CommunicationbetweenNerve Cells.V. Sutarmo Setiadji**VSS

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Multicellular organism- Function as one individuFrom Latin word which meancan not be devided -->Individu with one personallity Ech cell in the organism can communicate to each other Each cell is equiped with many kinds of communication tools **VSS

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Cell membraneThe important part of the cell that participate in communication is the cell membrane. It is important that you know the structure of the cell membrane**VSS

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Head, which is hydrophilicTail, which is hydrophobicWaterloveAfraidWater insolubleCell membrane is composed mostly by lipid bilayer. Lipid molecule has two part:Water solubleWaterSo, if one piece of membrane which is composed from one layer of lipid molecules is incubated to the water, automatically it will make a two layers**VSS

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Structure of the Cell Membran (Plasma Membrane) Lipid bilayerHydrophilic headHydrophobic tail**VSS

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If the cell membrane is composed only from lipid bilayer, water and electrolytes which are needed by the cell, can not pass the membrane. For this reason, the cell membrane is equiped with membrane proteins which function as chemical receptors, ion channels, enzymes, gap junction, transporters, etc.**VSS

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LigandReceptorIon channel moleculeIon channel is closedIon channel is opened.Na+ from the external of the cell enter the cell passively.INTRACELLEXTRACELLNa+Receptor and Ion channelLigand gated Ion Channel**VSS

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Ion channel moleculeIon channel is closedINTRACELLEXTRACELLNa+Other kinds of ion channels- Mechanically gated- Voltage gated- Thermal gated- Etc.**VSS

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Kadar (mM) kation dan anion Cell membrane separates the intracellular components and the extracellular components.**VSS

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Zat terlarut

Cairan antarsel

Cairan intrasel

Na+

145

15

K+

4,5

150

Ca++

1,8

10-7

Mg++

2

2

Cl-1

100

12

HCO3-1

24

4

HPO4=

2

40-95

Protein-1

16

54

Anion lain

8

31-86

The different composition of the intra- and extracellular fluid make a 70 mVpotential different between intra- and extracellular fluid in neuron. In resting cell, this potential different is called resting membrane potential the cell has70 mV potential it mean that intracell is more negative than extracell.**VSS

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Muscle cell has potential about 90 mV.Because of this potential different between intra- and extracell, nerve and muscle tissues are sensitive to stimulus, especially electrical stimulus they have a special characteristic which is called excitable tissue. The other cell that also include to excitable tissue is glands.But almost all cell in the body are sensitive to a special stimulus.**VSS

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Reaction of cell to stimulus.**VSS

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In nerve cell, the neurotransmitter stimulate the opening or closing of ion channel, or other reaction.Opening of sodium channel, make sodium ions penetrate the channel and enter the cell.This make the cell depolarise decreasethe potential different between intra- and extracell. For example from -70 mV to -50 mV. The amplitude of depolarisation is depend to the intensity of stimulus graded potential.**VSS

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Axon terminalDendritSomaAxon hillockTerminal buttonNode of RanvierSchwann cellNerve cell = Neuron**VSS

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This kind of depolarization can happen in many places in soma and dendrite ofnerve cell and will be summed. If the sum of the depolarization in axon hillock reach certain value called firing level, it will stimulate the opening of voltage gated Na+ channel and more and more depolarization in the axon hillock. This depolarization become very fast and is called action potential.**VSS

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This action potential will induce other action potential in the nearest node of Ranvier of the axon and then action potential in the node of Ranvier will also induce action potential in the next node of Ranvier. So the action potential will be conducted by saltatory conduction to the axon terminal.**VSS

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Stimulus- 70- 500 mV**VSS

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The conducted action potential is called impulse. In the terminal button the impulse will depolarize its membrane and make voltage gated Ca2+ channel open Ca2+ ion enter the cell bind to calmodulin to become Ca-calmodulin. In the terminal button Ca-calmodulin stimulate a cascade of chemical reaction that result in exocytosis of neurotransmitter.**VSS

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Exocytosis is the release of neurotransmitter to the synaptic cleft.**VSS

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Axon terminalDendritesSomaAxon hillockAxonTerminal buttonNode of RanvierSchwann cellSel Saraf = Neuron**VSS

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By exocytosis, neurotransmitters are secreted to the synaptic cleft and will diffuse to the postsynaptic membrane and bind to their specific receptors and make depolarization and action potential in the next cells. By this mechanism, the impulse is conducted to the next neuron or effector.**VSS

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aA special circuit of neurons (reflex arc) can contain only 1 synapse (mono-synaptic) or many synapses (multi-synaptic) circuit. Neuron, where it is located, always connected to the other neuron/s through many synapses making circuits. The circuit can already has a function or not yet.**VSS

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SkinSense organAfferent fiberEfferent fiberMuscle (as an effector)Central nervous systemReflex arc as a smallest unit of neuron circuit**VSS

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A long distance pathway process initiate by a stimulus or a change in the environment as an information which is received by sense organ, integrates the information, and uses the nervous system, endocrine system, or both, to react appropriately.Definition of reflex**VSS

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A reflex arc contains a sensory receptor, afferent or sensory fiber, central nervous system as an integratve center, efferent or motor fiber, and an effector.A reflex arc maybe already to function or not yet.To function effectively the reflex arc must be conditioned. Pavlov experiment shows how to make a reflex arc to function.**VSS

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Pavlov experiment**VSS

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In a reflex arc, muscle is one of an effector. There are 4 kinds of effectors: Skeletal muscle Smooth muscle Heart Gland (exocrine & endocrine)Somatic reflex skeletal muscleAutonomic reflex heart, smooth muscles, and glands**VSS

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The sense organ it may a special receptor cells (rods and cones in eyes, hair cells in cochlea and vestibular apparatus, receptor cells in taste buds)or the end of sensory nerve fiber in other senses with or without special structures.**VSS

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