Ch 30 How animals move
Locomotion
Swimming, gravity is negated so supporting the body is aided, friction from
water hinders movement. Leg movements shooting jets of water, moving the body
from side to side., aquatic mammals undulate the body up and down, sleekstreamlined shape is an adaptation for rapid swimming.
On land. The problems opposite those in the water. Little resistance from air,
but little support against gravity. Walking running or hopping muscles propel the
animal and keep it from falling.
Hopping—large leg muscles, tendons stretch and store energy on landing
that is available for the next jump.
Walking-running—each leg moves in turn, friction with ground, three legs on
ground, bipeds are less stable on ground [birds, humans]. When running
momentum stabilizes body position.
Crawling—snake, earthworm—friction is great. Snakes undulate or lift a
portion of the body to move, earth worm uses peristalsis.
Flying—wings develop lift to overcome gravity, wing shape causes air
passing over the top move farther than the air under the wing. This causes low
pressure above the wing = lift.
Movement based on two possible contractile systems.
Microtubules or microfilaments.
Consume energy and move protein strands against each other
Bending microtubules = cilia, flagella
Microfilaments are used in muscle tissue
Skeletons
Functions
Attachment for muscle, support against gravity [land organisms],
create shape, protect soft parts,
Hydrostatic skeleton—fluid under pressure, earthworm, hydra elongation, jelly fish
movement.
Exoskeleton---Arthropods, non-living layers of protein and the
polysaccharide chitin. [includes insects, spiders, crustaceans]
Muscles attach to the inner part of the exoskeletons. The exoskeleton is thin
and flexible at the joints.
Must be shed for growth, molting.
Mollusks, [clams, etc] grow by adding new layers of calcium carbonate to
their shells
Endoskeleton-hard or leathery parts mixed among the soft tissue.
Sponges, tough protein lattice
Sea urchins, hard plates under their skin.
Vertebrates-cartilage and or cartilage and bone. Cartilage where flexibility is
needed.
Vertebrates
Axial skeleton, skull, vertebrae, ribs, pelvic girdle
Appendicular skeleton, appendages
Bone
Moist living tissue covered by connective tissue
Cartilage, thin sheet of material at joints for cushioning and sliding
Bone, living cells secreting surrounding material [flexible collagen protein
fibers-flexible and nonbrittle; and hard calcium and phosphate crystals
resisting compression].
Long bones Compact bone around a central cavity. Yellow bone marrow-fat.
The ends of long bones are a honeycomb of material filled with red marrow
where blood is produced.
Repair, bone is living tissue and when broken it may repair itself. 2 broken bones /
person average.
Osteoporosis, low bone mass, deterioration of bone. Destruction exceeds
replacement. Weight bearing exercise strengthens bone, Ca and P plus vitamin D
Joint types- ball and socket, pivot, hinge, sliding, pivot
Ligaments
Tendons
connects bone to bone.
connect muscle to bone.
Muscle contraction and movement.
Muscles are paired, one extends the other flexes a joint.
Muscle—muscle fiber—myofibril—sarcomere
Sarcomere
Z line-light band-dark band-light band-Z line
Thick myosin protein filaments
Thinner actin filaments hooked to Z line
Myosin filaments “climb” the actin filaments pulling the Z lines together.
Myosin head grabs the actin [create a cross bridge] , P and ADP are released causing
head to bend [slides filaments past each other], ATP causes myosin, to release and
straighten, the head may regrab the actin and repeat the cycle
Control of muscle contraction involves the protein Tropomyosin which covers the
binding sites on the actin strands. Calcium is released when an action potential
reaches the sarcomere. Calcium, stored in smooth endoplasmic reticulum
[sarcoplasmic reticulum] floods the sarcomere causing the tropomyosin to move
exposing the binding sites. Actin/Myosin cross-bridges form-a contraction occurs.
The Ca+ is restored in the sarcoplasmic reticulum for use in the next contraction.
Aerobic respiration supplies the energy for exercise.
Muscle is a mixture of fast twitch, intermediate and slow twitch fibers. Different
forms of myosin.
Slow twitch cycles through cross-bridge formation rapidly, forceful, powerful
contraction e.g. hitting a baseball.
ATP used at breakneck speed therefore fermentation provides ATP
replacement. Combination of fast twitch and slow twitch sprinters
Slow twitch forms cross-bridges at a slower rate, less ATP is necessary, less forceful
contractions that may be continued for extended period of time. Long distance
runners.
Intermediate fibers add power to the middle distance runner