A&P 1 exam 2 (part 7)
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A&P 1 exam 2 (part 7)
Muscle Microanatomy cont Fall 2014
where is z-line found?
right in middle of I-band
I-band is ?
where are a-bands found?
towards the center
where are thin filaments found?
in both dark and light bands because they overlap with thick filament s
what are pulled closer together during contraction?
when z-bands are pulled closer together, what happens?
shortens length of sarcomere
which band is reduced in length during contractions of striated muscle?
what happens to a-bands during contraction?
there is no change
z line is pulled towards center
no change in thick filaments
as z-line moves towards center, I-bands ____ but a-bands _____ ___ ___
stay the same
what is important for contraction in striated muscle?
sarcoplasmic recticulum is aka
smooth ER for a muscle fiber
what is sarcoplasmic recticulum used for?
what does sarcoplasmic recticulum store?
it stores calcium ions
what do calcium ions act as?
triggers for contractions
what happens when calcium ions are exposed?
calcium interacts with myofilaments
when there is not calcium present?
muscle is relaxed
what is the interior of cell filled with?
what initiates release of calcium ions?
what does the sarcolema do with calcium ions?
it produces an electrical impulse that releases calcium ions to lead sarcomplasmic recticulum powered by diffusion gradient
the cell membrane becomes ____ to __ __
what happens when calcium floods to outside?
it causes sarcomeres to contract
associated with sarcoplasmic recticulum
transvere tubules (t-tubules)
1 region of sarcoplasmic recticulum
what is a triad?
a t-tubule and 2 lateral sacs
what goes through out cell itself?
what do triads ensure?
that all contract at the same time
how do you stop muscle contractions?
get rid of calcium by putting it back into sarcoplasmic recticulum
whens stopping muscle contractions, calcium must?
go against concentration gradient by using active transport
it costs energy to cause muscle fiber to
it takes energy to ___ and stop ____ in muscles
muscles are ready to ____ all the time
arrangement of fibers in striated muscle?
each individual cell in striated muscle is wrapped with
3 types of connective tissue in striated muscle
wraps individual muscle fibers and provides insulation
wraps entire fascicle
wrapped around entire muscle itself (organ)
_____ is continuous with periosteum which is continuous with _____
why is connective tissue needed?
to get force to skeletal system from contraction
continuation of all connective tissue, which attaches to bones
what is continuous with tendon?
the diameter of ____ is smaller than diameter of ____
why is having tendons with small diameters helpful?
allows you to apply a lot of force to a big area with out having the big muscle right there
ex of helpful small tendon diametes?
fingers, muscle in forearm move fingers, the force goes through small tendons making fingers still have great strength
skeletal muscle contracts?
much more quickly
has more speed, high velocity
during contraction, skeletal muscles?
consume a lot more energy and can fatigue relatively easily and quickly
contraction in skeletal system starts via?
nervous system, consciously control contractions
only way to initiate contraction in skeletal is by?
from nervous system
in skeletal muscle, the fibers contract from what lengths?
1/2 to 2/3 of resting length
where is cardiac muscle found?
embedded in wall of heart
cardiac muscle is very limited in its
cardiac muscle has what type of fibers? caused by?
caused by myofibrils made of repeating units
involuntary muscle fiber?
how is cardiac muscle different from striated?
it doesn't have cells fusing together, meaning the cells are not multinucleated
cells in cardiac muscle are not?
how are cardiac muscle fibers attached?
from end to end
what is found where cardiac muscle fibers attach at ends?
what type of muscle fibers are branched? unbranched?
position of nucleus is centrally located
cardiac muscle fiber contraction?
each fiber has one rate of contraction
each fiber can contract without any signaling by themselves
rates of cardiac muscle fibers?
some rates are slow, some are fast _-- they go at their own pace
contraction in cardiac muscle fibers spreads from?
cell to cell
if cardiac muscle fibers are in a group then?
they will contract together, they contract at the frequency of the fiber with the quickest rate of contraction
cardiac muscle fiber contraction can also be initated by?
nervous system, slow down or speed up
specialized fibers for regulating info in the different chambers of heart
purkinje fibers are specialized in?
coordinating contractions in different chambers of heart
cardiac muscle fibers rate of contraction?
relatively slow, resistant to fatigue
smallest unit that contracts?
has actin, but lacks myosin
has myosin and actin
__ ___ stays the same shape, but __ ___ shortens
yolk sac is?
order of striated muscle?
order of smooth muscle?
circular muscle cells
longitudinal muscle cells