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Chapter 30 How Animals Move PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Elephants Do the "Groucho Gait" • Movement is one of the most distinctive features of animals, from elephants to Groucho • Movement is dependent on precise interaction among three organ systems – Nervous system issues commands to muscular system – Muscular system exerts force that makes the animal move – Skeletal system provides the firm structure that muscular force works against Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings MOVEMENT AND LOCOMOTION 30.1 Diverse means of animal locomotion have evolved • Locomotion: active travel from place to place – Animal must use energy to overcome friction and gravity • Swimming – Water supports against gravity but offers frictional resistance – Different body structures are used to swim – A streamlined body aids rapid swimming Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Locomotion on Land: Hopping, Walking, Running, and Crawling – Animals that hop, run, or walk must expend energy to propel themselves and stay upright – Burrowing or crawling animals must overcome friction • May move by side-to-side undulation or by peristalsis Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-1d Longitudinal muscle relaxed (extended) Circular muscle contracted Circular muscle relaxed Longitudinal muscle contracted Head Bristles • Flying – The wings of birds, bats, and flying insects are airfoils • Shape alters air currents • Pressure differences create lift • At the cellular level, all animal movement has similarities – Based on contractions of microtubules or microfilaments Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-1e Video: Clownfish and Anemone Video: Flapping Geese Video: Soaring Hawk Video: Swans Taking Flight Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings SKELETAL SUPPORT 30.2 Skeletons function in support, movement, and protection • A skeleton has many functions – Body support – Movement as muscles act against it – Protection of internal organs Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Hydrostatic skeleton – Consists of fluid held under pressure in a closed body compartment – Works well for aquatic animals and those that burrow by peristalsis • Most are soft and flexible (example: hydra) Video: Hydra Eating Daphnia Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Exoskeleton – Rigid, external covering with muscles attached at inner surface – Arthropod chitin exoskeleton • Thin and flexible at joints • Secreted by living cells • Must be molted periodically, leaving the animal unprotected – Mollusc calcium carbonate exoskeleton • Enlarges by adding to outer edge Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-2c Shell (exoskeleton) Mantle • Endoskeleton – Hard or leathery supporting elements situated among the soft tissues – Vertebrate skeleton consists of cartilage or combination of cartilage and bone Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 30.3 The human skeleton is a unique variation on an ancient theme • Skeletons of vertebrates have a number of similarities – Axial skeleton • Skull, vertebrae, and ribs – Appendicular skeleton in most • Shoulder girdle, upper limbs, pelvic girdle, lower limbs Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The human skeleton reflects bipedal evolution – Skull is large, flat-faced, balanced on top of backbone – Backbone is S-shaped – Pelvic girdle is shorter, rounder, and oriented vertically – Bones of hands and feet are adapted for different functions • Hands: grasping and manipulating • Feet: support the entire body bipedally Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-3a Skull Examples of joints Shoulder girdle Clavicle Scapula Sternum Ribs Humerus Vertebra Radius Ulna Pelvic girdle Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges LE 30-3b Baboon (quadrupedal) Human (bipedal) • The versatility of the vertebrate skeleton comes in part from its movable joints – Ball-and-socket joints allow movement in all directions – Hinge joints permit movement in one plane – Pivot joints allow bones to rotate Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-3c Head of humerus Humerus Scapula Ulna Ulna Radius Ball-and-socket joint Hinge joint Pivot joint 30.4 Bones are complex living organs • Bones consist of several kinds of moist, living tissue – Fibrous connective tissue covers the outer surface – Cartilage cushions the joints – Bone cells live in a matrix of flexible collagen fibers embedded in hard calcium and phosphate Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Long bones have a central cavity – Stores yellow bone marrow, which is mostly stored fat • Spongy bone is at the ends of long bones – Contains red marrow, which produces blood cells • Blood vessels and nerves coursing through channels service bone cells Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-4 Cartilage Spongy bone (contains red bone marrow) Compact bone Central cavity Yellow bone marrow Fibrous connective tissue Blood vessels Cartilage CONNECTION 30.5 Broken bones can heal themselves • Two factors determine whether a bone might break – Strength of skeleton – Angle and amount of force applied • Bone cells can build new bone and heal a break, given the opportunity – Realignment; splint or cast; traction • Severely injured or diseased bone must be replaced Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CONNECTION 30.6 Weak, brittle bones are a serious health problem, even in young people • Osteoporosis is a bone disease characterized by low bone mass and structural degeneration of the bone matrix • Lowered estrogen production makes this a problem among older women • Unhealthy lifestyles have made osteoporosis a serious concern for young people Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings MUSCLE CONTRACTION AND MOVEMENT 30.7 The skeleton and muscles interact in movement • Muscles are connected to bones by tendons • Antagonistic pairs of muscles produce movement – A muscle can only contract – To extend, a muscle must be pulled by the contraction of an opposing muscle Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-7 Biceps contracted, triceps relaxed (extended) Triceps contracted, biceps relaxed Biceps Biceps Triceps Triceps Tendon 30.8 Each muscle cell has its own contractile apparatus • A muscle consists of bundles of parallel muscle fibers • Each muscle fiber is a bundle of smaller myofibrils – A single cell with many nuclei • Each myofibril consists of repeating units called sarcomeres • A sarcomere, composed of overlapping thick myosin and thin actin filaments, is the muscle's contractile apparatus Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-8 Muscle Bundle of muscle fibers Single muscle fiber (cell) Nuclei Video: Sliding Filament Theory Myofibril Light band Dark band Light band Z line Sarcomere Thick filaments (myosin) Light band Dark band Light band Thin filaments (actin) Z line Z line Sarcomere 30.9 A muscle contracts when thin filaments slide across thick filaments • The sliding-filament model of muscle contraction – A sarcomere contracts when its thin filaments slide across its thick filament – Contraction is caused by energy-consuming interactions of myosin and actin molecules Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – The sequence of detach-extend-attach-pull occurs repeatedly • ATP binds to a myosin head, which is released from an actin filament • Hydrolysis of ATP extends the myosin head • The myosin head attaches to an actin binding site • The power stroke slides the actin (thin) filament toward the center of the sarcomere Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-9b-4 Thick filament (myosin) Thin filament (actin) Z line ATP Myosin head ATP binds to a myosin head, which is released from an actin filament. ADP P Hydrolysis of ATP extends the myosin head. SlidingFilament.MOV ADP P The myosin head attaches to an actin binding site. New position of Z line ADP + P The power stroke slides the actin (thin) filament toward the center of the sarcomere. 30.10 Motor neurons stimulate muscle contraction • A motor unit consists of a motor neuron and the muscle fibers it controls • A motor neuron can stimulate more than one muscle fiber because of its many branches – Neuron's axons form neuromuscular junctions with muscle fibers – Action potential from neuron triggers release of acetylcholine Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – Acetylcholine diffuses across neuromuscular junctions to muscle fibers – Change in fiber membrane permeability triggers action potentials that pass into the center of the muscle cell – Calcium released from the endoplasmic reticulum initiates filament sliding and muscle contraction Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings LE 30-10a Spinal cord Motor Motor unit 1 unit 2 Nerve Motor neuron cell body Motor neuron axon Neuromuscular junctions Nuclei Muscle fibers (cells) Muscle Tendon Bone LE 30-10b Motor neuron axon Action potential Mitochondrion Tubule Endoplasmic reticulum (ER) Ca2+ released from ER Myofibril Plasma membrane Sarcomere CONNECTION 30.11 Athletic training increases strength and endurance • Aerobic and anaerobic exercise must be balanced • Aerobic exercise increases efficiency and fatigue resistance of muscles – Increases blood flow and mitochondria size – Strengthens heart and circulatory system Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Anaerobic exercise builds larger muscles that generate greater power – Increases size of muscle fibers – More glycogen stored as fuel reserve Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 30.12 The structure-function theme underlies all the parts and activities of an animal • Animal movement is a visible reminder that function emerges from structure – Integrates the sensory, nervous, and motor systems • Athletic ability results from adaptations that have been refined through natural selection and contribute to our survival as a species Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings