Term
| description of skeleton muscle: |
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Definition
attaches to skeleton
voluntary muscle
appears striated when viewed w/microscope= striated muscle |
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Term
| What is the shape of muscle cells/fibers? |
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Definition
| elongated, cylinder-shaped cells |
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Term
| What do skeletal muscle cells have a lot of? |
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Definition
| they are multi-nucleated, up to 100s |
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Term
| How big are skeletal muscle cells? |
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Definition
Run entire lenth of specific muscle (end to end)
Large, up to 100mm in diameter (from less than an inch to 2 ft in length depending on muscle) |
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Term
| What are skeletal muscle cells specialized to do? |
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Definition
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Term
| What allows for skeletal muscle cells to contract? |
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Definition
| large concentration of cytoskeletal filaments known as myofilaments |
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Term
| What are 2 types of myofilaments? |
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Definition
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Term
| Organization of skeletal muscle cell ? |
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Definition
thick and thin myofilament ->
Sarcomeres->
Myofibrils->
Skeletal muscle cell |
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Term
| Describe thick filaments: |
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Definition
each myosin has 2 identical subunits wrapped around each other-
one is expanded into head region-
they both contain an actin binding and ATPase site
Myosin heads contain a hinge region that lets the heads rotate |
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Term
| Each thick filament contains: |
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Definition
| many myosin molecules; half oreintated one direction, and half in the opposite |
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Term
| What do myosin heads face? |
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Definition
| thin filaments so that they can attache |
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Term
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Definition
| thick and thin filaments arranged in a highly ordered fashion; form sarcomeres |
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Term
| What is the functional contractile unit of skeletal muscle? |
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Definition
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Term
| What does each sarcomere consist of? |
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Definition
z disk (line) (which is a protein)
Thick and thin filaments |
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Term
| How is a sarcomere arranged with z disks? |
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Definition
| a sarcomere extends from z disk to z disk |
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Term
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Definition
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Term
| Where are thick filaments in sarcomere? How do they connect to z disks? |
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Definition
| in the center. Titin (elastic) connect thick filaments to Z disk |
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Term
| How is a myofibril formed? |
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Definition
| Sarcomeres align end to end forming myofibrils |
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Term
| What makes up a skeletal muscle cell? |
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Definition
| many myofibrils make up a skeletal muscle cell which extend from end to end of cell |
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Term
| What causes the striations in skeletal muscle? |
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Definition
| A Bands and I bands of adjacent sarcomeres align causing light and dark alternating bands |
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Term
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Definition
| part of sarcomere with thick filaments -dark regions |
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Term
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Definition
| areas of thin filaments of adjacent sarcomeres- light regions |
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Term
| describe sarcoplastic reticum in skeletal muscle: |
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Definition
=Smooth ER
Extensive network of tubules surrounding each myofibril
stores calcium
ca2+ released when electrical signals reach SR, initiating contraction
Ca2+ returned to SR in order for relaxation |
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Term
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Definition
invaginations of plasma membrane
-conduct electrical signals from surface to SR around myofibrils in center of muscle cell
-At junction of every A and I band |
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Term
| What is the current theory of contraction? And how does it work? |
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Definition
Sliding filament Mechanism
-filaments slide past each other
-there is an area of overlap between thick and thin filaments
-when stimulated to contract, the filaments slide past each other in these areas of overlap. |
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Term
| Which filaments shorten in sliding filament mechanism? |
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Definition
| Neither thick or thin, they slide past each other |
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Term
| What allows the filaments to slide past each other? |
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Definition
Cross-bridges
-myosin heads bind to actin on thin filaments; rotate to pull thin filaments toward center |
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Term
| 6 major locations of smooth muscle: |
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Definition
walls of circulatory vessels
respiratory tubes
digestive tubes
urinary organs
reproductive organs
inside eye |
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Term
| inside the eye, smooth muscle: |
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Definition
| focuses and controls pupil diameter |
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Term
digestive tubes
urinary organs &
reproductive organs
Smooth muscle: |
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Definition
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Term
walls of circulatory vessels &
respiratory tubes
smooth muscles: |
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Definition
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Term
| Describe smooth muscle tissue: |
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Definition
spindle shaped
One central nucleus
non-striated (no sarcomeres)
thick and thin filaments are present |
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Term
| smooth muscle tissue is separated by- |
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Definition
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Term
| What signals contraction for smooth muscle fiber? |
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Definition
| Ca2+ entry into the cytoplasm |
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Term
| Where does the Ca2+ come from to signal contraction and why? |
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Definition
| there is minimal smooth ER in smooth muscle tissue so most Ca2+ comes from outside |
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Term
| What are tiny infoldings of the sarcolemma called and what do they do? |
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Definition
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Term
| What is analogous to Z disks in smooth muscle tissue? WHY? |
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Definition
| Dense bodies; where thin filaments attach |
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Term
| How does smooth muscle tissue contract? |
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Definition
| sliding filament mechanism |
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Term
| How is smooth muscle tissue grouped? |
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Definition
| into sheets in walls of hollow organs |
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Term
| What are the two layers of smooth muscle tissue? |
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Definition
| Longitudinal and circular layer |
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Term
| How does the longitudinal layer run? |
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Definition
| fibers are parallel to organs long axis |
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Term
| How does the circular layer run? |
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Definition
| around the circumference of the organ |
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Term
| In smooth muscle tissue, describe the contraction |
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Definition
slow and sustained
-takes 30 times longer to contract than skeletal muscle fibers, but maintains force for a long time |
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Term
| How is smooth muscle tissue innervated? What are exceptions? |
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Definition
By Autonomic nervous system;
only a few fibers are innervated in each sheet but the impulse spreads through gap junctions making the whole sheet contract as a unit.
Exceptions-iris of eye and arrector pili muscles |
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Term
| What tick layer do cardiac muscle tissue form? |
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Definition
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Term
| Is cardiac muscle tissue striated> |
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Definition
| yes like skeleton muscle they have sarcomeres |
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Term
| How cardiac muscle tissue contract> |
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Definition
| sliding filament mechanism |
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Term
| describe cardiac muscle tissue |
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Definition
single cells- no fascicle like skeletal muscle
cells are branched
each cell contains one or two centrally-located nuclei |
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Term
| How are cardiac muscle tissues seperated? |
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Definition
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Term
| Where do cardiac muscle tissue cells join at? |
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Definition
| intercalated discs (complex junctions) |
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Term
| What are intercalated discs? |
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Definition
complex juntions
adjacent sarcolemmas interlock
Possess 3 types of cell junctions |
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Term
| What 3 types of cell junctions do intercalated discs possess? |
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Definition
desmosomes
fasciae adherans -long desmosome-like junctions
Gap junctions |
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Term
| Are all cardiac cells innervated? |
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Definition
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Term
| How do cardiac muscles contract/innervated? |
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Definition
| will contract in rythmic manner w/out innervation |
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Term
| Inherent rhythmicity is the basis for rythmic heart beat which = |
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Definition
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