chapter 9

the greater the diameter of an axon, the ____ the impulse

faster

the nervous system contains specialized communicating nerve cells called and supporting cells called

neurons and neuroglia

narrow gaps in the myelin sheath are called

nodes

what is the function of the autonomic nervous system

not-controlled, involuntary, smooth muscle

_______ form myelin in the central nervous system

oligodendrocytes

the internist layer, the ___ _____, is thin and contains many blood vessels and nerves

pia matter

in the autonomic motor system, motor pathways include two fibers: a _______ leaves the CNS, and a _______ fiber that innervates the effector

preganglionc, postganglionic

_____ axons conduct impulses over their entire membrane surface

unmyleinated

an _____ _____ is not graded, therefore it is an all-or-none response. a greater intensity of stimulation does not produce a stronger response, instead; it produces more _____ _____ per second

action potential, action potentials

the middle layer, the ____ _____, is thin and lacks blood vessels and looks like a spider web

arachnoid matter

function of the neurolimma?

assist in repairing damaged axons

_____ are near blood vessels and support structures, aid in metabolism, and respond to brain injury by filling in spaces

astrocytes

in what structure is the cell body of the second neuron located?

automatic ganglion

nerve fibers contain a solitary outgoing ___ and numerous _____ which bring in impulses from receptors

axon and dendrite

Nerves are bundles of

axons

the central nervous system is composed of the

brain and spinal cord

fibers in the parasympathetic division arise from the _____ and the ____ region of the spinal cord, and synapse in the ganglia close to the effector organ.

brainstem and sacral

1. structure: a neuron has a ____ ____ with mitochondria, lysosomes, a golgi apparatus, chromatophillic substance (nissil bodies) containing rough endoplasmic reticulum, and neurofibrils

cell body

neuroglia fills spaces, support neurons, provide structural frameworks, produce myelin, and carry phagocytosis. four types are found in the and one main type is found in the.

cns and pns

what is the function of the somatic nervous system

controlled movements

A single neuron within a pool may receive impulses from two or more fibers. This is called __________, and makes it possible for the neuron to summate impulses from different sources.

convergence

impulses leaving a neuron in a pool may be passed into several output fibers. this is called _____ and serves to amplify an impulse.

divergence

the brain and spinal cord are surrounded by membranes called meninges that lie between the bone and the soft tissues. the outermost later is made up of tough dense connective tissue, contains many blood vessels, and is called the ______ _____

dura matter

_____ cover choroid plexuses and form inner linings that enclose ventricles of the brain

ependyma

the stealth around the spinal cord is separated from the vertebrae by a ____ space

epidural

the outer layer of covering in the mylienated pherphrial neurons called the ______

neurolimma

what are the general functions of the nervous system

gather information, connect it to the nerve impulses, infrigerate sensory impulses in the brain as perceptions, desisions leading to motor skills

_______ are multipolar neurons within the cns that forms links between other neurons

interneurons

what is the function of the autonomic nervous system

maintain homeostasis of visceral activities without conscious effort

______ cells are small cells that phagocytize bacterial cells and cellular debris

micrological

Nerves containing both sensory and motor fibers are called _____________ nerves.

mixed

____ neurons are multipolar neurons that conduct impulses from the cns to effectors

motor

_____ nerves carry impulses from the CNS.

motor

2. classifications of structures: name the 3 types of neurons as classified by structure. how do they differ?

multipolar-many nerve fibers. bipolar, single axon and single dendrite unipolar

larger axons in the PNS are enclosed by _____ sheaths provided by _____ cells

myelin and schwann

____ axons conduct impulses from node of Raniver to node of Ranvier, a phenomenon called ___ conduction. this conduction is many times faster.

myelinated , saltatory

the pheripheral nervous system is composed of pheriprial

nerves

a reflex arc includes a sensory ____, a ____ neuron, one of more _____ that serve as a reflex center, a _____ neuron whose axons pass out of the CNS, and a ____ ____ that carries out the reflex response.

receptor, sensory, effectors, interneuron, motor neuron

______ cells are the myelin-producing neuroglia of the pheriphal nervous system

schwann cells

nerves that bring sensory information into the CNS are called ______ neurons

sensory

3. classification by function: _____ neurons (affrent neurons) conduct impulses from pheriphereal receptors to the cns, and usually have a ______ stricture, but may also have a ____ structure.

sensory, unipolar, bipolar

between the middle and the innermost layers is a ____ space containing _____ fluid.

subarachnoid, cerebrospinal

a particular neurons of a pool may receive excitatory or inhibitory stimulation; if the net effect is excitatory but _____ the neuron becomes more excitable to incoming stimulation (a condition called facilitation)

subthreshold

What are the 2 divisions of the autonomic nervous system?

sympathetic and parasympathetic

fibers in the sympathetic division arise from the ____ and ___ regions of the spinal cord, and synapse in ____ ganglia close to the vertebral column.

thoracic, lumbar, paracertabral