Download The animal body and how it moves Chapter 42

The animal body and how it
moves
Chapter 42
Tissues, organs,
skeleton, muscles
Tube within a tube
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Coelom is internal
body cavity, usually
subdivided
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Peritoneal cavity and
pleural cavity
Skeleton – jointed
bones, vertebrae
surround nerve cord
Cells – tissue – organ
– organ system
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Tissues are groups of cells
similar in function
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Organs – Body structures
composed of several
different tissues
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3 embryonic tissues =
endoderm, mesoderm,
ectoderm
4 primary tissues
epithelial, connective,
muscle, nervous
Heart = cardiac muscle,
connective tissue,
epithelial tissue and nerve
tissue
Organ system = group of
organs that performs major
activities (digestive
system)
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Necessary for complex
activities
Epithelial Tissue
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Epithelial membrane - covers
surface of every vertebrate
body and lines cavities
Substances must enter/exit
through
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Simple – one cell layer thick
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Regulation
Diffusion
Stratified – several layers thick
Glands develop from
invaginated epithelium
Muscle
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Motors of vertebrate body
Actin and myosin filaments in
cells
Smooth and striated (skeletal
and cardiac)
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Nerves can stimulate or regulate
Skeletal muscle long, multinucleate
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Appear to have transverse
stripes when viewed in
longitudinal section
Skeletal = voluntary, smooth
and cardiac = invol.
stimulated by nerve, amt of
contraction can vary
Cardiac – smaller,
interconnected
Connective Tissue
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From embryonic mesoderm
Connective and special connective
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Abundant extra-cellular material because cells are placed widely
apart
Matrix -- crystals in bone, plasma in blood
© Adipose cells – fat cells
© Ligaments, tendons
(sc) Cartilage – tissue that does not stretch
and is far tougher

(sc) Bones – modeled in cartilage –
calcified
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(sc) Blood – abundant extracellular
material
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Extracellular crystallized matrix, spongy bone,
compact bone
Erythrocytes and leukocytes
-blast vs. -cyte
Nerve tissue
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Neurons and
supporting cells –
neuroglia
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Produce, conduct
electrochemical events
– impulse
Cell body, dendrite,
axon
CNS/PNS
Ganglia = collection
of nerve bodies
Skeletal systems
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Hydrostatic – soft bodied, fluidfilled cavities surrounded by
muscles
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Exoskeleton – rigid hard case,
chitin
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Contract and push fluid
Protection, resist bend,
muscles attach
Molting, limits size
Endoskeleton – rigid internal,
muscles attach, flexible exterior
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Cellular, living, repair
Vertebrate = axial,
appendicular
Muscle
contractions
move bones
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Contraction and shortening of muscles
Joint/articulation = bone meets bone
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Immovable – skull
Slightly movable – bones bridged by cartilage
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Intervertebral discs – shock absorbers
Freely movable – synovial, articulating ends have synovial
capsule (diff. mvmts)
Actions of muscles
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Ends of muscle attached to different
bones
Attached via tendon
Origin is stationary
Insertion moves when muscle
contracts
Synergists vs. antagonists
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Quads and quads vs. hamstrings
To shorten – must overcome
existing forces (gravity)
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Isotonic (same strength) bicep curl
Isometric (same length) hold stationary
Muscle contraction
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In each muscle are many muscle
fibers, each fiber cell has a bundle
of myofibrils, myofibrils are made of
myofilaments
Myofibrils have alternating
dark/light bands on myofilaments –
appear striated
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Thick myofilaments = dark, A bands,
myosin
Thin = light, I band, divided in half by
protein (Z line), actin
Sarcomere is from Z line to Z line and
crosses myosin
Thin overlaps thick, but does not meet
in center
Contraction = muscle shorten
because filaments slide closer
together = sliding filament
mechanism
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Crossbridges between thick and thin myofilaments
Thick is many myosin proteins with myosin heads
Thin is many actin proteins in helix
Myosin head + ATP binds to actin, makes bent
conformation, slides
Controlling muscle contractions
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Muscle relaxed, myosin head is cocked and ready, but
does not bind
Competitive inhibition from tropomyosin on thin filament
Troponin holds tropomyosin in place
When Ca++ binds, troponin moves, displacing
tropomyosin, allowing myosin head to bind, break ATP,
slide
Muscles store Ca++ in modified ER – sarcoplasmic
reticulum
http://www.blackwellpublishing.com/matthews/myosin.html
Nerves stimulate contraction
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Muscles stimulated by motor neurons
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Somatic motor neurons
Axon of nerve cell makes synapse with multiple muscle
fibers
Neurotransmitter released (acetylcholine) stimulates
muscle to create own electrochemical impulses
Carried through muscle, stimulates release of Ca++
Stimulation stops, troponin back to place, tropomyosin
blocks cross bridge
Excitation-contraction coupling
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Release of Ca++ links excitation of muscle by neuron to
perform contraction
http://www.blackwellpublishing.com/matthew
s/myosin.html
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Motor unit – one stimulation
contracts a unit of muscles
(coordination of muscles)
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Muscle metabolism –
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More control = smaller motor units
(fewer muscle fibers per neuron)
(tapping toe vs. moving leg)
At rest = aerobic respiration of fatty
acids
At work = also glycogen and blood
glucose
ATP needed for slide and to repump
Ca++
45-90 secs = anaerobic, O2 not
increased fast enough
Muscle fatigue – decrease in
force generated after much use
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Correlated to lactic acid build up
Endurance training does not
increase muscle size (slower
breakdown of glycogen)
Modes of locomotion
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Actively move requires propulsive and control
mechanisms
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Contracting muscles
Quantity, quality, position determined by nervous system
Appendicular or axial locomotion
Water – ciliary, slither, creep, limbs, feet
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Bouyancy reduces effect of gravity
Body shape important to reduce friction and turbulence
Swimming = undulation of whole body, posterior or appendicular
Land – mollusks, arthropods,
vertebrates
Mollusks – muscular foot and slime
 A & V – body raised above ground,
appendages push against ground
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Legs = support and locomotion
Arthropods = more legs, less control, less speed
Leapers
Invertebrates = peristaltic mvmt
(resemble eel, but more analogous,
not homologous)
Air – insects, pterosaurs, birds,
bats
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Flight evolved 4 times
Propulsion achieved by pushing
down against air
Alternates flexor and extensor
Contractions stimulate
contractions (1000 times per
second, faster than nerve
impulses)
Night vs. day resources
Label the sarcomere, thin
filaments, thick filaments, M line
Label the thick filaments, thin filaments,
myosin head, actin helix, describe what
tropomyosin does and what troponin does