Midterm 2 Flashcards
skeletal muscle features
striated and multi-nucleated
cells are organizes into long sections
cardiac muscle features
mono nucleated and striated
smooth muscle features
not striated but multi-nucleated, can contract in multiple directions
functions of muscles (6)
- produce skeletal movement
- maintain posture and body position
- support soft tissues
- guard entrances and exits
- maintain body temperature
- store nutrient reserves
muscle characteristics (4)
contractility, excitability, extensibility, and elasticity
contractility
ability to shorten with force, only creates pulling forces
excitability
capacity to respond to a stimulus
extensibility
ability to be stretched beyond normal resting length
elasticity
ability to return to normal resting length after being stretched due to PEC
organization of connective tissue in muscle
epimysium - surrounds entire muscle
perimysium - surround muscle fascicules, group of muscle fibres, functional unit of muscle
endomysium - surrounds muscle fibre, a group of myofibrils
myofibrils
- contain bundles of protein filaments called myofilaments
- two types of protein filaments: thin (actin) and thick (myosin)
- myofibrils actively shorten > contraction
sarcoplasmic reticulum
- tubular network that surrounds myofibril, have openings into sarcolemma forming a passageway from inside to outside
- store calcium ions needed for contraction cycle
sarcomere
- basic contractile unit of muscle fibre
- arrangement of thick and thin filaments creates a banded appearance
- have A band, I band, and H band, and M line and Z line
A band
region from end to end of myosin filaments
I band
region of only actin filaments, actin filaments end connect to form Z line
H band
region of only myosin filaments
M line
where the myosin ends are bound to each other
Z line
where actin filaments ends and bound to each other
titin
attached myosin to Z line or actin, helps with elasticity
tropomyosin
2-chained helical coil protein, that in complex with troponin, covers the active sites on actin
troponin
associated with tropomyosin, blocks the binding site on actin
myosin features
- can hinge
- head can connect to actin
- has ability to breakdown ATP to generate energy for head
myosin
multiple strands make up thick filament, has a long tail and head that can hinge
sliding filament mechanism
- during muscle contractions, actin and myosin filaments slide over each other
- creates tension (pulling force)
- muscles always pull, they never push