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Nervous system Ch

Chapter 10 definitions

TermDefinition
Nervous system Constantly receives signals, processes information, and powers our ability to learn, feel, create, and experience emotion; most complex system
Central nervous system CNS;consists of the brain and spinal cord
Peripheral nervous system PNS; consists of the vast network of nerves throughout the body
Sensory division Afferent division of the PNS that carries signals from nerve endings to the CNS
Motor division Efferent division of the PNS that transmits information from the CNS to the rest of the body
Somatic sensory Part of the afferent division that carries signals from skin, bones, joints, and muscles
Visceral sensory Part of the afferent division that carries signals from the viscera of the heart, lungs, stomach, and bladder
Somatic motor Part of the efferent division that allows voluntary movements of skeletal muscles
Autonomic motor Part of the efferent division that provides "automatic" activities such as control of blood pressure and heart rate
Sympathetic division From the autonomic motor division that arouses the body for action
Parasympathetic division From the autonomic division that has a calming effect
Neuroglia Glial cells; supportive cells of the nervous system
Neurons Excitable, impulse-conducting cells that perform the work of the nervous system; nerve cell
Blood-brain barrier BBB; Exists throughout the brain and allows small molecules to diffuse across to the brain but blocks larger molecules
Gliomas Highly malignant, rapid growing tumors made up of glial cells
Sensory neurons Afferent neurons that detect stimuli and then transmit information about the stimuli to the CNS
Motor neurons Efferent neurons that relay messages from the brain to the muscle or gland cells
Interneurons Found only in the CNS;connect the incoming sensory pathways with the outgoing motor pathways; make each of us unique; 90% of the body's neurons
Multipolar neurons Have 1 axon and multiple dendrites; most common neuron and includes most neurons of the brain and spinal cord
Bipolar neurons Have 2 processes; an axon and a dendrite with the cell body in between the 2; found in the retina of the eye and olfactory nerve in the nose
Unipolar neurons Have 1 process - an axon - that extends from the cell body before branching in a T shape; mostly reside in the sensory nerves of the PNS
Soma Cell body; control center of the neuron; contains the nucleus
Dendrites Look like bare tree branches; receive signals from other neurons and conduct this to the cell body
Axon Carries nerve signals away from the body; longer than the dendrite and has few branches
Myelin sheath Encases many (but not all) neurons; insulates the axon; formed by Schwann cells in the PNS; formed by oligodendrocytes in the CNS
Nodes of Ranvier Gaps in the myelin sheath; occur at evenly spaced intervals
Synaptic knob The end of each axon terminal; within it are vesicles containing a neurotransmitter
Neurilemma Outer layer of the myelin sheath that contains the nucleus and most of the cytoplasm of the Schwann cell; essential for an injured nerve to regenerate
Membrane potential Ions with opposite electrical charges are separated by a membrane and the potential for them to move toward one another exists
Polarized A membrane that exhibits membrane potential; excess of positive ions on one side of a membrane and an excess of negative ions on the other
Resting potential Inside of a cell has a negative charge and the outside has a positive charge; interior rich in K+; exterior rich in Na+; state of being inactive and polarized
Depolarize Stimulus causes Na+ to enter the cell; region of the interior changes from negative to positive
Action potential Channels in adjacent areas open and more Na+ enters the cell; nerve impulse continues down the length of the axon; nerve impulse
Repolarize K+ flows out of the cell and the electrical balance is restored;
Refractory period The membrane is polarized but the K+ and the Na+ are on the wrong sides of the membrane; sodium-potassium pump works to restore ions to their rightful sides; neuron won't respond to stimuli
Saltatory conduction Signal conduction in which nerve impulses "leap" from node to node
Synapse Space between the junction of 2 neurons in a neural pathway
Cauda equina Bundle of nerve roots resembling a horses tail, extending from the end of the spinal cord
Gray matter Nervous tissue containing mostly cell bodies of motor neurons and interneurons; appears gray because of its lack of myelin
White matter Nervous tissue containing bundles of axons that carry impulses from one part of the nervous system to another; has an abundance of myelin
Tracts Bundles of axons in the spinal cord that serve as routes of communication to and from the brain
Epidural space Small space that lies btween the outer covering of the spinal cord and the vertebrae; it contains a cushioning layer of fat as well as blood vessels and connective tissue
Central canal Carries cerebrospinal fluid through the spinal cord
Dorsal nerve root Posterior nerve root that contains fibers that carry sensory information into the spinal cord; enters the dorsal horn of the spinal cord
Ganglion Cell bodies of the dorsal neurons that are clustered in a knot-like structure
Spinal nerve Single nerve resulting from the fusion of the dorsal and ventral nerve roots; mixed nerve
Mixed nerve Nerve that contains both sensory and motor fibers
Ventral nerve root Anterior nerve root that contains fibers that carry motor information out of the spinal cord; exits from the ventral horn of the spinal cord
Pia mater Transparent, innermost layer of the meninges that clings to the outer surface of the brain and spinal cord
Arachnoid mater Resembling a cobweb, it's the delicate layer of the meninges that lies between the pia mater and the dura mater
Dura mater Tough outer layer of the meninges
Dorsal column Ascending tract that relays sensations of deep pressure and vibration as well as those needed to create awareness of the body's position
Spinocerebellar tract Ascending tract responsible for proprioception
Proprioception Awareness of the body's position
Spinothalamic tract Ascending tract that relays sensations of temperature, pressure, pain, and touch
Corticospinal tract Descending tract responsible for fine movements of hands, fingers, feet, and toes on the opposite side of the body; also called pyramidal tract
Extrapyramidal tracts Group of descending tracts associated with balance and muscle tone
Decussation The crossing of the spinal cord tracts from one side of the body to the other in the brainstem
Cervical plexus Contains nerves that supply the muscles and skin of the neck, tops of the shoulders, and part of the head; contains the phrenic nerve
Phrenic nerve Nerve that stimulates the diaphragm for breathing; located in the cervical plexus
Brachial plexus Innervates the lower part of the shoulder and the arm; contains the axillary nerve, radial nerve, and median nerve
Lumbar plexus Supplies the leg and thigh; derived from the fibers of the first 4 lumbar vertebrae; contains the femoral nerve
Sacral plexus Formed from fibers from nerves L4, L5, and S1-S4; often referred to as the lumbosacral plexus; contains the sciatic nerve
Dermatomes Specific areas of the skin innervated by spinal nerves
Reflex arc Neutral circuit which bypasses regions of the brain where conscious decisions are made
Somatic reflex Reflex involving contraction of a skeletal muscle after being stimulated by a somatic motor neuron; often help protect the body against harm
Longitudinal fissure Deep groove that separates the cerebrum into right and left hemispheres
Corpus callosum Thick bundle of nerves that runs along the bottom of the longitudinal fissure
Gyri Thick ridges marking the surface of the cerebrum
Sulci Shallow grooves that divide the gyri
Fissures Deep sulci
Diencephalon Region of the brain that sits between the cerebrum and the midbrain
Cortex` Gray matter that covers the cerebrum and cerebellum
Nuclei Patches of gray matter throughout the white matter
Dural sinuses Spaces created by separation of the dura mater that collect blood that has passed throught the brain and is on its way back to the heart
Subdural space Separates the dura mater from the arachnoid mater
Subarachnoid space Separates the arachnoid mater from the pia mater
Cerebrospinal fluid CSF; clear, colorless fluid that fills the ventricles and central canal; bathes the outside of the brain and spinal cord
Midbrain Part of the brainstem that contains tracts that relay sensory and motor impulses; contains centers for auditory and visual reflexes as well as clusters of neurons integral to muscle control
Pons Part of the brainstem that contains tracts that convey signals to and from different parts of the brain; includes cranial nerves V, VI, VII, and VIII
Medulla oblongata Part of the brainstem that connects the brain to the spinal cord; includes cranial nerves IX, X, XI, and XII
Thalamus Shaped like 2 eggs sitting side by side; resides on top of the brainstem; involved in memory and emotion; acts as a gateway for nearly every sensory impulse; located in the diencephalon
Hypothalamus Controls the ANS; contains centers responsible for thirst, hunger, and temperature regulation; controls the pituitary gland; involved in fear, anger, pleasure, and aggresion; located in the diencephalon
Hippocampus Part of the limbic system charged with converting short-term memory into long-term memory; crucial for memory and learning
Amygdala Part of the limbic system concerned with anger, jealousy, and fear; stores, and can recall, emotions from past events; 2 almond-shaped masses of neurons on either side of the thalamus
Primary motor cortex Sends impulses to muscles necessary to pronounce words
Primary visual cortex Stimulated by written words
Broca's area Plans the muscle movements required of the larynx, tongue, cheeks, and lips to form words then sends the appropriate impulses back to the primary motor cortex
Wernicke's area Formulates words into phrases that comply with learned grammatical rules; responsible for language comprehension
Angular gyrus Translates written words into a form that can be spoken
Olfactory association area Interprets the sense of smell
Auditory association area Gives us the ability to recognize familiar sounds
Primary auditory complex Responsible for hearing
Primary gustatory complex Handles the interpretation and sensation of taste
Visual association area Interprets information acquired through the primary visual cortex; allows us to recognize familiar objects
Primary visual cortex Responsible for sight; governs the recognition of size, color, light, motion, and dimension
Cranial nerves 12 pairs of nerves that relay messages to the rest of the body
Autonomic nervous system ANS; Subdivision of the nervous system responsible for regulating the activities that maintain homeostasis; visceral motor system
Sympathetic division Division of the ANS that prepares the body for physical activity; called into play during extreme stress, anger, or fear; "fight or flight" reaction; thoracolumbar division
Parasympathetic division Division of the ANS that has a calming effect on body functions; craniosacral division
Adrenal medulla Center of the adrenal gland that secretes a mixture of the hormones epinephrine and norepinephrine into the bloodstream when stimulated
Cholinergic fibers Neurotransmitter of the ANS that secretes acetylcholine; includes the preganglionic fibers of both the sympathetic and parasympathetic divisions as well as the postganglionic fibers of the parasympathetic division
Adrenergic fibers Neurotransmitter of the ANS that secretes norepinephrine; includes most of the postganglionic fibers of the sympathetic division
Nicotinic receptors Cholinergic receptors that are excited by ACh;occur within the ganglia of the ANS, in the adrenal medulla, and the neuromuscular junction
Muscarinic receptors Cholinergic receptors with a vaiable response to ACh; occur on the glands, smooth muscle, and cardiac muscle cells of the organs innervated by cholinergic fibers
Alpha-adrenergic receptors Excited by norepinephrine
Beta-adrenergic receptors Inhibited by norepinephrine
Dual innervation Occurs in most organs; organs receive nerve fibers from both the sympathetic and parasympathetic divisions
Created by: cbooher16