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Lecture 16, 14 October 2004Chapter 10, Muscle

Chapter 11, Behavior Initiation

Vertebrate PhysiologyECOL 437

University of ArizonaFall 2004

instr: Kevin Boninet.a.: Nate Swenson

1. MuscleA. Cardiac MuscleB. Smooth Muscle

2. Behavior Initiation

Vertebrate Physiology 437

Cardiac muscle

Fig. 10-49Randall et al. 2002

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Hi All,

This Friday's Doings, Oct 15th, will be presented by Michael Urquhart (UA, Psio) on the dynamic topic of:

"Shake, Rattle and Role of Elastic Recoil Potential Energy."

Brief abstract:By observing the Western Diamondback Rattlesnake Tail Shaker Muscle (TSM), howcan we address questions of minimizing energy expenditure? The TSM exhibitsproperties characteristic to other animals. In addition, the TSM creates highcontraction frequencies, 65-70 Hz at very low energy expenditure. It washypothesized that the TSM maybe taking advantage of Elastic Recoil PotentialEnergy.See you there. Doings meets from 4-5pm in 601 Gould-Simpson Bldg.

Cheers - CR

************************************************Cindy Rankin, Ph.D.Dept of Physiology Physiological Sciences Interdisciplinary ProgramPhone: 520-621-3104 Fax: 520-621-8170email: crankin@u.arizona.eduOffice: 274 BioSciences WestMail: 101 Gittings, PO Box 210093University of ArizonaTucson AZ 85721-0093

Cardiac Muscle (the other striated muscle)

-Small muscle fiber cells with only one nucleus

-Individual fibers are connected to neighbors electronically via gap junctions

-Two types of fibers:1. Contractile (similar to skeletal muscle)2. Conducting (including pacemaker cells)

Do not contract, but transmit electrical signal

-Cardiac contraction myogenic (arises within heart)Can be influenced by autonomic nervous system(alpha, beta adrenoreceptors increase [Ca2+])

-Long-lasting AP with long plateau phase, and longrefractory period - why?

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Cardiac Muscle (the other striated muscle)

-Intracellular calcium from SR and across plasma membrane (unlike in skeletal)

-Dihydropyridine receptors in T-tubules arevoltage-activated calcium channels

-Ryanodine receptors then release more calcium from SR into the cytoplasm (calcium-induced calcium release)

-During relaxation, Calcium pumped actively back into SR and out across plasma membrane

Smooth Muscle

-Lacks sarcomeres, isn’t striated -Walls of hollow organs – visceral functions

(GI tract, urinary bladder, uterus, blood vessels)

-Heterogenous-Innervated by autonomic NS-Each fiber is individual cell with one nucleus-No T-tubules-Organized into bundles of actin and myosin anchored to dense bodies or to the plasma membrane

-Can be single-unit or multi-unit

-Myogenic and electronically linked via gap junctions(peristaltic waves in GI tract)

Neurogenic (walls of blood vessels, iris)

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Smooth Muscle

-Autonomic NT released from varicosities along axon, not at motor endplate, affecting many cells

-Poorly developed SR, calcium mostly across plasma membrane

-Some smooth muscle responds to stretch (vessels, GI)

-Several ways to regulate calcium concentration (no troponin)

-One is via calcium-calmodulincomplex that then binds to caldesmon, removing caldesmon from blocking actin binding sites

-Processes all very slow and require little energy

-Latch stateprolonged contraction, low energy use (0.3% striated)

Smooth Muscle

Low rate of cross-bridge cycling

Mechanism not well-understood

Fig. 10-53Randall et al. 2002

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--

Uta stansburiana

Sceloporus magister

Sceloporus undulatus

Sceloporus virgatus

Uma notata

Callisaurus draconoides

Cophosaurus texanus

Holbrookia maculata

Phrynosoma cornutum

Phrynosoma modestum

Phrynosoma mcallii

SceloporusGroup

Sand

Horned

11 Species of Phrynosomatidae

High-SpeedTreadmill

6

Twitch Speed (SPRINTING)

SO = Slow OxidativeFOG = Fast-Oxidative Glycolytic

Muscle Fiber-Type Composition

FG = Fast GlycolyticFOG = Fast-Oxidative Glycolytic

Oxidative Capacity (ENDURANCE)

Iliofibularis muscle

Iliofibularis Muscle (IF)cross-section with darker oxidative core that appears red in fresh tissue

Dorsal view oflizard hindlimb

IF

Histochemistry

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Femur

Cross Section of Hindlimb at

Mid-Thigh

Histochemistry

IF

Iliofibularis Muscle (IF)

SuccinicDehydrogenase

(SDH)

His

toch

emis

try

Myosin ATPase

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mATPase(fast-twitch)

SDH(oxidative)

SO(slow-oxidative; light mATPase,

dark SDH)

FG(fast-twitch

glycolytic; dark mATPase, light SDH)

FOG(fast-twitch oxidative

glycolytic; dark mATPase and

dark SDH)

HistochemistrySerial sections stained for:

Proportional area of all three fiber types sums to 1.

FG + FOG + SO = 1

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--

Uta stansburiana

Sceloporus magister

Sceloporus undulatus

Sceloporus virgatus

Uma notata

Callisaurus draconoides

Cophosaurus texanus

Holbrookia maculata

Phrynosoma cornutum

Phrynosoma modestum

Phrynosoma mcallii

SceloporusGroup

Sand

Horned

11 Species of Phrynosomatidae

1. Whole-leg muscle area

2. Proportion of a muscle in the thigh

3. Change in size of individual fibers

4. Variation in fiber-type composition

Focus on the Iliofibularis muscle

Which Muscle Components May Predict Speed Differences?

10

0

10

20

30

40

50

60

1 10 100

Body Mass (g)

Thig

h M

uscl

e X-

Sect

iona

l Are

a

0

4

8

12

16

1 10 100

Body Mass (g)

Iliof

ibul

aris

as

% o

f Thi

gh M

uscl

e

(mm

2 )

Horned lizards have marginally slimmer thighs, but relative iliofibularissize does not vary among subclades

Scelop. GroupSand LizardsHorned Lizards

0

100

200

300

400

500

600

1 10 100

Body Mass (g)

Size

of S

ingl

e

F

iber

µm2

0

100

200

300

400

500

600

1 10 100

Body Mass (g)

Size

of S

ingl

e

F

iber

Iliofibularis fiber size varies with respect to fiber type and mass, but not subclade

Scelop. GroupSand LizardsHorned Lizards

FG

µm2

SO

11

0

10

20

30

40

50

60

70

80

1 10 100

Body Mass (g)

% F

ast-G

lyco

lytic

0

10

20

30

40

50

60

70

80

1 10 100

Body Mass (g)

% S

low

-Oxi

dativ

e

Iliofibularis FG and FOG compositionsvary among phrynosomatid subclades;composition of SO fibers does not vary

Scelop. GroupSand LizardsHorned Lizards

%Fa

st G

lyco

lytic

(FG

)

% S

low

Oxi

dativ

e (S

O)

0

0.2

0.4

0.6

0.8

1

proportion FOG fibers

prop

ortio

n FG

fibe

rs

Because slow oxidative (SO)composition is rather stable,

0 0.2 0.4 0.6 0.8 1

Scelop. GroupSand LizardsHorned Lizards

Fast-Oxidative Glycolyticfiber proportional area

Fast

Gly

coly

ticfib

er p

ropo

rtion

al a

rea FG and FOG

trade-off(but only AMONG subclades)

P < 0.001conventional r = -0.95phylogenetic r = -0.89

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1. Whole-leg muscle areaHorned lizards may have slim thighs

2. Proportion of iliofibularis in thighdoes not vary among subclades

3. Change in size of individual fiberscorrelates with body mass, not speed

4. Variation in fiber-type compositionlikely explains speed differences

Which Muscle Components May Predict Speed Differences?

0.200.35

0.500.65

0.80

% FG Fibers in IF Muscle1.25

1.501.75

2.00Hindlimb Span / SVL

0.00

0.20

0.40

0.60

0.80

log

Sprin

t Spe

ed

Scelop. GroupSand LizardsHorned Lizards

proportion FG area

in iliofibularis muscle

hindlimb span/SVL

log

sprin

t spe

ed(m

/s) Proportion

of fast glycolyticfibers and

relative hindlimb

span predictspeed

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Fiber-type composition has evolved dramatically since

the Sand – Horned split:

Cnemidophorus

FG

FG

Horned Scelop. Sand

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Cnemidophorus

FOG

Fast Glycolytic and Fast-Oxidative Glycolytic fiber compositions exhibit a trade-off (because of the

constant Slow Oxidative proportion)

Do Speed and Endurancetrade-off similarly?

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The Speed - Endurance trade-offquestion is unresolved

Taxa

Humans18 mammal spp.

Garter snakes

1 Sceloporus1 Lacertid

4 Lacertids12 Lacertids

Trade-off?

dependsNONO

NONO

YESYES

Inter/Intra

IntraInterspecific

Intra

IntraIntra

InterspecificInterspecific

Reference

Heinrich 1985Garland et al. 1988

Brodie and Garland 1993

Tsuji et al. 1989Sorci et al. 1995

Huey et al. 1984Vanhooydonck et al. 2001

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-1 -0.5 0 0.5 1

log Endurance (s)

log

Spri

nt S

peed

(m/s

)

Scelo po rusSandHo rnedC ro t aphyt idaeA g amid aeTeiidaeLacert id aeScincid aeA ng uidae

Speed and Endurance are positively correlated

23 Species(Adult Males)

Residuals(from regressions

on body mass)Speed and Endurance

do nottrade-off

r2 = 0.187p = 0.039

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The evolution of both speed and endurance does not seem to be constrained across a broad range of lizard taxa.

Vertebrate Physiology 437

1. Behavior Initiation(CH11)

2. Jokes from the audience...

Fig. 11-12Randall et al. 2002

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~Behavior Initiation

Chapter Eleven

Bring together nervous, endocrine, muscular systems, etc.

Complex

Reflexes / Learned / Plasticity

Respond to situation(s)Parallel Processing Complicated

NeuronalCircuitry

Animal Behavior,Neurobiology

Simple Reflexes – basis of neuronal circuitry

Reflex Arc, Stereotypic Behaviore.g., stretch reflex (patellar tendon)

- Tonic tension in muscle- Important for maintenance

of posture via negative feedback

- Only 2 neurons required

- monosynaptic reflex

Stretch receptor activates1a-afferent neuron

Alpha-motor neuron activates quadriceps

Sherwood 1997 (see 11-1 in Eckert)