Neuronal and Cellular Signalling LECTURE 1: Main components of the nervous system Functional classes of neurons: - Motor (efferent) -> away from the CNS - Sensory (afferent) > towards the CNS Spinal nerves contain both motor and sensory nerve fibres Cranial nerves are either mixed or contain ONLY sensory or motor Cells of the nervous system: neurons and glia Neurons: - Input component > dendrites and cell body - Transmission component -> Axon - Output component -> Axon terminals Information flow: Upstream neuron > dendrite > cell body > axon Glial cells - Don't directly participate in electrical signalling -> support cells cell body - More complex a nervous system the more glial cells that are present CNS Astrocytes - Structural and metabolic support to neurons - Made up of ions - Help in regrowth of axons -> spinal cord injury Oligodendrocytes - Insulate axons ( lipid rich myelin sheath) - Speed up electrical transmissions Microglia - Remove macrophages post debris - Mediate inflammatory reaction > release cytokines dendrite 4 -myein shean amon terminal PNS Schwaan Cells - Insulate axons (lipid rich myelin sheath) - Speed up electrical transmissions - SYNAPSES CHEMICAL Cell 1 Complex Simple Slow One-way Bi-directional Cell 2 H. Augustin ELECTRICAL Fast G. Howat
Electrical signal into muscle contraction - Motor neurons from CNS propagate electrical signal via action potential (AP) - NMJ ( nueromusucal junction ) = site between motor neurons and muscle fibres - AP causes a release of neurotransmitter (NT) - NT binds to post synaptic receptor - Channel receptors open - Positive lons rush in > Muscle action potential is generated - Muscle contraction Neuronal and Cellular Signalling Meter acares M Muscle cell Samice Kelly