Chapter 12

Nerves that lie in the outer regions of the nervous system

Originates from the brain

Originates from the spinal cord

Consists of all incoming sensory pathways

Consists of all outgoing motor pathways

Carries information to the somatic effectors (skeletal muscles)

Carries feedback information to somatic integration center in the Central Nervous System

Prepares the body to deal with immediate threats to the internal enviroment; produces fight or flight response

Coordinates the body's normal resting activities; sometime called the "rest and repair" division

conduct impulses away from spinal cord or brain toward muscles or glandular tissue

conduct impulses to spinal cord or brain

onle one axon and one dendrite; least numerous kind of neuron

one process comes off neuron cell body but divides almost immediately into two fibers; central fiber and peripheral fiber

one axon and several dendrites

Dendrites and cell body are in what functional region of the neurons

Axon hillock are in what functional region of the neuron

axon is in what function region of the neuron

telodedria and synaptic knobs of axon are in what function region of the neuron

a single process extending from the axon hillock, sometimes covered by a fatty layer is called a

swellings that make contact (synapse) with other cells

small knoblike protrusions on dendrites of some brain neurons; serve as connection points for axons of other neurons

conducts impulses to the CNA from the receptors

conduct impulses from the CNS to effectors (muscle or glandular tissue)

most common; consists of afferent neurons, interneurons, and efferent neurons

simplest form; consists of afferent and efferent neurons

nerves with predominatly motor neurons

nerves with predominantly sensory neurons

in gray matter and referred to as nuclei

in gray matter referred to as ganglia

in white matter the myelinated nerves

in white matter the myelinated tracts

fibrous coat surrounding numerous fascicles and blood vessels to form a complete nerve

connective tissue holding together fascicles (bundles of fibers)

delicate layer of fibrous connective tissue surrounding each nerve fiber

bundles fo peripheral nerve fibers held together by several layers of connective tissue

when a stimulus triggers the opening of additional K+ channels, increasing the membrane potential (hyperpolarization)

whena stimulus triggers theopening of additionl na+ channels, allowing the membrane potential to move toward zeoro (depolarization)

slight shift ways formt he resting membrane in a specific region of the plasma membrane

a membrane that exhibits a membrane potential

slight excess of positively charged ions on the outside of the membrane and slight deficientcy of positively charged ions on the inside of the membrane

the membrane potential of a neuron that is conducting an impulse; also known as a nerve impulse

brief period (0.5ms) during which a local area of a neuron's membrane resists restimulation and will not respond to a stimulus, no matter how strong

time during which the membrane is repolarized and restoring the resting membrane potential; the few milliseconds after the absolute refractory period; will respond only to a very strong stimulus

occurs where cells joined by gap junctions allow an action potential to simply contine along postsynaptic membrane

occur where presymaptic cells release chemical transmitters (neurotransmitters) across a tiny gap to the postsymaptic cell possible inducing an action potential there

timy buldge at the end of a terminal branch of a presymaptic neuron's axon that contains vesicles housing neurotransmitters

space between a symaptic knob and the plasma membrane of a postsymaptic neuron

axon signals postsynaptic dendrite; common

axon signals postsynaptic soma; common

axon signal postsynaptic axon; may regulate action potential of postsynaptic axon

adding together the effects of several knobs being activated simultaneously and stimulating different locations on the postsynaptic membrane producing an action potential

when synaptic knobs stimulate a postsynaptic neuron in rapid succession, their effects can summate over a brief period of time to produce an action potential

stored by facilitating (or inhibiting) synaptic transmission

(sec or min) may result from axoaxonic facilitation or inhibition of the presynaptic axon terminal

(min to weeks) happens when serotonin blocks potassium channels in the presynaptic terminal thus prolonging the action potential and increasing the amount of neurotrasmitter released

(month or yrs) requires structural changes at the synapse

means by which neurons communicate with one another; more than 30 compounds

the mechansim by which neurotrasmitters cause a change; function vary by location, they are usually classified according to chemical structure

neuropeptides

(nerve growth) stimulate neuron development but can act as neurotrasmitter

proposes neuron is basic structural and function unit of the nervous system and neurons are independent units connected by chemical synapses

proposes nervous system is best unerstood as a large integrated network

act as receptors to detect changes in the internal and external environment; relay information to integrator mechanisms in the CNS

tumors arising in nervous system structure

a common type of brain tumor

a type of brain tumor (glioma) that originates from astrocytes

a highly malignant form of astrocytic tumor that spreads throughout the white matter of the brain

a glial tumor arising from ependymal cells which line the fluid filled cavities of the brain and spinal cord

tumor that commonly occurs in the anterior portion of the brain and has a perak incidence at 40 yrs of age. Would be glioma of oligodendrocytes

a lesion of the sheath of Schwann cells surrounding the eighth cranial nerve, responsible for hearing and balance

is an inheritied disease characterized by numerous fibrous neuromas throughout the body

the enzyme that inactivates dopamine and serotonin

nerve growth factors that are release by various cells of the body