Week 2 - Muscles + Cell Adaptation Flashcards
Muscular System Function
- body movement
- maintenance of posture
- respiration
- communication
- constriction of organs and vessels
- heart beat
- production of body heat
Properties of Muscle
- excitability
- contractility
- extensibility
- elasticity
Excitability
capacity to respond to a stimulus (A.P)
Contractility
ability to shorten and generate a pulling force
Extensibility
ability to stretch
Elasticity
ability of a muscle to recoil to its resting length after being stretched
Skeletal Muscle
attached to bones via tendons
- striated with multiple nuclei
- 40% body weight
- locomotion (voluntary control)
- capable of rapid contraction
Skeletal muscle is controlled by:
somatic motor neurons
Muscle group is made up of ______ separated by perimysium
fascicles
Muscle fascicles composed of multiple _______ , each surrounded by endomysium
muscle fibers
Myofibrils
multiple repeating units within sarcomere that are responsible for muscle contraction
-contain thick filament (myosin) and thin filament (actin)
Epimysium
surrounds entire muscle
- dense, regular connective tissue
- connects to deep fascia and separates the muscle from surrounding organs
Perimysium
surrounds group of muscle fibers
- primarily collagen and elastic fibers
- contains BV and nerves
Endomysium
surrounds each individual muscle fiber
- loose connective tissue
- contains BV, nerves, satellite cells
Epimysium, Perimysium and Endomysium all come together to form a ________
tendon or aponeurosis (connects muscle to bones)
Sarcolemma
surrounds sarcoplasm
-where change in membrane potential and muscle contraction begin
Sarcoplasm
membrane around each muscle fiber
Transverse Tubules (T tubules)
transmit A.P. through the cell so that the entire muscle contracts at the same time
-encircle the sarcomere near the zones of overlap
Sarcoplasmic Reticulum (SR)
brings transmission of A.P. to the t-tubules
-forms chambers called cisternae that are also attached to the t-tubules
-releases Ca2+, causing myosin and actin to interact → muscle contraction
Triad
1 tubule + 2 terminal cisternae
Cisternae
concentrate Ca2+ and release Ca2+ into sarcomeres for muscle contraction
Sarcomere
contractile unit of muscle
-striations
A Band
overlap of thick and thin filaments
-stays the same during contraction
I band
thin filaments + “spring/coil” of thick filaments present (missing the body of the thick filaments)
-shortens with contraction