Biology 1030 [4] - Coordinated Motion 09 W · PDF fileNeeds for Locomotion Biceps ... • Structural support ... Biology 1030 [4] - Coordinated Motion 09 W notes [Compatibility Mode]

Biology 1030 Winter 2009

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Coordinated MotionChapters 48 (48.1–4); 49 (49.1); 50 (50.1,5–6)

Coordinated Movements• Unique animal tissues

– Muscle tissue

N ti– Nervous tissue

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The Neuron • Cell Body (Soma)

• Dendrites

• AxonHillock

Stimulus

Presynaptic cellNucleus

Organelles– Hillock

– Presynaptic terminals

• Neurotransmitters

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Synapse

Postsynaptic cellNeurotransmitter

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

– Complex integration

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Radial Nervous SystemsCindarians• A diffuse network

A nerve ring around the mouth– A nerve ring around the mouth– No ganglia

Echinoderms

• Secondary pentaradialsymmetry

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– Radial nerve

– Nerve ring

• Coordination

Bilateral Nervous SystemsPlatyhelminths

• Central nervous system

T l t l d ith ll b i– Two lateral nerve cords with a small brain

• Peripheral nerves

Annelids

• Paired ventral nerve cords

• Segmental ganglia

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Segmental ganglia

– Local control


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Bilateral Nervous SystemsArthropods

• Complex appendages– Anterior ganglia fused

• Complex control

– Segmental ganglia

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Bilateral Nervous SystemsMolluscs

– Consistent with life style

Bi l• Bivalves

– Simple network of ganglia

– No cephalization

• Gastropods and Polyplacophores

– Cephalization

More complex activities

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– More complex activities

• Cephalopods

– A highly organized brain

– Problem solving and observational learning


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The Muscle Fibre• Multinucleated cell

• Myofibrils

S

Nuclei

Myofibril

Plasma membrane

• Sarcomeres

– Thick filaments

– Thin filaments

Z lines

Sarcomere

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Thickfilaments(myosin)

M line

Z line

Thinfilaments(actin)

The Muscle• Muscle fibres

• Motor unit

Muscle

• Motor unit

• Muscle bodyBundle ofmuscle fibers

Single muscle

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Single musclefibre (cell)


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Types of Vertebrate Muscle• Skeletal (striated) muscle

– VoluntaryMuscle fibres containing myofibrils– Muscle fibres containing myofibrils

• Sarcomeres

– Also in active invertebrates

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Types of Vertebrate Muscle• Cardiac muscle

– InvoluntaryStriated

– Branched cellsOnly in the vertebrate– Striated – Only in the vertebrate heart

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Types of Vertebrate Muscle• Smooth muscle

– InvoluntaryUnstriated

– No myofibrils• Diffuse contractile proteins– Unstriated

• No sacromeres

• 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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Excitable Cell Membranes• Pumps

• Non-gated channels

V lt t d I h l• Voltage-gated Ion channels

• Ligand-gated Ion channels

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Excitable CellsResting State

• Na+/K+ATPase

N t d K+ h l• Non-gated K+ channels

Resting membrane potential

[Ca++]

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[Ca++][Ca++]


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Excitable CellsActive State

• Gated channels open– Key

– Cell/site specific

• Ion fluxes

• Transientdepolarizations[Ca++]

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[Ca++][Ca++]

Withdrawal Reflex

• External stimulus

1. Receptor

Spinal Cord

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2. Sensory neuron

3. Interneuron

4. Motor neuron

5. Target organ


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Perception• External stimuli

• The classical five ‘senses’– Vision

– Hearing

– Taste

– Smell

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– Touch

– …

Perception• Mechanoreceptors

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

• Thermoreceptors– Heat, cold

• Chemoreceptors– Smell, taste

• Photoreceptors

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Photoreceptors– Vision

• Nociceptors– Pain


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Perception • Stepping on a tack

• Nociceptors– Pain receptors

D l i ti

Pain

• Depolarization– Threshold

– Action potential

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Connectivetissue

Strongpressure

Nerve

Neuron ExcitationMicroelectrode

Voltagerecorder

Referenceelectrode+50

Stimuli

• ‘Stable’ VR

• Depolarization

mb

ran

e p

ote

nti

al (

mV

)

–50 Threshold

0

Threshold

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Mem

50

Restingpotential

–1000 2 3 4

Time (msec)

Depolarizations

1 5

Restingpotential


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Neuron Excitation

• ‘Threshold voltage

Microelectrode

Voltagerecorder

Referenceelectrode+50

Strong depolarizing stimulus

Actionpotential Threshold voltage

– Action potential

• All-or-none

mb

ran

e p

ote

nti

al (

mV

)

–50 Threshold

0

Threshold

p

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Mem

50

Restingpotential

–1000 2 3 4

Time (msec)

Depolarizations

1 5

Restingpotential

The Action Potential• Threshold

– Gated Na+ channels

• Na+ influx– Rapid depolarization

+50

0

Actionpotential

ote

nti

al (

mV

) 3

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Threshold

1

–50

Mem

bra

ne

po

–100Time

2

Resting potential


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The Action Potential• Action potential peak

– Gated Na+ channelsGated K+ channels– Gated K+ channels

• K+ efflux– Repolarization

4

Actionpotential

0

ote

nti

al (

mV

) +503

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1

4

1

–50

Mem

bra

ne

po

–100Time

2

The Action Potential• Hyperpolarization

– Gated K+ channels

– K+ efflux

4

+50

0

ote

nti

al (

mV

) 3

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1

5

4

1

–50

Mem

bra

ne

po

–100Time

2


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The Action Potential• Resting membrane V

– Gated K+ channels

– Na+/K+ATPase

4

+50

0

ote

nti

al (

mV

) 3

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1

5

4

1

–50

Mem

bra

ne

po

–100Time

2

AP Propagation• Isolated events

• Depolarization at point A

Axon

Actionpotential

Plasmamembrane

Depolarization at point A

– First action potential

– Na+ diffuses in cytosol

• Depolarization at point B

– Voltage-gated channels

CytosolNa+

K+

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– Second action potential

• Depolarization at point C

– Third action potential


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Refractory• Period of inexcitability

• Absolute refractory• Absolute refractory period– Little to no concentration

gradients

– Na+/K+ATPase

• Relative refractory

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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

Schwannll

Node of Ranvier

Myelin

• Schwann cells– Protective

Axon

cell

Myelinsheath

Nodes ofRanvier

Schwanncell Axon

0.1 µm

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– Insulative

• Nodes of Ranvier

AP Propagation

• Saltatory conduction– Nodes of Ranvier

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The End of the Axon• Cell-cell communication

– Physically separated

El t i l i l• Electrical signal

• Chemical signal

– Neurotransmitters

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Chemical Synapse• Presynaptic terminal

– Voltage-gated Ca++ channelsVessicles

[Ca++]

– Vessicles• Ca++-dependent trafficking

– Neurotransmitter release• Excitatory – acetylcholine• Inhibitory – GABA

[Ca++][Ca++]

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Excitatory Effects• Synaptic cleft

– Acetylcholine release• Postsynaptic cell• Postsynaptic cell

– Ligand-gated Na+ channels– Depolarization– Excitatory postsynaptic potential

nti

al

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Mem

bra

ne

Po

ten

Time

VR

ThresholdEPSP

Inhibitory Effects• Synaptic cleft

– GABA release• Postsynaptic cell• Postsynaptic cell

– Ligand-gated Cl– channels– Hyperpolarization– Inhibitory postsynaptic potential

nti

al

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Mem

bra

ne

Po

ten

Time

VR

Threshold

IPSP


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Net Effects• Multiple presynaptic neurons

– Inhibitory – GABA

E it t ACh– Excitatory - ACh

• Temporal summation

• Spatial summation

nti

al

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Mem

bra

ne

Po

ten

Time

VR

Threshold

Where Are We At?

Interneuron

Nociceptor

• Perception of pain• Sensory neuron

Spinal Cord

SensoryNeuron Motor

Neuron

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–––

• Repeat in interneuron• Repeat in motor neuron


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At the Muscle FibreSynaptic terminal

T TubuleSynaptic cleft

SRACh

• Synapse

ACh

Ca2+

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• T-tubules

• Sarcoplasmic reticulum

– Calcium store

At the Muscle FibreT Tubule

SRACh

• Wave of depolarization

Sarcoplasmic reticulum

ACh

Ca2+

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• Sarcoplasmic reticulum

– Voltage-gated Ca++ channels

– Cytosolic calcium


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Muscle Proteins• Contractile proteins

– Thick filaments (myosin)

M line

• M-line

– Thin filaments (actin)

• Z-line

• Sarcomeres

Z lineSarcomere

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Muscle Proteins

TropomyosinTroponin complex

Ca++-binding sitesMyosin-binding site

• Other proteins– Troponin

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• Calcium binding sites

– Tropomyosin

• Myosin binding sites


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Role of Calcium

• Ca++ from the SR

• Binds troponin

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Binds troponin– Conformation change

• Pulls tropomyosin– Myosin binding sites

Muscle Contraction• Sliding filament model

• Actomyosin crossbridges ATPActomyosin crossbridges

1. Bind ATP

2. Cleave ATP

– Shape change

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ADPPi


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Muscle Contraction• Sliding filament model

• Actomyosin crossbridgesActomyosin crossbridges

3. Bind actin

4. Release ADP

– Shape change

– Filament slides

ADPPi

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ADPPi

Muscle Contraction

• Actomyosin cross-bridges

M

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– 1000s per sarcomere

– Pulling Z-line

• Sarcomeres shorten= Contraction


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Where Are We At?

Interneuron

Nociceptor

• Perception of pain• Sensory neuron

Spinal Cord

SensoryNeuron Motor

Neuron

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• Interneuron• Motor neuron• Target effect• Are we done yet?

Needs for Locomotion

BicepsExtensormuscle

Circularmuscle

• For coordinated motion:

1 Attach to a skeleton

Triceps

Flexormuscle Longitudinal

muscle

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1. Attach to a skeleton

2. Antagonistic pairs– Flexors– Extensors


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Types of Skeletons

• Structural support• Endoskeletons

– Por Ech Chor Moll

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– 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

Interneuron

Nociceptor

• Interneuron innervates

Spinal Cord

SensoryNeuron

MotorNeurons

Excitatory (ACh)

Inhibitory (GABA)

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multiple motor neurons

• Excitatory motor neuron

– Flexor contraction

• Inhibitory motor neuron

– Extensor relaxation

Crossed Extensor Reflex

Excitatory

• Interneuron crosses

Excitatory(ACh)

Inhibitory(GABA)

Excitatory(ACh)

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spinal cord

• One leg goes up

• One leg goes down


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Coordinated Motions• Depends on:

– Habitat

– Stage of live

• Aquatic– Swimming

• Terrestrial

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– Crawling

– Walking

– Jumping

– Flying

Swimming

• Jet propulsion– Water is forced

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through the smaller opening

– Cnidarian medusae • Circular ring of muscles


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Swimming• Cephalopds

– 40 km/h!

• Mantle cavity– Gas exchange

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Gas exchange

• Siphon– Contraction of muscles

– Directional

Swimming• Some peculiar

swimming styles can b b dbe observed– The swimming

anemone

– The swimming scallop

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Hydrostatic Skeletons• Moving with no bones

– Just a fluid-filled coelom

• Water is• Water is uncompressible– Change shape, not

volume

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Hydrostatic Movement• Nematode movement

– Longitudinal muscles

D l• Dorsal

• Ventral

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Hydrostatic Movement

• Unilateral contractions – Undulatory motion

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• Antagonistic muscle pair?

Hydrostatic Movement• Polychaete worms

– Lateral longitudinal muscles– Left vs. right contractionsLeft vs. right contractions

• Parapodia extend

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Hydrostatic Movement• Annelids

• Longitudinal muscles– Segment anchors

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– 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• 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

• Muscle attachment– Direct flight muscles

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g

– Indirect flight muscles

Direct Flight Muscles• Basalar muscle

– Physically pulls the wing down

• Dorsoventral muscleDorsoventral muscle– Pulls the dorsal skeleton (notum)

down– Indirectly pushes the wing up

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Indirect Flight Muscles• Change the body shape

• Dorsal longitudinal muscles

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muscles– Wings are indirectly pulled

down

• Dorsoventral muscles– Indirectly pulls the wings up

Documents

Biology 1030 [4] - Coordinated Motion 09 W · PDF fileNeeds for Locomotion Biceps ... • Structural support ... Biology 1030 [4] - Coordinated Motion 09 W notes [Compatibility Mode]