biology 1030 [4] - coordinated motion 09 w notes. · pdf fileneeds for locomotion triceps...

Biology 1030 Winter 2009

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Coordinated MotionChapters 45 (943-963); 48 (1011–1025); 49 (1063-1074)

Coordinated Movements• Unique animal tissues

– Muscle tissue

– Nervous tissue

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The Neuron • Cell Body (Soma)

• Dendrites

• Axon– Hillock

– Presynaptic terminals

• Neurotransmitters

Stimulus

Presynaptic cellNucleus

Organelles

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Synapse

Postsynaptic cellNeurotransmitter


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Neurons• Sensory

• Interneurons

• Motor

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The Nerve• ≠ a neuron

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Animal Nervous Systems• Radiata vs. Bilateria

– Diffuse net vs. ganglia

C l i t ti

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– Complex integration


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Radial Nervous SystemsCindarians• A diffuse network

– A nerve ring around the mouth– No ganglia

Echinoderms

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Echinoderms

• Secondary pentaradialsymmetry

– Radial nerve

– Nerve ring

• Coordination

Bilateral Nervous SystemsPlatyhelminths

• Central nervous system

– Two lateral nerve cords with a small brain

• Peripheral nerves

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Annelids

• Paired ventral nerve cords

• Segmental ganglia

– Local control

Bilateral Nervous SystemsArthropods

• Complex appendages– Anterior ganglia fused

• Complex control

– Segmental ganglia

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– Segmental ganglia


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Bilateral Nervous SystemsMolluscs

– Consistent with life style

• Bivalves

– Simple network of ganglia

– No cephalization

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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

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Sarcomere

Thickfilaments(myosin)

M line

Z line

Thinfilaments(actin)

The Muscle• Muscle fibres

• Motor unit

• Muscle body

Muscle

Bundle ofmuscle fibers

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muscle fibers

Single musclefibre (cell)


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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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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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step on a nail?

Excitable Cell Membranes• Pumps

• Non-gated channels

• Voltage-gated Ion channels

• Ligand-gated Ion channels

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Excitable CellsResting State

• Na+/K+ATPase

• Non-gated K+ channels

Resting membrane potential

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[Ca++]

[Ca++][Ca++]


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Excitable CellsActive State

• Gated channels open– Key

– Cell/site specific

• Ion fluxes

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Ion fluxes

• Transientdepolarizations[Ca++]

[Ca++][Ca++]

Withdrawal Reflex

Spinal Cord

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• External stimulus

1. Receptor

2. Sensory neuron

3. Interneuron

4. Motor neuron

5. Target organ

Perception• External stimuli

• The classical five ‘senses’– Vision

Hearing

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– Hearing

– Taste

– Smell

– Touch

– …


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Perception• Mechanoreceptors

– Compression, bending, stretch– Touch, pressure, proprioception, hearing, balance

• Thermoreceptors– Heat, cold

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• Chemoreceptors– Smell, taste

• Photoreceptors– Vision

• Nociceptors– Pain

Perception • Stepping on a tack

• Nociceptors– Pain receptors

• Depolarization– Threshold

– Action potential

Pain

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Connectivetissue

Strongpressure

Nerve

Neuron Excitation

• ‘Stable’ VR

• Depolarization

Microelectrode

Voltagerecorder

Referenceelectrode+50

enti

al (

mV

)

Stimuli

0

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Mem

bra

ne

po

te

–50 Threshold

Restingpotential

–1000 2 3 4

Time (msec)

Depolarizations

1 5

Threshold

Restingpotential


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Neuron Excitation

• ‘Threshold voltage– Action potential

• All-or-none

Microelectrode

Voltagerecorder

Referenceelectrode+50

enti

al (

mV

)

0

Strong depolarizing stimulus

Actionpotential

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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

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+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

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1

4

Actionpotential

0

1

–50

Mem

bra

ne

po

ten

tial

(m

V)

–100Time

2

+503


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The Action Potential• Hyperpolarization

– Gated K+ channels

– K+ efflux

+50

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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

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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

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• Depolarization at point B

– Voltage-gated channels

– Second action potential

• Depolarization at point C

– Third action potential


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Refractory• Period of inexcitability

• Absolute refractory period– Little to no concentration

di t

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gradients

– Na+/K+ATPase

• Relative refractory period– Small concentration

gradients

Conduction Velocity• Increasing speed

– Axon diameter

• Squid giant axon– 1 mm diameter!

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Conduction Velocity

• Increasing speed– Temperature

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Conduction Velocity• Increasing speed

– Myelination

• Insulative layer– Charge leakage

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Myelination

Axon

Schwanncell

Myelinsheath

Nodes ofRanvier

Node of Ranvier

Schwanncell

Myelin

Axon0.1 µm

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• Schwann cells– Protective

– Insulative

• Nodes of Ranvier

AP Propagation

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• Saltatory conduction– Nodes of Ranvier


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The End of the Axon• Cell-cell communication

– Physically separated

• Electrical signal

• Chemical signal

– Neurotransmitters

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Chemical Synapse• Presynaptic terminal

– Voltage-gated Ca++ channels– Vessicles

• Ca++-dependent trafficking– Neurotransmitter release

E citator acet lcholine

[Ca++]

[Ca++][Ca++]

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• Excitatory – acetylcholine• Inhibitory – GABA

Excitatory Effects• Synaptic cleft

– Acetylcholine release• Postsynaptic cell

– Ligand-gated Na+ channels– Depolarization

E citator posts naptic potential

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– Excitatory postsynaptic potential

Me

mb

ran

e P

ote

nti

al

Time

VR

ThresholdEPSP


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Inhibitory Effects• Synaptic cleft

– GABA release• Postsynaptic cell

– Ligand-gated Cl– channels– Hyperpolarization

Inhibitor posts naptic potential

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– 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

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• Spatial summation

Me

mb

ran

e P

ote

nti

al

Time

VR

Threshold

Where Are We At?

Spinal Cord

SensoryNeuron Motor

Neuron

Interneuron

Nociceptor

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• Perception of pain• Sensory neuron

–––

• Repeat in interneuron• Repeat in motor neuron


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At the Muscle FibreSynaptic terminal

T TubuleSynaptic cleft

SRACh

Ca2+

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• Synapse

• T-tubules

• Sarcoplasmic reticulum

– Calcium store

At the Muscle FibreT Tubule

SRACh

Ca2+

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• 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

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• Sarcomeres


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Muscle Proteins

TropomyosinTroponin complex

Ca++-binding sitesMyosin-binding site

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• Other proteins– Troponin

• Calcium binding sites

– Tropomyosin

• Myosin binding sites

Role of Calcium

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• 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

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– Shape change

ADPPi


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Muscle Contraction• Sliding filament model

• Actomyosin crossbridges

3. Bind actin

4. Release ADP

ADPPi

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– Shape change

– Filament slides

ADPPi

Muscle Contraction

M

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• Actomyosin cross-bridges– 1000s per sarcomere

– Pulling Z-line

• Sarcomeres shorten= Contraction

Where Are We At?

Spinal Cord

SensoryNeuron Motor

Neuron

Interneuron

Nociceptor

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• Perception of pain• Sensory neuron• Interneuron• Motor neuron• Target effect• Are we done yet?


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Needs for Locomotion

Triceps

BicepsExtensormuscle

Flexormuscle

Circularmuscle

Longitudinalmuscle

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• For coordinated motion:

1. Attach to a skeleton

2. Antagonistic pairs– Flexors– Extensors

Types of Skeletons

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• Structural support• Endoskeletons

– Por., Ech., Chor., Moll.• Exoskeletons

– Arth., Moll.• Hydrostatic skeletons

– Cnid., Nem., Platy., Ann., Moll.

Antagonistic Muscle Pairs

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• Flexors – bend joints

• Extensors – straighten joints

• Opposing effects


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In our Scenario

Spinal Cord

SensoryNeuron

MotorNeurons

Interneuron

Nociceptor

Inhibitory (GABA)

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• 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)

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• Interneuron crosses spinal cord

• One leg goes up

• One leg goes down

Excitatory(ACh)

Coordinated Motions• Depends on:

– Habitat

– Stage of live

• Aquatic

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– Swimming

• Terrestrial– Crawling

– Walking

– Jumping

– Flying


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Swimming

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• Jet propulsion– Water is forced

through the smaller opening

– Cnidarian medusae • Circular ring of muscles

Swimming• Cephalopds

– 40 km/h!

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• Mantle cavity– Gas exchange

• Siphon– Contraction of muscles

– Directional

Swimming• Some peculiar

swimming styles can be observed– The swimming

anemone

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– The swimming scallop


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Hydrostatic Skeletons• Moving with no bones

– Just a fluid-filled coelom

• Water is uncompressible– Change shape, not

volume

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volume

Hydrostatic Movement• Nematode movement

– Longitudinal muscles

• Dorsal

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• Ventral

Hydrostatic Movement

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• 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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Hydrostatic Movement• Annelids

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• 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

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Insect Flight• Antagonistic muscle pairs

– One pair causes the wings to raise

– One pair causes them to lower

• Joint is a lever and fulcrum

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• 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

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Indirect Flight Muscles• Change the body shape

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• Dorsal longitudinal muscles– Wings are indirectly pulled

down

• Dorsoventral muscles– Indirectly pulls the wings up

biology 1030 [4] - coordinated motion 09 w notes. · pdf fileneeds for locomotion triceps...

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