Coordinated Movements

Transcription

1 Biology 1030 Winter 2009 Coordinated Motion Chapters 48 (48.1 4); 49 (49.1); 50 (50.1,5 6) Coordinated Movements Unique animal tissues Muscle tissue Nervous N tissue ti 1

2 The Neuron Cell Body (Soma) Nucleus Organelles Presynaptic cell Stimulus Dendrites Axon Hillock Presynaptic terminals Neurotransmitters Synapse Neurotransmitter Postsynaptic cell Neurons Sensory Interneurons Motor 2

3 The Nerve a neuron Animal Nervous Systems Radiata vs. Bilateria Diffuse net vs. ganglia Complex integration 3

4 Radial Nervous Systems Cindarians A diffuse network A nerve ring around the mouth No ganglia Echinoderms Secondary pentaradial symmetry Radial nerve Nerve ring Coordination Bilateral Nervous Systems Platyhelminths Central nervous system Two lateral l nerve cords with a small brain Peripheral nerves Annelids Paired ventral nerve cords Segmental ganglia Local control 4

5 Bilateral Nervous Systems Arthropods Complex appendages Anterior ganglia fused Complex control Segmental ganglia Bilateral Nervous Systems Molluscs Consistent with life style Bivalves Simple network of ganglia No cephalization Gastropods and Polyplacophores Cephalization More complex activities Cephalopods A highly organized brain Problem solving and observational learning 5

6 The Muscle Fibre Plasma membrane Myofibril Sarcomere Z lines Nuclei Multinucleated cell Myofibrils Sarcomeres Thick filaments Thin filaments Thick filaments (myosin) M line Thin filaments (actin) Z line The Muscle Muscle Muscle fibres Motor unit Bundle of muscle fibers Muscle body Single muscle fibre (cell) 6

7 Types of Vertebrate Muscle Skeletal (striated) muscle Voluntary Muscle fibres containing myofibrils Sarcomeres Also in active invertebrates Types of Vertebrate Muscle Cardiac muscle Involuntary Branched cells Striated Only in the vertebrate heart 7

8 Types of Vertebrate Muscle Smooth muscle Involuntary Unstriated No sacromeres No myofibrils Diffuse contractile proteins Common in the invertebrates Except voluntary What happens when you step on a nail? 8

9 Excitable Cell Membranes Pumps Non-gated channels Voltage-gated t Ion channels Ligand-gated Ion channels Excitable Cells Resting State Na + /K + ATPase Non-gated K + channels Resting membrane potential [Ca ++ ] [Ca ++ ] 9

10 Excitable Cells [Ca ++ ] Active State Gated channels open Key Cell/site specific Ion fluxes Transient depolarizations [Ca ++ ] Withdrawal Reflex Spinal Cord External stimulus 1. Receptor 2. Sensory neuron 3. Interneuron 4. Motor neuron 5. Target organ 10

11 Perception External stimuli The classical five senses Vision Hearing Taste Smell Touch Perception Mechanoreceptors Compression, bending, stretch Touch, pressure, proprioception, hearing, balance Thermoreceptors Heat, cold Chemoreceptors Smell, taste Photoreceptors Vision Nociceptors Pain 11

12 Perception Pain Stepping on a tack Nociceptors Pain receptors Depolarization Threshold Action potential Nerve Connective tissue Strong pressure Neuron Excitation +50 Stimuli Microelectrode Voltage recorder Reference electrode Mem mbrane potential (mv) 0 50 Threshold Stable V R Depolarization Resting potential Depolarizations Time (msec) 12

13 Neuron Excitation Mem mbrane potential (mv) Strong depolarizing stimulus 50 Threshold Action potential Microelectrode Voltage recorder Reference electrode Threshold voltage Action potential All-or-none 100 Resting potential Depolarizations Time (msec) Membrane po otential (mv) The Action Potential Threshold Gated Na + channels Na + influx Rapid depolarization Action potential 50 Threshold Time 2 3 Resting potential 13

14 The Action Potential Action potential peak Gated Na + channels Gated K + channels (mv)+50 Membrane po otential K + efflux Repolarization 0 50 Action potential Time The Action Potential Hyperpolarization Gated K + channels K + efflux Membrane po otential (mv) Time 5 14

15 The Action Potential Resting membrane V Gated K + channels Na + /K + ATPase Membrane po otential (mv) Time 5 AP Propagation Isolated events Depolarization at point A First action potential Na+ diffuses in cytosol Depolarization at point B Voltage-gated channels Second action potential Action potential Na + K + Axon Plasma membrane Cytosol Depolarization at point C Third action potential 15

16 Refractory Period of inexcitability Absolute refractory period Little to no concentration gradients Na + /K + ATPase Relative refractory period Small concentration gradients Conduction Velocity Increasing speed Axon diameter Squid giant axon 1 mm diameter! 16

17 Conduction Velocity Increasing speed Temperature Conduction Velocity Increasing speed Myelination Insulative layer Charge leakage 17

18 Myelination Node of Ranvier Myelin Schwann cell Axon Myelin sheath Nodes of Ranvier Schwann cell Axon 0.1 µm Schwann cells Protective Insulative Nodes of Ranvier AP Propagation Saltatory conduction Nodes of Ranvier 18

19 The End of the Axon Cell-cell communication Physically separated Electrical signal Chemical signal Neurotransmitters Chemical Synapse Presynaptic terminal Voltage-gated Ca ++ channels Vessicles Ca ++ -dependent trafficking Neurotransmitter release Excitatory acetylcholine Inhibitory GABA [Ca ++ ] [Ca ++ ] 19

20 Excitatory Effects Synaptic cleft Acetylcholine release Postsynaptic cell Ligand-gated Na + channels Depolarization Excitatory postsynaptic potential Membrane Poten ntial V R EPSP Threshold Time Inhibitory Effects Synaptic cleft GABA release Postsynaptic cell Ligand-gated Cl channels Hyperpolarization Inhibitory postsynaptic potential Membrane Poten ntial V R IPSP Time Threshold 20

21 Net Effects Multiple presynaptic neurons Inhibitory GABA Excitatory t - ACh Temporal summation Spatial summation Membrane Poten ntial V R Threshold Time Where Are We At? Nociceptor Sensory Neuron Motor Neuron Interneuron Spinal Cord Perception of pain Sensory neuron Repeat in interneuron Repeat in motor neuron 21

22 At the Muscle Fibre Synaptic terminal Synaptic cleft T Tubule ACh SR Ca 2+ Synapse T-tubules Sarcoplasmic reticulum Calcium store At the Muscle Fibre T Tubule ACh SR Ca 2+ Wave of depolarization Sarcoplasmic reticulum Voltage-gated Ca ++ channels Cytosolic calcium 22

23 Muscle Proteins Contractile proteins Thick filaments (myosin) M-line Thin filaments (actin) Z-line Z line M line Sarcomere Sarcomeres Muscle Proteins Troponin complex Ca ++ -binding sites Tropomyosin Myosinbinding site Other proteins Troponin Calcium binding sites Tropomyosin Myosin binding sites 23

24 Role of Calcium Ca ++ from the SR Binds troponin Conformation change Pulls tropomyosin Myosin binding sites Muscle Contraction Sliding filament model Actomyosin crossbridges ATP 1. Bind ATP 2. Cleave ATP Shape change ADP P i 24

25 Muscle Contraction Sliding filament model Actomyosin crossbridges 3. Bind actin ADP P i 4. Release ADP Shape change Filament slides ADP P i Muscle Contraction Actomyosin crossbridges 1000s per sarcomere Pulling Z-line M Sarcomeres shorten = Contraction 25

26 Where Are We At? Nociceptor Perception of pain Sensory neuron Interneuron Motor neuron Target effect Are we done yet? Sensory Neuron Motor Neuron Interneuron Spinal Cord Needs for Locomotion Biceps Extensor muscle Circular muscle Triceps For coordinated motion: 1. Attach to a skeleton 2. Antagonistic pairs Flexors Extensors Flexor muscle Longitudinal muscle 26

27 Types of Skeletons Structural support Endoskeletons Por., Ech., Chor., Moll. Exoskeletons Arth., Moll. Hydrostatic skeletons Cnid., Nem., Platy., Ann., Moll. Antagonistic Muscle Pairs Flexors bend joints Extensors straighten joints Opposing effects 27

28 In our Scenario Nociceptor Inhibitory (GABA) Sensory Neuron Excitatory (ACh) Interneuron innervates multiple motor neurons Excitatory motor neuron Flexor contraction Inhibitory motor neuron Extensor relaxation Motor Neurons Interneuron Spinal Cord Crossed Extensor Reflex Inhibitory (GABA) Excitatory (ACh) Interneuron crosses spinal cord One leg goes up One leg goes down Excitatory (ACh) 28

29 Coordinated Motions Depends on: Habitat Stage of live Aquatic Swimming Terrestrial Crawling Walking Jumping Flying Swimming Jet propulsion Water is forced through the smaller opening Cnidarian medusae Circular ring of muscles 29

30 Swimming Cephalopds 40 km/h! Mantle cavity Gas exchange Siphon Contraction of muscles Directional Swimming Some peculiar swimming styles can be observed The swimming anemone The swimming scallop 30

31 Hydrostatic Skeletons Moving with no bones Just a fluid-filled coelom Water is uncompressible Change shape, not volume Hydrostatic Movement Nematode movement Longitudinal muscles Dorsal Ventral 31

32 Hydrostatic Movement Unilateral contractions Undulatory motion Antagonistic muscle pair? Hydrostatic Movement Polychaete worms Lateral longitudinal muscles Left vs. right contractions Parapodia extend 32

33 Hydrostatic Movement Annelids 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 33

34 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 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 34

35 Indirect Flight Muscles Change the body shape Dorsal longitudinal muscles Wings are indirectly pulled down Dorsoventral muscles Indirectly pulls the wings up 35