Exam 1 Info- Slides Contd Flashcards
(functions of the NS) sensory input:
information gathered by sensory receptors about … and … changes
internal; external
(functions of the NS)
…: interpretation of sensory input
integration
(functions of the NS) motor output:
activation of … (.. and …) produces a response
effector organs; muscles; glands
central nervous system:
… and …
… and … center
brain; spinal
integration; command
peripheral nervous system (PNS)
paired … and … carry messages to and from the CNS
spinal and cranial nerves
(peripheral nervous system- PNS) two functional divisions:
1. sensory (…) division:
somatic afferent fibers – convey impulses from …, …, and …
visceral afferent fibers - convey impulses from …
afferent;
skin; skeletal muscles; joints;
visceral organs
(peripheral nervous system- PNS) motor (efferent) division:
transmits impulses from the .. to …
CNS; effector organs
(motor division of PNS) … (…) NS:
conscious control of skeletal muscles
somatic; voluntary
(motor division of PNS) … (…) NS (ANS):
visceral motor nerve fibers
regulates …, …, and …
two functional subdivisions: …, …
autonomic; involuntary;
smooth muscle; cardiac muscle; glands;
sympathetic; parasympathetic
two principal cell types in NS:
…: excitable cells that transmit electrical signals
… (… cells): supporting cells
neurons;
neuroglia; glial
(neuroglia) glial cells include: ... (CNS) ... (CNS) ... (CNS) ... (CNS) ... (PNS) ... (PNS)
astrocytes; microglia; ependymal cells; oligodendrocytes; satellite cells; schwann cells;
(neuroglia) astrocytes:
most abundant, versatile, and highly branched glial cells
cling to …, …, and …
… and … neurons
neurons; synaptic endings; capillaries;
support; brace
(neuroglia) astrocytes: help determine ... guide ... of young neurons control the ... participate in ... int he brain
capillary permeability;
migration;
chemical environment;
information processing
(neuroglia) … are the most abundant CNS neuroglia
astrocytes
(neuroglia) microglia:
small, ovoid cells with thorny processes
migrate toward … neurons
… microorganisms and neuronal debris
injured;
phagocytize
(neuroglia) … are defensive cells in the CNS
microglial cells
(neuroglia) ependymal cells:
range in shape from … to …
may be …
squamous; columnar; ciliated
(neuroglia) ependymal cells:
may be ciliated:
line the … of the brain and spinal column
separate the … from the … in the cavities
central cavities;
CNS interstitial fluid;
cerebrospinal fluid
(neuroglia) ependymal cells line … cavities
cerebrospinal fluid-filled
(neuroglia) oligodendrocytes:
… cells
processes wrap CNS nerve fibers, forming …
branched;
insulating myelin sheaths
(neuroglia) satellite cells:
surround … in the PNS
neuron cell bodies
(neuroglia) schwann cells:
surround … and form …
vital to regeneration of
peripheral nerve fibers; myelin sheaths
(neuroglia) schwann cells:
vital to … of damaged peripheral nerve fibers
regeneration
(neurons-nerve cells) special characteristics:
long-llived (100 yrs or more)
…
high … rate - depends on continuous supply of oxygen and glucose
terminal differentiation;
metabolic
(neurons-nerve cells) special characteristics: plasma membrane functions in: ... ... during development
electrical signaling;
cell-to-cell interactions
(neurons-nerve cells) cell body (... or ...) biosynthetic center of a neuron spherical ... with ... well-developed ... network of ... (...)
perikaryon; soma;
nucleus; nucleolus;
Golgi apparatus;
neurofibrils; neurofilaments
(neurons-nerve cells) cell body:
… - cone-shaped area from which axon arises
clusters of cell bodies are called … in the CNS, … in the PNS
axon hillock;
nuclei; ganglia
(neurons- Processes)
… and …
bundles of processes are called … in the CNS, … in the PNS
dendrites; axons
tracts; nerves
(dendrites)
short, tapering, and diffusely branched
… (…) region of a neuron
convey … signals toward the cell body as …
receptive; input;
electrical; graded potentials
(the axon) one axon per cell arising from the ... long axons (...) occasional branches (...)
axon hillock;
nerve fibers;
axon collaterals
(the axon)
numerous … branches
knoblike … (… or ..)
terminal;
axon terminals; synaptic knobs; boutons
(the axon) axon terminals:
… region of neuron
release … to excite/inhibit other cells
secretory; neurotransmitters
(the axon)
… region of a neuron
generates and transmits … (…) away from the cell body
conducting;
nerve impulses; action potentials
(the axon)
molecules and organelles are moved along axons by motor molecules in two directions:
… - toward axonal terminal (e.g. mitochondria, membrane components, enzymes)
… - toward the cell body (e.g. organelles to be degraded, signal molecules, viruses, bacterial toxins)
anterograde;
retrograde
cells of nervous system: axons transport
… axonal transport: moves material by … (cytoplasmic) flow at 0.2-2.5 mm/day
… axonal transport: moves organelles at rates of up to 400 mm/day
slow; axoplasmic;
fast
cells of nervous system: axons transport
fast axonal transport:
… (or … ) transport: from cell body to axon terminal
… (or …) transport: from axon terminal to cell body
forward; anterograde;
backward; retrograde
fast axonal transport of membranous organelles:
- peptides synthesized and packaged
- fast axonal transport along … network
- vesicle contents released by …
- ….
- … fast axonal transport
- old membrane components digested in …
microtubule; exocytosis; synaptic vesicle recycling; retrograde; lysosomes
(myelin sheath) segmented … sheath most long or large-diameter axons
it functions to:
… and … the axon
increase … of nerve impulse transmission
protein-lipoid;
protect; electrically insulate;
speed
(myelin sheath) in PNS:
Schwann cells wrap many times around the axon –> …: concentric layers of schwann …
…: peripheral bulge of Schwann cell cytoplasm
myelin sheath; cell membrane;
neurilemma
(myelin sheath) in PNS:
…: myelin sheath gaps between adjacent Schwann; sites where … can emerge
nodes of Ranvier; axon collaterals
(myelin sheath) 1. a schwann cell envelopes an axon
- the schwann cell then rotates around the axon, wrapping its plasma membrane loosely around it in …
- the schwann cell … is forced from between the membranes. the tight … surrounding the axon form the myelin sheath
succesive layers;
cytoplasm;
membrane wrappings
thin nerve fibers are …
one schwann cell may incompletely enclose 15 or more …
unmyelinated;
unmyelinated axons
myelin sheaths in the CNS: formed by processes of ..., not the whole cells ... are present no ... thinnest fibers are ...
oligodendrocytes;
nodes of ranvier;
neurilemma;
unmyelinated
…: dense collections of myelinated fibers
…: mostly neuron cell bodies and unmyelinated fibers
white matter;
gray matter
structural classification-three types of neurons:
… - 1 axon and several dendrites
… - 1 axon and 1 dendrite
… (…) - single, short process that has two branches
multipolar;
bipolar;
unipolar; pseudounipolar
structural classification-three types of neurons:
multipolar neurons are the most … and are .. neurons and ..
.abundant; motor; interneurons
structural classification-three types of neurons:
… are rare; an example is retinal neurons
bipolar
structural classification-three types of neurons:
unipolar branches:
… process - more distal branch, often associated with a sensory receptor
… process - branch entering the CNS
peripheral;
central
functional classification-three types of neurons:
… (…): transmit impulses from sensory receptors toward the CNS
… (…): carry impulses from the CNS to effectors
… (… neurons): shuttle signals through CNS pathways; most are entirely within the CNS
sensory; afferent;
motor; efferent;
interneurons; association
neuron function:
neurons are highly …
respond to adequate stimulus by generating an … (nerve impulse)
impulse is always the same regardless of …
irritable;
action potential;
stimulus
(principles of electricity)
opposite charges attract each other
… is required to separate opposite charges across a membrane
… is liberated with the charges move toward one another
if opposite charges are separated, the system has …
energy;
energy;
potential energy
…: measure of potential energy generated by separated charge
voltage (V)
…: voltage measured between two points
potential difference
…: the flow of electrical charge (ions) between two points
current (I)
…: hindrance to charge flow (provided by the plasma membrane)
Resistance (R)
…: substance with high electrical resistance
…: substance with low electrical resistance
insulator;
conductor;
Ohm’s Law:
V = IR I = V/R
… serve as membrane ion channels
two main types of ion channels:
… (…) channels - always open
… channels (three types)
proteins;
leakage; nongated;
gated
gated ion channels:
… (…) channel: open with binding of a specific neurotransmitter
… channels: open and close in response to changes in membrane potential
… channel: open and close in response to physical deformation of receptors
chemically gated; ligand-gated;
voltage-gated;
mechanically gated
when gated channels are open:
ions diffuse quickly across the membrane along their …:
along chemical conc gradients from .. conc to … conc
along electrical gradients toward …
electrochemical gradients;
higher; lower
opposite electrical charge
when gated channels are open:
ion flow creates an … and … changes across the membrane
electrical current; voltage
(resting membrane potential - Vr) potential difference across the membrane of a resting cell:
approximately … in neurons (… side of membrane is negatively charged relative to other side)
-70 mV; cytoplasmic
(resting membrane potential - Vr)
generated by:
differences in ionic makeup of … and …
… of the plasma membrane
intracellular fluid (ICF); extracellular fluid (ECF); differential permeability
differences in ionic makeup:
ICF has lower conc of … and … than ECF
ICF has higher conc of … and … (A-) than ECF
Na+; Cl-;
K+; negatively charged proteins
differential permeability of membrane:
impermeable to …
slightly permeable to … (through leakage channels–higher …)
75 times more permeable to .. (more …, higher …)
freely permeable to …
A- (anionic proteins);
Na+; out of the cell
K_; leakage channels; in the cell;
Cl-
negative interior of the cell is due to much greater diffusion of … than …
… stabilizes the membrane potential by maintaining the concentration gradients for Na+ and K+
K+ out of the cell; Na+ diffusion into the cell;
sodium-potassium pump
membrane potential changes when:
… across the membrane change
… of membrane to … changes
changes in membrane potential are signals used to …, …, and … information
concentrations of ions;
permeability; ions;
receive; integrate; send
two types of signals:
… –> incoming short-distance signals
… –> long-distance signals of axons
graded potentials;
action potentials
depolarization
a … in the membrane potential (toward …)
inside of the membrane becomes less … than the resting potential
… the probability of producing a nerve impulse
reduction; zero;
negative;
increases
hyperpolarization:
an … in membrane potential (away from ..)
inside of the membrane becomes more … than the resting potential
… the probability of producing a nerve impulse
increase; zero;
negative;
reduces
graded potentials:
short-lived, … changes in membrane potential
… or …
spreads as … change the membrane potential of adjacent regions
localized;
depolarizations; hyperpolarizations;
local currents
(Action Potential- AP) brief reversal of membrane potential with a total amplitude of … mV
occurs in … cells and …
does not … over distance
principal means of … neural communication
about 100;
muscle; axons of neurons;
decrease in magnitude;
long-distance
properties of gated channels:
each Na+ channel has two voltage-sensitive gates:
…: closed at rest; open with depolarization
…: open at rest; block channel once it is open
activation gates;
inactivation gates
properties of gated channels:
each K+ channel has … gate
… at rest
opens slowly with …
one voltage-sensitive;
closes;
depolarization
depolarizing phase:
depolarizing local currents open …
… causes more depolarization
at threshold (… to … mV) positive feedback leads to opening of all … and a reversal of membrane polarity to … (spike of AP)
voltage-gated Na+ channels; Na+ influx; -55 to -50; Na+ channels; \+30 mV
repolarizing phase:
Na+ channel … close
membrane permeability to … declines to resting levels
slow … open
… exits the cell and internal negativity is restored
slow inactivation gates;
Na+;
voltage-sensitive K+ gates;
K+
hyperpolarization:
some … channels remain open, allowing excessive ..
this causes … of the membrane (…)
K+; K+ efflux;
after-hyperpolarization; undershoot
Na+-K+ pump: 1. Na+ binding 2. ... 3. ... causes Na+ release and K+ binding 4. ... induced ... leads to K+ release process repeats
phosphorylation;
conformational change;
dephosphorylation; conformational change
propagation of an action potential:
Na+ influx causes a patch of the axonal membrane to …
… occur
Na+ channels toward the point of origin are … and not affected by the …
depolarize;
local currents;
inactivated;
local currents
propagation of an action potential:
local currents affect adjacent areas in the … direction
depolarization opens … and triggers an AP
… wave follows the depolarization wave
forward;
voltage-gated channels;
repolarization
at threshold: membrane is depolarized by ... to ... mV ... increases ... exceeds ... the positive feedback cycle begins
15; 20;
Na+ permeability;
Na+ influx; K+ efflux
…: weak local depolarization that does not reach threshold
subthreshold stimulus
…: strong enough to push the membrane potential toward and beyond threshold
threshold stimulus
AP is an … phenomenon – action potentials either happen completely, or not at all
all-or-none
all actions potentials are alike and are independent of …
strong stimuli can generate action potentials … than weaker stimuli
the CNS determines stimulus intensity by the …
stimulus intesnity;
more often;
frequency of impulses
…: time from the opening of the Na+ channels until the resetting of the channels
ensures that each AP is an … event
enforces … of nerve impulses
absolute refractory period;
all-or-none;
one-way transmission
…: follows the absolute refractory period
most Na+ channels have returned to their resting state
some K+ channels are still open
… is occurring;
relative refractory period; repolarization
relative refractory period:
threshold for AP generation is …
… may generate an AP
elevated;
exceptionally strong stimulus
conduction velocities of neurons vary widely:
larger diameter fibers have … resistance to local current flow and have … impulse conduction
continuous conduction in unmyelinated axons is … than … in myelinated axons
less; faster;
slower;
saltatory conduction
conduction velocity:
myelin sheaths … and prevent …
saltatory conduction in myelinated axons is more than … faster –> … are located at the nodes; APs appear to jump rapidly from node to node
insulate; leakage of charge;
30 times; voltage-gated Na+ channels;
