Muscular physiology Flashcards
Mastery
Levels of organization of muscles
what surrounds groups
what surrounds fascicles
what surrounds fibres
what surround MYOFIBRILS
Groups- surrounded by epimysium
fascicles- surrounded by perimysium
Fibres - surrounded by endomysium
myofibrils - sarcolemma
myofilament(actin and myosin)
Fascicle patterns and why they form
Fascicles form patterns with respect to the
tendons
TPCFP
Tasty pies can fuel people
Triangular - pecs
Pennate - deltoid, more power
Circular - need to close
Fusiform - attachment in joints, muscle to tendon
Parallel - bicep-
lever systems regular
lever systems in muscles
Movement of skeletal muscles involves leverage
LEFL
Lever—a rigid bar that moves
Fulcrum—a fixed point
Effort—applied force
Load—resistance (opposes movement)
Bones act as levers
Joints act as fulcrums
Muscle contraction provides effort
Applies force where muscle attaches to bone
Load bone, overlying tissue, and anything lifted
microscopic Anatomy of muscle fibres
sarcolemma surrounds fibres
sarcoplasm is cytoplasm equivalent
The sarcoplasmic reticulum is RER
T tubule
Many nuclei
myofibrils chock full of actin and myosin
MYOFIBRIL ATTACHED TO MUSCLE WALL DUE TO DYSTROPHIN, pulls cell wall together and helps in contraction
high metabolism and myoglobin which stores oxygen
mitochondria for energy
glycogen granules for ready and quick energy
myosin activation in skeletal muscle
actin structure
two heads, one for binding one for ATP
always activated and ready to attach, that is why tropomyosin covers binding sites
double helix
Muscle Proteins
what do the structural ones do
CSR
Contractile: - - Myosin - - - Actin
Structural: - - Titin. - - Nebulin. - Myomesin - - Dystrophin
Regulatory: - -Troponin - - Tropomyosin
Titan stabilizes myosin - - Nebulin aligns actin
Myomesin, Part of the m-line
Dystrophin
Attaches myofilaments to sarcolemma (membrane) and
fascia
Helps transmit tension and shortening to muscle group
Cross bridge cycle steps
relaxation
ADP and P on myosin head and bind to actin bind site
power stroke, myosin head pivots, overlap of actin over myosin, USE ADP and P and LOSE it
stuck and need to unbind, so bind a new ATP in order to release from actin - rigour mortis
hydrolyze ATP into ADP and P so the myosin head can re-pivot
RELAXATION
Calcium SERCA pumps remove Ca back into the SR
Needs ATP
Tropomyosin slides over actin sites, no more Ca2+
No cross-bridges
Actin and myosin go back to resting length
ON THE TEST!!!!
changes in zones of sarcomere during contraction
Sarcomere decreases in size
I band decreases
H Zone decreases
A band stays the same
Overlap zones increase in size
Sarcomere anatomy
what they would look like in 3D
Z-Line (Z-Disc): Defines the boundaries of each sarcomere. The site where thin filaments (actin) attach.
M-Line: Located in the center of the sarcomere. Anchors thick filaments (myosin).
A-Band: The dark band where thick and thin filaments overlap. A band is the LENGTH of the myosin
I-Band: The light band that contains only thin filaments.
It spans two adjacent sarcomeres.
H-Zone: The central region of the A-band where there is no overlap between actin and myosin when the muscle is relaxed. Appears lighter in colour within the A-band.
3 types of levers
dont need to explain, just know WHAT CLASS is the most common
3 types of levers
First-class, second and third class
First Class Levers are not common
* fulcrum is between the effort and the load
Eg. seesaws, and lifting your head off your chest
Second Class Levers are Uncommon
- load is between the fulcrum and the effort
- lifting your heel
Third Class Lever are the most Common
- effort is between the fulcrum and the load.
Always at a mechanical disadvantage
- bicep curl
