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Nervous system Ch
Chapter 10 definitions
| Term | Definition |
|---|---|
| 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
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