| Question |
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| Answer |
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| Central Nervous System (CNS) consists of? |
The brain, spinal cord - in dorsal cavity. |
| The CNS is the __ of the nervous system. |
Integrating & command center. |
| The peripheral Nervous System (PNS) consists of? |
The nerves (bundles of axons) that extend FROM brain & spinal cord - spinal & cranial nerves. |
| The peripheral nerves serve as? |
Communication lines that link all parts of the body to CNS. |
| 2 functional subdivisions of PNS are? |
Motor/efferent division (to CNS) & sensory/afferent division (away from CNS). |
| Sensory/Afferent Division |
Consists of nerve fibers that convey impulses to the CNS from sensory receptors t/o the body. |
| Sensory fibers conveying impulses from skin, skeletal muscles, & joints are called __. |
Somatic afferent fibers (soma=body). |
| Sensory fibers transmitting impulses from visceral organs. |
Visceral afferent fibers |
| Role of the motor/efferent division? |
Transmits impulses from CNS to effector organs - muscles & glands - they effect a motor response. |
| The motor division of the PNS has 2 main parts. |
(1) Somatic nervous system (voluntary), (2) autonomic nervous system (ANS) (involuntary). |
| Another name for the somatic nervous system? |
Involuntary (autonomic) nervous system |
| The autonomic (involuntary) nervous system has 2 divisions. |
Sympathetic & parasympathetic |
| The sympathetic & parasympathetic work in __. |
Opposition - what one stimulates, the other inhibits. |
| Nervous tissue made of which 2 principal types of cells? |
(1) supporting cells, (2) neurons |
| Glia cells provide a __ for neurons. |
Supportive scaffolding |
| Name the neuroglia in the CNS. |
Astrocytes, microglia, ependymal cells, & ogligodendrocytes. |
| Like neurons, most glial cells have __. |
Branching processes (extensions) & central body. |
| Neuroglia can be distinguished by their __. |
Their much smaller size & darker - staining nuclei. |
| Neuroglia make up about __ mass of brain. |
Half |
| Astrocytes |
Most abundant & versatile glial cells - exchanges between capuillaries & neurons, guide migration of young neurons. |
| Which neuroglia "mop up" leaked potassium ions & recapturing released neurotransmitters. |
Signaling one another by slow-paced intracellular calcium pulses (calcium sparks) & they participate in info. processing in brain. |
| Microglia |
Small ovoid cells - monitor health of nearby neurons - phagocytize microorganisms or neuronal debris. |
| Cells of the immune system are denied access to the CNS, so __ are important to phagocytize invading microorganisms. |
Microglia |
| Ependymal Cells |
Squamous to columnar in shape & many are ciliated - line central cavities of brain & spinal cord - circulate the cerebrospinal fluid. |
| Oligodendrocytes |
Wrap their processes around neuron fibers to produce insulating coverings called myelin sheaths. |
| Name the 2 neuroglia of the PNS. |
(1) Satellite cells & (2) Schwann cells |
| Satellite cells |
Surround neuron cell bodies in PNS - unknown purpose. |
| Schwann cells |
Neurolemmocytes - form myelin sheaths around lg. nerve fibers in PNS. Vital to regen. of damaged peripheral nerve fibers. |
| Which neuroglia are vital to regeneration of damaged PN fibers? |
Schwann cells |
| Special characteristics of neurons are? |
(1) extreme longivity, (2) amitotic (can't divide), & (3) high metabolic rate. |
| Perikaryon |
Neuron cell body (soma) - major biosynthetic center of a neuron. |
| Nissl bodies |
Rough ER of neuron - probably the most active & best developed in body. |
| Neurofibrils |
Bundles of intermediate filaments (neurofilaments) - maintain cell shape & integrity. |
| Lipofuscin |
"Aging Pigment" - accumulates in neurons of elderly individuals. |
| Clusters of cell bodies in CNS are called __. |
Nuclei |
| Clusters of cell bodies that lie along nerves of PNS are called __. |
Ganglia |
| Bundles of neuron processes are called __ in the CNS and __ in the PNS. |
Tracts, nerves |
| Any long axon is called a __. |
Nerve fiber |
| Some axons have occasional branches called __. |
Axon collaterals |
| Axon endings usually have 10,000 or more __ per neuron. |
Terminal branches, or telodendria |
| Knoblike distal endings of terminal branches have various names like __. |
Axon terminals, synaptic knobs, or boutons. |
| The conducting region of the neuron. |
Axon |
| The axon functions to __ & __. |
Generates nerve impulses & transmits them. |
| Axons differ fromdendrites & cell body in 2 important ways. |
lacks nissl bodies (rough ER) & golgi apparatus. |
| Axon depends on __ to renew necessary proteins. |
Its cell body |
| Axolemma |
Axon plasma membrane |
| What viruses & bacterial toxins use retrograde axonal transport? |
Polio, rabies, herpes simples, & tetanus. |
| Dendrites are always __. |
Unmyelinated |
| Myelin sheaths in the PNS are formed by? |
Schwann Cells |
| Neurilemma |
Portion of Schwann cell's plasma membrane that bulges due to nucleus & cytoplasm. |
| Gaps in the myelin sheath are called __. |
Nodes of Ranvier or neurofibril nodes. |
| Axon collaterals emerge from the axon at __. |
Nodes of Ranvier (neurofibril nodes) - gaps in myelin sheath. |
| Myelin sheaths are formed by __ in the CNS. |
Oligodendrocytes |
| CNS myelin sheaths lack neurilemma because? |
Cell extensions are doing the coiling - by oligodendrocytes. |
| White matter contains __ fibers. |
Myelinated |
| Gray matter contains __ fibers. |
Unmyelinated |
| Neuorons are grouped structurally according to __. |
Numbers of processes extending from cell body. |
| 3 major neuron groups - structurally. |
Multipolar, bipolar, & unipolar (psudounipolar) |
| Most common polar class of neurons is __. |
Multipolar neurons - 99% |
| Bipolar neurons are rare & found where? |
Sense organs like retina of eye & olfactory mucosa. |
| Psudounipolar neurons are found where? |
In ganglia in PNS as sensory neurons. |
| 3 functional classes of neurons. |
Sensory, motor, & interneurons. |
| Virtually all sensory neurons are __. |
Unipolar |
| Sensory (afferent) neurons transmit impulses __ sensory receptors. |
To |
| Motor (efferent) neurons carry messages __ CNS to organs. |
Away from |
| Cell bodies of sensory neurons are located __ CNS while motor neurons are __ the CNS. |
Outside, in |
| 99% of neurons in body are __. |
Interneurons in CNS (multipolar). |
| Interneurons are organized in information-processing __. |
Blocks (circuits) |
| Reflex arc |
Sensory neurons synapse directly on motor neurons - simplest path of info flow. |
| CNS (Central Nervous System) |
Brain, spinal cord, interneurons |
| PNS (Peripheral Nevous System) |
Nerves - somatic & autonomic subdvisions |
| Ganglia |
Cell bodies of several neurons that occur in clusters. |
| Name a demyelinating disease. |
Multiple Sclerosis (MS) - autoimmune disease. |
| Group A nerve fibers |
Thick myelin sheaths & diameter - Somatic sensory & motor - sense skin, skeletal muscles, & joints. |
| Group B nerve fibers |
Lightly myelinated - autonomic NS - visceral organs, pain & touch of skin. |
| Group C nerve fibers |
Unmyelinated - smalles diameter - no saltatory conduction. |
| Synapses between axon ending of 1 neuron & dendrites of other are __ synapses. |
Axodendric |
| Synapse between axon of 1 neuron & cell bodies of others are __ synapses. |
Axosomatic |
| Neurons have between __ axon terminals making synapses. |
1000 - 10,000 |
| Electrical synapses |
less common - gap junctions - protein channels - eye jerks, embryonic tissue, glial cells in CNS. |
| Inhibitory synapses occur most often on the __. |
Cell body |
| Excitatory synapses occur most often on the __. |
Dendrites |
| __ & __ are the "language" of the N.S. |
Neurotransmitters & electrical signals. |
| Biogenic Amines |
Include: dopamine, norepinephrine, etc - are catecholamines & indolamines - emotional behavior & bio clock - mental illness. |
| Peptides |
Pain & pleasure - gut-brain peptides. |
| Purines |
ATP - fast excitatory responses, adenosine (inhibiter of caffine) |
| Dissolved gases |
Nitrous Oxide, & Carbon Monoxide |
| Channel-linked receptors |
Change shape - ligand-gated ion channels (ionotropic receptors) |
| G Protein-linked receptors |
Metabotropic receptors - slow, go-betweens |
| Neuronal pools |
Functional groups of neurons that process & integrate info. |
| Diverging Circuits |
Amplifying circuits - common in sensory & motor sys. |
| Converging Circuits |
Have concentrating effect - putting it all together. |
| Reverberating (oscillating) circuits |
Involved in control of rhythmic activities like: sleep-wake, breathing, arm swinging. Oscillates for seconds, hours, etc. |
| Serial processing |
Input travels along 1 pathway - reflex arc |
| Parallel processing |
Input travels along several pathways to be integrated in a different pathway. Associations. |
| N.S. originates from a __ & __ formed from surface __. |
Neural tube, neural crest - surface ectoderm. |
Ch.18 LTI-MA 509
