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

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

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

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

Gravity poses a major problem when flying. The key to flight is the aerodynamic structure of wings. Fig. 34.26 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

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

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

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

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 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.

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

Examples of other arthropods with exoskeletons

http://stammhirn.biologie.uni-ulm.de/w4fly/aktuell0208_en.html http://hannover.park.org/Canada/Museum/insects/evolution/muscles.html

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

(a) (b) Fig. 34.4 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

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

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

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 34.10 Hypothesis for the evolution of vertebrate jaws Figure 34.12a Ray-finned fishes (class Actinopterygii): yellow perch Figure 34.13

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

Limb bone modifications that are adaptations for certain forms of movement Convergent evolution of structures for gliding

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

Figure 34.30 Evolution of the mammalian jaw and ear bones

Fig. 49.28 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles move skeletal parts by contracting Muscles come in antagonistic pairs. Fig. 49.30 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

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

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

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. 49.35

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

Graded muscle contraction can also be controlled by regulating the number of motor units involved in the contraction. Fig. 49.38 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

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

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