Lecture 15: NS I – Cellular Flashcards
LO1: indicate the overall functions of the nervous system
1) stimulate muscles and glands
2) produce quick effects by electrochemical mechanisms
3) contribute to homeostatic feedback loops
central nervous system is composed of…
brain
spinal cord
CNS:
brain (explain)
central processing center
CNS:
spinal cord (explain)
gateway b/n brain and trunk/limbs
periopheral nervous system is composed of…
nerves
ganglia
PNS:
nerves (explain)
conducting wires (axons)
cordlike structures that conduct information
they are composed of axons of neurons
PNS:
ganglia (explain)
contain neuron cell bodies
knotlike swelling in a nerve. It serves as relay centers, where neurons synapse and transmit information to each other
what is the role of the CNS?
receives and processes information
initiates action
what is the role of the PNS?
transmits signals b/n the CNS and the rest of the body
what is the visceral division?
information from internal organs
what is the somatic division?
information from skin, muscles, bones, joints
what do sensory neurons do?
relay information about stimuli such as temperature, pressure, light, pain, and certain chemicals back to the brain
PNS:
somatic sensory division (function)
sensory nerves from the skin, skeletal muscles, bones, and joints
PNS:
somatic motor division (function)
voluntary muscle contractions
involuntary somatic reflexes
motor nerves that innervate skeletal muscles
PNS:
visceral sensory division (function)
detects changes in the viscera (the organs in the thoracic and abdominal cavities)
PNS:
visceral motor division (function)
autonomic NS –> it is largely autonomic
controls: cardiac muscle, smooth muscle, glands
LO4: describe the 3 functional properties found in all neurons
1) excitability
2) conductivity
3) secretion
describe the 3 functional properties found in all neurons:
1) excitability
irritability
respond to environmental changes (stimuli)
describe the 3 functional properties found in all neurons:
2) conductivity
produce electrical signals that travel along nerve fibers (axons) to reach other cells at distant locations
describe the 3 functional properties found in all neurons:
3) secretion
nerve fiber endings (axon terminals) release chemical neurotransmitters that influence other cells
are sensory cells afferent or efferent?
afferent
are motor cells afferent or efferent?
efferent
are afferent cells sensory or motor?
sensory
are efferent cells sensory or motor?
motor
examples of somatic sensory division organs
eye
skin
skeletal muscle
example of somatic motor division organs
skeletal muscle
example of visceral sensory division organs
urinary bladder
example of visceral motor division organs
heart
urinary bladder
structures of the PNS:
ganglia
nerves
structures of the CNS:
neural cortex
nuclei
tracts
columns
ganglia (what are they, what nervous system?)
collection of neuron cell bodies in the PNS
nerves (what are they, what nervous system?)
bundles of axons in the PNS
nuclei (what are they, what nervous system)
collection of neuron cell bodies int eh interior of the CNS
tracts (what are they, what nervous system)
bundles of CNS axons that share a common origin, destination, and function
columns (what are they, what nervous system)
several tracts that form an anatomically distinct mass
in the CNS
the CNS has various ___ that integrate all of the information
centers
lower centers in the CNS
include the spinal cord
carry out essential body functions
higher centers of the CNS
control more sophisticated information processing
afferent signals are ___ transmissions that come from ___
input
receptors
efferent signals are ___ transmissions that go to ___
output
effectors
pathway from PNS to CNS back to PNS
sensory (afferent) neurons –> interneurons –> motor (efferent) neurons
what do interneurons do? where are they located?
“between”
in charge of “integrative function”
confined w/in CNS
converts sensory (afferent) signal to motor (efferent) signal
dendrites (explain)
chemically regulated ion gates respond to stimulation by neurotransmitters
receive signals from other neurons
the more dendrites the more information it can receive
soma (explain)
AKA neurosoma, cell body, perikaryon
produces neurotransmitters
the neuron’s control center (metabolic and regulatory functions)
trigger zone (explain)
axon hillock + initial segment
plays important role in initiating nerve signal
axon (explain)
nerve fiber
only the axon has voltage regulated ion gates
“the conducting region”
where does the axon originate?
the axon hillock
what is axon collateral?
axons branches near the soma
cylindrical and relatively unbranched
what is terminal arborization?
extensive branches at the distal end of an axon
what is a terminal button?
a bulbous axon terminal at the end of each axon
what is the secretory region of the neuron?
the axon terminal
composition of the neurosoma:
the cytoskeleton of the neurosoma is made up of ___, which are…
neurofibrils
bundles of actin filaments
composition of the neurosoma:
neurofibrils compartmentalize the rough ER into dark-staining regions called ___
chromatophilic substance
composition of the neurosoma:
what is chromatophilic substance? AKA…
what is its function?
AKA Nissl bodies
stained masses of rough (granular) ER and ribosome
separated by bundles of neurofibrils
involved in protein synthesis
composition of neurosoma:
lipofuscin granules (explain)
products of lysosomal activity
“aging” pigment –> they accumulate with age and push the nucleus to one side of the cell
LO7: compare structural classes of neuron (according to the number of processes extending from the soma)
multipolar neurons (descriptions, types, and examples)
1 axon + multiple dendrites
most neurons fo the brain and spinal cord
ex. purkinje cell of cerebellum and pyramidal cell
LO7: compare structural classes of neuron (according to the number of processes extending from the soma)
bipolar neurons (descriptions, types, and examples)
1 axon + 1 dendrite
sensory neurons that are located in some special sense organs
ex. olfactory cell and retinal cell
LO7: compare structural classes of neuron (according to the number of processes extending from the soma)
unipolar neurons (descriptions, types, and examples)
a single process leading away from soma –> peripheral process (axon) and central process (axon)
most are primary or first-order sensory neurons (touch and pain)
ex. dorsal root ganglion cell
LO7: compare structural classes of neuron (according to the number of processes extending from the soma)
anaxonic neurons (descriptions, types, and examples)
no axon, just dendrites
they communicate locally (no action potential)
LO8: indicate which materials use retrograde and anterograde transport, and the direction and velocity of this transport
what do microtubules do in a neuron?
they are the track for organelle transport in neurons
LO8: indicate which materials use retrograde and anterograde transport, and the direction and velocity of this transport
axonal transport happens in ___ direction
each
LO8: indicate which materials use retrograde and anterograde transport, and the direction and velocity of this transport
retrograde (describe)
up the axon toward the soma
fast – transports recycled materials, pathogens, and toxins
LO8: indicate which materials use retrograde and anterograde transport, and the direction and velocity of this transport
anterograde (describe)
down the axon away from the soma
fast – organelles, enzymes, synaptic vesicles, small molecules
slow – enzymes, cytoskeletal components, supplies new axoplasm
LO9: name and functions of the 6 types of cells that aid neurons
there are ~___ neurons in the nervous system
~1 trillion
LO9: name and functions of the 6 types of cells that aid neurons
neuroglia (glial cells) outnumber neurons by at least ___ [non-neuronal cells]
10:1
LO9: name and functions of the 6 types of cells that aid neurons
general functions of glial cells
bind neurons together – “glia” means “glue”
in fetus, guide migrating neurons to their destination
cover mature neurons (except at synapses) – gives precision to conduction pathways
provide physical and metabolic support to neurons
LO9: name and functions of the 6 types of cells that aid neurons
peripheral nervous system – 2 types are…
Schwann cells
satellite cells
LO9: name and functions of the 6 types of cells that aid neurons
Schwann cell (what nervous system and what function)
PNS
assist in regeneration of damaged fibers
LO9: name and functions of the 6 types of cells that aid neurons
satellite cell (what nervous system and what function)
PNS
provide electrical insulation
regulate the chemical environment
LO9: name and functions of the 6 types of cells that aid neurons
central nervous system – 4 types are…
oligodendrocytes
ependymal cells
astrocytes
microglial cells
LO9: name and functions of the 6 types of cells that aid neurons
oligodendrocytes (what nervous system and what function)
CNS
their processes form myelin sheaths around CNS nerve fibers
LO9: name and functions of the 6 types of cells that aid neurons
ependymal cells (what nervous system and what function)
CNS
line cavities
produce cerebrospinal fluid (CSF)
cilia help to circulate CSF
LO9: name and functions of the 6 types of cells that aid neurons
astrocytes (what nervous system and what function)
CNS
the most abundant
convert glucose to lactate; supply this to neurons
produce growth factors
regulate the extracellular environment (chemical composition)
form the blood-brain barrier
LO9: name and functions of the 6 types of cells that aid neurons
microglial cells (what nervous system and what function)
CNS
specialized population of macrophages
defensive cells (phagocytic) – they remove damaged neurons and infections
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
insulation around the axon is ___% protein and ___% lipid
20% protein
80% lipid
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
myelin sheath is formed by plasma membrane of ___ from
glial cells
oligodendrocytes in CNS
Schwann cells in PNS
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
greater myelination means ___ action potential conduction velocity
greater
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
what is the neurilemma?
the outermost nucleated cytoplasmic layer of Schwann cells
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
regeneration of damaged PNS nerve fiber (axon) can occur if:
soma intact + at least some neurilemma remains
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
what is Node of Ranvier?
gaps b/n myelinated segments (internodes) of CNS axons
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
what is internode?
myelin-covered segments of CNS axons
LO10: Analyze the composition and importance of the myelin sheath covering certain fibers:
a Schwann cell folds its plasma membrane around ___ fibers
several
define action potential:
a sudden, fast, transitory, and propagating change of the resting membrane potential
phases of an action potential:
(2) depolarization (define and describe)
refers to the increase in the positivity of mb potential
when the cell reaches threshold, voltage-gated Na+ channels open, causing an AP
phases of an action potential:
(1) stimulus (define and describe)
ligand-gated sodium channels open in response to ACh, allowing for Na+ influx inside the cell and depolarize cell to threshold
phases of an action potential:
the negative resting membrane potentiation is primarily determined by…
the movement of K+ out of the cell
K+ leak channels are always open –> ask K+ leaks out, inside of membrane becomes more negative
phases of an action potential:
(3) depolarization (define and describe)
at high mb potential, Na+ channels close, and voltage-gated K+ channels open, repolarizing the cell
phases of an action potential:
(4) hyperpolarization (define and describe)
refers to the increase in negativity of mb potential
LO11: differentiate between local potentials vs action potentials:
how are local potentials produced?
produced by ligand-gated Na+ channels not eh dendrites and soma
LO11: differentiate between local potentials vs action potentials:
local potentials can be ___ or ___
excitatory (depolarizing)
inhibitory (hyperpolarizing)
LO11: differentiate between local potentials vs action potentials:
are local potentials graded or all-or-none?
graded – proportional to stimulus strength
stronger stimuli
LO11: differentiate between local potentials vs action potentials:
are local potentials irreversible or reversible?
reversible – returns to RMP if stimulation ceases before threshold is reached
LO11: differentiate between local potentials vs action potentials:
are local potentials local or self-propagating?
local – has effects for only a short distance from point of origin
incoming Na+ diffuses for short distances along the inside of the plasma mb
LO11: differentiate between local potentials vs action potentials:
are local potentials decremental or non-decremental?
decremental – signal grows weaker with distance
LO11: differentiate between local potentials vs action potentials:
how are action potentials produced?
produced by voltage-gated ion channels on the trigger zone and axon
(occurs only where there is a greater density of these channels)
LO11: differentiate between local potentials vs action potentials:
how do action potentials begin?
always begins w/ depolarization
LO11: differentiate between local potentials vs action potentials:
are action potentials graded or all-or-none?
all-or-none – if a stimulus depolarizes the neuron to threshold, the neuron fires at its maximum voltage (not graded)
if threshold is not reached – no AP
LO11: differentiate between local potentials vs action potentials:
are action potentials irreversible or reversible?
irreversible – goes to completion once it begins (it can’t be stopped once it begins)
LO11: differentiate between local potentials vs action potentials:
are action potentials local or self-propagating?
self-propagating – it has effects a great distance from point of origin
LO11: differentiate between local potentials vs action potentials:
are action potentials decremental or non-decremental?
nondecremental – signal maintains same strength regardless of distance
LO12: explain how the nerve signal is conducted down axon (propagation of an action potential)
local potential is created at dendrites
stimulus is produced in soma of presynaptic neuron
graded potential local current arrives at axon hillock –> depolarizes the membrane at that point
if local current reaches threshold voltage –> neuron fires and produces an action potential
AP current travels down axon and triggers postsynaptic mb dendrites –> creates local potential to postsynaptic cell
LO13: examine the factors that affect conduction velocity of nerve signals:
speed at which a nerve signal travels down an axon depends on ___ factors
the factors are…
2
diameter
myelination
LO13: examine the factors that affect conduction velocity of nerve signals:
how does diameter affect conduction velocity of nerve signals?
larger axons have more surface area and conducts signals more rapidly
conduction velocity is proportional to fiber diameter
there are a lot of ions flooding into the axon, so the more space they have to travel, the more likely they will be able to keep going in the right direction
LO13: examine the factors that affect conduction velocity of nerve signals:
how does myelination affect conduction velocity of nerve signals?
presence of myelin and thickness of myeline speeds up signal conduction
LO14: compare the action potential propagation in nonmyelinated to myelinated axons:
what is a nerve signal?
a traveling wave of excitation produced by APs
LO14: compare the action potential propagation in nonmyelinated to myelinated axons:
describe AP propagation in nonmyelinated axons
continuous conduction
uninterrupted wave of electrical excitation all along fiber
LO14: compare the action potential propagation in nonmyelinated to myelinated axons:
describe AP propagation in myelinated axons
saltatory conduction
depolarization only occurs at the internodes. At internal segments, conduction is very fast but decremental
