Week 6 Muscle Tissue Flashcards
(28 cards)
What are the main functions of muscle tissue?
Movement, posture, storing/moving substances, and heat generation.
What are the four properties of muscle tissue?
Excitability, contractility, extensibility, elasticity.
What are the three types of muscle tissue?
Skeletal, cardiac, and smooth.
What are features of skeletal muscle?
Striated, voluntary, multinucleated, attached to bones, long cylindrical fibres.
What are features of cardiac muscle?
Striated, involuntary, branched, single nucleus, intercalated discs with desmosomes and gap junctions.
What are features of smooth muscle?
Non-striated, involuntary, spindle-shaped cells with single central nucleus.
What are the three connective tissue layers in skeletal muscle?
Epimysium (whole muscle), perimysium (fascicles), endomysium (individual fibres).
What is the sarcolemma?
The plasma membrane of a muscle fibre.
What are T-tubules?
Invaginations of the sarcolemma that help spread action potentials into the fibre.
What does the sarcoplasmic reticulum do?
Stores and releases calcium ions for muscle contraction.
What are myofibrils?
Contractile organelles in muscle fibres containing actin and myosin.
What are the contractile proteins?
Myosin (thick) and actin (thin).
What are regulatory proteins in muscle?
Tropomyosin and troponin – regulate actin-myosin interaction.
What is the role of titin?
Stabilises thick filaments and prevents overstretching of sarcomeres.
What is the A band?
Dark area; contains thick filaments (myosin).
What is the I band?
Light area; contains thin filaments (actin) only.
What is the H zone?
Central region with only thick filaments.
What is the Z line?
Boundary between sarcomeres; anchors thin filaments.
What is the M line?
Centre of sarcomere where thick filaments are connected.
What triggers muscle contraction?
Ca2+ binds to troponin, moving tropomyosin and exposing myosin binding sites on actin.
What shortens during contraction?
Sarcomere, I band, and H zone – A band remains the same.
Where is smooth muscle found?
Walls of hollow organs, blood vessels, airways, GI tract, uterus, bladder.
What is the role of calmodulin in smooth muscle?
Binds Ca2+ and activates contraction without troponin.
What are dense bodies?
Anchor points for thin filaments in smooth muscle, analogous to Z lines.
