animal locomotion-skeleton and muscles Flashcards
what are skeletons for
body support, locomotion, protection
what are the three broad catigories of skeletons
hydrostatic, exoskeleton, endoskeleton
what skeleton type has limited protection
hydrostatic
what skeleton type must be shead for growth and what is this process called
its called ecdysis and exoskeletons do this
what skeleton type is exposed to bodily fluids and H+ as a byproduct of metabolism
endoskeleton
what are the two types of endoskeletons
-calcium carbonate and protein fibers, it easily devolves in acid (starfish)
-calcium phosphate and protein fibers, more resistant to acid, internal stores of Ca+ and PO4- (us)
what do vertebrate skeletons rely on
Ca++ homestasis
in vertebrate skeletons what is blood Ca++ tightly regulated by
endocrine negative feedback loops
what are muscles responsible for
responsible for movement of body
where are contractile cells found
in all animals
what did true muscle first evolve in
cnidarins
what are muscle contractions
shortening based in interactions between:
supporting filament (actin)
a motor protein (myosin)
what are the three types of vertebrate muscle
skeletal, cardiac, and smooth
what muscle is volentary
skeletal muscle
what muscle is striated
skeletal, and cardiac
what muscle is unstriated
smooth muscle
what is involuntary muscle
cardiac and smooth
what is neurogenic muscle
voluntary muscle
what is myogenic muscle
involuntary muscle
all muscle is…
bioelectric (produces membrane action potential)
what is the average and largest usual length of a skeletal muscle cell
ave 3cm, up to 30cm
what does shortening of the muscle generate
force and movement
what is proximal insertion of muscle
muscle connects closer to the joint-speed
what is the distal insertion of a muscle
further away from the joint- strength
what are antagonistic pairs
muscles are grouped as such
can antagonistic pairs be active at the same time
yes
what is sliding filament theory
explains muscle contraction
what is the composition of a muscle
muscle—bundle of muscle fibers—muscle fiber—myofibril
what is a portion of a myofibril
M line - Z line - A band (H zone in middle) I band
on a myofibril what is the dark band and what is the light band
dark A band, light I band
how does the neuromuscular junction work
-it has a motor neuron axon terminal (presynaptic)
-muscle fiber (postsynaptic)
-acetylcholine causes a muscle fibre depolarization
-depol results in muscle action potentials
what are some features of the neuromuscular junction
-it has acetylcholine gated cation channels (nicotinic receptor)
-and indents on the plasma mem of the cell for increased SA
how is muscle AP conducted to the interior of the muscle fiber
along the membrane of the t-tubules
what is the plasma membrane and the T tubules of the interior of the muscle fiber like
plasma mem- sarcolemma (folded)
T tubles- continous with the sarcolemma
when you hear the word sarco what can you assume
that its related to muscle
what is the sarcoplasmic reticulum
-its like the ER
-it stores Ca+
-keeps cytoplasmic Ca+ low, SR Ca+ high
how does the sarcoplasmic reticulum keep the Ca+ gradient how it should be
-uses Ca-ATPase to pump Ca++ form cytoplasm to sarcoplasm
what us a ryanodine receptor (RyR)
Ca++ channel in sarcolemma
what is a dihydropyridine receptor (DHPR)
voltage gated channels in t-tubule membrane-at rest plugs RyR
what does the muscle action potential (MAP) do to dihydropyridine receptor (DHPR)
-it produces a conformational change in DHPR
-which unblocks RyR
-Ca+ defuses out of sarcoplasmic reticulum into sarcoplasm along large concentration gradient
what are muscle cell contractions stimulated by
motor neurons form somatic nervous system
one myofibril is many…
sarcomeres
what part of the myofilaments is myosin
A band
what part of the myofilaments is actin
I band
what is the H zone on a myofibril
myosin only, bisected by M line
what is the Z disk on a myofibril
it anchors actin
what is the M line on a myofibril
it anchors myosin
what regulates interactions with actin and myosin
troponin and tropomyosin
what happens when actin and myosin come into contact
interactions make contractions, actin slides on myosin
what gets pulled closer as actin and myosin come into contact
Z line gets pulled closer
what causes actin and myosin to move filaments past eachother
change in myosin shape after cross bridge formation
where does Ca2+ bind to on actin filaments
it binds to troponin
what happens in presents of high sarcoplasmic Ca+
the cycle of binding and unbinding continues
what is ATP required for when it comes to cross bridge binding
-required to detach actin/myosin
-also needed for Ca+ pump on sarcolemma
what happens if no ATP is produced to detach actin and myosin
then filaments remain bound (rigor mortis)
what is the muscle contraction due to
-continual crossbridgle cycling
-the formation of many crossbridges per sarcomere
what is the length of a sarcomere
2.5 micro m
what is the distance each sarcomere can shorten
0.25 micro m
what is neural regulation of skeletal muscles
reflex arcs
what is reflex arcs
stretch receptors and motor neurons connected to the CNS
how do reflex arcs operate
-automatically
-integrated with conscious motor control by CNS
what are reflex arcs important for
in posture, coordinating limb movements
what does neural stimulation always do to skeletal muscles
it always shortens it
what is one motor unit
motor unit=one neuron plus all muscle fibers it contacts
what controls muscle activity
threshold
what will a a restimulated action potentials with rest in between result in
single twitches
what will a action potental that has been restimulated before it has completely relax result in
summed twitches
what is tetanus
-if muscle is stimulated so rapidly that it doesnt have opportunity to relax at all between stimuli
-at the end it goes down because stimulations ceases or fatuigue begins
what is an example of stretch activated muscles
asynchronous flight muscle
what are asynchronous flight muscles
-smaller SR-more sarcomeres
-indirectly attached to wing
Mn AP:cantractions <1 (one AP leads to many contractions of muscle)
-mechanical coupling, more efficent use of ATP
