CHAPTER 49 SENSORY AND MOTOR SYSTEMS Copyright © 2002 Pearson Education, Inc., publishing as...

CHAPTER 49SENSORY AND MOTOR SYSTEMS

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

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

• 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


Fig. 49.25

• 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.


• 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.


• Gravity poses a major problem when flying.– The key to flight is the aerodynamic structure of wings.


Fig. 34.26

• 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.


Figure 49.x3 Swimming

Figure 49.x4 Locomotion on land

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

Figure 49.x5 Flying

• 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.

Skeletons support and protect the animal body and are essential to movement


Figure 49.27 Peristaltic locomotion in an earthworm

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 bodyMay 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.

Mollusks are enclosed in a calcareous exoskeleton.


Exoskeletons: hard encasements depositedon the surface of an animal

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.

Examples of other arthropods with exoskeletons

http://hannover.park.org/Canada/Museum/insects/evolution/muscles.html

http://stammhirn.biologie.uni-ulm.de/w4fly/aktuell0208_en.html

• 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.

Four anatomical features characterize the phylum Chordata


Fig. 34.2

The notochord is the basic skeletal element in the early Chordate groups that are ancestral to all vertebrates


Fig. 34.4

(b)(a)

Figure 25.0 Fossil of a fish: perch

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.

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).

http://www.ece.eps.hw.ac.uk/Research/oceans/projects/flaps/bcfmodes.htm

Figure 34.13Figure 34.12a Ray-finned fishes (class Actinopterygii): yellow perch

Figure 34.10 Hypothesis for the evolution of vertebrate jaws

Skeletal elements are modified to take on new support functions to assist indevelopment of new functions and expand the diversity of the group.

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.


Limb bone modifications thatare adaptations for certainforms of movement

Convergent evolution of structures for gliding

Archaeopteryx, a fossil in the ancestoral linkage of birds and reptiles

Form fits function: the avian wind and featherin modern bird. The feathers forming a flight surface and hollow bones reduce the weight

Figure 34.27x

Figure 34.25

Figure 34.30 Evolution of the mammalian jaw and ear bones

Fig. 49.17


Fig. 49.28

http://www.mongabay.org/images/cr_flyingmonkey.gif

http://www.kingston.ac.uk/Muybridge/img0008.jpg

• Muscles come in antagonistic pairs.

Muscles move skeletal parts by contracting


Fig. 49.30

• The sliding-filament model of muscle contraction.

Interactions between myosin and actin generate force during muscle contractions

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin CummingsFig. 49.33

Actin

Myosin

Energy Need supplied by ATP

• 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. 49.31

Fig. 49.35

Calcium ions and regulatory proteins control muscle contraction

Follow the action potential.

When an action potential meets the muscle cell’s sarcoplasmic reticulum (SR) stored Ca2+ is released.

• 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.

Diverse body movements require variation in muscle activity


Fig. 49.37

– Graded muscle contraction can also be controlled by regulating the number of motor units involved in the contraction.


Fig. 49.38

– 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.


– Cardiac muscle: similar to skeletal muscle

• 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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