question 55

Cardiac Action Potential: Repolarization; Decrease Ca2+ influx and increased K+ efflux

Answer 55

Phase 3

Question 56

Cardiac Action Potential: Resting Membrane Potential

Answer 56

Phase 4

Question 57

Calcium Regulation of Cardiac Muscles: Increases intracellular Calcium

Answer 57

Calcium Channels

Question 58

Calcium Regulation of Cardiac Muscles: Decreases intracellular Calcium

Answer 58

3Na+-1Ca2+ CountertransportCa-ATPase pump

Question 59

More developed Transverse Tubule

Answer 59

Cardiac muscle

Question 60

More developed Sarcoplasmic Reticulum

Answer 60

Skeletal muscle

Question 61

Electromechanical Coupling in Cardiac muscle

Answer 61

Ca2+-induced Ca2+ release

Question 62

Electromechanical Coupling in Skeletal muscle

Answer 62

DHPT and RYR interaction

Question 63

Location of Transverse Tubules of Cardiac muscle

Answer 63

In the Z lines

Question 64

Location of Transverse Tubules of Skeletal muscle

Answer 64

Ends of I band

Question 65

(+) Syncytium

Answer 65

Cardiac muscle

Question 66

(+) Tetany

Answer 66

Skeletal muscle

Question 67

Why is there no tetany in Cardiac muscles?

Answer 67

Due to the long Refractory Period brought about by Phase 2

Question 68

Equivalent to Troponin I; Phosphorylated (inhibited) by Ca-Calmodulin Complex

Answer 68

Caldesmon, Calponin

Question 69

Similar to Z discs of Skeletal muscles

Answer 69

Dense Bodies

Question 70

Rudimentary compared to skeletal muscle

Answer 70

Sarcoplasmic Reticulum (SR)

Question 71

Rudimentary T-tubules

Answer 71

Caveoli

Question 72

Connect dense bodies with cytoskeletal network

Answer 72

Intermediate Filaments (Desmin, Vimentin)

Question 73

Uses more ATP

Answer 73

Skeletal muscles

Question 74

Faster onset of contraction

Answer 74

Skeletal muscles

Question 75

Longer duration of contraction

Answer 75

Smooth muscles

Question 76

Stronger force of contraction (4-6kg/cm2)

Answer 76

Smooth muscles

Question 77

For Extrafusal fibers of Anterior Motor Neuron

Answer 77

Alpha motor neuron

Question 78

For Intrafusal fibers of Anterior Motor Neuron

Answer 78

Gamma motor neuron

Question 79

Spinal cord neuron that connects up, down & with each other

Answer 79

Interneurons

Question 80

Synapse with pool of motor neurons by which they are stimulated; Predominantly inhibitory; Facilitate lateral inhibition

Answer 80

Renshaw Cell

Question 81

Sense of awareness of position of the body in space

Answer 81

Proprioception

Question 82

Mechanoreceptors that provide the CNS with information regarding muscle length, position, & tension (force)

Answer 82

Proprioceptors

Question 83

Arranged in a parallel manner to extrafusal muscle fibers; Detects changes in muscle length & rate of change of muscle length

Answer 83

Muscle Spindles

Question 84

Arranged in a series manner to extrafusal muscle fibers; Detects changes in muscle tension

Answer 84

Golgi Tendon

Question 85

"The silent area of the brain"; Sequences motor activity; Monitors and adjusts motor activities; Helps in planning sequential movement

Answer 85

Cerebellum

Question 86

Functional Unit of Cerebellum

Answer 86

Purkinje (middle layer-always inhibitory) and Deep Nuclear Cell