| function of the nervous system | organized to detect changes in internal and external environment, eveulaate the info and imitate an appropriate response |
| central nervous system | consist of the brain and the spinal cord, integrates sensory info, evaluates it, and inters an outgoing response |
| cperipheral nervous system | nerves that lie in the outer regions of the nervous system |
| cranial nerves | originate from the brain |
| spinal nerves | originate from the spinal cord |
| fafferent divison | consist of all incoming sensory pathways |
| efferent divison | econsist of all outgoing motor pathways |
| somatic nervous system | carries info to the somatic effectors (skeletal muscles), and carries feedback info to the somatic integration centres in the CNS |
| autonomic nervous system | efferent division carries info to the autonomic or visceral effectors (cardiac muscles, smooth muscles, glands & adipose tissues) |
| glia cells | support the neurons |
| astrocytes | in the CNS, star shaped, largest and most numerous type of glia, connect to both neurons and capillaries, transfer nutrient from the blood to the neurons |
| microglia | in CNS small usually stationary cells found in inflamed brain tissue, they enlarge and move about. they cary on phagocytes |
| ependymal | in CNS, resemble epithelial cells and form thin sheets that line fluid filled cavities in the CNS, some produce fluid and other aid in circulation of fluid |
| oligodendrocytes | in CNS, smaller than astrocytes with fewer processes, hold nerve fibres together and produce the myelin sheath |
| schawn cells | in PNS, found only in peripheral neurons, support nerve fibres and form myelin sheaths |
| myelin sheath | these gaps are often called nodes of ranvier |
| neurilemma | ormed by the cytoplasm of the Schwann cells, wrapped around the myelin sheath, essential fro nerve regrowth |
| satellite cells | they are Schwann cells that cover and support cell bodies in the PNS |
| neurons | excitable cells that imitate and conduct impulses that make possible all nervous system functions |
| components of neurons | cell body, ribosomes, rough endoplasmic reticulum, Golgi apparatus |
| ribosomes, rough ER and golgi | provide protein molecules needed for transmission of nerve signals from one neurone to another, neurotransmitters are packaged into vesicles, provide proteins for maintaining and regenerating nerve fibres |
| mitochondria | provide energy (ATP) for neurone, and some are transported to end of an axon |
| dendrites | conduct nerve signals to the cell body of the neuron |
| axon | a single process extending form the axon hillock, sometimes covered by a fatty layer called a myelin sheath, conducts nerve impulses away from the cell body of the neuron, distal tips of axons are telodendria |
| input zone | dendrites and cell body |
| summation zone | axon hillock |
| conduction zone | axon |
| output zone | telodendria and synaptic knobs of axon |
| multipolar | one axon and several dendrites |
| bipolar | only on axon and one dendrite, least numerous kind of neuron |
| unipolar (pseudo unipolar) | one process come off neuron cell body, but divides almost immediately into two fibres central fibre and peripheral fiber |
| afferent neurons | conduct impulses to spinal cord or brain |
| efferent neurons | conduct impulses away from spinal cord or brain toward muscles or glandular tissue |
| reflex arc | a signal conduction route to and from the CNS with the electrical signal beginning in receptors and ending in effectors |
| three neuron arc | most common, consists of afferent neurons, interneurons and efferent neurons |
| synapse | when nerve signals are transmitted from one neuron to another |
| chemical synapse | located at the junction of the synaptic knob of one neuron and the dendrites or cell body of another neuron |
| nerves | bundles of peripheral nerve fibres held together by several layers of connective tissues |
| endonurium | delicate layer of fibrous connective tissue surrounding each nerve fibre |
| perineurium | connective tissue holding together fascicles (bundles of fibers) |
| epineurium | fibrous coat surrounding numerous fascicles and blood vessels to form a complete nerve |
| e tracts | bundles of nerve fibres within the CNS, unlike nerves, tracts do not have connective tissue coverings |
| white mater- PNS | myelinated nerves |
| white mater- CNS | myelinated tracts |
| egrey matter | made up of cells bodies and unmyleinated fibres |
| grey mater- CNS | referred to as nuclei |
| grey matter-PNS | referred to as ganglia |
| mixed nerves | contain sensory and motor neurons |
| sensory nerves | nerves with predominantly sensory neurons |
| motor nerves | nerves with predominantly motor neurons |
| membrane potentials | slight excess of positively charged ions on the outside of the membrane and slight deficiency of positively charged ions on the inside of the membrane |
| nerve impulse- potential | difference in electrical charge |
| polarized membrane | a membrane that exhibits a membrane potential |
| resting membrane potential | The membrane’s selective permeability characteristics help maintain a slight excess of positive ions on the outer surface of the membrane |
| sodium potassium pump | active transport mechanism in plasma membrane that transports Na+ and K+ in opposite directions and at different rates |
| local potentials | slight shift away from the resting membrane in a specific region of the plans membrane |
| excitation | when a stimulus triggers the opening of additional Na+ channels, allowing the membrane potential to move toward 0 (depolarization) |
| inhibition | when a stimulus triggers the opening of additional K+ channels, increasing the membrane potential (hyperpolarization) |
| graded potentials | the magnitude of deviation form the resting membrane potential is proportional to the magnitude of the stimulus |
| action potential | the membrane potential of a neuron the tis conducting an impulse, also known as nerve impulse |
| absolute refractor period | brief period during which a local area of a neurons membrane resists re stimulation and will not respond to a stimulus, no matter how strong |
| relative refractory period | time during which the membrane is depolarized and restoring the resting membrane potential, the few milliseconds after the absolute refractor person, will respond to ONLY a very strong stimulus |
| electric synapses | the cells join dby gap junctions allow an action potential to simply contrite along postsynaptic membrane |
| chemical synapses | presynaptic cells release chemical transmitters across a tiny gap to the postsynpatical cell possibly inducing an action potential there |
| synaptic knob | tiny bulge at the end of a terminal branch of a presynaptic neurons axon that contains vesicles housing neurotransmitters |
| synaptic cleft | space between a synaptic knob and the plasma membrane of a postsynaptic neuron |
| axodendrite | axon signals postsynaptic dendrite, they are common |
| axiomatic | axon signals postsynaptic soma, they are common |
| axoaxonic | axon signals postsynaptic axon, may regulate action potentials of postsynaptic axon |
| plasma | membrane of a postsynaptic neuron, has protein molecules that serve s receptors for the neurotransmitters |
| acetylcholine | small molecule neurotransmitter, present at various locations, sometimes in an excitatory role; other times, inhibitory |
| amines | synthesized from amino acid molecules, found in various regions of the brain, affecting learning, emotions, motor control |
| amino acids | the most common neurotransmitters of the CNS, in the PNS amino aids are stored in synaptic vesicles and used in neurotransmitters |
| neuropeptides | short strands of amino acids called polypeptides, they have regulatory effects in the digestive tract and act as neurotransmitters in the brain |
| sensory neurons | act as receptors to detect changes in the internal and external environment; relay information to integrator mechanisms in the CNS, |
