1. CHAPTER 49 SENSORY AND MOTOR SYSTEMS
Section F1: Movement And Locomotion
1. Locomotion requires energy to overcome friction and gravity
2. Skeletons support and protect the animal body and are essential to movement
3. Physical support on land depends on adaptations of body proportions and posture
4. Muscles move skeletal parts by contracting
5. Interactions between myosin and actin generate force during muscle contractions
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2. A comparison of the energy costs of various modes of locomotion.
Locomotion is active movement from one place to another. Locomotion requires energy to overcome friction and gravity
A comparison of the energy costs of various modes of locomotion.
Fig
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3. However, since water is dense, friction is more of a problem.
Swimming.
Since water is buoyant gravity is less of a problem when swimming than for other modes of locomotion.
However, since water is dense, friction is more of a problem.
Fast swimmers have fusiform bodies.
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4. For locomotion on land powerful muscles and skeletal support are more important than a streamlined shape.
When hopping the tendons in kangaroos legs store and release energy like a spring that is compressed and released – the tail helps in the maintenance of balance.
When walking having one foot on the ground helps in the maintenance of balance.
When running momentum helps in the maintenance of balance.
Crawling requires a considerable expenditure of energy to overcome friction – but maintaining balance is not a problem.
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5. Gravity poses a major problem when flying.
The key to flight is the aerodynamic structure of wings.
Fig
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6. Cellular and Skeletal Underpinning of Locomotion.
On a cellular level all movement is based on contraction.
Either the contraction of microtubules or the contraction of microfilaments.
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7. Figure 49.x3 Swimming

8. Figure 49.x4 Locomotion on land

9. Figure 49.29 Posture helps support large land vertebrates, such as bears, deer, moose, and cheetahs

10. Figure 49.x5 Flying

11. Skeletons support and protect the animal body and are essential to movement
Hydrostatic skeleton: consists of fluid held under pressure in a closed body compartment.
Form and movement is controlled by changing the shape of this compartment.
The hydrostatic skeleton of earthworms allow them to move by peristalsis.
Advantageous in aquatic environments and can support crawling and burrowing.
Do not allow for running or walking.
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12. Figure 49.27 Peristaltic locomotion in an earthworm

13. Many groups of invertebrates use hydrostatic skeleton
to provide the rigid structure upon which muscles can act.
However the same in in many other some parts of a body
May rely on containing fluid in a structure to maintain the
form or shape, e.g. trunk of elephant where fluid in tissues
provide rigidity, tongue of animals, penis is mammals, and etc.

14. Exoskeletons: hard encasements deposited on the surface of an animal
Mollusks are enclosed in a calcareous exoskeleton.
The jointed exoskeleton of arthropods is composed of a cuticle.
Regions of the cuticle can vary in hardness and degree of flexibility.
About 30 – 50% of the cuticle consists of chitin.
Muscles are attached to the interior surface of the cuticle.
This type of exoskeleton must be molted to allow for growth.
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15. Examples of other arthropods with exoskeletons

17. Four anatomical features characterize the phylum Chordata
Although chordates vary widely in appearance, all share the presence of four anatomical structures at some point in their lifetime.
These chordate characteristics are a notochord; a dorsal, hollow nerve cord; pharyngeal slits; and a muscular, postanal tail.
Fig. 34.2
The notochord is the basic skeletal element in the early
Chordate groups that are ancestral to all vertebrates
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18. (a)
(b)
Fig. 34.4
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19. Vertebrates either developed a cartilaginous skeleton (e
Vertebrates either developed a cartilaginous skeleton (e.g sharks) or a boney skeleton (all other vertebrates) based on the underlying chordate plan outlined above. The skeletal elements are the support structures upon which the muscles act.
Figure 25.0
Fossil of a fish:
perch

20. Body/Caudal Fin Propulsion
The following diagramm depicts the specific swimming modes identified
within BCF propulsion, based on the (extended) classification scheme proposed originally by Breder in1926.                                                              
BCF propulsion modes, based on Lindsey (1978).

21. development of new functions and expand the diversity of the group.
Skeletal elements are modified to take on new support functions to assist in
development of new functions and expand the diversity of the group.
Figure Hypothesis for the evolution of vertebrate jaws
Figure 34.12a Ray-finned fishes
(class Actinopterygii): yellow perch
Figure 34.13

22. Physical support on land depends on adaptations of body proportions and posture
In the support of body weight posture is more important than body proportions.
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23. Limb bone modifications that are adaptations for certain
forms of movement
Convergent evolution of
structures for gliding

24. Figure 34.27x
Archaeopteryx,
a fossil in the ancestoral
linkage of birds and reptiles
Figure 34.25
Form fits function: the avian wind and feather
in modern bird. The feathers forming a flight
surface and hollow bones reduce the weight

25. Figure 34.30 Evolution of the mammalian jaw and ear bones

26. Fig
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28. Muscles move skeletal parts by contracting
Muscles come in antagonistic pairs.
Fig
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29. Interactions between myosin and actin generate force during muscle contractions
The sliding-filament model of muscle contraction.
Energy
Need
supplied
by ATP
Actin
Myosin
Fig
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30. Structure and Function of Vertebrate Skeletal Muscle.
The sarcomere is the functional unit of muscle contraction.
Thin filaments consist of two strands of actin and one tropomyosin coiled about each other.
Thick filaments consist of myosin molecules.
When a contraction occurs the sarcomere shortens, m line disappears and I band shortens.
Fig
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31. Follow the action potential.
When an action potential meets the muscle cell’s sarcoplasmic reticulum (SR) stored Ca2+ is released.
Calcium ions and regulatory proteins control muscle contraction
Fig

32. Diverse body movements require variation in muscle activity
An individual muscle cell either contracts completely or not all.
Individual muscles, composed of many individual muscle fibers (cells), can contract to varying degrees.
One way variation is accomplished by varying the frequency of action potentials reach the muscle from a single motor neuron.
Fig
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33. Graded muscle contraction can also be controlled by regulating the number of motor units involved in the contraction.
Fig
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34. Fatigue is avoided by rotating among motor units.
Recruitment of motor neurons increases the number of muscle cells involved in a contraction.
Some muscles, such as those involved in posture, are always at least partially contracted.
Fatigue is avoided by rotating among motor units.
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35. Cardiac muscle: similar to skeletal muscle
Smooth muscle: lacks the striations seen in both skeletal and cardiac muscle.
Contracts with less tension, but over a greater range of lengths, than skeletal muscle.
Slow contractions, with more control over contraction strength than with skeletal muscle.
Found lining the walls of hollow organs.
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