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131 CNS Tissue
CNS Tissue
| Question | Answer |
|---|---|
| CNS is made up of (2) | brain, spinal cord |
| PNS is made of (2) | nerves (cranial and spinal), ganglia (clusters of neuronal cell bodies) |
| sensory signals, aka __ | afferent signals |
| Motor signals, aka __ | efferent signals |
| sensory input (basic function) | signals picked up by sensory receptors throughout the body and are carried by nerve fibers of PNS to CNS |
| motor output (basic function) | signals carried away from CNS by nerve fibers of PNS to innervate muscles to contract, or glands to secrete |
| sensory input & motor output (location) | somatic body region, visceral body region (viscera within ventral body cavity, inner tube) |
| nervous system (summarized function) | interprets sensory input and decides what to do (integration), and dictates a response (motor output) |
| nervous tissue cell types | neurons, neuroglial cells |
| excitatory cells | neurons |
| non-conducting, wrap around, nourish, insulate, protect neurons | neuroglial cells |
| neuron (appearance) | large, complex. cell body, neuron processes (dendrites and axons), |
| neuron (what they do) | conduct electrical impulses from one part of body to another, signals transmitted along plasma membrane as nerve impulses |
| receives messages in neuron | dendrites |
| transmits messages in neuron | axons |
| cell body of neuron (simple description) | single nucleus surrounded by cytoplasm |
| chromatophilic bodies (Nissl bodies) | in cytoplasm of cell body of neutron. clusters of rough ER and free ribosomes |
| Neurofibrils | bundles of intermediate filaments that form a network between chromatophilic bodies. also prevents tearing by tensile forces |
| cell body of neuron (location) | most in CNS. clusters form ganglia of PNS |
| the 2 types of neuron processes that extend from cell body | axon, dendrites |
| dendrites (function) | receive signals from other neurons. transmit electrical signals towards cell body |
| axon (look) | 1 per neuron, arising from cone-shaped region called axon hillock. uniform diameter. |
| axon hillock | cone-shape region of cell body, where axon emerges |
| axon (function) | impulse generator and conductor, transmits impulse away from cell body |
| what gives structural support to axon | neurofilaments, actin filaments, microtubules |
| structural support aids in ______ of substances to and from cell body | axonal transport |
| longest axon? | from lumbar spine to foot, can be 3-4 ft. (axon can be short though) |
| how does diameter of axon affect impulse? | larger diameter=faster impulse because less resistance for current |
| which branches more, axons or dendrites? | dendrites |
| axons branch at ____ degree angles | 90 |
| terminal branches | branching happens usually at terminus of axon, called __ |
| axon terminals | knobbly ends of terminal branches. aka end bulbs aka boutons |
| neuron vs nerve fiber vs nerve | nerve cell; axon; collection of parallel nerve fibers of PNS |
| nerve impulse path (w/in 1 neuron) | generated where axon emerges from axon hillock; down axon; neurotransmitters poop out at synaptic cleft |
| what does nerve impulse do | excite or inhibit neurons or organs |
| describe synapse between 2 neurons | axon terminal of pre-synaptic neuron, presynaptic membrane, synaptic cleft, post-synaptic membrane, postsynaptic dendrite |
| what does presynaptic neuron do? | conducts signal towards synapse |
| what does postsynaptic neuron do? | transmits electrical activity way from synapse |
| synapses are (simple/elaborate) cell junctions | elaborate |
| synaptic vesicles (describe) | membrane-bound sacs with neurotransmitter chemicals |
| what provides energy for secretion of neurotransmitters? | mitochondria |
| what separates the plasma membrane of 2 adjacent neurons | synaptic cleft |
| structural classification of neurons (based on # processes) | multipolar, bipolar, unipolar |
| multipolar neuron (appearance) | >2 processes. 1 axon, many dendrites |
| bipolar neuron (appearance) | 2 processes: one fused dendrite, and axon on opposite side |
| unipolar (pseudounipolar) neuron (appearance) | 1 process, short. divides into 2 longer branches: central process (axonal, extends into CNS), peripheral process (dendritic, extends peripherally to receptors) |
| multipolar neuron (types, how abundant) | most are interneurons (conduct impulses within CNS), some motor neurons. 99% of neurons in body |
| bipolar neuron (types, how abundant) | in special sensory organs: inner ear, olfactory epithelium of nose, retina of eye. RARE |
| unipolar neuron (types, abundance) | sensory ganglia of PNS, as sensory neurons. rare. common in dorsal root ganglia along spinal cord and sensory ganglia of cranial nerves |
| pseudounipolar | most unipolar starts as bipolar neurons during development |
| functional classification of neurons (based on direction of nerve impulse relative to CNS) | sensory neurons, motor neurons, interneurons |
| sensory (afferent) neurons (which direction does impulse travel?) | towards CNS |
| motor (efferent) neurons (which direction does impulse travel?) | away from CNS |
| interneurons (association neurons) (which direction does impulse travel?) | uh, both? confined within CNS |
| sensory neurons (location) | cell bodies in ganglia outside CNS; central process runs into CNS, peripheral process to receptors |
| sensory neurons (structural classification?) | almost all unipolar |
| motor neurons (where does impulse go?) | effector organs: muscles and glands |
| motor neurons (structural classification?) | multipolar. |
| motor neurons (location) | cell bodies within CNS |
| motor neurons (what does it do) | forms junctions with effector cells, causing muscles to contract, or glands to secrete |
| interneurons (location) | confined to CNS, between motor and sensory neurons |
| interneuron (function) | integrates sensory input and motor output |
| interneurons (appearance) | diverse size and branching. can be single neuron connecting sensory and motor neuron, or link into chains |
| interneuron (structural classification) | multipolar |
| interneuron (abundance) | 99.98% of neurons in body |
| 3 characteristics of neurons | extreme longevity, most can't mitotic division, high metabolic rate |
| why do you get brain damage if you hold your breath too long? | neurons have high metabolic rate; need abundant oxygen and glucose; die after 5 minutes without oxygen |
| supporting cells, aka | nueroglial (glial) cells |
| glial (neuroglial, supporting) cells | cover nonsynaptic regions of neurons. insulating. |
| # of types of supporting (glial, neuroglial) cells | 4 in CNS, 2 in PNS |
| List the CNS supporting neuroglial cell types | astrocytes, oligodendocyte, microglial, ependymal |
| List the PNS supporting neuroglial cell types | satellite, schwann |
| most abundant neuroglial cell | astrocytes |
| these cell's processes form myelin sheaths around CNS nerve fibers | oligodendrocytes |
| defensive cells of CNS supporting glial cells | microglial |
| cells that line cerebral fluid filled cavities | ependymal |
| cells that surround neuron CELL BODIES within ganglia | satellite cells |
| form myelin sheaths and surround AXONS in PNS | schwann cells |
| ratio of neuroglial cells of CNS to neurons | 10:1 |
| neuroglial cells of CNS (appearance) | smaller than neurons, cell body with branching processes |
| what makes up half the mass of the brain? | neuroglial cells of CNS |
| neuroglial cells of CNS (can/cannot) divide mitotically throughout life | can |
| astrocyte (describe) | processes (look like spider) whose bulbous ends cling to neurons or capillaries |
| astrocyte (function-simple answer) | extract blood sugar from capillaries for energy |
| ____ regulates neurotransmitter levels by increasing uptake in regions of high neuronal activity | astrocyte |
| ___ signals increased blood flow through capillaries in active regions of brain | astrocyte |
| ___ takes up and releases ions to influence iconic environment around neurons | astrocyte |
| ___ helps synapses form in developing neural tissue | astrocyte |
| ___ produces molecules necessary for neural development, eg BDTF | astrocyte |
| ___ propagates calcium signals involved in memory | astrocyte |
| oligodendroctyes have (more/less) branches than astrocytes | less |
| ___ lines up in small groups and wraps their cell processes around thicker axons in CNS | oligodendrocytes |
| oligodendrocytes produce insulating coverings called ___ | myelin sheaths |
| smallest and least abundant glial cell | microglia |
| elongated cell bodies with cell processes that have many pointed projections | microglia |
| the macrophages of the CNS | microglia |
| microglia is a phagocyte. what does it do? | engulfs invading microorganisms and dead neurons |
| __ does not originate from nervous tissue, and possibly plays role in maturation of synaptic clefts | microglia |
| ___ is derived from blood cells called ___ which migrate to CNS during fetal stage | microglia; monocytes |
| Defense cells of CNS | microglia |
| ependymal cells (location) | simple epithelium that lines central cavity of spinal cord and brain |
| ___ bears cilia that help circulate cerebrospinal fluid | ependymal cells |
| Neuroglia of PNS: __ surround cell bodies, ___ surround axons | satellite, schwann (think long neck) |
| myelin sheaths are produced by __ & __ | oligodendrocytes; schwann |
| myelin sheaths surround all axons (T/F) | false, only thick |
| __ are segmented structures made of lipoprotein | myelin sheaths |
| describe a segment of myelin (made of, looks) | made of plasma membrane of a supporting cell. rolled in concentric layers |
| purpose of myelin sheath | insulates: prevents leakage, faster current |
| one schwann cell myelinates __# axon(s) | one |
| neurilemma (what is it, where) | outer layer of myelin sheath: nucleus & cytoplasm of schwann cell |
| what's the difference between thick and thin PNS axons? | thick are myelinated, and conduct impulses faster |
| describe schwann cell around a thin axon | schwann cell surrounds, but doesn't concentrically coil around axon (or bundle of axons) |
| one schwann cell can surround [one/multiple] unmyelinated axon(s) | multiple (in bundles) |
| PNS thin axons (location) | autonomic nervous system. sensory fibers |
| how are oligodendrocites different from schwann cells? | oligodendrocites have multiple processes that myelinate several axons; also have nodes of Ranvier |
| one oligodendrocite myelinates ___# axons | multiple different |
| Nodes of Ranvier | only oligodendrocites of CNS |
| thinnest axons in CNS... (what surrounds it) | are unmyelinated. covered by many processes of glial cells (ex/ astrocyte) |
| multiple sclerosis: immune system attacks ____ | the myelin around axons in CNS |
| Multiple sclerosis in men vs women | more common in women. for men, more fast and devastating |
Created by:
kokayama