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Transcript of Lecture 16, 14 October 2004 - University of Arizona | … 16, 14 October 2004 Chapter 10, Muscle...
1
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
2
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: [email protected]: 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?
3
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)
4
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
5
--
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
7
Femur
Cross Section of Hindlimb at
Mid-Thigh
Histochemistry
IF
Iliofibularis Muscle (IF)
SuccinicDehydrogenase
(SDH)
His
toch
emis
try
Myosin ATPase
8
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
9
--
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
12
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
13
Fiber-type composition has evolved dramatically since
the Sand – Horned split:
Cnemidophorus
FG
FG
Horned Scelop. Sand
14
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?
15
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
16
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
17
~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)