Muscular System Flashcards
characteristics of skeletal muscle
- long, cylindrical + multi-nucleated
- voluntary movement
- striated
- contraction = heat released
fibers > fascicles > muscle
connective tissue: fascia
- encloses groups of muscles
epimysium: surrounds muscle
perimysium: wraps fascicles
endomysium: wraps each muscle fiber
connective tissue: tendons
- attaches muscle to bone
- extensions of fascia coverings (epimysium, perimysium, endomysium)
connective tissue: aponeurosis
- sheet like tendon
- encloses muscle to CT
muscle fibers consist of…
sarcolemma
T-tubules
sarcoplasm
sarcoplasmic reticulum
fibers: sarcolemma
specialized muscle cell plasma membrane
fibers: T-tubules
continuation of sarcolemma deep in muscle fibers
fibers: sarcoplasm
cytoplasm of muscle fibers
fibers: sarcoplasmic reticulum
- smooth ER with terminal cisternae
- triads are T-tubules with 2 terminal cisternae
myofibril characteristics
- organelles that form muscle fibers
- made of bundles of myofilaments
- formed by attached sarcomeres end to end
- consists of thin and thick myofibril
thin myofibrils composed of…
1) actin: muscle contractions
2) tropomyosin: breaks binding sites until contraction
3) troponin: binds to calcium during contraction
thick myofibrils are composed of…
- myosin: contains rod like tail + globular heads
- globular heads bind on actin
- titin: protein connecting globular heads to Z band
characteristics of sarcomere
- myofibrils organized in groups on myofilaments
- dark + light bands (striated appearance)
dark: overlap
light: no overlap
sarcomere consist of…
1) A bands
2) H band
3) I band
4) Z disk
5) M line
6) T tubules
causes of movement
- muscles pulling on bone when contracting (origin & insertion)
- using group actin: (agonist, antagonist, synergist)
**agonist: main muscle
antagonist: oppose against
synergist: extra force by preventing undesirable
effects - lever systems: bone + muscle interact at joint
- *lever: bone
joint: fulcrum
effort: contraction against
naming: location
- tibialis anterior
- tibialis posterior
naming: relative size
- maximus
- medius
- minumus
naming: direction of muscle fibers
- rectus: straight
- transversus: 90 angle
- oblique: not 90 angle
naming: num. of origins
- biceps brachii > 2 points on scapula
- triceps brachii > 3 points on scapula + humerus
- quadriceps femoris > 4 points on ilium + fermur
naming: shape of muscle
- deltoid > triangular shape
- trapezius > trapezoid shape
naming: action
- flexors: decrease angle b/w bones
- extensors: increase angle b/w bones
- abductors: move limb away from midline
- adductors: move limb toward midline
naming: origin + insertion
origin: fixed point (does not move during contraction)
insertion: moving point
ex:
sternocleidomastoid
- origin: sternum + clavicle
- insertion: mastoid process of temporal bone