Nervous System Organization of the Nervous System1. List the structural and functional divisions of the nervous system, and describe their relationship to each other.Central nervous system: brain and spinal cord- Many different kind of sensory information- The source of though, emotions, and memory- Gives rise to signals that stimulate muscles to contract and glands to secretePeripheral nervous system : nervous tissue that lie in the periphery or outer regions of the body.- Cranial nerves, spinal nerves, ganglia, enteric plexuses in small intestine- Somatic nervous system: sensory neurons that convey information from somatic receptos in the head, body wall, and limbs and from recepts for the special senses of vision, hearing, tast, and smell to the CNS and motor neurons that conduct impulse from the CNS to skeletal muscles only. VOLUNTARY- Autonomic nervous system: sensory neurons that convey information from autonomic sensory receptors to the CNS and motor neurons tha toncduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands. INVOUNTARY- Enteric nervous system: brain of the gut. INVOLUNTARY 12 cranial nerves and 31 spinal nerves connect CNS to PNS.Sensory function: is afferent (toward the CNS); detect- Somatic afferents: from skin, skeletal muscles, and joints.- Visceral afferents: from your guysIntegravie function: processes sensory informationMotor function: is efferent (away from the CNS), may elicit an appropriate motor response by activating effectors- Somatic efferent: voluntary nervous system of skeletal musclesAutonomic nervous system: involuntary of smooth muscles, cardiac muscles, glands, adipose tissue and other.- Sympathetic: fight-or-flight- Parasympathetic: rest-and-digestGRAPH ON PAFE 449:SNS: From CNS, somatic motor neurons (voluntary) skeletal muscles. Somatic and special sensory receptors and somatic sensory neurons go to the CNS.ANS: From the CNS, automatic motor neurons (involuntary): sympathetic and parasympathic divisions (1) smooth muscle, cardiac muscle, and glands or (2) enteric motor neurons (invontary) in enteric plexuses. Autonomic sensory receptors and autonmic sensory neurons go to the CNS.ENS: Enteric snesoty receptors and enteric sensory neurons in GI tract and enteric plexuses go to the CNS and enteric motor neurons (involuntary) in enteric plexuses smooth muscle, glands, and endoctine cells of GI tractHistology of Nervous Tissue 2. Describe the types of glial cells, their function, and location in the nervous system.NEUROGLIA: glial “glue” cells; half volume of CNS. Do not generate or propagate action potentials, and they can multiply and divide in the mature nervous system.CNS: Astrocytes: (star) are glial cells of the CNS; regulate chemical environment around neurons and exchange between neurons and capillaries. Largest and most numerous. - Contain microfiliments that five them strength - wrap around blood capillaries isolate neurons of the CNS from various potentially harmful substances in blood by secreting chemicals that maintain the unique selective permeability characteristics of the endothelial cells of the capillaries.- Embryo: secrete chemicals that appear to refulare the frowht, mifration, and interconnection among neurons in the brain- Help to maintain the appropriate chemical environment for the generation of nerve impulses- Play a role in learning and memory by influencing the formation of neural synapseCNS: Microglia: monitor health of CNS and perform immune functions for neurons- phagocyteCNS: Ependymal Cells: glial cells of CNS line cavities of brain and spinal cord and help circulate spinal fluid- Blood-brain barrierCNS: Oligodenrocytes: glial cells of the CNS that wrap around neurons to form myelin sheaths- Forming and maintain myelin sheath around CNS axons (several)PNS: Satellite Cells: surround neuron cell bodies within gaglia- Providing structural support- Regulate the exchanges of materal between beuronal cell bodies and interstitial fluidPNS: Schwann Cells/Nerolemmocytes: surround nerve fibers, forming a myelin sheath• - myelinates a single axon• - participate in axon regeneration3. Explain the physiological characteristics of mature neurons.Speicalized cells that conduct messages in the form of nerve impulses from one part of the body to another.1. They have extreme longevity-given good nutrition neurons can function optimally for a lifetime2. They are amitotic- Neurons assume their roles as communicating links of the nervous system, they lose their ability to divide.4. Discuss the anatomy of a neuron, and the function of each structure.Cell body: a major biosynthetic center containing the usual organelles except for centriplesDendrites: cell process that are the receptive regions of the cellAxon: generates and conducts nerve impulses away from the cell body to the axon terminals.5. Describe the anatomy and function of the myelin sheath, and differentiate between myelinated and unmyelinated neurons.The myelin sheath is a whitish, fatty segmented covering that protects, insulates, and increases conduction velocity of axons.6. Define the structural and functional categories of neurons, and compare how the structural class of a neuron relates to its functional class.STRUCUTRAL CATEGORIESMultipolar neuron: three or more processes. All motor neurons.Bipolar neuron: single axon and dendriteUnipolar neuron: single process extending from the cell body that is associated with receptors at the distal end. Ganglia of spinal and cranial nerves. Sensory receptors.FUNCTIONAL CATEGORIESSensory: (afferent) neurons conduct impulses toward the CNS from receptorsMotor: (efferent) neurons conduct impulses from the CNS to effectorsInterneurons: (association neurons) conduct impulses between sensory and motor neurons, or in CNS integration pathways.Most sensory neurons are unipolar in structure.Motor neurons are multipolar in structure.Most interneurons are multipolar in structure.Neurophysiology 7. Define the terms voltage, potential difference, and current, and describe how electrical current travels in the body.Voltage is a measure of the amount of difference in electrical charge between two points, called the potential difference.The flow of electrical charge from point to point is called current, and is dependent on voltage and resistance (hindrance to current flow).In the body, electrical currents are due to the movement of ions across cellular membranes.8. Name the various types of
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