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UAG - Nervous system
Question | Answer |
---|---|
Structural Nervous System | Central Nervous System (CNS) - brain and spinal cord<P><P><P>Peripheral Nervous System (PNS) - remainder of nervous system outside of the CNS |
Functional Nervous System | Somatic Nervous System (SNS)<P><P><P>Autonomic Nervous System (ANS) |
Nervous Tissue | two main cell types<P>1. Neurons (nerve cells)<P>2. Neuroglia (glial cells) which support the neurons |
Neurons | structural & functional units of nervous system for rapid communication; cell body with dendrites (impulses to body) & an axon (impulses away from body)<P>myelin sheath=myelin(layers of lipid) + protein substances to increase velocity of impulses |
Multipolar motor neurons | 2+ dendrites & single axon that may have 1+ collateral branches; most common in CNS & PNS; all motor neurons controlling skeletal muscles & comprising the ANS |
Pseudounipolar sensory neurons | short, apparently single (but double), process extending from cell body; into peripheral process conducting from receptor organ (touch/pain/temp) toward the cell body & a central process continuing from cell body in CNS; outside CNS in sensory ganglia |
Neuroglia (glial cells/glia) | approx 5 times as abundant as neurons, non-neuronal/excitable cells forming major component of nervous tissue, supporting/insulating/nourishing neurons |
Central Nervous System (CNS) | brain and spinal cord; integrate & coordinate incoming and outgoing neural signals & to carry out higher mental functions (thinking & learning) |
Gray Matter | made of nerve cell bodies in the CNS=nucleus; in transverse section of spinal cord, gray matter appears to be an "H" in the white matter; right & left posterior(dorsal)/anterior(ventral) horns=supports of the "H" |
White Matter | interconnecting fiber tract system (bundle of nerve fibers/axons within the CNS connecting neighboring or distant nuclei of cerebral cortex) |
Meninges | 1. Pia Mater - innermost, delicate, transparent layer <P>2. Arachnoid Mater - middle layer <P>3. Dura Mater - thick, tough layer<P><P><P>Cerebrospinal fluid (CSF) is b/w pia mater & arachnoid mater |
Peripheral Nervous System (PNS) | consists of nerve fibers & cell bodies outside CNS that conduct impulses to or away from CNS; organized into nerves that connect CNS with peripheral structures |
Nerve Fiber | axon, neurolemma (cell membranes of Schwann cells surrounding axon,has 2 forms), & surrounding endoneurial connective tissue |
Nerve Fiber - classes | 1. myelinated, consisting of Schwann cells specific to individual axon, organized in a continuous series forming myelin cells <P>2. unmyelinated, composed of Schwann cells that don't make up an apparent series, multiple axons are separately embedded |
Nerve tissue coverings | 1.Endoneurium =delicate, immediately surrounding neurilemma cells/axon<P>2.Perineurium =dense connective tissue enclosing fascicle, effective barrier against foreign substances<P>3.Epineurium =thick connective sheath around bundle of fascicles |
PNS afferent (sensory) fibers | convey neural impulses to the CNS from the sense organs (e.g., the eyes) & from sensory receptors in various parts of the body (e.g., in the skin) |
PNS efferent (motor) fibers | convey neural impulses from the CNS to effector organs (muscles and glands) |
Cranial Nerves | exit the cranial cavity through foramina (openings), identified by descriptive name or Roman numeral; 11 of the 12 pairs arise from the brain, the other pair arises from the superior part of the spinal cord |
Spinal (Segmental) Nerves | exit the vertebral column (spine) through intervertebral foramina; bilateral pairs from specific segment of the spinal cord; 31 spinal cord segments & 31 pairs of nerves are identified by letter & number (Cervical, Thoracic, Lumbar, Sacral, Coccygeal) |
Spinal Nerves - roots | arise from rootlets & converge to form 2 nerve roots<P>1.Anterior(ventral) =motor(efferent)fibers, from nerve cell bodies to effector organs<P>2.Posterior(dorsal) =sensory(afferent)fibers from cell bodies in spinal sensory to spinal cord gray matter |
Rami of Spinal Nerves - motor & sensory | 1. Posterior (1*)=supply nerve fibers to synovial joints of spine, deep muscles of back, & overlying skin in segmental pattern<P>2. Anterior (1*)=supply nerve fibers to larger remaining area, anterior/lateral regions of trunk & UL/LL, most merge together |