Biology 4: Nervous System dendrites Neurons nerve terminals Afferent: Ascend spinal cord node of ranvier Interneurons: Between other neurons (saltatory conduction) cell Body Efferent: Exit spinal cord (soma) Summations Temporal: Same space / Different time Spatial: Different space / Same time axon Schwann cell (PNS) Oligodendrocyte (CNS) myelin sheath Action Potential (faster) nucleus Astrocytes: Blood-brain barrier. Controls solutes moving from bloodstream nervous tissue. K+ out ation Repolariz Na+ in Depo lariza tion Glial Cells Ependymal Cells: The barrier between cerebrospinal fluid and interstitial fluid of the CNS. Microglia: Digest waste in CNS. Schwann Cells: PNS, makes myelin. Oligodendrocytes: CNS, makes myelin. Na+ / K+ Pump 3 Na+ out / 2 K+ in White / Grey Matter White Matter: Myelinated sheaths. Grey Matter: Cell bodies and dendrites. Unmyelinated. Brain: White deep / Grey outer Synapse Spinal Cord: Grey deep / White outer Reflex Arcs Monosynaptic: Sensory neuron Polysynaptic: Sensory Central Nervous System motor neuron interneuron motor - Brain & Spinal Cord Peripheral Nervous System Somatic Voluntary Sensory: Afferent Motor: Efferent Autonomic Sympathetic Neurotransmitter removed from synaptic cleft via either: • Breakdown by enzymes • Reuptake • Diffusion out of cleft Parasympathetic Fight / Flight Relax bronchi Blood to locomotion ¯Peristalsis Rest / Digest Reduce bronchi Conserve energy #Peristalsis Neurotransmitters: Preganglionic: Acetylcholine Postganglionic: Epi / Norepi Neurotransmitters: Preganglionic: Acetylcholine Postganglionic: Acetylcholine