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75 Cards in this Set
- Front
- Back
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multiunit smooth muscle controlled by
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controlled mainly by nervous stimuli
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multiunit smooth muscle consists of
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separate, discrete fibers
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Multiunit smooth muscle
each fiber is innervately separarely and? |
controlled by a single nerve ending (as in skeletal)
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multiunit smooth muscle
each fiber contracts |
independently
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multiunit smooth muscle
each fiber is insulated |
independently by separate basement membrane
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MUSM
fibers seldom |
contract spontaneously
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MUSM
locations |
eye, iris, ciliary muscles, piloerector muscle (hairs erect by sympathetic NS
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SINGLE UNIT SMOOTH MUSCLE also called
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single whole mass, also called visceral
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SUSM
1.Represents a large number of fibers that act? |
(CONTRACT) together as a single unit
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2. Single unit smooth muscle contracts as a ?
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unit, usually controlled by non-nervous stimuli
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single unit smooth muscle are arranged in
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sheets or bundles
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single unit smooth muscle
cells held together, many ? |
adherences, very effective force transfer.
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SUSM
many gap junctions that are sights of? |
direct electrical connections, "syncytical" smooth muscle
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many gap junctions/syncytical smooth muscle allows ?
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ions to move freely from 1 cell to the next
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where is single unit smooth muscle found
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visceral smooth muscle in all hollow organs, gut, ureters, blood vessels, bile ducts uterus
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CONTRACTION OF SMOOTH MUSCLE
CHEMICAL BASIS 1.Cells contain? |
actin and myosin but not troponin complex
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A. CHEMICAL BASIS
2. ? and ? interact to cause contraction |
actin and myosin
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A. CHEMICAL BASIS
3. Contraction activated by ? |
calcium and uses ATP for energy
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B. PHYSICAL BASIS
1. Actin bound together in groups by? |
dense bodies, some inside (intracellular bridges)
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B. PHYSICAL BASIS
2. some dense bodies attach filaments to the ? |
cell membrane and adjacent cells bind together
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The intercellular protein bridges?
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transmit the force of contraction
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Physical basis
3. ? interspersed randomly between action ? |
myosin interspersed randomly between ation filament
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C. SMOOTH VS SKELETAL MUSCLE
1. CROSS BRIDGE CYCLING A. Occurs at much ? frequency in smooth muscle |
much slower (skeleltal 10x to 300x faster)
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2. cross bridge interaction between actin and myosin last musch longer in ?
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smooth muscle
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smooth muscle fibers have less ?
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ATPase activity
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ENERGY REQUIREMENTS
a. ? ENERGY used in smooth muscle |
less 10-300x less
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the gut and blood vessels maintain a ? level of ?
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tonic level of contraction
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SPEED OF CONTRACTION/RELAXTION CYCLE
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1-3 sec, excite-contracts-relax about 30x longer than skeletal muscle
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Smooth Muscle is able to generate greater ? than
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force than skeletal muscle due to the longer time of interaction
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Smooth muscle shortening, effectively able to shorten?
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2/3 of its entire length (verses skeletal at 1/4 to 1/3 of total length
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smooth muscle is able to shorten 2/3 of its entirle length due to ?
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random arrangement of filament not in synchrony
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SKELETAL MUSCLE
Myosin:Actin ratio |
1:2
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smooth muscle
myosin/actin |
1:15 (no troponin) actin bound toether by dense bodies
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skel
cross bridge cycling |
10-300x faster
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smooth
Cross bridge |
slower frequency/ 10-300x slower
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myosin/actin interaction
muscle |
shorter
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myosin/actin int. smooth
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longer
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energy requirement for skel
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more
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energy for smooth
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10 to 300 times less
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speed of contrat/rela
skeletal |
faster
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speed of contraction/relax
smooth |
30x longer/prolonged due to plateau(=delayed repolarization)
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force of muscle contraction
skleltal |
less force
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force of contraction/smooth
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greater force
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muscle shorten/skeletal
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1/4 to 1/3 of its total length
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muscle shorten/smooth
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2/3 ot its total length
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stimuli/skeletal
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neural input
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stimuli/smooth
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multiple triggers, vasodil, lactic acid, ions, hormones, angiotensin, ADH, oxytoxin
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nerve junc/skel
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motor end plate
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nerve junc/smooth
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varicosities(sites of NT release along axon)
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regulatory protein/skeletal
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troponin
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regulatory protein/smooth
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calmodulin activates myosin kinase, phosphorylates myosin, so M-A interact (muscle relaxes by myosin phosphatase)
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Nt/skele
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Ach
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Nt/smooth
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ach or ne
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resting memebrane pot/ske
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-70 - -90mv
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restin/smooth
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-50 - -60mv
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pos feedback mech/skel
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na+ influx (more Na gates)
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pos feedback Mec/smooth
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ca++ influx, few na gates
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cal. sources/skel
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sr's terminal cisternae
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cal. sources/smooth
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diffusion from ecf
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sarcoplasmic reticulum/ske
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extensive
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sarcoplasmic retic/smooth
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less extensive
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ca pump/ske
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resequester faster
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ca pump/smooth
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slower ca++ pump
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multiunit smooth muscle
locations |
iris, ciliary muscles, piloerector muscle
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multiunit smooth muscle
separate fibers insulated by/ |
separate basement membrane, innervated by single nerve ending
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mult unit smooth muscle
contracts? |
independently
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seldom contract
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spontaneously
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contact junctions , like NMJ by?
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varicosities sites of NT release along axon
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mult unit smooth muscle react by ? stimuli only
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nerve
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single unit smooth muscle
location |
visceral hollow organs, GIT, ureters bile ducts, uterus, blood vessels
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single unit smooth muscle
held together (adherences) in |
large sheets
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single unit smooth
many gap junctions for |
fast connections
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single unit smooth contracts as a
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unit
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singel unit smooth muscle ? junctions
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diffuse (AP travels down or NT diffuses down)
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single unit smooth reacts to ?
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nervous and non nervous stimuli; such as vasodilation, certain ion levels like decresed O2, Increased CO2, Inc H+, incr K+, dec Ca++ diffuses from ECF, In lactic acid, histamine, serotonin, hormones like angiotensin, vasopressin (ADH), oxytocin
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