Muscle and Bone
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3 kinds of muscle
- skeletal muscle
- cardiac muscle
- smooth muscle
what is skeletal muscle? what does it connect?
voluntary muscle tissue
connects one bone to another via tendon
tendon v. ligament
tendon = muscle to bone
ligament = bone to bone
agonist and antagonist
agonist = muslce repsonsible for movement (contracts)
antagonist = second muscle (stretches)
when antagonist contracts, in what direction does the muscle move?
opposite direction as to when it was move when the agonist was contracted
assists agonist by stabilizing the origin bone
Skeletal muscle can squeeze blood and lymph vessels, what advantages does this have?
muscle is like what kind of machine?
muscle = leverage to apply force to the bone to move
Is greater or lesser force required to move the bone?
contraction of skeletal muscle - releases energy?
what is shivering?
rapid contraction of skeletal muscle to warm the body
skeletal muscle contraction: sacromere
composed of thick and thin filaments
sacromere lumen is filled with
mitochondria and nuceli
does sacromere have a single or many nuclei?
only type of muscle like this
thick and thin filament - actin and myosin
thick = myosin
thin = actin
5 stage cycle -
actin and myosin work together to.....
1st stage in contraction
preventing myosin head from bonding-
tropomyosin covers the active site on actin
why would we not want the myosin head to bind?
head has high energy position with P and ADP attached
2nd stage in contraction
exposing the active site
troponin pulls the tropomyosin back
3rd stage in contraction
myosin head expels a P and ADP (low energy position)
what is this 3rd stage called (when myosin head expels a P and ADP)?
it causes shortening of the sacromere and the muscle contraction
4th stage of contraction
ATP reaches to myosin head from active site
5th stage of contraction
ATP splits into P and ADP causing myosin head to cock in high-energy position
overall scheme of contraction
tropomyosin covers active site and has troponin attached
when Ca2+ bind to troponin, it changes conformation and moves the tropomyosin
mvmt. opens myosin binding sites on the actin
when they bind the move (contract)
How is the muscle contraction initiated?
neron attaches to muscle cell and releases neurotransmitter into synapse
what neurotransmitter is released into begin muscle contraction?
how does the action potential reach deep into the muscle?
stimulated T-tubules spread action potentially rapidly to
what does an activated sacroplasmic reticulum do
becomes permeable to Ca2+ ions
calcium begins 5-stage cycle
what happens to Ca2+ after contraction?
it is actively pumped back to sacroplasmic reticulum
in contraction what sections reduce in size and which stay the same?
H and I get smaller
A band doesn't change
does skeletal muscle contract all at once?
no, single neuron innervates each muscle fiber
they contract independently of each other
skeletal muscle types
1. slow oxidative muscle
2. fast oxidative muscle
3. fast glycolytic fibers
slow-twitch: color, rate to split ATP
red - large amounts of myoglobin
split ATP at a slower rate
slow to split ATP means....
- slow to fatigue
- slow contraction velocity
fast-twitch: color? rate to split ATP
split ATP at high rate
split ATP at fast rate
resistant to fatigue
fast-glycolytic color and rate of contraction
white (b/c of low myoglobin content)
- contract very rapidly
- contain large amounts of glycogen
what does myoglobin do?
stores O2 inside muscle cell
do muscle cells undergo mitosis?
instead, change over time when exposed to repetitive contraction
cardiac muscle: striate? nuclei, mitochondria? voluntary?
contains only 1 nucleus
much more mitochondria - stronger
how are action potentials spread in a cardiac muscle?
smooth muscle: voluntary? nuclei?
involuntary - innervated by ANS
does smooth muscle contain thick and thin filaments if it has only one nucleus?
yes, but not organized into sacromeres
intermediate filaments and dense bodies in smooth muscle: picture
single unit and multi unit
cells connected by gap junctions spreading action potential from a single neuron
single unit: do cells contract separately? where are they found?
no contracts as a whole
intestines, arteries, veins, stomach, uterus, urinary bladder
each unit fiber is directly attached to a neuron
fibers contract independently
is bone living tissue?
3 types of cells are:
what are they surrounded by?
surrounded by extensive matrix
- 1. osteoblasts
- 2. osteocytes
- 3. osteoclasts
secrete collagen and organic compounds that form bone
differentiate into osteocytes
do osteoblasts undergo mitosis?
exchange nutrients and waste with blood
do osteocytes undergo mitosis?
- reabsorb bone matrix,
- releasing materials back into blood
where do osteoclasts develop from
white blood cells: monocytes
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