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36 Cards in this Set

  • Front
  • Back
Central nervous system (CNS)
Structural and functional center of entire nervous system
• Consists of the brain and the spinal cord
• Integrates sensory information, evaluates it, and initiates
an outgoing response
Peripheral nervous system (PNS)
• Nerves that lie in “outer regions” of nervous system
• Cranial nerves —originate from brain
• Spinal nerves —originate from spinal cord
Afferent division
consists of all incoming sensory pathways
Efferent division
consists of all outgoing motor pathways
Somatic nervous system (SNS)
• Somatic sensory division —carries feedback information
to somatic integration centers in the CNS; Afferent fibers

• Somatic motor division —carries information to the
somatic effectors (skeletal muscles); Efferent fibers.
Autonomic nervous system (ANS)
• Afferent (visceral sensory) division—carries feedback
information to autonomic integrating centers in the CNS
• Efferent division of ANS —carries information to the autonomic or visceral effectors (smooth and cardiac muscles and glands)
Sympathetic division
prepares the body to deal with immediate threats to the internal environment; produces ““fight or flight” response
Parasympathetic division
coordinates the body’s normal resting activities; sometimes called the “rest and repair” division
Five major types of glia
• Astrocytes (in CNS)
• Microglia (in CNS)
• Ependymal cells (in CNS)
• Oligodendrocytes (in CNS)
• Schwann cells (in PNS)
Astrocytes (in CNS)
Star-shaped, largest, and most numerous type of glia

Astrocytes transfer nutrients from the blood to the neurons

Form tight sheaths around brain capillaries, which, with tight junctions between capillary endothelial cells, constitute the blood-brain barrier (BBB)
Microglia (in CNS)
Small, usually stationary, cells

In inflamed brain tissue, they enlarge, move about, and carry on phagocytosis
Ependymal cells (in CNS)
Resemble epithelial cells and form thin sheets that line fluid filled cavities ( ventricles) in the CNS
Oligodendrocytes (in CNS)
Hold nerve fibers together and produce the myelin sheath
Schwann cells (in PNS)
Found only in PNS

Support nerve fibers and form myelin sheaths

Gaps in the myelin sheath are called nodes of Ranvier
tha increase conduction velocity
Neurons
Excitable cells that initiate and conduct impulses that make possible all nervous system functions
Cell body (perikaryon)
Ribosomes, rough endoplasmic reticulum (ER), Golgi apparatus
Dendrites
Conduct nerve signals to the cell body of the neuron
Axon
Conducts nerve impulses away from the cell body of the
neuron
Multipolar
One axon and several dendrites
Bipolar
Only one axon and one dendrite

Least numerous kind of neuron
Unipolar (pseudounipolar)
one process comes off
neuron cell body but divides almost immediately into two
fibers: central fiber and peripheral fiber
Afferent neurons
-sensory

-conduct impulses to spinal cord or brain
Efferent neurons
-motor

-conduct impulses away from spinal cord or brain toward muscles or glandular tissue
Three-neuron arc
Most common common

Consists of afferent neurons, interneurons, and efferent
neurons
Two-neuron arc
Simplest form

Consists of afferent and efferent neurons
Synapse
• Where nerve signals are transmitted from one neuron
to another
• Two types: electrical and chemical

Chemical are typical in the adult
Nerves
bundles of peripheral nerve fibers held together by several layers of connective tissue
What are the Three types of Nerves?
- Endoneurium
- Perineurium
- Epineurium
Endoneurium
delicate layer of fibrous connective tissue surrounding each nerve fiber
Perineurium
connective tissue holding together fascicles (bundles of fibers)
Epineurium
fibrous coat surrounding numerous fascicles and blood vessels to form a complete nerve
Tracts
within the CNS, bundles of nerve fibers are called tracts rather than nerves
White matter
PNS- myelinated nerves

CNS- myelinated tracts
Gray matter
Made up of cell bodies and unmyelinated fibers

-CNS- Referred to as nuclei

PNS- Referred to as ganglia
Electrical synapses
occur where cells joined by gap junctions allow an action potential to simply continue along postsynaptic membranecontinue membrane
Chemical synapses
occur where presynaptic cells release chemical transmitters (neurotransmitters) across a tiny gap to the postsynaptic cell, possibly inducing an action potential thereinducing there