Motor Physiology Flashcards
Red/ slow twitch
Type 1
Endurance
Type 1
White/ fast twitch
Type 2
Powerful muscle contraction
Type 2
Are united/contract together as one
Contain gap junctions
Course muscle control rough
Unitary smooth muscle
Example of Unitary smooth muscle
Uterus
No GAP junction
Fine motor control
Act on their own
Multi-unit Smooth muscle
Example of Multi-unit Smooth muscle
Ciliary, pupil
Intrafusal
Muscle spindle
For muscle contraction
Extrafusal
Rhythmic, intermittent
Physic Smooth Muscles
Continuously active
Tonic Smooth muscle
This is characteristic of type II muscle fiber?
Larger in size
Functional unit of muscle
Sarcomere
Surrounds muscle fiber
Endomysium
Surrounds muscle fascicle
Perimysium
Surrounds skeletal muscle
Epimysium
Border
Z line
Thick filament
A
Only actin
No myosin
I band
Middle
M line
Plasma membrane surround muscle fiber
Sarcolemma
Endoplasmic reticulum surrounding nyo fibril
Contains calcium
Sarcoplasmic reticulum
Invagination a of the Sarcoplasmic in close proximity to the terminal cistern are of the Sarcoplasmic reticulum
Transverse tubules
Tethers Mysosin to Z lines (scaffolding); binds z lines to M line
Titin
Largest protein in the body
Titin
Stabilizes sarcoma a & prevents contraction-induced rupture
Dystrophin
Binds Actin to Z lines
Actin in, Capz protein
Binds Z lines to sarcolemma
Desmin
Acts as a molecular ruler that sets the length of actin during assembly
Nebulin
Area between two Z lines
Exhibited by skeletal and cardiac muscles
Has thick and thin filaments
Sarcomere
Myosin
Thick filaments
Actin
Tropomyosin
Troponin
Thin filament
Attaches troponin complex to tropomyosin
Troponin T
Inhibits actin-myosin binding
Troponin I
Calcium binding protein
Troponin C
Involves motor neurons and extramural fibers
Skeletal Muscle contraction
Sliding filament model
Skeletal Muscle contraction
What is the distance achieved in each cross-bridge cycle?
10 nanomeres
Blocks release of Ach from pre-synaptic terminals
Botulinus toxin
Competes with Ach for receptors on Motor End Plate
Curare
Inhibits Acetlycholinesterase
Neostigmine
Blocks reputable of Choline into pre synaptic terminal
Hemicholinium
Which of the following temporal sequences is correct for excitation contraction coupling in skeletal muscle?
Action potential in the muscle membrane, depolarization of T tubules, release of Ca from the Sarcoplasmic reticulum
In skeletal muscle, which of the following events occurs before depolarization of the T tubules in the mechanism of excitation-contraction coupling?
Depolarization of the sarcolemmal membrane
Purely intracellular Ca/SR
Skeletal
Both intracellular & extracellular Ca
Cardiac
Purely extracellular Ca
Rudimentary SR/ ill develop
Smooth Muscle
All muscle fibers innervated by a single motor nerve fiber
Motor unit
Also called FINAL COMMON PAthway, Lower motor Neuron
Alpha Motor Neurons
Small motor units are recruited first before Big Motor Units
Size Principle
Multiple Fiber Summation
Spatial Summation
Frequency Summation
Temporal Summation
Each contraction occurs after complete relaxation producing stronger contraction each time
Staircase (Treppe) Effect
Basis for Treppe Effect
Ca accumulation, pH changes, increased temperature
Complete fusion of individual muscle contraction when ca is all used up
Tetany
Which of the following tetanizes at lower stimulus frequency?
Slow twitch fiber
Which of the following has larger maximal force during tetany?
Fast twitch fiber
Tension developed when muscle is stretch: increases
Passive tension
Tension developed when muscle is contracted: decreases
Active Tension
Force contraction:
Increases
Active tension
of cross-bridges that cycle
Velocity of contraction
Speed of cross-bridge cycling
What happens to velocity of contraction if after load is increased?
Decreases
Length is held constant
Isometric Contraction
No muscle shortening/lengthening
Isometric Contraction
Example of Isometric Contraction
Pushing against the sall
Load is held constant
Isotonic Contraction
With muscle shortening: concentric contraction
Isotonic Contraction
Example of concentric contraction
Pulling a weight up
With muscle lengthening: eccentric contraction
Isotonic Contraction
Example of eccentric contraction
Lowering a weight down
Protective mechanism to prevent muscle cell injury or death (Berne and Levy)
Muscle fatigue
Directly proportional to rate of depletion of muscle glycogen and creatinine phosphate store and the accumulation of lactic acid
Muscle fatigue
Due to Na influx (cardiac muscle contraction)
Phase 0
Brief period of Repolarization (cardiac muscle contraction)
Due to K Efflux and decreases in Na influx
Phase 1
Plateau of AP (cardiac muscle contraction)
Due to Ca influx
Phase 2
Repolarization (cardiac muscle contraction)
Decreases Ca influx and increased K efflux
Phase 3
Resting membrane potential (cardiac muscle contraction)
phase 4
Predominant; voltage fated
L-type or Slow Calcium Channel / Dihydropyridine Receptors or DHPR
Decreases intracellular calcium
3Na - 1Ca Countertransport
Decreases intracellular calcium
Ca-ATPase Pump
Des isomers, gap junctions, fascia adherents (desmosomes)
Intercalated disk
Exhibits syncitium
Cardiac muscles
Dihydropyridine Receptor and Ryanodine receptors are seen
cardiac muscles
More developed transverse tubule
Cardiac muslcle
Less developed transverse tubule
Skeletal muscles
Less developed Sarcoplasmic reticulum
Cardiac muscle
More developed Sarcoplasmic reticulum
Skeletal muscles
Ca induced
Ca Release
Cardiac Muscles
DHPR and RYR interaction
Skeletal Msucles
In the z lines of transverse tubules
Cardiac muscles
At ends of I bands of transverse tubules
Skeletal Muscles
Syncitium present
Cardiac Muscles
Absent Syncitium
Skeletal Muscle
Present tetany
Skeletal muscle
Why is there no tetany in cardiac muscles?
Due to the long refractory period before phase 2
Less ATP use
Smooth Muscles
More ATP use
Skeletal Muscles
Slower onset of contraction
Smooth Muscle
faster onset of contraction
Skeletal Muscles
Longer duration of contraction
Smooth Muscle
shorter duration of contraction
Skeletal Muscles
Stronger (4-6 kg/cm2) force of contraction
Smooth Muscles
Weaker (3-4 kg/cm2) force of. Contraction
Skeletal Muscles
For extrafusal fiber
Alpha Motor neuron of Anterior Motor neurons
For intrafusal fibers
Gamma Motor neuron of anterior motor neurons
Similar to z disc of skeletal muscles
Dense bodies
Rudimentary compared to skeletal muscles
Sarcoplasmic reticulum
Desmin & Vimentin
Connect dense bodies with cytoskeletal network
Intermediate filaments
Rudimentary t-tubules
Caveoli
Synapse with a pool of motor neurons by which they are stimulates
Predominantly inhibitory
Facilitate lateral inhibition
Renshaw Cell
Position of the body in space
Proprioception
Arrange in a parallel manner to extrafusal muscle fibers
Muscle spindles
Detects changes in muscle length & rate of change of muscle length
Muscle spindles
Arranged in a series manner to extrafusal muscle fiber
Golgi tendon
Detects changes in muscle tension
Golgi tendon
The silent area of the brain
Cerebelllum
Functions of Cerebellum
Sequences motor activity
Monitors and adjusts motor activities as they are performed
helps in planning sequential movement
