Gross_Anatomy_Lecture_Exam_1_part_2[1]

Gross_Anatomy_Lecture_Exam_1_part_2[1] - Nervous System...

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Nervous System Enables the body to react to continuous changes in its external and internal environments Controls circulation and respiration Divided into groups o Structurally, the Central Nervous System (CNS) brain, and spinal cord o Structurally, the Peripheral Nervous System (PNS) nerve fibers, and cell bodies outside the CNS o Functionally, the Somatic Nervous System (SNS) voluntary nervous system. Carries “pain” from the skin and joints and supplies skeletal muscle. o Functionally, the Autonomic Nervous System (ANS) involuntary nervous system. Supplies smooth muscle, glands, and viscera in the body cavities. Nervous tissue is divided into 2 main cell types: o Neurons (nerve cells) structural and functional units of nervous system specialized for rapid communication Composed of a cell body with “extensions” known as dendrites and an axon which carry impulses to and away from the cell body. Myelin layers of lipid and protein substances forms a myelin sheath around some axons, which increases the velocity of impulse conduction. Neurons communication via synapses, which are points of contact between neurons. The communication occurs by means of neurotransmitters, which are chemical agents released or secreted by one neuron, which may excite or inhibit another neuron. o Neuroglia (non-neuronal, non-excitable glial cells) 5 times as abundant as neurons; are a major component of nervous tissue; support, insulate, and nourish the neurons Central Nervous System Consists of the brain and spinal cord Role is to integrate and coordinate incoming and outgoing neural signals and to carry out higher mental functions (thinking, & learning) A nucleus is a collection of nerve cell bodies in the CNS A tract is a bundle of nerve fibers (axons) connecting neighboring or distant nuclei Nerve cell bodies are contained in the gray matter Interconnecting fiber tract systems form the white matter There are 3 membranous layers that constitute the meninges o Pia mater innermost meningeal layer; delicate & transparent o Arachnoid mater Cerebrospinal fluid is located between the arachnoid mater and the pia mater o Dura mater thick; tough Peripheral Nervous System Consists of nerve fibers and nerve cell bodies that connect the CNS with peripheral structures Peripheral nerves consist of bundles of nerve fibers, their connective tissue coverings, and blood vessels o Consists of an axon; it’s neurolemma; and it’s endoneurium Neurolemma of myelinated nerve fibers- have a neurolemmal (myelin) sheath that is a continuous series of neurolemma cells enwrapping an individual axon, forming myelin Neurolemma of unmyelinated nerve fibers- consist of multiple axons separately embedded within the cytoplasm of each neurolemma cell do not produce myelin Peripheral nerves are strong because they are supported by 3 tissue covering layers: o
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