Nervous System Part 1 Flashcards
deals with normal functioning and disorders of
the nervous system
neurology
is a physician who diagnoses and treats
disorders of the nervous system
neurologist
neurons enclosed within skull
brain
connects to brain and enclosed within spinal
cavity
spinal cord
bundles of many axons of neurons
nerves
groups of neuron cell bodies located outside of
brain and spinal cord
ganglia
networks in digestive tracts
ENTERIC PLEXUSES
monitor changes in internal or external
environments
SENSORY RECEPTORS
3 functions of the nervous system
sensory, integrative and motor function
Carry information into brain and spinal cord
through cranial and spinal nerves
Sensory receptors and sensory nerves
awareness of sensory input
perception
sensory receptors : afferent nerves
integration : _____________
information processing
Signals to muscles and glands (effectors)
motor activity
consist of Brain and spinal cord
CENTRAL NERVOUS SYSTEM (CNS)
consist of All nervous system structures outside of the CNS
PERIPHERAL NERVOUS SYSTEM (PNS)
also called as Nerve cells
neurons
Possess electrical excitability, the ability to respond to a stimulus and convert it into an action potential (electrical signal/nerve impulse) that travels along neurons
neurons
support, nourish and protect neurons
neuroglia cells
3 parts of neurons
cell body
axon
dendrites
yellowish brown granules in the
cytoplasm; product of neuronal lysosomes
Lipofuscin
collection of cell bodies outside the
CNS; serve as relay stations or
distributing centers
ganglion
neuronal process that emerges from the
cell body
nerve fiber
Little trees
Receiving or input portions
Contain numerous receptor sites
Highly branched structures that carry impulses
to the cell body
Cytoplasm contains Nissl bodies, mitochondria,
and other organelles
dendrites
Conducts nerve impulses away from the cell
body toward another neuron, muscle fiber or
gland cells
Long, thin, cylindrical projection
Emerges at cone-shaped axon hillock (small
hill)
axon
axon part nearest the axon hillock
initial segment
nerve impulses arises; junction of
the axon hillock and initial segment
trigger zone
Axon cytoplasm
axoplasm
Axon plasma membrane
axolemma
fine processes at the end of the axon
Synaptic end bulbs and varicosities
contain synaptic vesicles that can
release neurotransmitters
axon terminal
A molecule released from the synaptic
vesicle
Excites/Inhibits another neuron, muscle
fiber or gland cell
neurotransmitter
structural class that: Have several or many dendrites and one axon Most common type in brain and spinal cord
multipolar
Have one dendrite and
one axon
bipolar
where can bipolar processes extending from the body be found?
in retina of eye
inner ear
olfactory area of the brain
Have fused dendrite and
axon that emerges from
the body
unipolar
where can unipolar processes extending from the body be found?
Sensory neurons of spinal
and cranial nerves
what begins in the embryo as bipolar neurons
Pseudounipolar neurons
Convey impulses into CNS (brain or spinal
cord)
sensory neurons (afferent)
Mainly located within the CNS between sensory
and motor neurons.
Interneurons (ASSOCIATION NEURONS)
Convey action potentials away from the CNS to
effectors (muscles and glands) in the periphery
(PNS) through cranial or spinal nerves.
MOTOR (EFFERENT) NEURONS
Cells smaller but are 5-25 times more
numerous than neurons
neuroglia
brain tumors derived from neuroglia
gilomas
Largest and most numerous of the neuroglia.
astrocytes
astrocytes that have many short branching processes and are found in gray matter
Protoplasmic astrocytes
astrocytes that have many long unbranched processes and are located mainly in white matter
Fibrous astrocytes
Resemble astrocytes but are smaller and
contain fewer processes
oligodendrocytes
a multilayered lipid and protein
covering around some axons that insulates
them and increases the speed of nerve impulse
conduction
myelin sheath
Small cells with slender processes that give off
numerous spinelike projections
Functions as phagocytes
MICROGLIA OR MICROGLIAL CELLS
Cuboidal to columnar cells arranged in a single
layer that possess microvilli and cilia.
ependymal cells
what completely surround axons and cell bodies
NEUROGLIA OF THE PNS
encircle PNS axons and
participate in axon regeneration,
which is more easily accomplished in the PNS
than in the CNS
schwann cells
flat cells that surround the cell bodies of
neurons of PNS ganglia
satellite cells
what does the satellite cells regulate during the exchange of materials
neuronal cell bodies and interstitial
fluid
what do you call it when Axons covered with a myelin sheath
Myelinated
what happens if there are many layers of lipid and protein:
insulates the neurons
outer nucleated cytoplasmic layer of the Schwann cell; encloses the myelin sheath
Neurolemma
gaps in the myelin
nodes of ranvier
cluster of cell bodies in PNS
ganglion
cluster of cell bodies in CNS
neurons
bundle of axons in PNS
nerve
bundle of axons in CNS
tract
primarily myelinated axons
white matter
cell bodies, dendrites, unmyelinated axons,
axon terminals, neuroglia
grey matter
when can axons and dendrite in the PNS only be repaired?
if cell body is intact and Schwann cells are functional
used for short-distance communication
only
graded potentials
allow communication over long
distances within the body
action potentials
action potential that occurs in a neuron
nerve cell
nerve action potential or nerve impulse
what 2 types of electrical signals do neurons use to communicate with each other
action and graded potentials
an electric potential
(voltage) difference across cell membrane
membrane potential
allow ions to move by diffusion
from high to low concentration
ion channels
termed as the Resting membrane potential
voltage
Open and close on command
Respond to changes in membrane so
can generate and conduct action
potentials
gated channels
allow ions to leak
through membrane; there are more for K+
than for Na+
leakage channels
what happens if an ion channel is open?
allow specific ions to
move across the plasma membrane down their
electrochemical gradient
when does the creation of a flow of electrical
current that can change the membrane
potential happen?
when the ions move
what is the typical resting membrane potential?
-70 mV
a small deviation from the resting membrane potential that makes the membrane either more polarized or less polarized
graded potential
occurs when two or more graded
potentials add together to become larger in
magnitude
summation
determine what phase of action potential;
Na+ channels open → as more Na+ enters cell,
membrane potential rises and becomes positive
–70 → 0 → + 30 mv
depolarizing phase
determine what phase of action potential;
K+ channels open → as more K+ leave cell,
membrane potential is returned to resting value
+ 30 → 0 → –70 mv
repolarizing phase
Levels of ions back to normal by action of
Na+/K+ pump
recovery
In unmyelinated fibers; slower form of
conduction
continuous conduction
In myelinated fibers; faster as impulses “leap”
between nodes of Ranvier
saltatory conduction
Factors that increase rate of conduction
o Amount of myelination
o large axon diameter
o warm nerve fibers
