Upload
lehanh
View
216
Download
1
Embed Size (px)
Citation preview
Biology 1030 Winter 2009
1
Scott circa 2009
Coordinated MotionChapters 45 (943-963); 48 (1011–1025); 49 (1063-1074)
Coordinated Movements• Unique animal tissues
– Muscle tissue
– Nervous tissue
Scott circa 2009
The Neuron • Cell Body (Soma)
• Dendrites
• Axon– Hillock
– Presynaptic terminals
• Neurotransmitters
Stimulus
Presynaptic cellNucleus
Organelles
Scott circa 2009
Synapse
Postsynaptic cellNeurotransmitter
Biology 1030 Winter 2009
2
Neurons• Sensory
• Interneurons
• Motor
Scott circa 2009
The Nerve• ≠ a neuron
Scott circa 2009
Animal Nervous Systems• Radiata vs. Bilateria
– Diffuse net vs. ganglia
C l i t ti
Scott circa 2009
– Complex integration
Biology 1030 Winter 2009
3
Radial Nervous SystemsCindarians• A diffuse network
– A nerve ring around the mouth– No ganglia
Echinoderms
Scott circa 2009
Echinoderms
• Secondary pentaradialsymmetry
– Radial nerve
– Nerve ring
• Coordination
Bilateral Nervous SystemsPlatyhelminths
• Central nervous system
– Two lateral nerve cords with a small brain
• Peripheral nerves
Scott circa 2009
Annelids
• Paired ventral nerve cords
• Segmental ganglia
– Local control
Bilateral Nervous SystemsArthropods
• Complex appendages– Anterior ganglia fused
• Complex control
– Segmental ganglia
Scott circa 2009
– Segmental ganglia
Biology 1030 Winter 2009
4
Bilateral Nervous SystemsMolluscs
– Consistent with life style
• Bivalves
– Simple network of ganglia
– No cephalization
Scott circa 2009
p
• Gastropods and Polyplacophores
– Cephalization
– More complex activities
• Cephalopods
– A highly organized brain
– Problem solving and observational learning
The Muscle Fibre• Multinucleated cell
• Myofibrils
• Sarcomeres
– Thick filaments
– Thin filaments
Nuclei
Myofibril
Z lines
Plasma membrane
Scott circa 2009
Sarcomere
Thickfilaments(myosin)
M line
Z line
Thinfilaments(actin)
The Muscle• Muscle fibres
• Motor unit
• Muscle body
Muscle
Bundle ofmuscle fibers
Scott circa 2009
muscle fibers
Single musclefibre (cell)
Biology 1030 Winter 2009
5
Types of Vertebrate Muscle• Skeletal (striated) muscle
– Voluntary– Muscle fibres containing myofibrils
• Sarcomeres
– Also in active invertebrates
Scott circa 2009
Types of Vertebrate Muscle• Cardiac muscle
– Involuntary– Striated
– Branched cells– Only in the vertebrate
heart
Scott circa 2009
Types of Vertebrate Muscle• Smooth muscle
– Involuntary– Unstriated
• No sacromeres
– No myofibrils• Diffuse contractile proteins
– Common in the invertebrates• Except voluntary
Scott circa 2009
Biology 1030 Winter 2009
6
What happens when you step on a nail?
Scott circa 2009
step on a nail?
Excitable Cell Membranes• Pumps
• Non-gated channels
• Voltage-gated Ion channels
• Ligand-gated Ion channels
Scott circa 2009
Excitable CellsResting State
• Na+/K+ATPase
• Non-gated K+ channels
Resting membrane potential
Scott circa 2009
p
[Ca++]
[Ca++][Ca++]
Biology 1030 Winter 2009
7
Excitable CellsActive State
• Gated channels open– Key
– Cell/site specific
• Ion fluxes
Scott circa 2009
Ion fluxes
• Transientdepolarizations[Ca++]
[Ca++][Ca++]
Withdrawal Reflex
Spinal Cord
Scott circa 2009
• External stimulus
1. Receptor
2. Sensory neuron
3. Interneuron
4. Motor neuron
5. Target organ
Perception• External stimuli
• The classical five ‘senses’– Vision
Hearing
Scott circa 2009
– Hearing
– Taste
– Smell
– Touch
– …
Biology 1030 Winter 2009
8
Perception• Mechanoreceptors
– Compression, bending, stretch– Touch, pressure, proprioception, hearing, balance
• Thermoreceptors– Heat, cold
Scott circa 2009
• Chemoreceptors– Smell, taste
• Photoreceptors– Vision
• Nociceptors– Pain
Perception • Stepping on a tack
• Nociceptors– Pain receptors
• Depolarization– Threshold
– Action potential
Pain
Scott circa 2009
p
Connectivetissue
Strongpressure
Nerve
Neuron Excitation
• ‘Stable’ VR
• Depolarization
Microelectrode
Voltagerecorder
Referenceelectrode+50
enti
al (
mV
)
Stimuli
0
Scott circa 2009
Mem
bra
ne
po
te
–50 Threshold
Restingpotential
–1000 2 3 4
Time (msec)
Depolarizations
1 5
Threshold
Restingpotential
Biology 1030 Winter 2009
9
Neuron Excitation
• ‘Threshold voltage– Action potential
• All-or-none
Microelectrode
Voltagerecorder
Referenceelectrode+50
enti
al (
mV
)
0
Strong depolarizing stimulus
Actionpotential
Scott circa 2009
Mem
bra
ne
po
te
–50 Threshold
Restingpotential
–1000 2 3 4
Time (msec)
Depolarizations
1 5
Threshold
Restingpotential
The Action Potential• Threshold
– Gated Na+ channels
• Na+ influx– Rapid depolarization
+50
Scott circa 2009
+50
Threshold
0
1
–50
Actionpotential
Mem
bra
ne
po
ten
tial
(m
V)
–100Time
2
Resting potential
3
The Action Potential• Action potential peak
– Gated Na+ channels– Gated K+ channels
• K+ efflux– Repolarization
+50
Scott circa 2009
1
4
Actionpotential
0
1
–50
Mem
bra
ne
po
ten
tial
(m
V)
–100Time
2
+503
Biology 1030 Winter 2009
10
The Action Potential• Hyperpolarization
– Gated K+ channels
– K+ efflux
+50
Scott circa 2009
1
5
4
+50
0
1
–50
Mem
bra
ne
po
ten
tial
(m
V)
–100Time
2
3
The Action Potential• Resting membrane V
– Gated K+ channels
– Na+/K+ATPase
+50
Scott circa 2009
1
5
4
+50
0
1
–50
Mem
bra
ne
po
ten
tial
(m
V)
–100Time
2
3
AP Propagation• Isolated events
• Depolarization at point A
– First action potential
– Na+ diffuses in cytosol
Axon
Cytosol
Actionpotential
Na+
K+
Plasmamembrane
Scott circa 2009
• Depolarization at point B
– Voltage-gated channels
– Second action potential
• Depolarization at point C
– Third action potential
Biology 1030 Winter 2009
11
Refractory• Period of inexcitability
• Absolute refractory period– Little to no concentration
di t
Scott circa 2009
gradients
– Na+/K+ATPase
• Relative refractory period– Small concentration
gradients
Conduction Velocity• Increasing speed
– Axon diameter
• Squid giant axon– 1 mm diameter!
Scott circa 2009
Conduction Velocity
• Increasing speed– Temperature
Scott circa 2009
Biology 1030 Winter 2009
12
Conduction Velocity• Increasing speed
– Myelination
• Insulative layer– Charge leakage
Scott circa 2009
Myelination
Axon
Schwanncell
Myelinsheath
Nodes ofRanvier
Node of Ranvier
Schwanncell
Myelin
Axon0.1 µm
Scott circa 2009
• Schwann cells– Protective
– Insulative
• Nodes of Ranvier
AP Propagation
Scott circa 2009
• Saltatory conduction– Nodes of Ranvier
Biology 1030 Winter 2009
13
The End of the Axon• Cell-cell communication
– Physically separated
• Electrical signal
• Chemical signal
– Neurotransmitters
Scott circa 2009
Chemical Synapse• Presynaptic terminal
– Voltage-gated Ca++ channels– Vessicles
• Ca++-dependent trafficking– Neurotransmitter release
E citator acet lcholine
[Ca++]
[Ca++][Ca++]
Scott circa 2009
• Excitatory – acetylcholine• Inhibitory – GABA
Excitatory Effects• Synaptic cleft
– Acetylcholine release• Postsynaptic cell
– Ligand-gated Na+ channels– Depolarization
E citator posts naptic potential
Scott circa 2009
– Excitatory postsynaptic potential
Me
mb
ran
e P
ote
nti
al
Time
VR
ThresholdEPSP
Biology 1030 Winter 2009
14
Inhibitory Effects• Synaptic cleft
– GABA release• Postsynaptic cell
– Ligand-gated Cl– channels– Hyperpolarization
Inhibitor posts naptic potential
Scott circa 2009
– Inhibitory postsynaptic potential
Me
mb
ran
e P
ote
nti
al
Time
VR
Threshold
IPSP
Net Effects• Multiple presynaptic neurons
– Inhibitory – GABA
– Excitatory - ACh
• Temporal summation
• Spatial summation
Scott circa 2009
• Spatial summation
Me
mb
ran
e P
ote
nti
al
Time
VR
Threshold
Where Are We At?
Spinal Cord
SensoryNeuron Motor
Neuron
Interneuron
Nociceptor
Scott circa 2009
• Perception of pain• Sensory neuron
–––
• Repeat in interneuron• Repeat in motor neuron
Biology 1030 Winter 2009
15
At the Muscle FibreSynaptic terminal
T TubuleSynaptic cleft
SRACh
Ca2+
Scott circa 2009
• Synapse
• T-tubules
• Sarcoplasmic reticulum
– Calcium store
At the Muscle FibreT Tubule
SRACh
Ca2+
Scott circa 2009
• Wave of depolarization
• Sarcoplasmic reticulum
– Voltage-gated Ca++ channels
– Cytosolic calcium
Muscle Proteins• Contractile proteins
– Thick filaments (myosin)
• M-line
– Thin filaments (actin)
• Z-line
Z lineSarcomere
M line
Scott circa 2009
e
• Sarcomeres
Biology 1030 Winter 2009
16
Muscle Proteins
TropomyosinTroponin complex
Ca++-binding sitesMyosin-binding site
Scott circa 2009
• Other proteins– Troponin
• Calcium binding sites
– Tropomyosin
• Myosin binding sites
Role of Calcium
Scott circa 2009
• Ca++ from the SR
• Binds troponin– Conformation change
• Pulls tropomyosin– Myosin binding sites
Muscle Contraction• Sliding filament model
• Actomyosin crossbridges
1. Bind ATP
2. Cleave ATP
ATP
Scott circa 2009
– Shape change
ADPPi
Biology 1030 Winter 2009
17
Muscle Contraction• Sliding filament model
• Actomyosin crossbridges
3. Bind actin
4. Release ADP
ADPPi
Scott circa 2009
– Shape change
– Filament slides
ADPPi
Muscle Contraction
M
Scott circa 2009
• Actomyosin cross-bridges– 1000s per sarcomere
– Pulling Z-line
• Sarcomeres shorten= Contraction
Where Are We At?
Spinal Cord
SensoryNeuron Motor
Neuron
Interneuron
Nociceptor
Scott circa 2009
• Perception of pain• Sensory neuron• Interneuron• Motor neuron• Target effect• Are we done yet?
Biology 1030 Winter 2009
18
Needs for Locomotion
Triceps
BicepsExtensormuscle
Flexormuscle
Circularmuscle
Longitudinalmuscle
Scott circa 2009
• For coordinated motion:
1. Attach to a skeleton
2. Antagonistic pairs– Flexors– Extensors
Types of Skeletons
Scott circa 2009
• Structural support• Endoskeletons
– Por., Ech., Chor., Moll.• Exoskeletons
– Arth., Moll.• Hydrostatic skeletons
– Cnid., Nem., Platy., Ann., Moll.
Antagonistic Muscle Pairs
Scott circa 2009
• Flexors – bend joints
• Extensors – straighten joints
• Opposing effects
Biology 1030 Winter 2009
19
In our Scenario
Spinal Cord
SensoryNeuron
MotorNeurons
Interneuron
Nociceptor
Inhibitory (GABA)
Scott circa 2009
• Interneuron innervates multiple motor neurons
• Excitatory motor neuron
– Flexor contraction
• Inhibitory motor neuron
– Extensor relaxation
Excitatory (ACh)
Inhibitory (GABA)
Crossed Extensor Reflex
Inhibitory(GABA)
Excitatory(ACh)
Scott circa 2009
• Interneuron crosses spinal cord
• One leg goes up
• One leg goes down
Excitatory(ACh)
Coordinated Motions• Depends on:
– Habitat
– Stage of live
• Aquatic
Scott circa 2009
– Swimming
• Terrestrial– Crawling
– Walking
– Jumping
– Flying
Biology 1030 Winter 2009
20
Swimming
Scott circa 2009
• Jet propulsion– Water is forced
through the smaller opening
– Cnidarian medusae • Circular ring of muscles
Swimming• Cephalopds
– 40 km/h!
Scott circa 2009
• Mantle cavity– Gas exchange
• Siphon– Contraction of muscles
– Directional
Swimming• Some peculiar
swimming styles can be observed– The swimming
anemone
Scott circa 2009
– The swimming scallop
Biology 1030 Winter 2009
21
Hydrostatic Skeletons• Moving with no bones
– Just a fluid-filled coelom
• Water is uncompressible– Change shape, not
volume
Scott circa 2009
volume
Hydrostatic Movement• Nematode movement
– Longitudinal muscles
• Dorsal
Scott circa 2009
• Ventral
Hydrostatic Movement
Scott circa 2009
• Unilateral contractions – Undulatory motion
• Antagonistic muscle pair?
Biology 1030 Winter 2009
22
Hydrostatic Movement• Polychaete worms
– Lateral longitudinal muscles– Left vs. right contractions
• Parapodia extend
Scott circa 2009
Hydrostatic Movement• Annelids
Scott circa 2009
• Longitudinal muscles– Segment anchors– Setae dig in
• Circular muscles– Segment extends
• Waves of contraction
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
Scott circa 2009
Biology 1030 Winter 2009
23
Insect Flight• Antagonistic muscle pairs
– One pair causes the wings to raise
– One pair causes them to lower
• Joint is a lever and fulcrum
Scott circa 2009
• Muscle attachment– Direct flight muscles
– Indirect flight muscles
Direct Flight Muscles• Basalar muscle
– Physically pulls the wing down
• Dorsoventral muscle– Pulls the dorsal skeleton (notum)
down– Indirectly pushes the wing up
Scott circa 2009
Indirect Flight Muscles• Change the body shape
Scott circa 2009
• Dorsal longitudinal muscles– Wings are indirectly pulled
down
• Dorsoventral muscles– Indirectly pulls the wings up