Muscle Flashcards
_____ contain sarcomeres
Myofibrils
_____ is a bundle of myofibrils
Muscle cell/fiber
Endomysium surrounds?
Muscle fiber
____ is a bundle of muscle fibers
Muscle fasciculus
Perimysium surrounds?
Muscle fasciuli
Epimysium surrounds?
Whole muscle
__% of nerve fibers are efferent and __% are afferent
60% efferent, 40% afferent
Efferent nerve fibers in muscle are called?
Alpha motor neurons
Role of alpha motor neurons
Carry info into muscle
Afferent nerve fibers are associated with?
- Mechanoreceptors
2. Chemoreceptors
A triad is made of?
Cisternae + t-tubule + cisternae
Cisternae is associated with?
Calcium release
Cisternae is located between?
Longitudinal or light SR
What is calsequestrin?
Binding protein which reduces gradient
Calsequestrin plays a role in?
Ca reuptake
What is DHP?
T-tubule protein similar to voltage-sensitive Ca channel
What is ryanodine?
Functional Ca release channel
Sarcomere is defined from?
Z line to Z line
H zone during contraction
Gets smaller
I band during contraction
Gets smaller
Actin are _____ filaments
Thin
Myosin are _____ filaments
Thick
Which filaments make up A band?
Myosin
A band during contraction
Does not change length
What is the A band?
Length of the myosin
What is the H zone?
Length between actin filaments
What is the I band?
Distance between 2 discrete myosin filaments
2 types of myosin
- Light meromyosin
2. Heavy meromyosin
Hinge region is located between?
Light and heavy meromyosin
Hing region is active in?
Coupling chemical to mechanical energy
Myosin ATPase is located on?
Myosin head
2 isoenzymes of myosin ATPase
- Fast
2. Slow
Fast twitch fibers are used for?
Locomotion
Slow twitch fibers are used for?
Posture
2 enzymes located in M-line
- Creatine phosphokinase (CPK)
2. Myokinase
CPK catalyzes what reaction?
ADP + CrP → ATP + Cr
Myokinase catalyzes what reaction?
ADP + ADP → ATP + AMP
Tropomyosin plays what type of role?
Regulatory
2 proteins on actin
- Tropomyosin
2. Troponin
Major protein of Z-line
Alpha-actinin
3 types of troponin
- TN-I
- TN-C
- TN-T
TN-I function
Inhibits active binding site
TN-C function
Contains Ca binding site
TN-T function
Binds to tropomyosin
Z-line during contraction
Gets shorter
l(0) is?
Optimal length (Z-line to Z-line)
Ideal l(0)
2.0-2.2 um
1 myosin filament interacts with ___ actin filaments
6
Titin function
Acts like anchor/spring to keep myosin filaments in place
Nebulin function
Molecular ruler in assembly of actin
Dystrophin function
Anchors contractile proteins to cellular membrane
alpha-actinin function
Located in Z-line and connects actin filaments together
Motor unit
Innervates one or more m. fibers
All m. fibers connected to motor unit have same?
Contractile and metabolic properties
Synaptic cleft is how wide?
50 nm
Acetylcholinesterase functions
Cleaves Ach for reuptake into presynaptic cell
When Ach binds to motor end plate, what happens?
- Na+ influx via gated ion chanel
- Depolarization (end plate potential)
- EEP comes out of cleft → starts AP across cell membrane
Chemoreceptors are Group ___
Group IV
Chemoreceptors sense?
[H+], K+, Pi
3 types of mechanoreceptors
- Muscle spindles
- Golgi tendon organs
- Group III
I(a) fibers aka?
Muscle spindles
I(b) fibers aka?
Golgi tendon organs
Group III fiber myelination
Thinly myelinated
GTO activation
Inhibits alpha-motor neuron output
Muscle spindles run parallel with?
Extrafusal fibers
Primary annulospiral ending function
Quick responders to changes in muscle length (dynamic)
Secondary flower-spray ending function
Tonic input to m. length (static)
Gamma efferents stimulate intrafiusal fibers to?
Contract
Alpha-motor neuron stimulates intrafusal fibers to/
Contract