Overview of the Nervous SystemKnow the medical morphemes and definitions listed in the CP- Inter = between- Intra = within- --algia = pain- --esthesia = perceive sensations - --mural = wall- -- plegia = paralysis- Ganglion (pl. ganglia): an anatomically distinct collection of the neuron cell bodies located in the PNS - Gray matter: CNS tissues which contains a predominance of nerve cell bodies and non-myelinated axons- White matter: CNS tissue that is predominantly myelinated axons; organized into tracts- Plexus: a complex, interwoven network of peripheral nerves - Nerve: a bundle of axons in the PNS, which are held together by layers of connective tissue- Tract: bundle of axons located in the CNS- Nucleus: a collection of neuron cell bodies located in the CNSWhat are the functions of the nervous system? - 1) Sensory neurons: monitors the external and internal environment o Exteroceptors: “somantic sensory”, proprioception, consciously aware of these stimuli. Ex. pain, hot/cold, touch, body positiono Interoreceptors: “visceral (gut) sensory”, NOT consciously aware of these stimuli. Ex. blood pressure, gas levels, internal temperature, stretch- 2) Integrative neurons: processes incoming information (sensory) and initiates a response (motor) - 3) Motor neurons: produces an action in response to environmental stimuli o Somantic motor neurons innervate SKELETAL muscleo Visceral motor neurons innervate CARDIAC muscle, SMOOTH muscle, and GLANDS. - The general goal of the NS is to RAPIDLY maintain homeostasis by adjusting to the environment. What are the general differences between the NS and the Endocrine System?- NSo Direct Connectiono Electrical Impulse & Chemical NTo Rapid speed of response: millisecondso Very brief duration of response: milliseconds- Endocrineo Indirect connectiono Glands secrete hormones to bloodo Slower speed of response: minutes, hours, dayso Much longer duration of response: hours to years- Shared NS and Endocrine Traits o Chemical communication with targeted tissueso Nervous system: relatively swift but brief responseso Endocrine: Slower but they often last much longerKnow the histological components of a typical neuron and understand their significance - Cell body ( soma): contains nucleus- Axon: single long process of cell body- Dendrites: tree like multiple processes that radiate from a neuron cell body—act as a receptor- Synaptic knobs (terminals): terminal regions of axon pass information on- Synapse: how a neuron communicates with a dendrite or cell body of anotherneuron, muscle, and glandUnderstand the path in which sensory information travels to the CNS as well as how motor information exits the CNS- Sensory neuronso Afferento Make up less than 1% of neuronso Carry impulses TOWARD the CNS- Motor neuronso Efferento Make up less than 1% of neuronso Carry impulses AWAY from CNS toward the muscles- Interneuronso Make up less than 99% of the neurons o Located in the CNSo Connect sensory and motor neuronso Process information in the CNSBriefly list some of the functions performed by glial cells. Do they conduct nerve impulses?- Glial cells are the second type of nervous system cellso They are supporting cells!!!- Do NOT conduct nervous systems impulses- Perform different types of functionso Structural: provide framework for neural tissueo Protective: act as phagocyteso Maintenance: maintain intercellular environment- The number of glial cells exceeds the number of neurons in the nervous system by a 5:1 ratio- Examples of glial cell functiono Astrocytes: form blood-brain barriero Ependymal cells: help produce CSFo Microglial cells: perform phagocytosis; remove dead or damaged nervous tissueo Oligodendrocytes: produce myelin which covers axons in the CNSKnow the difference in the anatomy and functions of the CNS vs. PNS. What are the effectors of the PNS? Know the different types of sensory receptors? - CNSo Includes the brain, spinal cord, meninges and CSFo CNS is responsible for integrating, processing, and coordinatingo CNS is responsible for intelligence, memory, learning, and emotion- PNSo Includes Cranial nerves, spinal nerves, and neural tissue outside CNSo PNS is responsible for conducting sensory information to the CNSo PNS is responsible for transmitting motor commands to the 4 peripheral tissues: (Skeletal, smooth, cardiac and glands)Understand neuron classifications - Definitions- Somatico Voluntary or consciously awareo Skin, skeletal muscles, bone, joints, ligaments, and tendonso General senses: touch, pain, pressure, hot/cold, vibration, proprioceptiono Special sense: taste, smell, vision, hearing, balance- Visceral o Involuntary or not perceived o Viscous: internal organ in ventral body cavity o Organ, smooth muscle, cardiac muscle, and glandso BP, blood gases, stretch/distention of organs- Efferento Motoro Effectors: transmits impulse from CNS to Somatic (Skeletal Muscle), or visceral (smooth muscle, cardiac muscle, or glands)- Afferento Sensoryo Receptors: transmits impulses from somatic or visceral structures to CNS- GSE = General Somatic Efferent neuronso Motor neurons with cell bodies located in the ventral/anterior horn of the spinal cord or anterior regions of the brainstemo Voluntary motor system neuronso Carry efferent (motor) outflow to skeletal muscle fibers; make these muscles contracto Somatic motor neurons- GSA = General Somatic Afferent neuronso Sensory neurons with cell bodies located in the dorsal/posterior root gangliono Consciously perceived sensory informationo Carry pain, vibration, pressure, heat/cold, stretch, and proprioceptive information back to the CNS; may also carry information regarding the special senses (sight, hearing, balance taste, smell)o THESE SENSATIONS CAN BE LOCALIZEDo Sensory receptors located in: skin, skeletal muscle, bone, ligaments, tendons, and special sense organso Do NOT originate in smooth muscle, cardiac muscle, or exocrine glandso Somatic sensory neurons- GVE = General Visceral Efferent neuronso Neurons of the Autonomic Nervous System o Involuntary motor system neuronso Carry efferent (motor) outflow to cardiac muscle, the smooth muscle of visceral organs and blood vessels, and glandso Classified as either Sympathetic or Parasympathetic efferent neuronso Autonomic motor neurons- GVA = General Visceral Afferent neurons o Sensory neurons with cell bodies in the dorsal/posterior root ganglion; associated with the GVE neurons of the ANSo Transmit the following stimuli from visceral
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