| A | B |
|---|
| neurons | nerve cells |
| nerve impulses | information sent as electrochemical changes on neurons |
| cell body | rounded area of the cell |
| dendrites | may be numerous, recieve electrochemical messages |
| axons | extensions that send information in the form of nerve impulses |
| nerves | bundles of axons |
| neuroglial cells | provide physical support, insulation and nutrients for neurons |
| central nervous system (CNS) | brain and spinal cord |
| peripheral nervous system (PNS) | composed of the nerves that connect the central nervous system to the other partsof the body |
| sensory receptors | at the ends of peripheral neurons, gather information by detecting chemical changes inside and outside the body |
| effectors | responsive structures that pick up the chemical messages |
| somatic nervous system | consciously controlled nerves, ie skeletal muscles |
| autonomic nervous system | controls effectors that are involuntary, ie the heart |
| myelin | a fatty lipoprotein on neurons |
| Schwann cells | neuroglial cells that form a myelin sheath around xons |
| neurofibrils | a network of fine threads that extend into the axon |
| chromatophilic substance | numerous membranous sacs scattered throughout the cytoplasm |
| neurilemma | surrounds the myelin sheath |
| nodes of Ranvier | narrow gaps between Schwann cells |
| trigger zone | a sensitive region of the axon that begins the nerve impulse |
| ganglia | specialized masses of nervous tissue located outside the brain and spinal cord |
| resting potential | potential difference between the region inside the membrane and the region outside the membrane |
| threshold potential | the result of summated potentials |
| action potential | the rapid sequence of depolarization and repolarization |
| nerve pathways | complex pathways on which nerve impulses travel on |
| synapse | the junction between any two communicating neurons |
| neurotransmitters | biochemicals that carry out synaptic transmission |
| excitatory | neurotransmitters that increase postsynaptic membrane permeability to sodium ions that will bring the postsynaptic menmbrane closer to threshold and may trigger nerve impulses |
| inhibitory | neurotransmitters that make it less likely that threshold will be reached |
| neuronal pods | pods in which the neurons in the central nervous system are organized into |
| facilitation | when a neuron is more excitable to incoming stimulation than before |
| convergence | what axons originating from different parts of the nervous system and lead to the same neuron exhibit |
| divergence | what impulses leaving a neuron of a neuronal pool experience |
| sensory fibers | neuron processes that bring sensory information into the CNS |
| afferent fibers | neuron processes that bring sensory information into the CNS |
| motor fibers | neurons that carry impulses from the CNS to effectors |
| efferent fibers | neurons that carry impulses from the CNS to effectors |
| sensory nerves | nerves that conduct impulses to the brain or spinal cord |
| motor nerves | nerves that carry impulses to muscles or glands |
| mixed nerves | nerves that include both sensory and motor fibers |
| reflex arc | a nerve pathway that forms the structural and functional bases for a reflex |
| reflexes | involuntary actions |
| meninges | layered membranes that lie between the bony covering and the soft tissues of the central nervous system, protecting the brain and spinal cord |
| dura mater | outermost layer of the meninges |
| arachnoid mater | a thin, weblike membrane without blood vessels that lies between the dura and pia maters |
| cerebrospinal fluid (CSF) | a clear, watery substance in the space between the arachnoid and pia maters |
| pia mater | a very thin layer that contains many nerves and blood vessels that nourish underlying cells of the brain and spinal cord |
| spinal cord | a slender nerve column that passes downward from the brain into th vertebral canal |
| spinal nerves | a pair of nerves in the spinal column that branch to various body parts and connect them with the central nervous system |
| nerve tracts | major nerve pathways consisting of longitudial bundles of myelinatde nerve fibers |
| central canal | contains cerebrospinal fluid |
| ascending tracts | the tracts that carry sensory information to the brain |
| descending tracts | the tracts that conduct motor impulses from the brain to the muscles and glands |
| spinal reflexes | reflex arcs that pass through the spinal cord |
| cerebrum | the largest part of the brain, includes nerve centers associated with sensory and motor functions and provides higher mental functions |
| brain | composed of about 100 billion multipolar neurons which communicate with one another and with neurons in other parts of the nervous system |
| diencephalon | processes sensory information |
| brainstem | includes nerve pathways that connect various parts of the nervous system and regulate certain visceral activities |
| cerebellum | includes centers that coordinate voluntary musclar movements |
| cerebral hemispheres | two large masses, left and right, mirrior images of each other |
| corpus callosum | a deep bridge of nerve fibers that connects the cerebral hemispheres |
| convolutions | many shallow ridges on the surface of the cerebrum that are seperated by many grooves |
| sulcus | a shallow groove |
| fissure | a deep groove |
| cerebral cortex | a thin layer of grey matter that forms the outermost portion of the cerebrum |
| motor areas | the region of the brain from which impulses to muscles or glands originate |
| sensory areas | a portion of the cerebral cortex that receives and interprets sensory nerve impulses |
| association areas | region of the cerebral cortex controlling memory, reasoning, judgement, and emotions |
| dominant hemishpere | controls the ability to use and understand language |
| ventricles | a series of interconnected cavities within the cerebral hemispheres and brainstem |
| choroid plexuses | tiny, reddish, cauliflower-like mases of specialized capillaries from pia mater |
| thalamus | a mass of gray matter at the base of the cerebrum |
| hypothalamus | a region of the diencephalon that is a mass of grey matter |
| optic tracts | formed by the optic nerve fibers crossing over each other |
| optic chiasma | formed by the optic nerve fibers crossing over each other |
| infundibulum | a conical process behind the optic chiasma to which the pituitary gland attaches |
| posterior pituitary gland | hangs from the floor of the hypothalamus |
| mammillary bodies | appear as two rounded structures behind the infundibulum |
| pineal gland | a cone-shaped structure attached to the upper portion of the diencephalon |
| limbic system | controls emotional experience and expression |
| midbrain | a short section of the brainstem between the diencephalon and the pons that has several masses of grey matter serving as reflex centers |
| pons | a rounded bulge on the underside of the brainstem that relay sensory impulses from peripheral nerves to higher brain centers |
| medulla oblongata | extends from the pons to the foramen magnum |
| reticular formation | a network of nerve fibers that extend from the upper portion of the spinal cord into the diencephalon |
| cerebellar cortex | a thin layer of grey matter on the cerebellum's surface |
| cranial nerves | twelve pairs of nerves that arise from the upper side of the brain |
| olfactory nerves | associated with the sense of smell |
| optic nerves | associated with the eyes |
| oculomotor nerves | associated with the eyelid |
| trochlear nerves | associated with the fith voluntary muscle in the eye, smallest |
| trigeminal nerves | associated with the facial muscles, largest |
| abducens nerves | associated with the movement of the eye |
| facial nerves | associated with the movement of facial expressions |
| vestibulocochlear nerves | associated with the ear |
| glossopharyngweal nerves | associated with the tounge and pharynx |
| vagus nerves | associated with the larynx |
| accessory nerves | associated with the parnyx and larynx |
| hypoglossal nerves | associated with speaking, eating and swallowing |
| spinal nerves | associated with the spinal cord |
| dorsal root | the posterior or sensory root, the sensory branch of a spinal nerve by which it joins the spinal cord |
| ventral root | motor branch of a spinal nerve by which it connects which the spinal cord |
| plexuses | complex networks of spinal nerves |
| cervical plexuses | lie deep in the neck on either side and form the branches of the first four cervical nerves |
| phrenic nerves | right and left, conduct motor impulses to the muscle fibers of the diaphragm |
| brachial plexuses | a network of nerve fibers located deep in the shoulders between the neck and axillae |
| musculocutaneous nerves | nerves that branch off of the brachial plexuses |
| ulnar nerves | nerves that branch off of the brachial plexuses |
| median nerves | nerves that branch off of the brachial plexuses |
| radial nerves | nerves that branch off of the brachial plexuses |
| axillary nerves | nerves that branch off of the brachial plexuses |
| lumbosacral plexuses | networks of nerve fibers that extend from the lumbar region of the back into the pelvic cavity, that give rise to a number of motor and sensory fibers associatedwith the muscles and skin of the lower abdominal wall, external genitalia, buttocks, thighs, legs, and feet |
| obturator nerves | a major branch of the lumbosacral plexuses |
| femoral nerves | a major branch of the lumbosacral plexuses |
| sciatic nerves | a major branch of the lumbosacral plexuses |
| intercostal nerves | nerves that supply motor impulses to the intercostalm uscles and the upper abdomnal wall muscles, and recieve sensory impulses from the skin of the thorax and abdomen |
| sympathetic division | portion of the autonomic nervous system that arises from the thoracic and lumbar regions of the spinal cord |
| parasympathetic division | portion of the autonomic nervous system that arises from the brain and sacral region of the spinal cord |
| preganglionic fiber | an axon that lies on a neuron between the brain and the spinal cord that leaves the CNS and synapses with one or more neurons whose cell bodies are housed within an autonomic ganglion |
| postganglionic fiber | the axon of a neuron between the brain and the spinal cord that extends to a visceral effector |
| cholinergic fibers | the preganglionic fibers of the sympathetic and parasympathetic divisions that secrete acetlcholine |
| adrenergic fibers | the sympathetic postganglionic fibers that secrete norepinephrine |
| basal nuclei | several masses of grey matter deep within the cerebral hemisphere |
