Muscle fiber anatomy Flashcards
(25 cards)
the smallest contractile unit in a muscle
sarcomere
Purpose of sarcoplasmic reticulum
Stores calcium ions and pumps them into sarcoplasm when muscle is stimulated
Myoglobin
Molecule, made of proteins, that carries oxygen throughout sarcoplasm
What is area does a sarcomere cover
From one z-line to the next z-line
For full desired contractions to occur:
cross-bridges must be broken and repeated
What prevents unwanted muscle contractions:
Tropomyosin and troponin block actin-binding sites
Tropomyosin
Myofibril that blocks binding sites
nebulin
actin binding protein strand
Channels of sarcolemma:
Respond to neurotransmitter to allow sodium ions to enter the cell
areas with no actin overlap are known as:
H-zone
actin
“thin filament”
double, twisted strand of protein
1) What organelle is especially abundant in sarcoplasm
2) Why?
1) Mitochondria
2) Creates ATP for the cell to use as energy
Types of myofibrils (4 types)
1) actin
2) myosin
3) tropomyosin
4) troponin
Cell membrane of muscle cells is called:
Sarcolemma
Myosin name and purpose
“thick filament”
contains heads that temporarily bind to specific proteins along actin
What action requires ATP
what action does not require ATP
1) breaking cross-bridges
2) formation of cross-bridges
Strands of actin are attached to:
Z-lines
Abundant, small fibers in sarcoplasm:
myofibrils
Cross-bridge
Binding sites between myosin heads and actin
z-line:
A skeletal fiber that attaches actin so that it anchors it in place
Specialized endoplasmic reticulum in sarcoplasm:
Sarcoplasmic reticulum
As contraction occurs:
the h-zone decreases in size and actin strands are brought closer to one another
Troponin
Holds tropomyosin in place
Proteins that bind the myosin heads known as:
Myosin binding sites
