ch. 12 Flashcards
two major divisions of the nervous system
CNS and PNS
brain and spinal cord
central nervous system
cranial and spinal nerves
peripheral nervous system
2 functional divisions of the nervous system
afferent division
efferent division
brings sensory information to CNS from receptors
afferent division
carries motor commands from CNS to effectors
efferent division
muscles and glands
effectors
2 components of the efferent division
somatic ns and autonomic ns
controls skeletal muscle contractions
somatic ns
provides automatic regulation of smooth muscle, cardiac muscle and glands
autonomic ns
functional units of the nervous system
neurons
short extensions from the cell body; usually many and highly branched
dendrites
functions of dendrites
receives info from other neurons
one extends from cell body
long, slender, cylindrical process with uniform diameter
end has many fine branches which end at synaptic terminals
axon
function of axon
conduct impulses away from cell
small, numerous dendrites; no axon
anaxonic neurons
fx: poorly understood
anaxonic neurons
in brain and in special sense organs
anaxonic neurons
1 dendrite and 1 axon with cell body between the 2
bipolar neuronns
in specialized parts of eye nose and ears; rare
bipolar neurons
fx: relay info about sight, smell or hearing
bipolar neurons
dendrites and axon are continuous and cell body lies off to side
unipolar neurons
fx: carry info/senses into CNS
unipolar neurons
most common neuron in CNS
mulltipolar neurons
fx: control skeletal muscles
multipolar neurons
carry instructions from cns to effectors
motor efferent neurons
outnumber all other types of neurons combined
interneurons
fx: distribution of sensory info and coordination of motor activity; involved with all higher functions
interneurons
carry impulses from sensory receptors to cns
sensory (afferent) neurons
are unipolar and cell bodies are located in ganglia
sensory neurons
two types of motor neurons
somatic motor neurons
visceral motor neurons
innervate skeletall muscles
somatic neurons
innervate smooth muscle, cardiac muscle and glands
visceral neurons
glial cells
neuroglial cells
supporting cells within nervous tissue
neuroglial cells
what is the role of the calcium ion in the synapse
enters synaptic knob triggering exocytosis of neurotransmitter into synaptic cleft
chemicals released by one neuron to affect the transmembrane potential of another
neurotransmitter
2 classes of neurotransmitter
excitatory
inhibitory
causes depolarization and promote generation of action potentials
excitatory
causes hyper polarization and suppress generation of action potentials
inhibitory
why is the classification of neurotransmitters not always precise
depends on the receptors not really the neurotransmitter- sperm going into woman
how many neurotransmitters ID
100
excitatory at all neuromuscular junctions
ACh
what effects ACh and what does it do
alzheimers- decrease ACh
typically excitatory
norepinephrine
increases arousal, dreaming and mood
norepinephrine
may be either excitatory or inhibitory
dopamine
dopamine and parkinson disease
decreases-causes stiffness
dopamine and nicotine
increases -pleasure
cocaine and dopamine
blocks repute of dopamine-causes a high
effects mood and emotional state
serotonin
inhibitory
serotonin
depression and serotonin
decreases
tryptophan and serotonin
increases serotonin-causes sleepiness
generally inhibitory
gaba
gaba in CNS
decreases anxiety
gaba and valium
increases receptor binding of gaba
how many neuroglial cells are found in CNS
4 types
how many neuroglial cells are found in PNS
2 types
fx: act as phagocytes
provide structural framework for neural tissue
help secrete and monitor composition of CSF
control interstitial environment within CNS
myelinate CNS axons
FX CNS
fx: myelinate axons
regulate interstitial environment around PNS neurons
FX PNS
2 types of neuroglial cells that myelinate axons
oligodendrocytes on CNS axons
schwann cells on PNS axons
how do the 2 types of neuroglial cells cover the axon
wrap themselves many times around the axon to form many layer along the length of an axon.
this forms lipid rich myelin sheath covering on outside of axon
small gaps in axon covering between cells
nodes of ranvier
axons with myelin sheath?
white matter
no myelin sheath
gray matter
why is it white matter
because of lipids
what causes gray matter
unmyelinated nerve fibers, cell bodies, and dendrites form gray matter in CNS
myelin coating in CNS demyelinate and forms hard scars that block the underlying neurons from transmitting messages- muscles no longer receive input from motor neurons-stops contracting-atrophy
multiple sclerosis
autoimmune
guiliain-barre syndrome
demyelination of peripheral nerves (extremity weakness-paralysis-problems breathing)
guiliain-barre syndrome
potential electrical difference across a cell membrane- cell membrane is electrically charged polarized
transmembrane potential
transmembrane potential in an undisturbed/resting cell
resting potential
the numerical value of the resting potential in a neuron
-70 millivolts in neurons
why is the numerical value of the resting potential in a neuron negative
inside of the cell membrane contains excess of negative ions compared with the outside
explain how the resting potential is maintained in a neuron
Sodium-potassium pumps move two potassium ions inside the cell as three sodium ions are pumped out to maintain the negatively-charged membrane inside the cell
shift of potential to become more positive
depolarization
what causes depolarization
causes from Na+ entering cell
restoring potential to normal resting potential
repolarizing
if potential is becoming more negative
hyperpolarizing
what causes hypolarizing
result from K+ leaving cell
when charge is going up
threshold
graded potential at opposite ends of the cell are linked by a what
action potential
junction between 2 neurons where nerve impulses travel across to the next neuron
the synapse
there is a charge across membrane
transmembrane potential
inside the membrane is more what
negative
outside the membrane is more what
positive
whatever is not is a resting state
refractory period
action potential is relayed from one location to another down an axon
propagation
which is faster continuous or saltatory and why
saltatory- not as many action potential and moves farther in distance quicker
the first SSRI
prozac
collection of neuron cell bodies
ganglia
passive movement of Na parallel to the inner and outer surfaces of a membrane
local current
depolarizing
Na in
repolarizing
K out
motor neurons is the same as
efferent neurons
sensory neurons is the same as
afferent neurons
