Download 28.2_Movement_and_Support

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Apply Concepts How do muscles enable
movement
CH 28 ANIMAL SYSTEMS II
28.2 Movement and Support
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To move all animals must:
Generate physical force
Apply that force against air, water, or land in
order to push or pull themselves around.
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Animals have three main kinds of skeletal systems:
 Hydrostatic
skeletons
 Exoskeletons
 Endoskeletons.
Hydrostatic Skeletons
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Consists of fluids held in a gastrovascular cavity
Alters the body’s shape drastically by working with
contractile cells in its body wall
Cnidarians and annelids.
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Hydra closes its mouth and the cells encircling its
body wall constrict
Elongates and its tentacles extend
Mouth opens, allowing water to flow out, and
longitudinal cells in its body wall contract,
shortening the body.
Exoskeletons
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External skeleton usually made of chitin or calcium
carbonate
Many arthropods and most mollusks
Jointed exoskeletons allow to swim, fly, burrow,
walk, crawl, and leap
May be water tight
Offer protection from predators.
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Molting
 Breaking
out of their exoskeleton and grow a new one
to allow for growth
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Relatively heavy especially in large arthropods.
Endoskeletons
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Structural support system within the body.
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Vertebrates have an endoskeleton made of
cartilage or a combination of cartilage and bone
 Sharks
and some other fishes have skeletons made
entirely of cartilage
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Girdles
 Support
limbs and allow for movement.
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Cannot protect an animal the way that an
exoskeleton can
Internal skeleton can grow as an animal grows, so
the animal does not need to molt
Lighter weight than exoskeleton.
Joints
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Places where parts of a skeleton are held together
that allows them to move with respect to one
another.
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Ligament
 Connects
bones together at
joints
 Strong connective tissues.
Muscles and Movement
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Specialized tissues that produce physical force by
contracting when stimulated
Muscles relax when they aren’t stimulated
Generate force in only ONE direction.
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Muscles are arranged in pairs or groups that pull
parts of the skeleton in opposite directions.
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Tendon
 Attaches
muscle to bones around
the joints
 Tough connective tissue.
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Exoskeleton
 Muscles
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are attached to the inside of the exoskeleton
Endoskeleton
 Muscles
are attached around the outside of bones.
Vertebrate Muscular and
Skeletal Systems
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The shapes and relative positions of bones,
muscles, and joints are linked very closely to the
functions they perform
 Many
very different arrangements
 Many very different kinds of movement.