Transcript Ch. 49 Movement and Locomotion notes

Movement and Locomotion
Ch. 49
AP Biology
Ms. Haut
Locomotion

Requires energy to overcome friction and gravity
 Swimming
– Buoyancy reduces gravity issue
– Density of water increases friction problem
– Shape of organism reduces this problem

Locomotion on land
– Development of body support and ability to move
against gravity and maintain balance

Flying
– Development of wing structure and ability to develop
“lift”
Skeletal Support
Essential

Cniderians, flatworms,
nematodes, and annelids
have a Hydrostatic skeleton
 Movement due to muscles
changing shape of fluidfilled compartments
 Nematodes-longitudinal
muscles lead to thrashing
 Segmented worms-circular
and longitudinal muscles
lead to Peristalsis
Skeletal Support Essential

Exoskeleton-hard encasement deposited on
surface of animal
– Mollusks have calcareous shells
– Arthropods have jointed exoskeleton called
cuticle-composed of chitin
Skeletal
Support
Essential

Endoskeletonconsists of
bones, buried
within soft
tissue
– chordates
Muscles Move
Skeletal Parts

Skeletal Muscle
– Each muscle fiber is a single
cell with many nuclei
– Each fiber is composed of a
bundle of myofibrils which
contain myofilaments


Thin filaments—2 strands of actin
Thick filaments—staggered arrays
of myosin
– Striated appearance due to
sarcomeres (basic functional
unit)
Muscle Contractions:
“Sliding-Filament
Model”

Thin and thick filaments of
the sarcomere slide past
one another to shorten the
length of the muscle
Cyclic Interaction Between Actin
and Myosin in Muscle Contraction
4.
5.
6.
7.
Ca++ binds Troponin
Troponin moves Tropomyosin
Tropomyosin uncovers myosin binding site on actin
Myosin binds actin
• uses ATP to "rachet" once
• releases, "unratchets", and binds to next actin
•
8. Myosin pulls actin chain along in one direction
9. Sarcomere shortens (Z discs move closer together)
10. Whole fiber shortens, ....... Contraction!
11. Ca++ ATPase pumps restore Ca++ to S.R. ...... Relaxation!
Fast Twitch Muscles

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Short contraction-relaxation cycles (~30 ms), e.g.
muscles that move the eyes
Fibers adapted to produce rapid contractions
Contain many mitochondria and sarcoplamsmic
reticulum to produce a lot of Ca++
Tire easily. Contain little myoglobin (oxygenbinding proteins)
Contain few capillaries. Make up white muscle
Slow Twitch Muscles


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Long contraction-relaxation cycles (~3 s), e.g.
muscles in back to maintain posture
Fibers adapted to produce prolonged, steady
contractions
Contain more mitochondria than fast twitch and
do not have or need a lot of Ca++
Contain a lot of myoglobin (oxygen-binding
proteins)
Extensive capillaries. Make up red muscle.