click below
click below
Normal Size Small Size show me how
A&P I Chapter 11
Question | Answer |
---|---|
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 |
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. |