Muscle Physiology Flashcards
Anchor for thick filaments (myosin) that lies between the h-zone, a lighter staining area in the midst of the dark A band
M line
Anchor for thin filaments (actin). A dark line in the light-colored I band.
Z-line
Major protein in M line?
Myomesin
Dark area of myosin
A band
Light area of actin, thin myofilaments
I band
Myosin
Makes up thick myofilaments
Rodlike tail, 2 globular heads
Heads contain binding sites for actin and ATP
Actin (f-actin)
Makes up thin myofilaments
Contain G actin, tropomyosin, and troponin
G actin twists in a double helix
Tropomyosin
Long thin stringlike molecule
Blocks myosin binding sites
Troponin
3 subunit complex
TnT attaches to tropomyosin
TnC binds calcium ions
TnI binds actin
Sarcoplasmic reticulum
Stores and regulates intercellular calcium
What is at the junction of A bands and I bands?
Terminal cisternae
T tubules? Why and what?
Finger like invaginations of the sarcolemma form a complex network of tubules that encircle every myofibril near the (A-I) band boundaries aka terminal cisternae of each sarcomere. Why? Uniform release of calcium ions to promote uniform contraction of the muscle. The myoneural junction is only at one spot, but the transverse tubule system helps with uniformity.
Sliding filament model of contraction
Thin filaments slide past thick filaments.
I band size decreases as thin filaments penetrate the a band.
H band nearly disappears
Sarcomere a shorten
A bands move closer together but length is the same
Motor end plate
On the muscle, a structure if muscle
The axon meeting here is only covered by a thin cytoplasmic extension from a Schwann cell
Junctional folds
Neurotransmitter at myoneural junctions?
Acetylcholine
Junctional folds
The wrinkly area of the ms plate, sarcoplasmic wrinkles increase surface area
Epicranius
Raises eyebrows
Characteristics of Muscle tissue
Excitability(receive and respond to stimuli)
Contractility (can shorten when stimulated)
Extensibility (can stretch)
Elasticity (can return to original shape)
Epimysium
Dense irregular ct
Perimysium
Dense regular connective tissue
Endomysium
Areolar
Origin
Point of attachment to to immovable or less moveable bone
Insertion
Point if attachment to moveable bone
Direct and indirect origins and insertions
Direct- epimysium fused to periosteum or perichondrium
Indirect- via tendons or aponeuroses
Aponeuroses
Sheet like fibrous membrane
Special organelles within the muscle fiber (cell) sarcoplasmic contains…
Glycosomes granules of stored glycogen
Myoglobin red pigment that carries oxygen
Sarcoplasmic reticulum does what important job?
Stores regulates and releases calcium
Power levers
Load is closer to the fulcrum than effort applied
Small effort can move a large load, but not very far proportionally
Speed levers
Effort is closer to the fulcrum than the load
Effort must be greater than the load to move it
First class lever
Fulcrum in middle
Advantage or disadvantage, depends on location of the in-between lever
Second class levers
Fulcrum load effort
Always mechanical advantage by definition
Power lever
Third class lever
Load effort fulcrum
Speed lever
Mechanical disadvantage
