Muscular Tissue Flashcards
What percentage of body mass is muscle?
40-50%
What are the three types of muscular tissue
Skeletal
Cardiac
Smooth
Skeletal Muscle
Move bones. Striated with protein bands
Cardiac Muscle
Striated. For involuntary action
Smooth muscle
Walls of hollow internal structures. Non striated. Involuntary action
4 functions of muscle
Produce body movement
Stabalizing body position
Storing and moving substances
Producing heat
4 properties of muscle
Electrical excitability
Contractility
Extensibility
Elasticity
Electrical excitability
Produce action potentials
Contractility
Contract forcefully when stimulated by an action potential
Extensibility
Stretch without being damaged
Elasticity
Return to original shape
Structure of skeletal muscle
Muscle belly connected by tendons to skeleton
Tendons
Tough, dense regular connective tissue attaching belly to skeleton
Aponeuroses
Tendons arranged in flat sheets
Endomysium
Thin wrapping of reticular fibers surrounding muscle fibers
Fasicle
Bundles of muscle fibers wrapped in a thicker layer of connective tissue
Perimysium
Dense irregular connective tissue covering fasicle
Epimysium
Thicker, dense irregular connective tissue covers perimysium and binds fascicles together to form muscle belly
Fascia
Dense irregular sheets protecting groups of skeletal muscle
Neurovascular Bundle
Nerves and blood vessels enter muscle near tendon attachment
Myoblast
Skeletal muscle fiber arises from fusion of myoblasts
Sattelite cells
Myoblasts remaining in mature skeletal muscle help regenerate damaged tissue
Fibrosis
Replacement of muscle tissue by fibrous scar tissue
Sarcolemma
Plasma membrane of muscle fiber
Transverse tubule
Thousands of tiny holes in sarcolemma tunnel towards center of transmit action potentials
Sarcoplasm
Cytoplasm of muscle fibers release glycogen for production of ATP
Myoglobin
Only in muscles. Binds oxygen molecules that diffuse into muscle fibers
Myofibrils
Little contractile threads in sarcoplasm
Sarcoplasmic Reticulum
System of fluid filled sacs surround each myofibril
Terminal Cisterns
Dilated end sacs of sarcoplasmic reticulum butt against either end of a transverse tubule
Triad
One transverse tubule and two terminal cisterns on either end
What triggers muscle contraction?
When triggered terminal cisterns release Ca into sarcoplasm
Filaments
Small protein structures within myofibrils are involved in contractile process
Sarcomeres
Basic functional unit of myofibril
Z- Discs
Dense protein plates seperate sarcomeres
A- Band
Dark middle part of sarcomere extends entire length of thick filaments
Zone of overlap
End of A- band where thick and thin filaments lay side by side
I- Band
Less dense area containing only thin filaments
Z- disc passes through centre
H- Zone
Centre of each A- Band contains only thick filaments
M- Line
Supporting proteins hold thick filaments together at middle of the sarcomere
3 kinds of proteins composing myofibrils
Contractile
Regulatory
Structural
Contractile proteins
Generate force
Regulatory proteins
Switch contractions on and off
3 functions of Structural proteins
Keep filaments in alignment
Give myofibril extensability/ elasticity
Link myofibrils to sarcolemma
2 contractile proteins
Myosin
Actin
Myosin
Motor protein that composes thick filaments. Looks like 2 twisted gold clubs
Motor proteins
Convert ATP’s chemical energy into mechanical energy
Which way to the myosin tails point?
Toward the M- Line