Download The Muscle

Biology 1030
Winter 2009
Coordinated Motion
Chapters 48 (48.1–4); 49 (49.1); 50 (50.1,5–6)
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Coordinated Movements
• Unique animal tissues
– Muscle tissue
– Nervous
N
tissue
ti
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Biology 1030
Winter 2009
The Neuron
Nucleus
Presynaptic cell
Organelles
Stimulus
• Cell Body (Soma)
• Dendrites
• Axon
– Hillock
– Presynaptic terminals
• Neurotransmitters
Synapse
Neurotransmitter Postsynaptic cell
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Neurons
• Sensory
• Interneurons
• Motor
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Biology 1030
Winter 2009
The Nerve
• ≠ a neuron
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Animal Nervous Systems
• Radiata vs. Bilateria
– Diffuse net vs. ganglia
– Complex integration
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Biology 1030
Winter 2009
Radial Nervous Systems
Cindarians
• A diffuse network
– A nerve ring around the mouth
– No ganglia
Echinoderms
• Secondary pentaradial
symmetry
– Radial nerve
– Nerve ring
• Coordination
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Bilateral Nervous Systems
Platyhelminths
• Central nervous system
– Two
T
lateral
l t
l nerve cords
d with
ith a small
ll brain
b i
• Peripheral nerves
Annelids
• Paired ventral nerve cords
• Segmental ganglia
– Local control
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Biology 1030
Winter 2009
Bilateral Nervous Systems
Arthropods
• Complex appendages
– Anterior ganglia fused
• Complex control
– Segmental ganglia
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Bilateral Nervous Systems
Molluscs
– Consistent with life style
Bi l
• Bivalves
– Simple network of ganglia
– No cephalization
• Gastropods and Polyplacophores
– Cephalization
– More complex activities
• Cephalopods
– A highly organized brain
– Problem solving and
observational learning
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Biology 1030
Winter 2009
The Muscle Fibre
Nuclei
Plasma membrane
Myofibril
Z lines
• Multinucleated cell
• Myofibrils
• Sarcomeres
S
– Thick filaments
– Thin filaments
Sarcomere
Thick
filaments
(myosin)
M line
Thin
filaments
(actin)
Z line
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The Muscle
• Muscle fibres
Muscle
• Motor unit
Bundle of
muscle fibers
• Muscle body
Single muscle
fibre (cell)
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Biology 1030
Winter 2009
Types of Vertebrate Muscle
• Skeletal (striated) muscle
– Voluntary
– Muscle fibres containing myofibrils
• Sarcomeres
– Also in active invertebrates
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Types of Vertebrate Muscle
• Cardiac muscle
– Involuntary
– Striated
– Branched cells
– Only in the vertebrate
heart
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Biology 1030
Winter 2009
Types of Vertebrate Muscle
• Smooth muscle
– Involuntary
– Unstriated
• No sacromeres
– No myofibrils
• Diffuse contractile proteins
– Common in the invertebrates
• Except voluntary
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What happens when you
step on a nail?
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Biology 1030
Winter 2009
Excitable Cell Membranes
•
•
•
•
Pumps
Non-gated channels
V lt
Voltage-gated
t d Ion
I channels
h
l
Ligand-gated Ion channels
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Excitable Cells
Resting State
• Na+/K+ATPase
• Non-gated
N
t d K+ channels
h
l
Resting membrane
potential
[Ca++]
[Ca++]
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Biology 1030
Winter 2009
Excitable Cells
Active State
• Gated channels open
– Key
– Cell/site specific
[Ca++]
• Ion fluxes
• Transient
depolarizations
[Ca++]
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Withdrawal Reflex
Spinal Cord
• External stimulus
1. Receptor
2. Sensory neuron
3. Interneuron
4. Motor neuron
5. Target organ
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Biology 1030
Winter 2009
Perception
• External stimuli
• The classical five ‘senses’
–
–
–
–
–
Vision
Hearing
Taste
Smell
Touch
–…
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Perception
• Mechanoreceptors
– Compression, bending, stretch
– Touch,
Touch pressure,
pressure proprioception,
proprioception hearing
hearing, balance
• Thermoreceptors
– Heat, cold
• Chemoreceptors
– Smell, taste
• Photoreceptors
– Vision
• Nociceptors
– Pain
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Biology 1030
Winter 2009
Perception
• Stepping on a tack
• Nociceptors
Pain
– Pain receptors
• Depolarization
D
l i ti
– Threshold
– Action potential
Nerve
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Connective
tissue
Strong
pressure
Neuron Excitation
Microelectrode
Voltage
recorder
Stimuli
Reference
electrode
Mem
mbrane potential (mV)
+50
• ‘Stable’ VR
• Depolarization
0
–50
50 Threshold
Resting
potential
–100
Depolarizations
0 1 2 3 4 5
Time (msec)
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Biology 1030
Winter 2009
Microelectrode
Neuron Excitation
Voltage
recorder
Strong depolarizing stimulus
Mem
mbrane potential (mV)
+50
Action
p
potential
Reference
electrode
Threshold voltage
• ‘Threshold
– Action potential
• All-or-none
0
–50
50 Threshold
Resting
potential
–100
Depolarizations
0 1 2 3 4 5
Time (msec)
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The Action Potential
• Threshold
– Gated Na+ channels
• Na+ influx
– Rapid depolarization
Membrane po
otential (mV)
+50
3
Action
potential
0
2
–50 Threshold
–100
1
Resting potential
Time
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Biology 1030
Winter 2009
The Action Potential
• Action potential peak
– Gated Na+ channels
– Gated K+ channels
• K+ efflux
– Repolarization
Membrane po
otential (mV)
+50
3
Action
potential
0
4
2
–50
1
–100
1
Time
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The Action Potential
• Hyperpolarization
– Gated K+ channels
– K+ efflux
Membrane po
otential (mV)
+50
3
0
2
4
–50
–100
1
1
5
Time
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Biology 1030
Winter 2009
The Action Potential
• Resting membrane V
– Gated K+ channels
– Na+/K+ATPase
Membrane po
otential (mV)
+50
3
0
2
4
–50
–100
1
1
5
Time
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AP Propagation
Axon
• Isolated events
• Depolarization at point A
– First action potential
– Na+ diffuses in cytosol
Action
potential
Na+
Plasma
membrane
Cytosol
K+
• Depolarization at point B
– Voltage-gated channels
– Second action potential
• Depolarization at point C
– Third action potential
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Biology 1030
Winter 2009
Refractory
• Period of inexcitability
• Absolute refractory
period
– Little to no concentration
gradients
– Na+/K+ATPase
• Relative refractory
period
– Small concentration
gradients
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Conduction Velocity
• Increasing speed
– Axon diameter
• Squid giant axon
– 1 mm diameter!
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Biology 1030
Winter 2009
Conduction Velocity
• Increasing speed
– Temperature
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Conduction Velocity
• Increasing speed
– Myelination
• Insulative layer
– Charge leakage
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Biology 1030
Winter 2009
Myelination
Node of Ranvier
Myelin
Schwann
cell
ll
Axon
Myelin
sheath
Nodes of
Ranvier
Schwann
cell
Axon
0.1 µm
• Schwann cells
– Protective
– Insulative
• Nodes of Ranvier
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AP Propagation
• Saltatory conduction
– Nodes of Ranvier
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Biology 1030
Winter 2009
The End of the Axon
• Cell-cell communication
– Physically separated
• Electrical
El t i l signal
i
l
• Chemical signal
– Neurotransmitters
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Chemical Synapse
• Presynaptic terminal
– Voltage-gated Ca++ channels
– Vessicles
• Ca++-dependent trafficking
– Neurotransmitter release
• Excitatory – acetylcholine
• Inhibitory – GABA
[Ca++]
[Ca++]
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Biology 1030
Winter 2009
Excitatory Effects
Membrane Poten
ntial
• Synaptic cleft
– Acetylcholine release
• Postsynaptic cell
– Ligand-gated Na+ channels
– Depolarization
– Excitatory postsynaptic potential
Threshold
EPSP
VR
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Time
Inhibitory Effects
Membrane Poten
ntial
• Synaptic cleft
– GABA release
• Postsynaptic cell
– Ligand-gated Cl– channels
– Hyperpolarization
– Inhibitory postsynaptic potential
Threshold
VR
IPSP
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Time
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Biology 1030
Winter 2009
Net Effects
• Multiple presynaptic neurons
– Inhibitory – GABA
– Excitatory
E it t
- ACh
Membrane Poten
ntial
• Temporal summation
• Spatial summation
Threshold
VR
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Time
Where Are We At?
Nociceptor
Interneuron
Sensory
Neuron
Motor
Neuron
Spinal Cord
• Perception of pain
• Sensory neuron
–
–
–
• Repeat in interneuron
• Repeat in motor neuron
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Biology 1030
Winter 2009
At the Muscle Fibre
Synaptic terminal
Synaptic cleft
T Tubule
SR
ACh
Ca2+
• Synapse
• T-tubules
• Sarcoplasmic reticulum
– Calcium store
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At the Muscle Fibre
T Tubule
SR
ACh
Ca2+
• Wave of depolarization
• Sarcoplasmic reticulum
– Voltage-gated Ca++ channels
– Cytosolic calcium
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Biology 1030
Winter 2009
Muscle Proteins
M line
• Contractile proteins
– Thick filaments (myosin)
• M-line
– Thin filaments (actin)
• Z-line
Z line
Sarcomere
• Sarcomeres
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Muscle Proteins
Troponin complex
Ca++-binding sites
Tropomyosin
Myosinbinding site
• Other proteins
– Troponin
• Calcium binding sites
– Tropomyosin
• Myosin binding sites
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Biology 1030
Winter 2009
Role of Calcium
• Ca++ from the SR
• Binds troponin
– Conformation change
• Pulls tropomyosin
– Myosin binding sites
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Muscle Contraction
• Sliding filament model
• Actomyosin crossbridges
1. Bind ATP
ATP
2. Cleave ATP
– Shape change
ADP
Pi
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Biology 1030
Winter 2009
Muscle Contraction
• Sliding filament model
• Actomyosin crossbridges
3. Bind actin
ADP
Pi
4. Release ADP
– Shape change
– Filament slides
ADP
Pi
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Muscle Contraction
M
• Actomyosin crossbridges
– 1000s per sarcomere
– Pulling Z-line
• Sarcomeres shorten
= Contraction
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Biology 1030
Winter 2009
Where Are We At?
Nociceptor
Interneuron
Sensory
Neuron
Motor
Neuron
Spinal Cord
•
•
•
•
•
•
Perception of pain
Sensory neuron
Interneuron
Motor neuron
Target effect
Are we done yet?
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Needs for Locomotion
Biceps
Circular
muscle
Extensor
muscle
Triceps
Flexor
muscle
Longitudinal
muscle
• For coordinated motion:
1 Attach to a skeleton
1.
2. Antagonistic pairs
– Flexors
– Extensors
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Biology 1030
Winter 2009
Types of Skeletons
• Structural support
• Endoskeletons
– Por.,
Por Ech.,
Ech Chor.,
Chor Moll.
Moll
• Exoskeletons
– Arth., Moll.
• Hydrostatic skeletons
– Cnid., Nem., Platy., Ann., Moll.
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Antagonistic Muscle Pairs
• Flexors – bend joints
• Extensors – straighten joints
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2009
effects
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Biology 1030
Winter 2009
In our Scenario
Nociceptor
Interneuron
Sensory
Neuron
Inhibitory (GABA)
Motor
Neurons
Spinal Cord
Excitatory (ACh)
• Interneuron innervates
multiple motor neurons
• Excitatory motor neuron
– Flexor contraction
• Inhibitory motor neuron
– Extensor relaxation
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Crossed Extensor Reflex
Excitatory
(ACh)
Inhibitory
(GABA)
Excitatory
(ACh)
• Interneuron crosses
spinal cord
• One leg goes up
• One leg goes down
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Biology 1030
Winter 2009
Coordinated Motions
• Depends on:
– Habitat
– Stage of live
• Aquatic
– Swimming
• Terrestrial
–
–
–
–
Crawling
Walking
Jumping
Flying
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Swimming
• Jet propulsion
– Water is forced
through the smaller
opening
– Cnidarian medusae
• Circular ring of muscles
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Biology 1030
Winter 2009
Swimming
• Cephalopds
– 40 km/h!
• Mantle cavity
– Gas exchange
• Siphon
– Contraction of muscles
– Directional
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Swimming
• Some peculiar
swimming styles can
b observed
be
b
d
– The swimming
anemone
– The swimming scallop
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Biology 1030
Winter 2009
Hydrostatic Skeletons
• Moving with no bones
– Just a fluid-filled coelom
• Water is
uncompressible
– Change shape, not
volume
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Hydrostatic Movement
• Nematode movement
– Longitudinal muscles
• Dorsal
D
l
• Ventral
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Biology 1030
Winter 2009
Hydrostatic Movement
• Unilateral contractions
– Undulatory motion
• Antagonistic muscle pair?
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Hydrostatic Movement
• Polychaete worms
– Lateral longitudinal muscles
– Left vs. right contractions
• Parapodia extend
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Biology 1030
Winter 2009
Hydrostatic Movement
• Annelids
• Longitudinal muscles
– Segment anchors
– Setae dig in
• Circular muscles
– Segment extends
• Waves of contraction
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Crawling
• Turbellarians crawl using ventral cilia
– thin film of water/mucus
• Molluscs use waves of contraction
– Direct waves ‘push’ the animal forward
– Retrograde waves ‘pull’ the animal forward
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Biology 1030
Winter 2009
Insect Flight
• Antagonistic muscle pairs
– One pair causes the wings to raise
– One pair causes them to lower
• Joint is a lever and fulcrum
• Muscle attachment
– Direct flight
g muscles
– Indirect flight muscles
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Direct Flight Muscles
• Basalar muscle
– Physically pulls the wing down
• Dorsoventral muscle
Pulls the dorsal skeleton (notum)
down
– Indirectly pushes the wing up
–
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Biology 1030
Winter 2009
Indirect Flight Muscles
• Change the body shape
• Dorsal longitudinal
muscles
– Wings are indirectly pulled
down
• Dorsoventral muscles
– Indirectly pulls the wings up
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