A&P.Ch11.nervous
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| functions of nervous system (5) | sensory input; integration; homeostasis; mental activity; control of muscles & glands
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| sensory input | conscious: sight, smell, hearing taste, touch, etc. unconscious: blood pH, blood gases, blood pressure, etc.
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| integration | brain & spinal cord process information - may respond immediately, store as memory, or ignore
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| homeostasis | regulate & coordinate trillions of cells; heart rate must deliver blood; nervous system controls structures to maintain homeostasis
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| mental activity | brain includes consciousness, thinking memory & emotions
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| control of muscles & glands | skeletal muscles are consciously controlled; cardiac & smooth muscles contract autorhythmically; also controlls secretions of glands, sweat glands, salivary, digestive, etc.
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| Central nervous system (CNS) | consists of brain & spinal cord
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| where are the brain & spinal cord continuous? | at foramen magnum
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| Peripheral nervous system (PNS) | external to central nervous system (CNS); consists of sensory receptors, nerves, ganglia and plexuses
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| sensory receptors | are 1.) endings of nerve cells or 2.) separate, specialized cells that detect terperature, pain, touch pressure light, sound, odors & other stimuli
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| nerve | a bundle of exons & their shetaths the connect the CNS to sensory receptors, muscles, & glands
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| Cranial nerves | twelve pairs originate from the brain
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| spinal nerves | originate from the spinal cord
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| Ganglion | a collection of neuron cell bodies located outside the Central nervous system
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| Plexus | extensive network of axons & also neuron cell bodies, located outside the CNS
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| Peripheral Nervous system has ___ divisions | 1.) the sensory or afferent division and 2.) the motor or efferent division
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| sensory or afferent division of PNS | transmits electric signals FROM sensory receptors TO CNS
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| motor or efferent division | transmits action potential s FROM CNS to effector organs, such as muscles & glands
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| Motor Division of CNS or PNS? is further dividied into ____ divisions | two divisions: 1) somatic nervous system and 2) autonomic nervous system (ANS)
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| Somatic nervous system transmits action potentials | from the CNS to skeletal muscles
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| afferent | L. "to bring to" -inflowing; conducting toward a center; denoting certain arteries, veins, lymphatics and nerves
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| efferent | L. efferens, to bring out - conducting ouward from an organ or part; e.g., efferent connections of a group of nerve cells, or excretory duct of an organ
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| synapse | junction of a nerve cell with another cell (can be muscle cell or other cells, smooth muscle cells, gland cells
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| Autonomic Nervous System (ANS) is subdivided into | sympathetic & parasympathetic divisions
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| sympathetic | active during physical activies
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| parasympathetic division | regulates resting or vegetative functions, such as digesting food or emptying the urinary bladder
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| Enteric nervous system | consists of plexuses within the wall of the digestive tract
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| where are cell bodies of sensory neurons? | in ganglia near the spinal cord OR near the origin of certain cranial nerves
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| synapse | junction of a nerve cell with another cell
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| the Autonomic nervous system (ANS) transmits | action potentials from the CNS to (3) smooth muscle, cardiac muscle and certain glands
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| Does the ANS handle subconscious control? | Yes
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| What is another word for the type of control the ANS has? | involuntary
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| enteric (def.) | relating to the intestine G. enterikos from enterika "bowels"
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| what does sensory divison of the PNS do? | detects stimuli and transmit information on the form of action potentials to the CNS
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| what are the components of the nervous system? | neurons and nonneural cells
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| what are the nonneural cells? | neuroglia or glial cells (nerve glue) hold brain together
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| what type of cell makes up more than 1/2 the brain's weight? | neuroglia cells
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| neurons | receive stimulia dn transmit action potentials to other neurons or effector organs
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| another name for neuron | nerve cells
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| neuron | the morphologic and functional unit of the nervous system
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| what are parts of neuron (3) | 1.cell body 2. dendrites 3. axon
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| axon | also called nerve fibers
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| axon | refers to "axis" straight alignment & uniform diameter of most axons
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| axon (def.) | the singles pppprocess of a nerve cell that under normal conditions conducts nervous impulses away from the cell body and its remaining processes (the dendrites)
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| where does the axon occur? | in most neurons, a single axon arises from a cone-shaped area of the neuron cell body called the axon hillock
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| do axons occur just one to a neuron? | no-it can branch to form collateral axons or side branches
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| what is the plasma membrane of the axon called? | axolemma (the axon husk)
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| what is at the end of the axon? | presynaptic terminals
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| what is another name for presynaptic terminals? | terminal boutons
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| what is in the presynaptic terminals? | many small vesicles containing neurotransmitters
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| neurotransmitters | any specific chemical agent released by a persynaptic cell on excitation that crosses the synaptic cleft and stimulates or inhibits the postsynaptic cell
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| where are action potentials generated? | at TRIGGER ZONE
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| where is trigger zone? | axon hillock and the part of the axon nearest to the cell body
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| do axons have transport mechenisms? | Yes, indeed they do--movement of cell materials, waste & germs can be transported. Ex. rabies can enter axon endings of damaged skin & are transported to the CNS
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| dendrites | short, highly branched cytoplasmic extensions that are tapered from their bases at the neuron cell body to their tips
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| what are dendrites? | the input part of the neuron; when stimulated, they generate small electric currents that are conducted to the neuron cell body
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| dendrites | branching processes of a neuron that receives stimuli and conducts potentials toward the cell body
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| types of neurons | neurons are classified according to function or structure
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| function classification of neurons | based on DIRECTION in which action potentials are conducted - afferent conduct TOWARD CNS while efferent conduct AWAY from CNS
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| structural classification of neurons | based on number of processes (multipoloar, bipolar, or unipolar)
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| neuroglia | "nerve glue" - there are two kinds - CNS (4 kinds) and PNS (2 kinds)
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| neuroglia of the CNS | astrocytes, ependymal cells; microglia; oligodendrocytes
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| astrocytes | astrocyte processes form fett that cover the surfaces of neurons and blood vessels; they provide structural support and form the blood-brain barrier
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| astrocyte role in the blood-brain barrier | astrocytes release chemical that mpromote the formation of tight junctions between the endothelial cells of capillaries; only certain substances can pass from blood into the nervous tissue of the brain & spinal cord
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| what is purpose of blood-brain barrier? | protects neurons from toxic substances in the blood;allows exchange of nutrients and waste products between neurons & blood; and keeps blood fluctuations from affecting the functions of the brain
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| ependymal cells | line the ventricles (cavities) of the brain & central canal of the spinal cord; secrete & circulate cerebrospinal fluid
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| choroid plexuses | specialized ependymal cells and blood vessels are in certain regions of the vesicles; secrete cerebrospinal fluid
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| what is on free surface of ependymal cells? | cilia - to circulate cerebrospinal fluid
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| microglia | specialized macrophages in the CNS that become momblie and phagocytic in response to inflammation--they phagocytize necrotic tissue; microorganisma, & foreign substances
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| how can a pathologist identify damaged areas in CNS during an autopsy? | large numbers of microglia migrate to areas damaged by infection, trauma, or stroke
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| oligodendrocytes | have cytoplasmic extensions that surround axons and form myelin sheaths
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| oligo dendrocytes | Gr. oligo - prefix meaning "few" a little; too little; too few
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| neuroglia of the PNS | Schwann cells (or neurolemmocytes) and satellite cells (within ganglia)
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| schwann cells or neurolemmocytes | wraps around an axon, forming a myelin sheat
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| what is difference between schwann cells & oligodendrocytes? | schwann cells wrap around just ONE CELL, whereas oligodendrocytes have feet which wrap around several
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| schwann cells | cells of ectodermal (neural crest)origin that compose a continuous envelope around each nerve fiber of peripheral nerves
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| satellite cell | surround neuron cell bodies in ganglia; provide support and nutrients to the neuron cell bodies
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| myelinated axons | extensions form (either from oligodendrocytes or schwann cells) which wrap around a segment of the axon; have small breaks
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| nodes of ranvier | interruptions in the myelin sheath
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| what are internodes? | the areas of the axon covered by myelin
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| unmyelinated axons | one schwann cell surrounds several axons
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