Transcript Lecture 2
The Nervous System http://www.youtube.com/watch?v=Q4uh2r1djWw An organ is composed of different tissues Epithelial cells Connective tissue Muscle tissue The Nervous System - General organization - The basic units- the cells - Neurophysiology - Neural interactions Brain, Spinal cord, Neuronal pathways, Special senses The Human Nervous System The Central Nervous System (CNS) The Peripheral Nervous System (PNS) The Nervous System Monitors changes Processes and interprets Causes a response Sensory receptors PNS CNS Central Nervous system sensory Peripheral Nervous system Sensory (Afferent) motor Motor (Efferent) Somatic (skin, skeletal muscle and joints) Visceral (internal organs) Somatic Autonomic Skeletal muscles Smooth and cardiac muscles; Glands Neurons “The Mysterious Butterflies of the Soul” Santiago Ramón y Cajal (1852-1934) “As the entomologist chasing butterflies of bright colors, my attention was seeking in the garden of gray matter, those cells of delicate and elegant forms, the mysterious butterflies of the soul, whose fluttering wings would someday—who knows?— enlighten the secret of mental life” Neurons “The Mysterious Butterflies of the Soul” Santiago Ramón y Cajal Nobel prize in physiology and medicine 1906 The neuron Most of our wiring is insulated Myelin sheath Myelin sheath • Whitish, fatty (protein-lipoid), segmented sheath around most long (NOT ALL) axons • It functions to: - Protect the axon - Electrically insulate fibers from one another - Increase the speed of nerve impulse transmission Myelin sheath • Formed by Schwann cells in the PNS • A Schwann cell: - Envelopes an axon in a trough - Has concentric layers of membrane that make up the myelin sheath Axons are bundled together to form fascicles CNS: axon bundles form tracts PNS: axon bundles form nerves Neurons are not alone The supporting neuroglia Astrocytes Microglia The “immune cells” of the CNS - Support and brace neurons - Control the chemical environment Ependymal cells - Circulating the CSF Oligodendrocytes - Insulators of the thick neurons of the CNS Ependymal cells - Ciliated epithelial cells lining the central cavities of the brain and spinal column - Forming a permeable barrier between the CSF and nervous tissue - Beating cilia helps circulating the CSF CSF (cerebrospinal fluid) -Beating cilia helps circulating the CSF A Banizs et al. Development (2005) B The supporting neuroglia Astrocytes Microglia The “immune cells” of the CNS - Support and brace neurons - Control the chemical environment Ependymal cells - Circulating the CSF Oligodendrocytes - Insulators of the thick neurons of the CNS The neural cells of the CNS The supporting neuroglia in the PNS - Schwann cells surround and insulate axons (the “oligodendrocytes” of the PNS) - Satellite cells Support, insulate and nourish cell bodies (“astrocytes” of the PNS) Fundamentals of the nervous system General Organization - CNS and PNS - PNS subgroups The basic units- the cells - Neurons - Glial cells Neurophysiology - Resting, graded and action potentials Neural interactions Post-lecture assignment in Connect - Use the slides and the textbook to review the material - The quiz can be answered only once - Please note: the deadline is Aug 28, 11:00pm - The quiz will be submitted automatically on Aug 28, 11 pm