56 Cards in this Set
Front | Back |
---|---|
3 functions of nervous system
|
sensory input, integration, motor output
|
Central Nervous System (CNS)
|
includes brain, spinal cord
--integrative and control centers >> motor output
|
Peripheral Nervous System (PNS)
|
includes cranial nerves and spinal nerves
--communication lines between CNS and the rest of the body
|
sensory (affarent) division
|
-towards CNS
-transmits all sensory info
-somatic and visceral sensory nerve fibers
-conducts impulses from receptors to CNS
|
motor (efferent) division
|
-motor nerve fibers
-conducts impulses from CNS to effectors (muscles and glands)
--affects all muscle types
--divides into somatic and autonomic nervous systems
|
somatic nervous system
|
-voluntary movement (somatic motor)
-skeletal muscles
|
autonomic nervous system (ANS)
|
-involuntary movement
-heartbeat, gastric motility, BP, gland secretion
--divides into sympathetic and parasympathetic divisions
|
sympathetic division
|
-fight or flight
-increases heart rate and breathing
-decreases smooth muscle contractions
|
parasympathetic division
|
-dominant when at rest
-decreased heart rate and breathing
-activates the GI tract
-rest and digest
|
two cell types of nervous system
|
neuroglia (glial cells) -- supporting cells
neurons
|
types of neuroglia cells
|
-astrocytes
-microglia
-ependymal cells
-oligodendrocytes
-satellite cells
-schwann cells
|
astrocytes
|
-most abundant, versatile, highly branched
-hold neurons together; cling to synaptic endings and capillaries
-support and brace neurons
-higher numbers than neurons
|
microglia
|
-small, resident macrophage w/ thorny processes
-migrate to injured neurons-- first defense
-phagocytize microorganisms and neuronal debris
|
ependymal cells
|
-line brain ventricles, aqueducts, central canal of spinal cord
-held together via tight junctions (water-tight)
-separate CNS interstitial fluid and cerebrospinal fluid in cavities
|
oligodendrocyte
|
-produce myelin sheath >> lipid insulator
-branched cells; "white matter" around neurons
-processes wrap CNS nerve fibers; able to wrap multiple
|
satellite cells
|
-surround neuron cell bodies in PNS
-assoc. w/ sympathetic, parasympathetic, and sensory
-regulate access to nutrients
-ONLY IN PNS
|
schwann cells
|
-produce myelin
-assoc. w/ only 1 neuron
-vital to regeneration of damaged peripheral nerve fibers
-speeds up conduction of signal via myelin
-no ion channels or proteins
|
neurons
|
-primary to nervous system
-CNS ONLY
-high metabolic rate--continuous oxygen and glucose dependent
-cell to cell interaction and electrical signaling
|
axon hillock
|
cone-shaped area from which axon arises; has to be stimulated for action potential to occur in axon
|
dendrite
|
-receptive region of a neuron
-short, tapering and diffusely branched
-conveys input towards cell body>> graded potential
|
axons
|
-one axon per cell, branches from axon hillock
-larger axon = faster conductor
-small axon = slow conductor
-knoblike axon terminals = boutons
|
node of ranvier
|
gap between schwann cells; exposed axon
|
white matter
|
dense collections of myelinated fibers
|
gray matter
|
mostly neuron cell bodies and unmyelinated fibers
|
functional classification of neuorns
|
1) sensory (affarent)
2) interneurons ((assoc. neurons)
3) motor (efferent)
|
sensory (affarent)
|
transmit impluse: sensory receptors to CNS
|
interneurons (assoc. neurons)
|
shuttle signals thru CNS
|
motor (efferent)
|
carry impulses from the CNS
|
voltage (V)
|
measure of potential E generated by separated charge; determined by action potential
|
potential difference
|
voltage measured between two points
|
resistance (R)
|
hindrance to charge flow (by plasma membrane)
|
insulator
|
substance w/ high electrical resistance
|
conductor
|
substance w/ low electrical resistance
|
depolarization
|
change in membrane potential towards zero (become less negative)
|
hyperpolarization
|
membrane potential increases; moves away from zero (become more negative)
|
absolute refractory period
|
in depolarized state
--cannot depolarize again; stimuli won't affect
--ends when membrane potential falls below threshold>> reset Na voltage gated channels >> enter relative refractory period
|
relative refractory period
|
not yet at normal state
--is able to depolarize again
--required greater stimulus than at normal resting state
|
conduction velocity
|
-varies within neurons
-determined by axon diameter and myelination
|
effects of axon diameter
|
-larger diameter fibers have lower resistance to local current flow and faster impulse conduction
--faster impulse due to more Na+ channels
|
effects of myelination
|
-continuous conduction in unmyelinated axons is slower that saltatory conduction in myelinated axons
|
how are nerve fibers classified?
|
diameter
degree of myelination (present or not)
speed of conduction
|
Group A fibers
|
largest diameter
all myelinated
fastest conduction
ex. somatic sensory and motor (volutary)
|
Group B fibers
|
intermediate diameter
lightly myelinated
moderate speed
ex. ANS fibers and involuntary motor
|
Group C fibers
|
smallest diameter
unmyelinated
slowest speed
ex. ANS fibers and pain fibers (dull ache)
|
what is the synapse?
|
the junction that mediates information transfer from one neuron to another neuron OR from one neuron to an effector cell
|
what are the three types of synapses?
|
axo-dendritic synapse: axon to dendrite
axo-somatic synapse: axon to soma
axo-axon synapse: axon to axon (very rare)
|
what is the difference between a presynaptic and postysnaptic neuron?
|
pre: conducts impulse towards the synapse
post: transmits impulse away from the synapse
|
what is the difference between electrical and chemical synapses?
|
E:
rare in CNS after development
common in rest of body
very rapid
unidirectional or bidirectional
important in embryonic nervous and heart tissues, some brain
C:
specialized for release and reception of neurotransmitter
unidirectional
|
what is the synaptic cleft?
|
fixed structure; fluid-filled space of a synapse
|
how does information transfer occur?
|
presynaptic neuron experiences rise in AP > triggers release of neurotransmitter in bouton > graded potential occurs in postsynaptic neuron
|
what are the different type of postsynaptic potentials?
|
EPSP- excitatory
IPSP- inhibatory
|
what are the different types of integration summation?
|
-temporal summation (additive)
-spacial summation
-spacial summation of EPSPs and IPSPs
|
what are the characteristics of norepinephrine?
|
-neurotransmitter version of adrenaline
-excitatory to brain
-inhibatory to GI tract
|
what are the characteristics of dopamine?
|
-"happy" neurotransmitter
-excitatory/inhibatory depending on receptor
-found in cocaine>> activates pleasure sensors
|
what are the characteristics of seratonin?
|
-found mainly in CNS
-middle #s= stable mood
-too high or too low #s= depression/suicide
-inhibatory
|
what characteristics does ATP have as a neurotransmitter?
|
-stimulates pain associated with nerve endings
-in severe conditions, breaks down from ADP to AMP to adensosine
-adenosine promotes neuron fatigue>> slows neuron activity
|