A comparison of the energy costs of various modes of locomotion. Locomotion requires energy to overcome friction and gravity.

• A comparison of the energy costs of various modes of locomotion.

Locomotion requires energy to overcome friction and gravity

• 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.

S p h e r e

D i s k

t e a r d r o p

L a m i n a r f l o w a n d t u r b u l e n c e

• For locomotion on land powerful muscles and skeletal support are more important than a streamlined shape.– hopping – walking – running– crawling

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

wings.

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

Fig. 34.26

• Hydrostatic skeleton: consists of fluid held under pressure in a closed body compartment.– Earthworm– Cniderian– Squid

Skeletons support and protect the animal body and are essential to

movement

• Exoskeletons

• Endoskeletons

• Exo & Endoskeletons

Human Skeleton Joint Movement

• Muscles come in antagonistic pairs.

Muscles move skeletal parts by contracting

• 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.

• The sliding-filament model of muscle contraction.

Interactions between myosin and actin generate force during muscle

contractions

• At rest tropomyosin blocks the myosin binding sites on actin.

• When calcium binds to the troponin complex a conformational change results in the movement of the tropomyosin-tropinin complex and exposure of actin’s myosin binding sites.

Calcium ions and regulatory proteins control muscle contraction

• But, wherefore the calcium ions?– Follow the

action potential.– When an action

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

• Review of skeletal muscle contraction.

• An individual muscle cell either contracts completely or not all.

• Individual muscles, composed of many individual muscle fibers, can contract to varying degrees.

Diverse body movements require variation in muscle activity

Contraction Response

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

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

Fig. 49.38

Slow-Twitch Versus Fast-Twitch

Muscle Fibers

ATP is Generated by:1. creatine phosphate

ADP + creatine phosphatecreatine + ATP

2. lactic acid fermentationFrom stored glycogen via anaerobic glycolysis; glucosepyruvic acid (no O2) lactic acid

O2

3. aerobic respirationKrebsCO2 + H2O + ATP

Energy for muscle contraction:Energy for muscle contraction:ATP is the only energy source ATP(ATPase + H2O) ADP + Pi

Fast glycolitic: white muscle fibers, low myoglobin, anaerobic glycolysis, few mitochondria, fast twitch fibers, high glycogen stores, short bursts, fatigues easily

Slow oxidative: red muscle, aerobic, high myoglobin, low glycogen stores, lots mitochondria, slow, tonic, long distance

Fast oxidative: red pink, aerobic, fast, high myoglobin, intermediate amt. of mitochondria, intermediate glycogen, intermediate fatigue resistance

Ratio- red:white (all 3 types in body)

Ex. fish- long distance blue fin tuna- mostly red meatquick bursts- yellow tail- more white meat

Sprinter- anaerobic respiration

Long distance Runner- aerobic respiration

• Other Types of Muscle.

– Smooth muscle:• No striations• Found lining the walls of hollow organs.• Autonomic Nervous System• Slow contractions

– Cardiac muscle:.• Intercalated discs facilitate the coordinated

contraction of cardiac muscle cells.• Striations• Autonomic Nervous System