Muscles Flashcards
Skeletal muscles
- muscle on bone
– Striated muscle attached to bones of the skeleton
– Control body movement
– Voluntary control; responds to somatic motor neurons
cardiac muscle
– Striated muscle found only in the heart w/ intercalated disks
– Moves blood through the circulatory system
– Involuntary control; responds to autonomic innervation, spontaneous contraction, modulated by the endocrine system
smooth muscle
- in arteries and veins, stomach intestines, lining of esophagus, etc.
- lacks striations
– Primary muscle of the internal organs and tubes
– Influence the movement of material into, out of and within the body
– Involuntary control; responds to autonomic innervation, spontaneous
contraction, modulated by the endocrine system
origin and insertion of skeletal muscles
– Origin: closest to the trunk or to more stationary bone ( more proximal and doesn’t move)
– Insertion: more distal or more mobile attachment (moves and more distal)
flexor and extensor skeletal muscles
- Flexor: brings bones together (majority = anterior side of body. Ex: biceps)
- Extensor: moves bones away (posterior side of body. Ex: triceps)
Flexor-extensor pairs form antagonistic muscle groups
- antagonistic = does the opposite
- ex: bicep is flexed so tricep is antagonistic
antagonistic muscles
- antagonistic muscle groups move bones in opposite directions
- muscle contraction can pull on a bone but cannot push a bone away
what are muscle cells called?
- muscle fibers
- long and cylindrical
- fused cells with many nuclei
satellite cells (stem cells)
- in charge of repair
- differentiate into muscle for growth or repair
fascicles
- fibers bundled into fascicles surrounded by connective tissue sheath
- blanket around muscle fiber and glues tendon to bon
connective tissue surrounds entire muscle
– Continuous with connective tissue sheath
– Holds muscle to bone with tendon
sarcolemma
cell membrane of muscle fiber
sarcoplasm
cytoplasm of muscle fibers
sarcoplasmic reticulum
- endoplasmic reticulum
- wraps around myofibrils like a lace
▪ Longitudinal tubes with enlarged ends called terminal cisternae
▪ Concentrates and sequesters - stores calcium
myofibrils
- accessory proteins associated w/ muscle fibers
- bundles of contractile and elastic proteins that help with contraction
- ex: myosin, actin, etc
transverse (t) tubules
- Continuous with the sarcolemma
- T-tubule + 2 flanking terminal cisternae = triad
- Allow action potentials to penetrate nearer to the internal structures of the fiber
thin filament
- actin
thick filament
- myosin: isoform. small changes
- heavy chains: motor domain; myosin ATPase
- light chains: regulatory fxn
regulatory proteins
- tropomyosin: covering actin binding sites
- troponin: on top of tropomyosin as gatekeeper. won’t come off unless it interacts w/ Ca2+
slow-twitch fibers (ST or type I)
- swimming
- rely primarily on oxidative phosphorylation
- looks red
- aerobic
fast-twitch fibers
- sprinting, 100 m dash, quick bursts of energy
– Develop tension faster
▪ Split ATP more rapidly
– Pump Ca2+ into sarcoplasmic reticulum more rapidly - Fast-twitch oxidative-glycolytic fiber (FOG or type IIA)
- Use oxidative and glycolytic metabolism
- Fast-twitch glycolytic fibers (FG or type IIB/X)
- Rely primarily on anaerobic glycolysis
isotonic contractions
- looking if it moves or produce force
- concentric action is a shortening action –> picking up table (biceps = shortening)
- eccentric action is a lengthening action –> lowering it (bicep = lengthening)
- promotes strength
isometric contractions
- contraction that produces force and nothing moves
- not strong enough or not putting enough force
- series elastic elements
- sarcomeres shorten while elastic elements stretch, resulting in little change in overall length
motor unit
- consists of one motor neuron and all the muscle fibers it innervates
- a muscle may have many motor units of diff types