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Nerves
cns and pns
65
Anatomy
11th Grade
02/10/2010

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Term
The central nervous system
Definition
brain and spinal cord
Term
peripheral nervous system
Definition
the nerves connecting the brain and spinal cord to other parts of the body (all nerves)
Term
autonomic nerve system
Definition
division of the human nervous system that regulates involuntary actions
Term
What are the three main parts of a neuron?
Definition
dendrites, cell body, axon
Term
What is a neuron?
Definition
nerve cell including its processes(axons and dendrites)
Term
What do dendrites do?
Definition
conduct impulses to the cell body of the neuron
Term
What does the axon do?
Definition
conducts impulses away from the cell body of the neuron
Term
neurons are classified according to?
Definition
function
Term
What are the 3 different types of neurons?
Definition
sensory, motor, and interneurons
Term
What do sensory neurons do?
Definition
conduct impulses to the spinal cord and brain
Term
What do motor neurons do?
Definition
conduct impulses away from brain and spinal cord to muscles and glands
Term
interneurons?
Definition
conduct impulses from sensory to neurons to motor neurons
Term
What are glia cells?
Definition
they are supporting cells and they bring the cells of the nervous tissue together structurally and fuctionally
Term
What is a nerve?
Definition
bundle of peripheral axons
Term
What is a tract?
Definition
bundle of central axons
Term
What is white matter?
Definition
brain or cord tissue composed primarily of myelinated axons(tracts)
Term
What is gray matter?
Definition
brain or cord tissue composed primarily of cell bodies and unmyelinated fibers
Term
What kind of tissue is nerve coverings?
Definition
Fibrous connective tissue
Term
what does the endoneurium do?
Definition
surrounds individual fibers within a nerve
Term
what does the perineurium do?
Definition
surrounds a group of nerve fibers (fascicle)
Term
What does the epineurium do?
Definition
surrounds the entire nerve
Term
What is a reflex arc?
Definition
allows an impulse to travel in only one direction
Term
What happens in a reflex arc?
Definition
nerve impulses are conducted from receptors to effectors over neuron pathways or reflex arc
Term
conduction by a reflex arc results in?
Definition
a reflex(that is contraction by a muscle or secretion by a gland
Term
What is the simplest reflex arc?
Definition
two-neuron arc
Term
What does a two-neuron arc consist of?
Definition
sensory neurons synapsing in the spinal cord with motor neurons
Term
What does the three neuron arc consist  of?
Definition
sensory neurons synapsing in the spinal cord with interneurons that synapse with motor neurons
Term
What is a nerve impulse?
Definition
self-propagating wave of electrical disturbance that travels along the surface of a neuron membrane
Term
What is the mechanism of nerve impulses?
Definition

1. a stimulus triggers the opening of Na+ channels in the plasma membrane of the neuron

2. inward movement of positive sodium ions leaves a slight excess of negative ions outside at a stimulated point; marks the beginning of a nerve impulse

Term
What is a synapse?
Definition
junction between adjacent neurons
Term
What are the 2 communicating systems of the body?
Definition
nervous system and the endocrine system
Term
How are the nervous system and the endocrine system different?
Definition

nervous system transmits info very rapidly by nerve impulses conducted from one body area to another

the endocrine system transmits info more slowly by chemical secretion and circulated throughout the body

Term
What are the organs of the nervous system?
Definition

1.brain and spinal cord

2. nerves of the body

3.specialized sense organs such as eyes and ears

4. microscopic sense organs like the ones in the skin

Term
What are the 2 types of cells found in the nervous system?
Definition
neurons and glia
Term

neurons conduct______

glia____neurons

Definition

1.impulses

2.support

 

Term
Sensory neurons can also be called______neurons
Definition
afferent
Term
motor neurons can be called______neurons
Definition
efferent
Term
Interneurons can be called____or_____neurons
Definition
central or connecting
Term
what is myelin? what forms it?
Definition

lipoid substance(white and fatty) found in the myelin sheath around some nerve fibers

-scwann cells

Term
What are scwann cells?
Definition
wrap around some axons outside the CNS
Term
myelinated fiber?
Definition
axons outside the cns that are surrounded by a segmented wrapping of myelin
Term
What are nodes of Ranvier?
Definition
indentations between adjacent scwann cells
Term
What the neurilemma?
Definition
outer cell membrane of a scwann cell
Term
Which has the potential to regenerate the brain and spinal cord or the PNS? why?
Definition
Pns bc the brain and spinal cord have no neurilemma which plays a significant role in regeneration of cut and injured axons
Term
What is action potentials?
Definition
nerve impulse
Term
what is a ganglion?
Definition
a region of unmyelinated nerve tissue (PNS)
Term
What happens at the synapse?
Definition

1. the nerve impulse stops at the synapse

2.chemical signals are sent across the gap

3.then the impulse continues along the dendrites,cell body, and axon of the motor neuron

4. then the motor neuron forms a synapse with the effector

Term
What is an effector?
Definition
Term
What is the effector? 2 types?
Definition

an organ that puts the nerve signals into effect(the responding organ)

-muscles or glands 

Term
what is a withdrawal reflex?
Definition
a reflex that moves the body part away from the an irritating stimulus
Term
All interneurons lie where?
Definition
within the gray matter of the brain or spinal cord
Term
how does a nerve impulse travel?
Definition

1. they have to be intitiated by a stimulus which is pressure temp or chemical reaction

2.the membrane of each neuron has a positive outside and a negative inside.

3.when a section of the membrane is stimulated Na+ rushes inward and it moves on down the line

Term
Saltatory conduction?
Definition
when a nerve impulse encounters myelin and jumps from one mode of ranvier to the next
Term
What 3 structures make up a synapse?
Definition

1. synaptic knob

2. synaptic cleft

3.the plasma membrane of the postsynaptic neuron

Term
presynaptic neuron? postsynaptic neuron?
Definition

1. a neuron situated proximal (nearest) to a synapse

2.a neuron situated distal to the synapse

Term
What is a synaptic knob?
Definition
tiny bulge at the end of a terminal branch of a presynaptic nuerons axon
Term
each synaptic knob contains what?
Definition
small sacs or vesicles
Term
What is the synpatic cleft?
Definition
space between the a synaptic knob and the plasma membrane of a postsynaptic neuron
Term
neurotransmitters?
Definition
chemicals in which neurons communicate
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