Ch. 48 Animal Movement Flashcards
types of movement
1) locomotion
2) movement of one part of the animal’s body relative the entire body
locomotion
movement of entire organism under its own power
- generated by muscle contraction
modes of locomotion
1) walking
2) swimming
3) flying/gliding
4) running
*depends on build/body type
muscle fiber
a single muscle cell
- composed of long, slender cells
- contains myofibril
myofibril
long, slender structure composed of contractile proteins organized into repeating units (sacromeres) in vertebrate heart muscle & skeletal muscle
- may be striped or striated
sacromere
light & dark areas of myofibril
- made up of actin & myosin
- shorten = contracted myofibril
- relax = longer myofibril
actin
a globular protein that can be polymerized to form filaments
- part of the cytoskeleton
- THIN FILAMENTS in skeletal muscle cells
- make up sacromere
- moves
myosin
any one of a class of motor proteins that use the chemical energy of ATP to move along actin filaments in muscle contraction, cytokinesis & vesicle transport
- thick filments
- does not move
sliding-filament model
the hypothesis that thin (actin) filaments & thick (myosin) filaments slide past each other, shortening the sacromere
- shortening of all the sacromere in a myofibril results in contraction of the entire myofibril
- proposed by Hugh Huxley & Jean Hanson
thin filament
a filament composed of 2 coiled chains of ACTIN and associated regulatory proteins
- anchored @ Z disk of the sacromere
- contain troponin & tropomyosin
thick filament
a filament composed of bundles of the motor protein MYOSIN
- anchored to the center of the sacromere
Z disk
the structure that forms each end of a sacromere
- contains a protein that binds tightly to actin
- anchors thin filaments
- other end is free to interact w/ thick filament
troponin
a regulatory protein
- present in thin (actin) filaments
- moves tropomyosin off the myosin-binding sites on thin filaments
- triggers muscle contraction
- activated by high intracellular calcium
CALCIUM
tropomyosin
a regulatory protein present in thin (actin) filaments
- blocks myosin-binding sites on thin filaments in resting muscle
- prevents muscle contraction
Actin can only interact with myosin after ________ bind with troponin, the troponin-tropomyosin complex.
calcium ions
T tubule
any of the membraneous tubes that extend into the interior of muscle cells
- propagates action potentials throughout the cell
- triggers release of calcium from the sacroplasmic reticulum
- connected to endoplasmic reticulum (releases calcium)
model for actin-myosin interaction
1) ATP binds to myosin head; head releases from thin filament
2) ATP hydrolyzed; head pivots; binds to new actin subunit
3) P1 released; heat pivots; moves filament
4) ADP released
cycle ready to repeat
muscle relaxed
tropomyosin & troponin work together to block myosin binding sites on actin
contraction begins
when a calcium ion binds to troposin, the troponin-tropomyosin complex moves, exposing myosin binding sites
calcium ions connect to sites open for myosin to bind
acetylcholine (Ach)
a neurotransmitter
- released by nerve cells @ nt junctions
- triggers contraction of skeletal muscle cells
- slows rate of contraction in cardiac muscle cells
- may also be used as nt btwn neurons
- released from motor neuron
- deposited into the synaptic cleft btwn the motor neuron & muscle cell
- parasympathetic neurons
movement process
1) action potential triggers the release of Ach
2) Ach binds to receptors on the membrane of the muscle cell; this depolarizes the muscle cell, which can trigger action potentials in the fibers
3) action potential spreads into the interior of the fiber through invaginated tubules (T tubules) of the cell membrane
4) T tubules interacts w/ smooth endoplasmic reticulum (ER), a special smooth ER known as the sacroplasmic reticulum; a protein in this ER changes its shape & allows Ca+ ions to enter
5) the myosin binding sites on the actin are exposed to enable a contraction
types of muscle tissue
1) smooth
2) skeletal
3) cardiac
skeletal muscle
the muscle tissue attached to the bones of the vertebrate skeleton
- long, unbranched muscle fibers
- striated appearance
- voluntary control
- multinucleate cells
- contains myofibril
- longer than smooth & cardiac muscles
- stimulated by somatic motor neurons
- neuron damage will result in paralysis
(aka) striated muscle
cardiac muscle
the muscle tissue of the vertebrate heart
- responsible for pumping blood
- long, branched fibers
- fibers are electrically connected end to end via intercalated discs & initiate their own contractions
- involuntary control
- contains myofibril & sacromeres
- contracts upon depolarization of muscle cell
intercalated disc
a type of specialized connection between adjacent heart muscle cells that contain gap junctions
- allow electrical signals to pass btwn cells
- critical to flow of electrical signals from cell to cell
- critical for coordination of the heartbeat
gap junctions
a type of cell attachment structure
- directly connects to cytosolic components of adjacent animal cells
- protein-lined openings
- allows passage of water, ions & small molecules btwn cells
smooth muscle
unstriated muscle tissue that lines the intestine, blood vessels & some otro organs
- tapered, unbranched cells that can sustain long contractions
- involuntary control
- lacks myofibrils & sacromeres
- often organized into thin sheets
- contains single nucleus
- contains autonomic motor neurons
- connected to parasympathetic neurons
(ie) found in lungs, blood vessels, urinary bladder & reproductive system
Sympathetic neurons & the adrenal gland release nts that _______ muscle contraction in the digestive tract.
inhibit