Protection, Support, and Protection, Support, and MovementMovement

Chapter 39Chapter 39

KEY CONCEPTSKEY CONCEPTS

• Many structures and processes have Many structures and processes have evolved in animals for protection, support, evolved in animals for protection, support, and movementand movement

Learning Objective 1Learning Objective 1

• Compare the functions of the Compare the functions of the external external epitheliumepithelium of invertebrates and vertebrates of invertebrates and vertebrates

Epithelial TissueEpithelial Tissue

• In both invertebrates and vertebratesIn both invertebrates and vertebrates• protects underlying tissuesprotects underlying tissues• specialized sensory or respiratory functions specialized sensory or respiratory functions

• Outer epithelium specialized to secreteOuter epithelium specialized to secrete• lubricants or adhesiveslubricants or adhesives• odorous or poisonous substancesodorous or poisonous substances

Epithelial TissueEpithelial Tissue in Invertebratesin Invertebrates

• Cuticle Cuticle • protective shell secreted by outer epithelium protective shell secreted by outer epithelium

Integumentary System of Integumentary System of VertebratesVertebrates

• Skin and structures that develop from it Skin and structures that develop from it

• Mammalian skin includesMammalian skin includes• hair, claws or nails, sweat glands, oil glands, hair, claws or nails, sweat glands, oil glands,

sensory receptorssensory receptors

Learning Objective 2Learning Objective 2

• Relate the structure of Relate the structure of vertebrate skinvertebrate skin to to its functionsits functions

Feathers and HairFeathers and Hair

• Feathers of birds and hair of mammals Feathers of birds and hair of mammals • form insulating layer form insulating layer • helps maintain constant body temperaturehelps maintain constant body temperature

Epidermis 1Epidermis 1

• Protects body from outer environment Protects body from outer environment

• Stratum corneumStratum corneum • most superficial layermost superficial layer• consists of dead cells filled with consists of dead cells filled with keratinkeratin

• KeratinKeratin• insoluble proteininsoluble protein• gives mechanical strength to skingives mechanical strength to skin• reduces water loss reduces water loss

EpidermisEpidermis 22

• Stratum basaleStratum basale • cells divide, are pushed up to skin surface cells divide, are pushed up to skin surface • cells mature, flatten, produce keratincells mature, flatten, produce keratin• eventually die and slough offeventually die and slough off

DermisDermis

• Consists of dense, fibrous connective tissue Consists of dense, fibrous connective tissue

• Rests on layer of Rests on layer of subcutaneous tissuesubcutaneous tissue• composed largely of insulating fatcomposed largely of insulating fat

Human SkinHuman Skin

Fig. 39-1, p. 829

Openings of sweat glands

CapillaryNerve endings

Stratum corneum

EpidermisStratum basale

Melanocyte (pigment cell)

Hair erector muscle

Dermis Hair shaftSensory receptor (Pacinian corpuscle)Subcutaneous

tissue

Hair follicleArtery

Vein Sweat gland Sebaceous gland

KEY CONCEPTSKEY CONCEPTS

• Epithelial coverings protect underlying Epithelial coverings protect underlying tissues and may be specialized for tissues and may be specialized for sensory, respiratory, or other functionssensory, respiratory, or other functions

Learning Objective 3Learning Objective 3

• Compare the structure and functions of Compare the structure and functions of different types of skeletal systems, different types of skeletal systems, including the including the hydrostatic skeletonhydrostatic skeleton, , exoskeletonexoskeleton, and , and endoskeletonendoskeleton

TheThe Skeletal SystemSkeletal System

• Supports and protects the body Supports and protects the body

• Transmits mechanical forces generated by Transmits mechanical forces generated by muscles muscles

Hydrostatic SkeletonHydrostatic Skeleton

• Fluid in closed body compartmentFluid in closed body compartment• transmits forces generated by contractile cells transmits forces generated by contractile cells

or muscleor muscle

• Found in soft-bodied invertebratesFound in soft-bodied invertebrates• cnidarians, flatworms, annelids cnidarians, flatworms, annelids

Hydrostatic SkeletonHydrostatic Skeleton

Fig. 39-2, p. 830

Longitudinal contractile fibers of epidermal layer

Circular contractile fibers of gastrodermis

(a) Contraction of circular contractile fibers elongates the body.

(b) Contraction of longitudinal fibers shortens the body.

Fig. 39-2, p. 830

(a) Contraction of circular contractile fibers elongates the body.

(b) Contraction of longitudinal fibers shortens the body.

Longitudinal contractile fibers of epidermal layer

Circular contractile fibers of gastrodermis

Stepped Art

ExoskeletonsExoskeletons

• Nonliving skeleton Nonliving skeleton • characteristic of mollusks and arthropodscharacteristic of mollusks and arthropods• doesn’t grow, arthropods must doesn’t grow, arthropods must moltmolt periodically periodically

• Arthropod skeletonArthropod skeleton• composed partly of composed partly of chitinchitin • jointed for flexibility jointed for flexibility • adapted for many lifestylesadapted for many lifestyles

EcdysisEcdysis

EndoskeletonsEndoskeletons• Consist of living tissueConsist of living tissue

• can growcan grow

• Found in echinoderms and chordatesFound in echinoderms and chordates

Learning Objective 4Learning Objective 4

• Describe the main divisions of the Describe the main divisions of the vertebrate skeletonvertebrate skeleton and the bones that and the bones that make up each divisionmake up each division

The Vertebrate Skeleton 1The Vertebrate Skeleton 1

• Axial skeletonAxial skeleton • skull skull • vertebral column vertebral column • rib cage rib cage • sternumsternum

The Vertebrate Skeleton 2The Vertebrate Skeleton 2

• Appendicular Appendicular skeletonskeleton • limbslimbs • pectoral girdlepectoral girdle• pelvic girdlepelvic girdle

Fig. 39-5, p. 832

Fig. 39-5a, p. 832

Skull

Sternum

Rib cage

Vertebrae

Axial skeleton (brown)

Fig. 39-5b, p. 832

Clavicle

Humerus

RadiusPelvic girdle

Ulna CarpalsMetacarpalsPhalanges

Femur

PatellaFibula

TibiaTarsalsMetatarsalsPhalanges

Scapula

Appendicular skeleton (brown)

KEY CONCEPTSKEY CONCEPTS

• Skeletal systems, whether they are Skeletal systems, whether they are hydrostatic skeletons, exoskeletons, or hydrostatic skeletons, exoskeletons, or endoskeletons, support and protect the endoskeletons, support and protect the body and transmit mechanical forces body and transmit mechanical forces important in movementimportant in movement

Learning Objective 5Learning Objective 5

• Describe the structure of a typical Describe the structure of a typical long long bonebone

• Differentiate between Differentiate between endochondralendochondral and and intramembranousintramembranous bone development bone development

A Long BoneA Long Bone

• Consists of Consists of • a thin outer shell of a thin outer shell of compact bonecompact bone

surrounding inner surrounding inner spongy bonespongy bone • a central cavity that contains a central cavity that contains bone marrowbone marrow

A Long BoneA Long Bone

Fig. 39-6, p. 833

Articular surface covered with cartilage

EpiphysisRed marrow in spongy bone

Metaphysis

Periosteum

Yellow marrow

Blood supply

Diaphysis

Compact bone

Articular cartilage

Epiphysis

Bone DevelopmentBone Development

• Long bonesLong bones• develop from cartilage templates during develop from cartilage templates during

endochondral bone development endochondral bone development

• Other bones (such as flat bones of skull)Other bones (such as flat bones of skull)• develop from noncartilage connective tissue develop from noncartilage connective tissue

model by model by intramembranous bone intramembranous bone developmentdevelopment

Bone CellsBone Cells

• OsteoblastsOsteoblasts• cells that produce bonecells that produce bone

• OsteoclastsOsteoclasts• cells that break down bonecells that break down bone

• Osteoblasts and osteoclasts work together Osteoblasts and osteoclasts work together to shape and remodel boneto shape and remodel bone

Learn more about the human Learn more about the human skeletal system and a typical skeletal system and a typical long bone by clicking on the long bone by clicking on the

figures in ThomsonNOW.figures in ThomsonNOW.

Learning Objective 6Learning Objective 6

• Compare the main types of Compare the main types of vertebrate vertebrate jointsjoints

JointsJoints

• Junctions of two or more bones Junctions of two or more bones

• LigamentsLigaments• connective tissue bands connective tissue bands • connect bones connect bones • limit movement in jointlimit movement in joint

Types of JointsTypes of Joints

• Immovable jointsImmovable joints• sutures of the skull sutures of the skull

• Slightly movable jointsSlightly movable joints• joints between vertebrae joints between vertebrae

• Freely movable jointFreely movable joint • enclosed by joint capsule lined with enclosed by joint capsule lined with

membrane that secretes membrane that secretes synovial fluidsynovial fluid

Learning Objective 7Learning Objective 7

• Relate the structure and function of Relate the structure and function of insect insect flight musclesflight muscles

Insect Flight MusclesInsect Flight Muscles

• Large numbers of mitochondria and Large numbers of mitochondria and tracheae (air tubes) tracheae (air tubes) • support high metabolic rate required for flightsupport high metabolic rate required for flight

Learning Objective 8Learning Objective 8

• Describe the structure of Describe the structure of skeletal musclesskeletal muscles and their and their antagonistic actionsantagonistic actions

Muscular SystemsMuscular Systems

• In vertebrates and most invertebrates In vertebrates and most invertebrates • muscle tissue contracts (shortens) muscle tissue contracts (shortens) • moves body parts by pulling on themmoves body parts by pulling on them

• Three types of muscleThree types of muscle• skeletal skeletal • smoothsmooth• cardiac musclecardiac muscle

The Muscular SystemThe Muscular System

Fig. 39-8a, p. 835

Muscles that flex fingers

Facial muscles

Sternocleido- mastoidPlatysma

Trapezius

Latissimus dorsiClavicleDeltoid

Rectus abdominis Pectoralis major

Linea alba Biceps brachii

External oblique Brachialis

Gluteus medius Wrist and finger flexorsGracilis

SartoriusQuadriceps femoris Triceps brachii

Patella

Gastrocnemius

Tibialis anterior

Soleus Tibia

Fig. 39-8b, p. 835

Biceps brachii

Sternocleidomastoid

Trapezius

DeltoidBrachialis

Triceps brachii Latissimus dorsi

Brachioradialis External oblique

Muscles that flex fingers

Gluteus maximus

Hamstring muscles

Gracilis SemitendinosusBiceps femorisSemi-membranosus

Gastrocnemius

Soleus

Achilles tendon

Calcaneus

Vertebrate Skeletal MusclesVertebrate Skeletal Muscles

• Pull on Pull on tendonstendons• connective tissue, attaches muscles to bones connective tissue, attaches muscles to bones

• Muscle contractionMuscle contraction• pulls bone toward or away from the bone with pulls bone toward or away from the bone with

which it articulateswhich it articulates

Muscle ActionsMuscle Actions

• Skeletal muscles act Skeletal muscles act antagonisticallyantagonistically to to one another one another

• AgonistAgonist • muscle that produces a particular actionmuscle that produces a particular action

• AntagonistAntagonist • produces the opposite movementproduces the opposite movement

Muscle ActionsMuscle Actions

Fig. 39-7, p. 834

Biceps relaxes

Triceps contracts

Triceps relaxes

Biceps contracts

Flexion Extension

Insert “Opposing muscle Insert “Opposing muscle action”action”

biceps_triceps.swfbiceps_triceps.swf

Skeletal Muscle Structure 1Skeletal Muscle Structure 1

• Skeletal muscle (such as biceps)Skeletal muscle (such as biceps)• organorgan made up of hundreds of made up of hundreds of muscle fibers muscle fibers

• Muscle fiberMuscle fiber consists of consists of • threadlike threadlike myofibrilsmyofibrils • composed of smaller composed of smaller myofilaments (filaments)myofilaments (filaments)

Muscle Muscle StructureStructure

Fig. 39-9a, p. 836

Biceps muscle

(a) A muscle such as the biceps in the arm consists of many fascicles (bundles) of muscle fibers.

Fig. 39-9b, p. 836

Muscle fibers

(b) A fascicle wrapped in a connective tissue covering.

Fig. 39-9c, p. 836

SarcolemmaSarcoplasmic reticulum

T tubuleMitochondria Nucleus

(c) Part of a muscle fiber showing the structure of myofibrils. The Z lines mark the ends of the sarcomeres.

Myofibril

Z line

Myofilaments

Sarcomere

Fig. 39-9d, p. 836

1 µm(d) TEM of a striated muscle.

Fig. 39-9e, p. 836

25 µm(e) LM showing striations.

Skeletal Muscle Structure 2Skeletal Muscle Structure 2

• Striations of skeletal muscle fibersStriations of skeletal muscle fibers• overlapping overlapping actin actin and and myosin filamentsmyosin filaments

• SarcomereSarcomere • contractile unit of contractile unit of actinactin (thin) and (thin) and myosinmyosin

(thick) filaments(thick) filaments

Sliding Filament ModelSliding Filament Model

Fig. 39-10a, p. 838

Cross bridges

Actin (thin filament)

Myosin (thick filament)

Sarcomere

A band I band

H zone

Cross bridgesActin (thin) filament Myosin (thick) filament

Insert “Sliding filament Insert “Sliding filament model”model”

sliding_filament_v2.swfsliding_filament_v2.swf

Learning Objective 9Learning Objective 9

• List, in sequence, the events that take List, in sequence, the events that take place during place during muscle contractionmuscle contraction

Muscle Contraction 1Muscle Contraction 1

• AcetylcholineAcetylcholine released by motor neuron released by motor neuron• binds to receptors on muscle fiber surface binds to receptors on muscle fiber surface

• Causes Causes depolarizationdepolarization of sarcolemma of sarcolemma • transmission of transmission of action potential action potential

• Action potentialAction potential spreads through spreads through T tubulesT tubules • releasing Ca ions from releasing Ca ions from sarcoplasmic reticulumsarcoplasmic reticulum

Muscle Contraction 2Muscle Contraction 2

• Ca ions bind to Ca ions bind to troponintroponin in actin filaments in actin filaments • causing troponin to change shape causing troponin to change shape

• Troponin pushes Troponin pushes tropomyosintropomyosin away from away from binding sites on actin filamentsbinding sites on actin filaments

Muscle Contraction 3Muscle Contraction 3

• ATPATP binds to myosin binds to myosin • ATP is split, putting myosin head in high-ATP is split, putting myosin head in high-

energy state (“cocked”) energy state (“cocked”)

• Energized myosinEnergized myosin heads attach to heads attach to exposed binding sites on actin filaments exposed binding sites on actin filaments • forming forming cross bridgescross bridges that link myosin and that link myosin and

actin filamentsactin filaments

Muscle Contraction 4Muscle Contraction 4

• Cross bridgeCross bridge flexes as phosphate is flexes as phosphate is released released • power stroke pulls actin filament toward power stroke pulls actin filament toward

center of sarcomerecenter of sarcomere

• ADPADP released during power stroke released during power stroke

• Myosin head binds a new ATPMyosin head binds a new ATP• lets myosin head detach from actinlets myosin head detach from actin

Muscle Contraction 5Muscle Contraction 5

• As long as calcium ion concentration As long as calcium ion concentration remains elevated remains elevated • new ATP is split, sequence repeats new ATP is split, sequence repeats

• Myosin reattaches to new active sitesMyosin reattaches to new active sites• filaments are pulled past one anotherfilaments are pulled past one another• muscle continues to shortenmuscle continues to shorten

Actin and Actin and Myosin Myosin

InteractionsInteractions

Fig. 39-11, p. 839

Acetylcholine (released by motor neuron) combines with receptors on muscle fiber, causing depolarization and an action potential.

ATP binding site

Myosin filament

ATP

P ADPTropomyosin

Ca

Actin filament

Binding site Troponin

Ca2+ bind to troponin, causing change in shape. Troponin pushes tropomyosin away, exposing binding sites on actin filaments.

ATP is split. Myosin head, now cocked, binds to exposed binding site, forming cross bridge.

43

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+ Ca2+

1

2 Impulse spreads through T tubules, stimulating Ca2+ release from sarcoplasmic reticulum.

Fig. 39-11, p. 839

Pi is released.Actin-myosin complex binds ATP, and myosin detaches from actin.

ADP

Cross bridge flexes, and actin filament is pulled toward center of sarcomere. This movement is the power stroke. ADP is released.

If Ca2+ is available

7

ATP

6

5

ADPCa2+

Ca2+Ca2+P

Learning Objective 10Learning Objective 10

• Compare the roles of Compare the roles of glycogenglycogen, , creatine creatine phosphatephosphate, and , and ATPATP in providing energy in providing energy for muscle contractionfor muscle contraction

Energy for Muscle ContractionEnergy for Muscle Contraction

• ATP ATP • immediate energy source for muscle contractionimmediate energy source for muscle contraction• ATP hydrolysis provides energy to “cock” myosinATP hydrolysis provides energy to “cock” myosin

• Creatine phosphateCreatine phosphate • intermediate energy storage compoundintermediate energy storage compound•

• GlycogenGlycogen • fuel stored in muscle fibersfuel stored in muscle fibers

KEY CONCEPTSKEY CONCEPTS

• During muscle contraction, energy from During muscle contraction, energy from ATP is used to slide muscle filaments so ATP is used to slide muscle filaments so that the muscle shortensthat the muscle shortens

Learning Objective 11Learning Objective 11

• How do muscles work, including factors How do muscles work, including factors that influence that influence contractioncontraction??

Muscle ContractionMuscle Contraction

• ContractionContraction of a whole muscle depends on of a whole muscle depends on(1) number of muscle fibers contracting(1) number of muscle fibers contracting

(2) tension developed by each fiber(2) tension developed by each fiber

A Motor UnitA Motor Unit

• All skeletal muscle fibers stimulated by a All skeletal muscle fibers stimulated by a single motor neuron single motor neuron

• Motor recruitmentMotor recruitment • messages from brain activate motor neurons messages from brain activate motor neurons

• The more motor units The more motor units recruited, recruited, • the stronger the contractionsthe stronger the contractions

A Motor UnitA Motor Unit

Fig. 39-12a, p. 840

Cross section of spinal cord

Neuromuscular junctions

(a) The motor unit illustrated here shows only a single motor neuron fiber.

Spinal nerve Muscle

Motor nerve fiber

Fig. 39-12b, p. 840

Neuromuscular junction

Motor nerve fiber

Part of muscle fiber 10 µm

(b) SEM of some of the fibers in a motor unit. Note how neurons branch to innervate all muscle fibers in the motor unit.

Skeletal Muscle ResponsesSkeletal Muscle Responses• Simple twitchSimple twitch

• activated by brief electrical stimulusactivated by brief electrical stimulus

• SummationSummation • 2 twitches add together when 22 twitches add together when 2ndnd stimulus is stimulus is

received before 1received before 1stst contraction is complete contraction is complete

• TetanusTetanus • smooth, sustained contraction smooth, sustained contraction • series of separate stimuli timed close togetherseries of separate stimuli timed close together

Summation and TetanusSummation and Tetanus

Muscle ToneMuscle Tone

• State of partial contractionState of partial contraction• characteristic of musclescharacteristic of muscles

Explore muscle action, structure, Explore muscle action, structure, and contraction as well as and contraction as well as summation and tetanus by summation and tetanus by clicking on the figures in clicking on the figures in

ThomsonNOW.ThomsonNOW.

KEY CONCEPTSKEY CONCEPTS

• Muscles contract; in most animals they Muscles contract; in most animals they move body parts by pulling on themmove body parts by pulling on them

Learning Objective 12Learning Objective 12

• Compare the structures and functions of Compare the structures and functions of the three types of the three types of skeletal muscle fibersskeletal muscle fibers

Slow-Oxidative FibersSlow-Oxidative Fibers

• Specialized for endurance activitiesSpecialized for endurance activities

• Contract slowly, fatigue slowly, rich in Contract slowly, fatigue slowly, rich in mitochondria, obtain most of their ATP mitochondria, obtain most of their ATP from aerobic respirationfrom aerobic respiration

• Red color due to high Red color due to high myoglobinmyoglobin content content• red pigment that stores oxygenred pigment that stores oxygen

Fast-Oxidative FibersFast-Oxidative Fibers

• Specialized for rapid response Specialized for rapid response

• Contract fast, have an intermediate rate of Contract fast, have an intermediate rate of fatigue, rich in mitochondria, obtain most fatigue, rich in mitochondria, obtain most of their ATP from aerobic respiration of their ATP from aerobic respiration

• Red color due to high Red color due to high myoglobinmyoglobin content content

Fast-Glycolytic FibersFast-Glycolytic Fibers

• Generate high power for a brief periodGenerate high power for a brief period

• Contract fast, fatigue quickly, have few Contract fast, fatigue quickly, have few mitochondria, use glycolysis as a major mitochondria, use glycolysis as a major pathway for ATP synthesis pathway for ATP synthesis

• White fibers White fibers