The Nervous System
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 Central Nervous System (CNS) The Peripheral Nervous System (PNS) The Human Nervous System
The Nervous System Monitors changes Processes and interprets Causes a response PNSCNS Sensory receptors
Peripheral Nervous system Central Nervous system sensorymotor Autonomic Smooth and cardiac muscles; Glands Somatic Skeletal muscles Motor (Efferent) Sensory (Afferent) Somatic (skin, skeletal muscle and joints) Visceral (internal organs)
“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” Santiago Ramón y Cajal ( ) Neurons “The Mysterious Butterflies of the Soul”
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
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 Myelin sheath
Axons are bundled together to form fascicles CNS: axon bundles form tracts PNS: axon bundles form nerves
Neurons are not alone
Astrocytes - Support and brace neurons - Control the chemical environment The supporting neuroglia Microglia The “immune cells” of the CNS 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)
Banizs et al. Development (2005) B A -Beating cilia helps circulating the CSF
Astrocytes - Support and brace neurons - Control the chemical environment The supporting neuroglia Microglia The “immune cells” of the CNS 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)
General Organization - CNS and PNS - PNS subgroups The basic units- the cells - Neurons - Glial cells Neurophysiology - Resting, graded and action potentials Neural interactions Fundamentals of the nervous system
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