Muscle Flashcards
what makes up light band and dark bands
light - I band
dark - A band
where does z line occur
runs through I -band
where is sarcomere and significance
between 2 I-lines - where muscle shortens
3 feature of skel. muscle fibers
- long and straight
- multinucleatied - peripheral
- no cell-cell junctions
4 features of cardiac cells
- short
- often branch
- one or two central nuclei
- have intercalcated disc between - at ends
what is contained in intercalcated discs (3)
- demosomes
- fascia adherents - anchor
- gap junctions - communicate
define myofibrils and myofilaments
myofibrils - cylindrical cells that are striated
myofilaments - what create the striations
2 types of myofilments
thick and thin
attachement of thin myofilaments
to z-discs and into sarcomere
arrangement of myfilaments
1 thick with numerous thin filaments surrounding it
2 different types of contractions
- isotonic - flexion occurs - myofilaments slide deeper
2. isometric - no movement
special attachement to T-tubule in skeletal muscle vs. cardiac
terminal cisternae - stores Ca and released if triggers
- cardiac must get Ca from outside
what is different about cardiac ultrastructure (3)
- less distinct myofibrils
- less dev. sarcoplasmic reticulum
- wider T-tubules
Features of a motor unit
- can innervate multiple muscles
2. all or nothing signal
synaptic muscle cell order of things
- voltage gates Ca channel opens
- Ca in
- releases vesicles of ACTH
- ACTH bind w. receptors
- Na channel opens
- muscle contracts
