36 questions about the Neuron What is it?Where is it?What does it do?What are the different kinds of neurons?What does a neuron look like?What are the functions of the different parts of a neuron?
4The Neuron What is it? Where is it? What does it do? Nerve Cell that is the building block of the nervous systemWhere is it?Throughout the bodyWhat does it do?Transmits information in both electrical and chemical forms throughout the bodyWhat are the different kinds of neuronsSensory, Motor, Interneurons
6The Neuron 8 parts of the neuron What are the functions of the different parts?Axon: Sending armDendrite: Receiving fingersSoma: Cell body not involved in transmissionMyelin Sheath: fatty insulatorySchwann Cell: forms myelin sheathNode of Ranvier: gaps in sheath to renew action potentialSynapse: gap separating neuronsNeurotransmitter: chemicals that allow message to “jump” across synapse
7A Nerve What is it? Where is it? What does it do? How is a nerve constructed?What does a nerve look like?What are the different kinds of nerves?How does a nerve communicate with the brain?
8What is it? Where is it? What does it do? cordlike structure of the body, comprising a collection of nerve fibersWhere is it?Throughout the bodyWhat does it do?Conveys impulses between a part of the central nervous system and some other body region.
9A Nerve How is a nerve constructed? Like a muscle: an outer covering: the epineurium.Nerve fibers organize into bundles: fasciclesEach fascicle surrounded by the perineuriumBetween individual nerve fibers is an inner layer of endoneurium.
10AND… More about Nerves What is a glial cell? (neuroglia) What is the difference between a stimulus, an impulse, irritability and conductivity?
12A Nerve What are the different kinds of nerves? Sensory, Motor, Autonomic(afferent, efferent)How does a nerve communicate with the brain?plexus: interconnection of fibers which form new combinationsspinal cord tracts (exception: Cranial Nerves)Sensory-somatic: conscious awareness of the external environment and all our motorAutonomic: involuntary communication between brain and internal organsCrossing Over of the Spinal TractsImpulses reaching the spinal cord from the left side of the body eventually pass over to tracts running up to the right side of the brain and vice versa
13Regeneration Regeneration of Nerve Fibers (cut or compressed axons) Separated ends seal off and swellAxon and myelin sheath (of injured site) disintegratesSchwann cells and macrophages migrate to site to phagocytize debrisNeurilemma remains intact and schwann cells proliferateAxon "sprouts", guided by schwann cells, gap to original contact
15Peripheral Nervous System What is the peripheral nervous system?What does it do?Where are the nerves of the peripheral nervous system?How do the nerves of the peripheral nervous system communicate with the brain?What are the divisions of the peripheral nervous system?
16Peripheral Nervous System What is the peripheral nervous system?One of the 2 divisions of the Nervous systemCentral (brain and spinal cord) and PeripheralWhat does it do?connects the central nervous system (CNS) to the limbs and organs.
17Peripheral Nervous System 3. Where are the nerves of the peripheral nervous system?Cranial: directly from brain to head and neck12 pairsEither sensory, motor or mixedSpinal Nerves: from spinal cord and extend throughout the body in dermatomes, pass out between the vertebrae31 pairs
18Cranial Nerves II. Optic III. Oculomotor IV. Trochlear V. Trigeminal I. OlfactoryII. OpticIII. OculomotorIV. TrochlearV. TrigeminalVI. AbducensVII. FacialVIII. VestibulocochlearIX. GlossopharyngealX. VagusXI. AccessoryXII. Hypoglossal
19Peripheral Nervous System How do the nerves of the peripheral nervous system communicate with the brain?Dermatomes: somatic or musculocutaneous areas served by fibers from specific spinal nervesspinal cord tracts (exception: Cranial Nerves)white matter of the spinal cord contains tracts which travel up and down the cordWhite matter: bundles of axons each coated with a sheath of myelinWhat are the divisions of the peripheral nervous system?Sensory-somatic (sensory and motor)Autonomic
21Autonomic Nervous System What is the Autonomic Nervous System?What does it do?What are the divisions of the Autonomic Nervous System?What do each of the divisions control?
22Autonomic Nervous System What is the Autonomic Nervous System?sensory neurons and motor neurons that run between the central nervous system and various internal organsWhat does it do?Monitors conditions in the internal environment and brings about appropriate changes in themWhat are the divisions of the Autonomic Nervous System?Sympathetic, Parasympathetic and Enteric
23Autonomic Nervous System What do each of the divisions control?Sympathetic: prepares the body for emergencies: for "fight or flight" (and, perhaps, enhances the memory of the event that triggered the response)prepares the body for violent activityParasympathetic: returns the body functions to normal after they have been altered by sympathetic stimulationreverses these changes when the danger is over.Enteric nervous system: meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, and gall bladder
24Autonomic Nervous System Sympathetic (Adrenalin)stimulates heartbeatraises blood pressuredilates the pupilsdilates the trachea and bronchistimulates glycogenolysis — the conversion of liver glycogen into glucoseshunts blood away from the skin and viscera to the skeletal muscles, brain, and heartinhibits peristalsis in the gastrointestinal (GI) tractInhibits contraction of the bladder and rectum
25Autonomic Nervous System Parasympatheticslowing down of the heartbeat (as Loewi demonstrated)lowering of blood pressureconstriction of the pupilsincreased blood flow to the skin and visceraperistalsis of the GI tract
26Reflexes What is a reflex? direct connection between stimulus and response, does not require conscious thought, a reflex is a quick involuntary action.Where does a reflex come from?spineHow does a reflex occurthe stimulus occurssensory neurons sense the stimulussends a message to your spinal cord (it doesn't reach the brain right then)spinal cord sends a message to motor neuronsreflex occursWhile this is happening, message goes on to brain (which is why you feel the pain slightly after the event)
27Reflex Reflex and Reflex Arc Reflex = rapid, predictable motor response to a stimulusFive components to reflex arc:Receptor (site of stimulus)Sensory neuron (transmits afferent impulses to CNS)Integration Center:Monosynaptic reflex (single motor or sensory neuron)Polysynaptic reflex (multiple interneurons)Motor neuron (conducts efferent impulses)Effector (muscle or gland
28Central Nervous System What are the components of the central nervous system?What are the functions of each structure in the CNS?What is the difference between gray matter and white matter?What are the names of the protective linings in the CNS?What is the name of the fluid surrounding the structures in the CNS?
30CNS What are the components of the central nervous system? Brain Cranial NervesSpinal Cord
31CNS What are the functions of each structure in the CNS? Spinal Cord conducts sensory information from the peripheral nervous system (both somatic and autonomic) to the brainconducts motor information from the brain to our various effectorsskeletal musclescardiac musclesmooth muscleglandsserves as a minor reflex centerBrainreceives sensory input from the spinal cord as well as from its own nerves (e.g., cranial nerves)devotes most of its volume and power to processing its various sensory inputs and initiating appropriate — and coordinated — motor outputs
32CNS What is the difference between gray matter and white matter? white matter = bundles of axons each coated with a sheath of myelingray matter = masses of the cell bodies and dendritesIn the spinal cord, the white matter is at the surface, the gray matter inside.In the brain, this pattern is reversed.
33CNS What are the names of the protective linings in the CNS? The MeningesBoth the spinal cord and brain are covered in three continuous sheets of connective tissue, the meningesFrom outside in, these are:the dura mater — pressed against the bony surface of the interior of the vertebrae and the craniumSubdural spacethe arachnoidSubarachnoid spacethe pia mater
34CNSWhat is the name of the fluid surrounding the structures in the CNS?CSF flows uninterrupted throughout the central nervous systemthrough the central cerebrospinal canal of the spinal cord andthrough an interconnected system of four ventricles in the brain