1 - Intro to Neuroanatomy & Neurocytology Flashcards
2 cell types: ____ (nerve cells) and ___ (non-neuronal cells)
neurons, glia
____: anatomical and functional units for signal transmission
neurons
____: supportive structural matrix, maintains homeostasis, nourishment, regulation of neuronal functions
glia
4 anatomical components of neuron?
- dendrites
- soma (cell body)
- axon
- presynaptic axon terminal
do dendrites send or receive signals?
receive
do axons send or receive signals?
send
____ neurons: 1 dendrite root and 1 axon with cell body central to those
bipolar
______ neurons: 1 dendrite root and 1 axon with cell body not in the exact middle
pseudounipolar (subclass of bipolar)
_____ neurons: multiple dendrites & 1 axon
multipolar (most common)
3 functional classifications of neurons?
- motor neurons
- sensory neurons
- interneurons
___: supporting cells, “glue” of nervous system
glia
3 types of macroglia?
- astrocytes
- oligodendrocytes
- schwann cells
astrocytes found in CNS or PNS?
CNS
oligodendrocytes found in CNS or PNS?
CNS
schwann cells found in CNS or PNS?
PNS
____: star shaped cells that include neuronal signaling (liaison, communications, pathways for neuronal migration), housekeeping, nutritive functions for neurons
astrocytes
_____: form myelin sheath in CNS
oligodendrocytes
____: form myelin sheath in PNS
schwann cells
_____: type of glial cells that work as immune system of CNS, function as phagocytes, activate during nervous system development, activate after injury or infection
microglia
3 types of glial cells?
glia, macroglia, microglia
____ is effective insulator, shielding neurons from extracellular environment, and helps speed up transmission
myelin
4 steps in sequence of events for neural transmission?
- receptor stimulated
- local potential
- action potential
- synapses
___ potential:
- small, graded potential in amplitude and duration
- receptor or synaptic potential
- spreads passively and confined to small area of neuron membrane
local
___ potential:
- large, “all or none” depolarizing signal
- actively propagates along neuron axon traveling 1-way to presynaptic terminal
action
____: transports signal to other neurons by release of neurotransmitters
synapses
neurons have ____ ____ membranes
selectively permeable
cell membrane is more permeable to __ than to ___
K+, Na+
____ ____: separation of different charges across the membrane creating electrical potential (___ mV)
membrane potential, -70
extracellular fluid is more ____ charged, intracellular fluid is more ___ charged when at resting membrane potential
extracellular = +
intracellular = -
what channel?
____ (____): small amount of ions diffuse through membrane at slow continuous rate
leak (non-gated)
what channel?
_____ (___ ___ only): opens in reaction to mechanical stimulation, temperature or chemicals
modality-gated (sensory neurons only)
what channel?
______: opens when neurotransmitter binds to post-synaptic receptors, generating local potentials
ligand-gated
what channel?
_____: opens in reactions to change in electrical potential, generating actions potentials
voltage-gated
At rest, inside of neuron is more (-) than outside:
- inside with more ___ and ____
- outside with more ___ and ____
inside with more K+ and anions-
outside with more Na+ and Cl-
Dynamic equilibrium of RP is maintained by:
- (-) charged anions trapped ____ neuron
- passive diffusion of __ and ___ thru leak channel
- Na+ and K+ pump requiring ____
- inside
- K+ and Na+
- ATP
Na+ - K+ pump: ___ K+ into cell and ___ Na+ out
2, 3
Na+ - K+ pump: 2 K+ ___ cell and 3 Na+ ___ of cell
into, out
when is it easier for the nerve to conduct, when depolarized or hyperpolarized?
depolarized
Stim has to reach threshold of ___mV to produce action potential
-55
will increasing stim intensity change amplitude or duration of AP?
no
Action potential:
- actively propagates along ____
- repeatedly generates signal
- travels in ___ direction
- can be produced by ___ or ___ summation
axon
1
spatial, temporal
___ ___ phase: more + from -70mV to +30 mV
rising depolarizing phase
____ ____ phase: more - from +30mV to -70mV
falling repolarizing phase
___ ____ phase: more - than RP at -90mV
re-setting hyperpolarizing
depolarization: small change in membrane voltage depolarizes it enough to open ___ channels
Na+ (voltage-gated Na+ channels)
Depolarization:
- small change in membrane voltage depolarizes it enough to open Na+ channels
- as more Na+ moves into the neuron, more and more Na+ channels open
- polarity rapidly changes to ___ from ___ to produce ___ ____
negativeto +, action potential
Repolarization to hyperpolarization to RP:
- ___ channels start to close and ___ voltage-gated channels start to open
Na+, K+
K+ channels are ___ to respond to the AP’s depolarization
slower
Repolarization to hyperpolarization to RP:
- Na+ channels start to close and K+ voltage-gated channels start to open
- K+ ions exit and membrane potential falls toward RP from + to - toward -70mV
- K+ channels remain open leading to ____ membrane potential (below -70mV)
- gradually active _____ ____ the ions to restore RP of -70mV
hyperpolarized
Na+-K+ pumps
what refractory period?
____: completely unresponsive to stimuli
absolute
what refractory period?
____: most of Na+ channels have been open and not yet reset to resting state
absolute
what refractory period?
___: may respond to stronger stimuli
relative
what refractory period?
____: most of Na+ channels are reset
relative
refractory period advantageous for promotion of ___ propagation of AP and prevent ___ flow
forward, backward
3 factors influencing action potential conduction velocity?
- diameter of axon
- myelin
- temperature
__ ___ __:
- placed q 0.2 to 2 mm
- location of AP generation and voltage-gated Na+ channels
nodes of ranvier
___ ___: AP leaps from node to node
saltatory conduction
___ occurs only at nodes of ranvier
depolarization
___ conduction:
- AP propagates along unmyelinated axon membrane
- step by step depolarization of each part of length of axon
- as Na+ flows into cell, voltage of next areas is impacted and their voltage-gated Na+ channels open
continuous
will continuous or saltatory conduction be faster?
saltatory
____ ____ fibers: peripheral sensory and motor axons
large myelinated
___ ____ fibers:
- short axons in gray matter of CNS
- some visceral autonomic axons
- some pain fibers
thin unmyelinated
Action potential in muscle cell:
- resting skeletal and cardiac muscle resting potential is ____mV
- resting visceral smooth muscles are ___mV to ____mV
- muscle AP lasts ___ msec
- cardiac and smooth muscle AP lasts ____ msec
-90mV
-20 to -50mV
1-5msec
10-300msec
Action potential in nerves:
- resting membrane potential is ___mV
- nerve AP is ____msec
- fasters nerve conduction is ___x faster than velocity over skeletal muscle fibers
-70mV
0.5-2msec
18x
