Nervous System Test 1/23/14 Flashcards
list 3 major functions of the nervous system
-to gather info -to process & interpret sensory input & decide if action is needed -to cause immediate responses
what is the nervous system subdivision that’s composed of the brain & spinal cord?
central nervous system
subdivision of the PNS that controls voluntary activities; activation of the skeletal muscles
somatic nervous system (voluntary)
nervous system subdivision that’s composed of the cranial/ spinal nerves, & ganglia
peripheral nervous system
subdivision of the PNS that regulates the activity of the heart & smooth muscle & of glands; involuntary nervous system
autonomic nervous system (involuntary)
a major subdivision of the nervous system that interprets info & gives orders
central nervous sytem
a major subdivision of the nervous system that serves as the communication lines, linking all parts of the body to the CNS
peripheral nervous system
Describe 3 parts of the functional pathway
-Sensory input: monitors changes occurring in/outside of body -Integration: to interpret sensory input & decide if action is needed -Motor output: to activate muscles/ glands (to respond to the stimuli)
organs of the CNS
brain & spinal cord
Carries impulses to & from spinal cord
Spinal nerves
Carries impulses to & from brain
Cranial nervies
serves as communication lines among sensory organs, the brain & spinal cord & glands or muscles
PNS
nerves extending from the brain & spinal cord
PNS
CNS or PNS?: interprets incoming sensory info, & issues outgoing instructions
CNS
Sensory division, a.k.a…
afferent division
motor division, a.k.a…
efferent division
nerve fibers that carry info to the CNS
sensory division
nerve fibers that carry info away from the CNS
motor division
the 2 subdivisions of motor division
somatic & autonomic nervous systems
2 major subdivisions of PNS
sensory & motor divisions
consciously controls skeletal muscles
somatic nervous system
somatic or autonomic? Involuntary
autonomic
somatic or autonomic? Voluntary
somatic
further divided into sympathetic & parasympathetic nervous systems
autonomic nervous system
cell bodies of neurons
ganglia
nervous tissue is made up of 2 types of cells called:
supporting cells & neurons
support cells in the CNS are grouped together as “___”
neuroglia
general functions of support cells or neuroglia
support, insulate, & protect neurons
abundant, star-shaped cells
astrocytes
brace (support) neurons
astrocytes
form barrier bw capillaries & neurons
astrocytes
control the chemical environment of the brain
astrocytes
spider-like phagocytes
microglia
dispose of debris > “cell-eaters”
microglia
line cavities of the brain & spinal cord
ependymal cells
cilia assist with circulation of cerebrospinal fluid
ependymal cells
wrap around nerve fibers in the CNS
oligodendrocytes
produce myelin sheaths, fatty insulating coverings
oligodendrocytes
2 types of support cells in PNS
satellite & schwann cells
protect neuron cell bodies (ganglia)
satellite cells
form myelin sheath in the PNS
schwann cells
Support Cells v. Neurons: both have extensions coming from a _______
larger body cell portion
support cells, neurons, both, or neither can transmit impulses?
Support Cells cannot transmit impulses, Neurons can
Support Cells V. Neurons: ___ never lose ability to divide, unlike ___
Support Cells never lose the ability to divide, unlike Neurons
Support Cells v. Neurons: Most brain tumors usually consist of ___
supporting cells
nerve cells, a.k.a…
neurons
cells specialized to transmit messages
neurons
___-nucleus & metabolic center of the cell
cell body
___- fibers that extend from the cell body
processes
specialized rough endoplasmic reticulum
nissl bodies
intermediate cytoskeleton, maintains cell shape
neurofibrils
conduct impulses TOWARD the cell body
dendrites
conduct impulses AWAY from the cell body
axons
neurons may have hundreds of ___, but only 1 ___
neurons may have hundreds of DENDRITES, but only 1 AXON
an axon arises from the cone-like region of the cell body, called the…
axon hillock
___ contains vesicles w/ neurotransmitters
axon terminals
___- gap between adjacent neurons ___- junction bw nerves
synaptic cleft- gap between adjacent neurons synapse- junction bw nerves
whitish, fatty material covering axons
myelin sheath
protects & insulates nerve fibers & increases speed of nerve impulse transmission
myelin sheath
produce myelin sheaths in jelly roll-like fashion around axons (PNS)
schwann cells
gaps in myelin sheath along the axon
Nodes of Ranvier
produce myelin sheaths around axons of the CNS
oligodendrocytes
most neuron cell bodies are found where?
CNS
cell bodies & unmyelinated (no insulating cells) fibers
gray matter
clusters of cell bodies within the white matter (with myelinated fibers) of the CNS
nuclei
collections of cell bodies outside the CNS
ganglia
bundles of nerve fibers in the CNS
tracts
bundles of nerve fibers in the PNS
nerves
collections of myelinated fibers (tracts)
white matter
collections of mostly unmyelinated fibers & cell bodies
gray matter
carry impulses from the sensory receptors to the CNS
sensory neurons
detect pain and touch
cutaneous sense receptors
detect stretch or tension in skel muscles, tendons, & joints
proprioceptors
carry impulses away from the CNS to internal organs, muscles, glands
motor neurons
found in neural pathways in the CNS
interneurons (association neurons)
connect sensory & motor neurons
interneurons (association neurons)
all motor & interneurons are ___
multipolar (most common structure)
Many extensions from the cell body.
multipolar neurons
located in special sense organs (nose & eyes). Rare in adults.
bipolar neurons
have a short single process leaving the cell body// sensory neurons found in PNS ganglia
unipolar neurons
ability to respond to stimuli
irritability
ability to transmit an impulse
conductivity
resting neuron: the plasma membrane at rest is ___
Polarized. fewer + ions are inside the cell than outside the cell
A stimulus depolarizes the neuron’s membrane.
depolarization
Membrane is now permeable to sodium as sodium channels open
depolarization
a ________ allows sodium to flow inside the membrane
a depolarized membrane
the movement of ions irritates a(n) ____ in the neuron due to a stimulus
action potential
a ___________ (localized depolarization) exists where the inside of the membrane is more positive & the outside is less positive
a graded potential
if enough sodium enters the cell, the action potential (nerve impulse) starts & is ___ over the entire axon
propagated
impulses travel faster when fibers have a _______
myelin sheath
potassium ions rush out of the neuron after sodium ions rush in, which ___ the membrane
repolarizes
repolarization involves restoring the inside of the membrane to a ___ charge, and the outside to a ___ charge
inside= negative
outside= positive
Repolarization: Initial ionic conditions are restored using the ___________
sodium-potassium pump.
This pump, using ATP, restores the original configuration
repolarization: 3 ___ ions are ejected from the cell while 2 ___ ions are returned to the cell
3 sodium
2 potassium
when the action potential reaches the axon terminal, the electrical charge opens ____ channels
calcium channels
calcium, in turn, causes the tiny vesicles containing the neurotransmitter chemical to fuse with the ______________
axonal membrane
the entry of calcium into the axon terminal causes openings to form, releasing the ____
transmitter
the neurotransmitter molecules diffuse across the synapse & bind to ___ on the membranes of the next neuron
receptors
eventually a(n) __________ (nerve impulse) will occur in the neuron beyond the synapse
action potential
the electrical changes prompted by neurotransmitter binding are ____
brief
at the end of Transmission of a signal at synapses, the neurotransmitter is quickly _____ from the synapse
removed
the pathway that information will flow
the reflex arc
____- rapid, predictable, & involuntary response to a stimulus.
Occurs over pathways called _________
- Reflex
- Reflex Arcs
direct route from a sensory neuron, to an interneuron, to an effector
reflex arc
2 types of reflex arcs:
somatic- reflexes that stimulate ________
autonomic- regulate the activity of _________, the heart, & glands
somatic- skeletal muscles
autonomic- smooth muscles
pulling hand away from hot object: example of which reflex arc?
somatic
regulation of smooth muscles, heart & bp, glands, digestive system: example of which reflex arc?
autonomic
what are the 5 elements of a reflex?
sensory receptor-
sensory neuron-
integration center-
motor neuron-
effector organ-
reacts to a stimulus
sensory receptor
carries message to the integration center
sensory neuron
(CNS) processes information & directs motor output
integration center
carries message to an effector
motor neuron
is the muscle/gland to be stimulated
effector organ
simplest type of reflex arc & example
two-neuron reflex arc
Ex: Patellar (knee-jerk) reflex
- consists of 5 elements: receptor, sensory neuron, interneuron, motor neuron, & effector.
- Also give example.
- three-neuron reflex arc
- Ex: Flexor (withdrawal) reflex
