muscle and skeleton Flashcards
sessile
non moving
non-sessile
freely moving
molecular motors
proteins capable of converting energy in ATP into movement
kinesins
move along microtubules by consuming ATP
found in all eukaryotic cells
dyneins
transport cellular cargo/organelles
cilia and flagella
dyneins
transport cellular cargo/organelles
cilia and flagella
myosin
head - binds actin, consumes ATP, force transduction
neck - lever
tail - regulation, interacts with proteins
found in all eukaryotic cells
myocytes
muscle cells needed to coalesce into larger structures
myofibrils
larger fibers constructed from myocytes
connected to other structures (when they move, other tissues move)
muscle evolution in sponges
contract body sections without muscle cells
require - molecular motors, contractile fibers, connection to cell cytoskeleton
contractile apparatus
filaments and molecular motors
triggered by calcium (calmodium)
used by sponges
muscle evolution properties
generates force through shortening (tension)
under conscious and unconscious control
dependent on the action of molecular motors
amoeboid
change cell shape
crawling motion done by protozoans, slime molds
actin/myosin motors
cilia and flagella
asymmetrical // symmetrical
one // many
axoneme
functional characteristics
contraction - fibers shorten, generate force and pull on bones, slide past each other
excitability - respond to stimulus, CNS, hormones, physical
extensibility - stretch past original length
elasticity - recoils after stretch
striated muscle anatomy
long cells innervated by neurons (conscious control)
usually associated with skeletons as anchorage points
smooth muscle anatomy
individual small cells
same molecular motors as striated
much higher efficiency
activated by stretch
sarcomere
contractile unit of striated muscle within muscle fibers
attached end to end, z-disk to z-disk, in series
sarcoplasmic reticulum
ER
ca2+ storage
terminal cisternae
ca2+ sequestering
transverse tubules
cell membrane invaginations
actin filament
thin filament, overlaps myosin filament
attached to z-disk
nebulin
scaffolding protein
tropomyosin
barrier to interaction between myosin and actin
keeps muscle from contracting
troponin
binds calcium to tropomyosin
C - binds ca2+
I - binds actin, preventing molecular interaction with myosin
T - binds tropomyosin
z disk
site of actin attachment, also attached to cell cytoskeleton
I band
region with only actin
A band
region of actin/myosin overlap
H zone
region with only myosin
M line
site of attachment of myosin
length-tension curve
relationship between muscle length (or sarcomere length) and tension development
ideal overlap = maximum number of crossbridges formed
invertebrate striated muscle
thick filament is 2-3x thicker, 2-5x longer
paramyosin attached to myosin
twitchin protein allows muscle to maintain resistance to stretch in absence of cross bridge
asynchronous
smooth muscle activation
ca2+ influx into cell
ca2+ binds to calmodulin
myosin light chain kinase is activated
myosin light chain is phosphorylated
cross bridge forms, tension develops
mechanochemical coupling
only power half of the action of the muscle
found in thorax and associated muscles
mechanical oscillator
thorax, stretch rubber band
can use smaller set of wings to generate more lift with less muscle
resilin
elastic protein found in fleas
striated muscle
skeleton
rigid weight bearing, composite with strength and flexibility
biomechanical advantage of skeletons
levers around a joint
joints
move without friction
endoskeleton
mineralized tissue (collagen), hydroxyapatite crystals
exoskeleton
limits growth
carry the weight
hydrostatic skeleton
flexible chamber filled with water
buoyancy
upward force exerted by a fluid that opposed the weight of an immersed object
