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Nervous system - Coggle Diagram
Nervous system
Action potential
Initiation: all or nothing, stimulus reaches threshold at -55mV
Depolarisation: influx of +ve ions into the cell, voltage increased to 40mV
Repolarization: exit of +ve ions out of the cell, restoration of resting membrane potential
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Resting potential: neuron at rest, gated channels closed, Na+/K+ pump maintaining potential at -70mV, high Na+ outside, high K+ inside
Depolarisation: stimulus reaches -55mV, Na+ channels open, Na+ flood axon, cell more +ve, continues until 40mV
Repolarization: return to -70mV, Na+ channels close, K+ channel open, K+ exit cell
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Continuous conduction: unmyelinated, slow signal, short axon
Node of ranvier, between myelin
Glial cells
Support, nourish, protect
Astrocytes, microgila, ependyma
Microgila: defense system (phagocytes), macrophages of CNS
Astrocyte: structural support, comprise blood-brain barrier, regulate concentration of ions and dissolved gasses
Satelite cells (PNS): Astrocyte like, cover nerve cell bodies for protection
Ependymal cells: from ependyma, lines ventricles of CNS, produces cerebral spinal fluid
Oligodendrocytes (CNS) : produce myelin, wrap processes around axon
Schwann cells (PNS): myelin production, axon insulation, conduction, regeneration and repair
Myelin: insulator, lipid rich protein complex, produced by the oligodendrocyte and Schwann cells, essential for signal conduction, short axon is unmyelinated
Neural communication
Excitable, conductive, secretory
Plasma membrane: lipid bi-layer, separates internal/external, electronic insulator, movement of substances
Resting potential (-70mV): facilitate entry and exit of ions, potassium, sodium, calcium, chloride
Ion channels: voltage gated/respond to a change in charge, chemically gated/responds to a change in chemical concentration, Mechanically gated/mechanical stimulus
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-3Na+ out, 2Ka in (against concentration gradient
Neuron to Nerve
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Endoneurium: Delicate CT surrounding myelin, fasicle
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Epineurium: outter most CT, protects
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PNS
Sensory pathway
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Somatic
Skin/muscle/skeleton, somatic receptor and visceral receptors
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Cells of nervous system
Neuron
Dendrite: sensors, receive information
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Axon: Pathway for electrical signaling, bi-directional flow
Axon terminal: Communication point, site of synapse
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Excitability, conductive, secretary
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