fundamentals of the nervous system (ch 11) Flashcards
all information has to go through…
the CNS
steps of the information pathway
sensory (different) –> integration –> motor (efferent)
AKA
stimulus - receptor - CNS - effector - response
divisions of the PNS
sensory and motor
the CNS consists of…
the brain and spinal cord
the PNS is…
the peripheral nervous system
the sensory PNS deals with…
bringing info in
the motor PNS deals with…
info going out
divisions of the motor PNS
autonomic and somatic
the autonomic motor PNS consists of…
smooth muscle
cardiac muscle
glands
(is self governed)
the somatic motor PNS consists of
skeletal muscle
(is voluntary)
somatic refers to…
surface
visceral refers to…
inside
special sense example
sight
divisions of the autonomic motor PNS
sympathetic and parasympathetic
sympathetic refers to…
working together (fight or flight)
parasympathetic refers to…
around the sympathetic (rest and digest)
neurons are…
nerve cells
somas are…
cell bodies
somas consist of…
a nucleus and organelles
in the CNS, somas are located in…
gray matter
in the PNS, somas are located in…
ganglia
ganglia are…
collections of somas outside the brain/spinal cord
dendrites are…
branches off the soma
function of dendrites
increases surface area for receiving messages
axon means…
axis
axons come off the soma at…
the axon hillock
the axon hillock is…
where most neuron APs form/start
axons are _____ process
single
axons end at…
terminal branches with synaptic knobs containing a NT
in the CNS, axons are located in…
white matter
in the PNS, axons are located in…
nerves
myelin consists of…
the wrapping of cell membranes which are phospholipids (fatty/nonpolar)
function of myelin
increases AP transmission speed and rate
neuroglia means…
glue
neuroglia are…
supporting cells
neuroglia to neuron ratio
10:1
astrocyte means…
star cell
astrocytes are most commonly found in…
the CNS
function of astrocytes
bracing and supporting neurons and BVs (aka the blood-brain barrier)
microglial cells mean…
small glue cells
characteristics of microglial cells
motile (moves)
defends CNS
cleans up damage
ependymal means…
put over/on
function of ependymal cells
lining CNS fluid-filled cavities
ependymal cells are made of…
epithelium with cilia
oligodendrocyte means…
few branch cell
function of oligodendrocytes
processes/projections form CNS myelin that wrap a few different axons
multiple sclerosis is…
an autoimmune disease against CNS myelin, means “many scars”
function of schwann cells
forming PNS myelin
multiple small single cells wrap their membranes along the axon
can support/surround multiple unmyelinated axons
function of satellite cells
surrounds/supports somas in ganglia
neuroglia found in CNS
astrocytes, microglial cells, ependymal cells, oligodendrocytes
neuroglia found in PNS
schwann cells, satellite cells
neuron structure classifications
multipolar
bipolar
unipolar
multipolar neurons make up _____% of neurons
over 99
bipolar neurons are…
rare, sensory
part of the retina and nose
unipolar neurons are…
sensory
neuron function classifications
sensory
motor
interneurons/association neurons
function of sensory neurons
bringing info into the CNS
function of motor neurons
carrying info out of the CNS
interneurons are found…
within the CNS, and are the most common neuron
voltage is…
the separation of charged particles (ions)
how are ions separated
across the membrane
resistance is…
the hinderance of charged particle flow
current is…
the flow of charged particles
equation for Ohm’s law
I = V/R
result of ion channel leakage
allows for a slow current because they are always open
gated ion channels can be ____ or ____
open, closed
ways to open/close gated ion channels
ligand/chemical
voltage
mechanical
in ligand gated ion channels…
a chemical binds to open or close ion channels
in voltage gated ion channels…
voltage changes on the membrane open or close the channel
in mechanically gated ion channels…
a pull on the membrane will open or close it
potential is…
the charge across a membrane
concentrations of the Na+ K+ ATP pump
more Na+ is outside
more K+ is inside
the charge inside of a neuron is around…
-70 mV
why is the inside of a neuron negative
leakage channels
at rest, the membrane is more permeable to ___ than ___
K+ than Na+
result of membrane permeability
K+ diffuses out until the inside membrane becomes more negative, continues until the charge reaches K+ equilibrium
graded (local) potentials are measured by…
voltage
graded potentials are…
a localized change to membrane Voltage
the current sink is…
where ions diffuse
steps of graded potentials
stimulus to cell induces ion channels to open, ions diffuse across the membrane at the current sink, which changes the charge across a membrane in a localized region
when Na+ channels are opened…
Na+ diffuses in, and charge becomes less negative
when K+ channels are opened…
K+ diffuses out, charge becomes more negative
when Cl- channels are opened…
Cl- diffuses in, charge becomes more negative
when Ca++ channels are opened…
Ca++ diffuses in, charge becomes less negative
characteristics of local/graded potential
graded
local
decremental
reversible
excitatory or inhibitory
graded refers to…
bigger stimuli open more ion channels, more ion flow, and a bigger voltage change
local means…
one area of the membrane
decremental means…
potential/voltage change decreases over distance
reversible means…
ions diffuse away, are pumped, and return to their original gradients
excitatory means…
chance of AP is increased (depolarization)
inhibitory means…
chance of AP is decreased (hyperpolarization)
APs are found in…
muscle cells and neurons
APs are…
brief, large depolarizations that are recreated along the membrane and acts as a signal over a distance
what happens in an AP
a stimulus depolarizes the membrane to threshold, opening voltage-gated channels for Na+ and K+, with Na+ first flowing in to depolarize the cell, then K+ flowing out to repolarize the cell
threshold is around ___ mV
-55
Na+ channels open up _____ and _____
quickly and briefly
K+ channels open up _____ and _____
slowly and for a longer period of time
depolarization stops at ___ mV
30
after a cell is repolarized, _____ occurs
after-hyperpolarization
characteristics of APs
non-decremental
irreversible
all or none rule
refractory periods
non-decremental means…
APs are recreated at the same voltage down a membrane
irreversible means…
once an AP starts, it keeps going
the all or none rule means…
there either is or isn’t an AP, and all APs will be the same
types of refractory periods
absolute and relative
absolute refractory period
occurs while Na+ channels are open
the time during which there cannot be another AP
relative refractory period
occurs while K+ channels are open
the time during after an AP when the stimulus needed to get to threshold is increased (encoded by increase in AP frequency)
factors in AP propagation/conduction
size of neuron
myelination
bigger axons mean…
more ion flow and increased speed
unmyelinated neurons have APs…
recreated along every membrane part
myelinated neurons have APs…
only formed at the nodes (APs will leap)
synapse means…
clasp or join
general structure of a synapse
presynaptic neuron sends
synapse acts as an NT in the synaptic cleft
post synaptic cell receives the signal
types of synapses
electrical and chemical
electrical synapses have _____ and are important in ____
gap junctions, nervous system development
chemical synapses predominate in _____ and use _____
the nervous system, neurotransmitters
a synapse is located where on a post-synaptic cell
where the axon attaches
what is ACh
a neurotransmitter for the brain and autonomic nervous system
function of Alzheimer’s medication
decreasing ACh breakdown by AChE in the CNS
types of amino acids
GABA
glycine
aspartic acid
glutamate
what is GABA/what does it do
the primary inhibitory NT in the CNS
opens channels for Cl-, resulting in hyperpolarization
amines mean…
nitrogen containing
types of neurotransmitters
ACh, amino acids, amines, neuropeptides, gases
types of amines
catecholamines
serotonin
histamines
types of neuropeptides
substance P
endorphins
enkephalins
types of catecholamines
made from tyrosine, can get converted to dopamine, to norepinephrine, to epinephrine
function of serotonin
mood
sleep/wake
balance/coordination
function of histamines
works within hypothalamus
neuropeptides are…
chains of amino acids
function of substance P
pain signals
function of endorphins and enkephalins
inhibiting pain
function of gases
most are neuromodulators, such as NO, CO, and H2S
neuromodulators are…
any chemical that can change or regulate any neuron activity not released at the synapse
synaptic transmission is…
a chemical synapse
steps of synaptic transmission
AP arrives at the synaptic knob, opening voltage gated Ca+ channels, diffusing in the presynaptic neuron, inducing exocytosis of synaptic vesicles containing an NT, which then diffuses across the synaptic cleft, binding to receptors to give its effect
the ionotropic effect…
uses ions
NT opens ion channels
ions diffuses across the postsynaptic membrane
the metabotropic effect…
is more common
NT binds to receptors on membrane of postsynaptic cell, receptor stimulates G protein, stimulating enzymes to create a second messenger
second messenger examples
cAMP, cGMP, Ca++
how does synaptic transmission stop
diffusion (of NT away)
enzyme (NT breakdown)
reuptake (by presynaptic neuron)
most common antidepressant meds are…
amine reuptake inhibitors
synaptic delay is…
when the synapse is the rate-limiting step for nervous information
EPSPs are…
excitatory post-synaptic potentials
when local depolarizations increase the chance of an AP
IPSPs are…
inhibitory post-synaptic potentials
when local hyperpolarizations decrease the chance of an AP
summation is…
adding up all the EPSPs and IPSPs
if summation reaches threshold (___ mV), then ____ occurs.
-55, an AP
temporal summation is…
“time”, involves one synapse firing repeatedly within a short timeframe
spatial summation is…
“space”, involves more that one synapse firing near similar time
synaptic plasticity means…
things change
process of synaptic plasticity
new synapses are formed
old synapses are lost
synapses work more effectively
types of neural processing
serial and parallel
types of neuron pools
divergent pathway
convergent pathway
reverberating circuit
parallel after-discharge
divergent pathways are…
when few neurons output many neurons
ex: motor cortex to skeletal muscle
convergent pathways are…
when many neurons output few neurons
ex: sensations to memories
reverberating circuits are…
when neurons can loop back to repeat or continue
ex: breathing and walking
parallel after-discharge is…
when neurons split off then recombine (prolonged message)
ex: math
