Term
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Definition
locomotion
movement of food
intracellular transport |
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Term
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Definition
1. myosin
2. dynein
3. kenesin
drive motion in living organisms, all three kinds are capable of chemomechanical transduction (transformation of chemical energy to mechanical energy) |
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Term
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Definition
kind of motor molecule
creates motion in vertebrate striated muscles by interacting with actin |
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Term
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Definition
kind of motor molecule
in cilia and flagella
causes sliding motion via beating of fibers of cilia and flagella |
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Term
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Definition
kind of motor molecule
creates movement via ATP binding/unbinding; kinesin "walks" across cytoskeleton |
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Term
| Muscle structure of striated muscles |
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Definition
muscle fibers: long, multinucleated cells
microbrils: in muscle fibers, made of sarcomeres
sarcomeres: contractile units where motion is generated |
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Term
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Definition
contractile unit where motion is generated
z-disk: two z-disks determine edges of sarcomere; they move in space
A band: large dark area; stays constant length during muscle contractions
I band: large light area; gets shorter during muscle contractions
H zone: smaller, lighter area in middle of A band; gets shorter during muscle contractions
**darkness/lightness is caused by overlapping of filaments
thick filaments: myosin (myofilaments have two thick filaments that coil around each other and cluster at end where there are myosin light chains)
thin filaments: actin (acts like a string of beads with tropomyosin and troponin wrapped around it)
**are all anchored on z-disk in a scaffold-like structure |
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Term
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Definition
-tension in apparatus is caused by compression of filaments (shorten/lengthen sarcomere)
-the longer the sarcomere, the greater the potential to create tension |
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Term
| How does sliding of filaments in muscle happen? |
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Definition
1. Actin and myosin bind in a weak bond
2. ATP breaks actin from Myosin
3. Myosin becomes Myosin-ATP, which phosphyorylates to become Myosin-ADP-Pi (changes shape)
4. Myosin-ADP-Pi reaches out and grabs Actin as it changes shape
5. Actin replaces the Pi
6. Actin and Myosin separate and restart cycle
"crossbridge cycling" |
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Term
| regulation of muscle contraction |
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Definition
-troponin: 3 protein complex
troponin C (binds Ca++), troponin I, troponin T
**in absense of Ca++, troponin blocks binding sites of myosin to actin
**in presence of Ca++, troponin T/I/C affinity is strengthened, and they lift off of binding sites to allow myosin to bind to actin
Ca++ exposes binding sites via cross-bridge cycling |
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Term
| How does an action potential result in Ca++ release in a muscle contraction/relaxation? |
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Definition
1. Neural input initiates depolarization
2. AP is conducted into muscle via t-tubules
3. Dihydropine receptors open ryanodine receptors
4. Ca++ floods out of sarcoplasmic reticulum until channels close
5. Ca++ binds to troponin, freeing myosin binding sites
6. unlinked myosin heads bind to actin
7. ATP releases and repeats the cycle
8. Ca++ pumps in sarcoplasmic reticulum lowers Ca++ level, binding sites on acting are obstructed |
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Term
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Definition
1. Tonic fibers; slow, continuous contraction, no twitches
no action potentials
efficiently generate isometric tension
often in postural muscles (constant use)
house stretch receptors
2. Slow-twitch fibers (Type I): contract slowly, fatigue slowly
generate all-or-none APs
3. Fast-twitch oxidative fibers (Type IIA): contract quickly, activate quickly, fatigue slowly
have many mitochondria, specialized for rapid repetition
4. Fast-twitch glycolitic fibers (Type IIB): contract quickly, fatigue quickly
have rapid Ca++ kinetics, have few mitochondria and are not able to sustain activity |
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Term
| types of muscle contraction |
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Definition
isometric contraction: having tension without change in length
isotonic contraction: change in length without constant tension |
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Term
| Why do we have different kinds of muscle fibers? |
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Definition
Trade off between speed and energetic cost
mechanical properties and energetic properties depend on V and Vmax
different Vmax profiles have different efficiency profiles |
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Term
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Definition
-change amount of thick and thin filament overlap
-change relative shortening velocity (V and Vmax)
-change time and duration of active state |
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Term
| energy storage in muscle systems |
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Definition
| store energy over time, can release it extremely quickly; some movements happen too quickly for muscles to function, so stored energy actually creates the motion |
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Term
| Movement in sound production |
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Definition
sound can be made by rapid contractions (rapid vibrations)
don't want summation to occur, so there would be a decrease in refractory period (via increased reuptake of Ca++)
sonic muscle adaption happens by having very high Ca++ levels so you can distinguish each AP |
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Term
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Definition
-motor neuron: each muscle fiber has only one motor neuron that can stimulate it
each motor neuron can activate multiple fibers
-motor unit: multiple fibers
-motor pool: units coming into a muscle
strength of a contraction is regulated by
-activation of different numbers of motor units
-frequency of activation
tension is correlated with percent of motor pool and strength of activation of motor units
fine control: smaller motor units (more of them, more dense)
course control: larger motor units (more spread out) |
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