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Anatomy Chapter 13: Neural Tissue


  
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Autonomic Nervous System (ANS)
 
componenets of CNS and PNS that are concerned with the control of visceral functions
Nucleus
 
a CNS center with discrete anatomical boundaries
Center
 
a group of neuron cell bodies in the CNS that share a common function
Tract
 
a bundle of axons within the CNS that share a common origin, destination, and function
Column
 
a group of tracts found within a specific region of the spinal cord
Pathways
 
Centers and tracts that connect the brain with other organs and systems in the body
Ganglia
 
an anatomically distinct collection of sensory and motor neuron cell bodies within the PNS
Nerve
 
a bundle of axons in the PNS
gray matter
 
nerual tissue dominated by neuron cell bodies
white matter
 
neural tissue dominated by myelinated axons
neurol cortex
 
a layer of gray matter at the surface of the brain
neuron
 
the basic functional unit of the nervous system; a highly specialized cell; a nerve cell
sensory neuron
 
a neuron whose axon carries sensory info form the PNS toward the CNS
motor neuron
 
a neuron whose axon carries motor commands from the CNS toward effectors in the PNS
soma
 
the cell body of a neuron
dendrites
 
neruonal processes that are specialized to respond to specific stimuli in the extracellular environment
axon
 
a long, slender cytoplasmic process of a neuron; capable of conducting nerve impulses (action potentials)
myelin
 
a membranous wrapping, produced by glial cells, that coats axons and increases the speed of action potential propagation
neuroglia or glial cells
 
supporting cells that interact with neruons and regulate the extracellular environment, provide defense against pathogens, and perform repairs within neural tissue
effector
 
a muscle, gland, or other specialized cell or organ that responds to neural stimulation by altering its activity and producing a specific effect
receptor
 
a specialized cell, dendrite, or organ that responds to specific stimuli in the extracellular environment and whose stimulation alters the level of activity in a sensory neuron
reflex
 
a rapid, stereotyped response to a specific stimulus
somatic
 
pertaining to the control of skeletal muscle acitivity (somatic motor) or sensory info from skeletal muscles, tendons, and joints (somatic sensory)
visceral
 
pertaining to the control of functions, such as digestion, circulation, etc (visceral motor) or sensory info from visceral organs (visceral sensory)
subconscious
 
pertaining to centers in the brain that operate outside a person's conscious awareness
action potential
 
sudden, transient changes in the membrane potential that are propagated along the surface of an axon or sarcolemma
Neuroglia in PNS
satellite cells
 
-surround neuron cell bodies in ganglia
-regualte O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia
Neuroglia in PNS
schwann cells
 
-surround all axons in PNS
-responsible for myelination of peripheral axons
-participate in repair process after injury
Neuroglia in CNS
Oligodendrocytes
 
-myelinated CNS axons
-provide structural framework
Neuroglia in CNS
Astrocytes
 
-maintain blood-brain barrier
-provide structural support
-regulate ion, nutrient, and dissolved-gas concentrations
-absorb and recycle neurotransmitters
-form scar tissue after injury
Neuroglia in CNS
microglia
 
-remove cell debris, wastes, and pathogens by phagocytosis
Neuroglia in CNS
ependymal cells
 
-line ventricles (brain) and central canal (spinal cord)
-assist in producing, circulating, and monitoring cerebrospinal fluid
afferent division
 
brings sensory info to CNS
efferent division
 
carries motor commands to muscles and glands
Anaxonic neruons
 
-small, can't distinguish between axons and dendrites
-found only in CNS and special sense organs
Bipolar neruons
 
-one long dendrite that branches at the end and normal axons
-rare but important in relaying sensory info concerning sight, smell, and hearing, un-myelinated
Pseudounipolar neurons
 
-cell body situated on one side
- sensory neurons, axons may be myelinated
Multipolar neurons
 
-have several dendrites off cell body, and one axons that may have branches (what you think of)
-most common neuron in CNS
somatic sensory neruons
 
transmit info about the outside world and our position within it
-receptors: exteroceptors and proprioceptors
visceral sensory neursons
 
transmit info about internal conditions and the status of other organ systems
-receptors: interoceptors
exteroceptors
 
(outside)
-provide info about external environment in the form of touch, temp, and pressure
proprioceptors
 
(one's own)
-monitor position and movement of skeletal muscles and joints
interoceptors
 
(inside)
-moniter organ systems and provide sensations of deep pressure, pain, and taste
excitability
 
the ability of a plasmalemma to conduct electrical impulses
action potential
 
-an electrical impulse
-develops after the plasmalemma is stimulated to a level known as the threshold
rate of impulse depends on:
2
 
1. presence or absense of myelin sheath - myelinated faster
2. the diameter of the axon - larger faster
vesicular synapses
 
-AKA chemical synapses
-occurs in one direction only - presnaptic to postsynaptic
-involves the passage of a neruotransmitter substance between cells
nonvesicular synapses
 
-AKA electrical synapses, rare
-can occur in either direction
-communication junctions permitting ion flow between cells
divergence
 
-spread of info from one neuron to several neurons
-permits the broad distribution of a specific input
convergence
 
several neurons synapse on the same postsynaptic neuron
serial processing
 
info is relayed in a stepwise sequence, from one neruon to another
parallel processing
 
-several neurons are processing the same info at one time
-many different responses occur simultaneously
reverberation
 
-collateral axons extend back toward the source of an impulse and further stimulate the presynaptic nerons
-once activated, it will continue to function until synaptic fatigue or inhibitoy stimuli breaks the cycle (walking)

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