Nervous System Flashcards
cns includes
brain & spinal cord
pns
all nerves except brain & spinal cord
two basic structure of nervous system
neurons & glial cells
gray matter made of
many cell bodies & dendrites; actually pinkish
white matter contains
many axons; axons are insulated by lipid-rich substance called myelin
ganglion
cluster of neuron cell bodies; in PNS
tract
bundle of axons, fibers found in CNS
nerve
bundle of axons, fibers in PNS
insulation for axons in nervous system is provided by
glial cells, oligodendrocytes in CNS, schwann cells in PNS
myelin
lipid-rich sheath that surrounds the axon & creates a myelin sheath that facilitates transmission of electrical along the axon
demyelination
myelin insulation of axons is compromised making electrical signaling slower; diseases like MS & Guillain-Barre syndrome
which of the following shows the correct order of nervous transmission
dendrite - soma - axon
cells of the nervous system are termed
neurons
neurons
highly specialized cells that conduct electrical impulses to communicate w/different cells; produce movement in response to stimuli
glial cells
considered supporting cells to the neurons
what are the four different types of glial cells CNS
astrocytes, oligodendrocytes, micorglial cells, ependrymal cells
two different glial cells in PNS
satellite cells, schwann cells
astrocytes
most common type have numerous processes that support neurons & connect them to nutrient-rich capillaries; support by maintaining concentration of chemicals in extracellular space, removing excess signaling molecules, reacting to tissue damage, contributing to blood brain barrier
oligodendroctyes
form myelin sheaths that protect neurons and increase conduction speed in CNS; provide myelin for multiple axon segments for same or different axons
ependymal cells
line central cavities of brain & spinal cord & ventricles, help produce & circulate cerebrospinal fluid;
microglia
provide immune system by using phagocytosis to remove pathogens that pass blood-brain barrier or are introduced directly into brain; originate as white blood cells macrophages; aka CNS resident macrophages
axon
fiber that emerges from cell body & projects to target cells
dendrites
receive information from other neurons at specialized areas of contact called synapses
what does is it mean when a neuron has polarity
information flows in this one direction
axon hillock
where axon emerges from cell body; tapering of cell body toward axon fiber
axoplasm
w/in axon hillock, cytoplasm changes to solution of limited components
initial segment of axon
axon hillock
node of ranvier
gap in myelin covering
axon segment
length of the axon between each gap, wrapped in myelin
axon terminal
end of axon; several branches extending toward the target cell ends in enlargement called synaptic end bulb
unipolar cells
one process emerging from the cell; found in invertebrate animals; cell bodies always found in ganglia
bipolar
2 processes; extend from each end of the cell body opposite to each other; one axon and one dendrite; not common; found in olfactory epithelium & retina
multipolar neurons
one axon and two or more dendrites;
blood brain barrier
keeps many substances that circulate in rest of body from getting into central nervous system; restricting what can cross from blood in CNS
satellite cell
found in sensory & autonomic ganglia; surround cell bodies of neurons; provide support, performing similar functions in periphery as astrocytes do in CNS
schwann cell
insulates axons w/myelin in periphery; wraps around portion of only one axon segment & no others; oligodendrocytes have processes that reach out to multiple axon segments whereas entire schwann cell surrounds just one axon segment
what is the extension of the cell membrane of neurons called
processes
what are the three primary vesicles developed
prosencephalon (front), mesencephalon (middle), rhombencephalon (hindbrain)
secondary vesicles developed
prosencephalon turns into telencephalon & diencephalon, telencephalon will become cerebrum & diencephalon turns into thalamus & hypothalamus
the part of the brain that acts as a relay for sensory information
thalamus
threshold
amount of stimulus needed to generate an action potential
conscious perception of a sensory stimulus is accomplished by which part of the brain
cerebral cortex
movement of an action potential along an axon
propagation
size exclusion
ion channels can specified by diameter of pore; distance between amino acid will be specific for diameter of ion; large pores are not ideal for smaller ions because water molecules will interact
nonspecific channel
ion channels are selective for charge but not size; allow cations (Na+, K+, Ca2+) to cross membrane but not anions
ionotropic receptor
ligand binds to protein ions across membrane changing its charge
mechanically gated channel
opens because of a physical distortion of the cell membrane; associated w/sense of touch
voltage-gated channel
responds to changes in electrical properties of membrane which is embedded; inner portion of membrane is negative voltage; less negative means channel allows ions to cross membrane
leakage channel
randomly gated; opens & closes at random; leakage channels contribute to resting transmembrane voltage of excitable membrane
membrane potential measures ____ charge relative to charge outside the cell
intracellular
depolarization of a cell
starting voltage is -70 mV; sodium cation entering cell will cause it to become more positive; membrane potential moves toward zero
repolarization of the cell
K+ leaves the cell and takes its positive charge w/ it; eventually the cell will reach a threshold and move back toward resting voltage of -70mV
what are the 2 types of voltage-gated Na+ Channels
activation gate; opens when membrane potential crosses -55 mV; inactivation gate- closes after a specific period of time
voltage-gated K+ channel
sensitive to -50 mV; doesn’t open as fast as Na+ channel; when Na+ flow peaks voltage-gated K+ channels open
continuous conduction
propagation along unmyelinated axon; slow; Na+ rushing into cell
saltatory conduction
propagation along myelinated axon
resistance in terms of electrical propagation along a neuron is due to
speed of depolarization is dependent on the width of the axon
action potentials are initiated by a release of ___ in the membrane through ion channels
sodium
generator potential
graded potentials develop in dendrites that influence generation of an action potential in axon of same cell; unipolar cells of sensory neurons
receptor potential
photoreceptors of retina, sensory receptor cells; graded membranes result in release of neurotransmitters at synapses
excitatory postsynaptic potential (EPSP)
causes membrane potential to move toward threshold
Postsynaptic potential (PSP)
graded potential in dendrites of neuron that is receiving synapses from other cells; depolarizing or hyperpolarizing
inhibitory postsynaptic potential (IPSP)
hyperpolarization in a postsynaptic potential; causes membrane potential to move away from threshold
summation
takes place in axon hillock; can be spatial & temporal, result of multiple graded potentials at different locations of the neuron or all at the same place but separated in time
spatial summation
associating activity of multiple inputs to a neuron w/each other
temporal summation
relationship of multiple action potentials from a single cell resulting in significant change in membrane potential
electrical synapse
direct connection between two cells so that ions pass directly from one cell to the next; if one cell is depolarized than the other does as well
chemical synapses
involve transmission of chemical info from one cell to the next; ex. NMJ; contain neurotransmitter, presynaptic element, synaptic cleft, receptor proteins, postsynaptic element, neurotransmitter elimination or re-uptake
what are the two receptors in cholinergic system
nicotinic receptor & muscarinic receptor
amino acids
group of neurotransmitters; includes glutamate, GABA, glycine
biogenic amine
group of transmitters enzymatically made from amino acids; serotonin, dopamine, norepinephrine, epinephrine
neuropeptides
neurotransmitter molecule made up of chains of amino acids connected by peptide bonds
summation of graded potentials refers to
cumulative changes in membrane potential across a neuron
amount of electrical voltage change in a membrane due to a stimulus is determined most significantly by
size of the stimulus
graded potential is associated w/which part of the neuron
dendrites
what happens to amino acid neurotransmitters after they are active in a stimulus transmission
recycled & used again
aorta
carries recently oxygenated blood away from heart; first branch supply heart w/nutrients & O2; next branches lead into common carotid arteries & internal carotid arteries
internal carotid artery enters the cranium in temporal lobe through which canal
carotid canal
which arteries pass through foramen magnum of occipital bone
vertebral arteries; supply CNS
after passing through CNS, blood returns to circulation through what
dural sinuses & veins
ventricles
open spaces w/in brain where CSF circulates
CSF function
circulates to remove metabolic wastes from interstitial fluids of nervous tissues & return them to bloodstream
the four ventricles w/in brain
within central canal; lateral ventricles (2), space between L & R sides of diencephalon; space between cerebellum & pons & upper medulla
where is cerebrospinal fluid produced
w/in ventricles by choroid plexus; fluid is clear & made of water, small molecules & electrolytes
perfusion to the brain is maintained by
circle of willis
Dura Mater
covers brain; entire CNS & major blood vessels that enter cranium
arachnoid mater
middle layer of meninges; sac like enclosure around CNS; circulates CSF;
Pia Mater
outer surface of CNS covered in thin fibrous membrane; continuous layer of cells providing a fluid-impermeable membrane
corpus callosum
provides pathway for communication between two hemispheres of the cerebral cortex
basal nuclei
responsible for cognitive processing
basal forebrain
contains nuclei that are important in learning & memory
limbic cortex
part of limbic system; collection of structures involved in emotion, memory, behavior
temporal lobe
auditory sensation, memory
parietal lobe
somatosensation; general sensations associated w/body; postcentral gyrus (primary somatosensation) tactile senses
frontal lobe
motor functions; precentral gyrus (primary motor cortex); premotor area (thinking of movement to be made); frontal eye fields (eliciting eye movements); broca’s area (production of language, speech); prefrontal lobe (personality, short-term memory, consciousness)
hippocampus & amygdala
long term memory formation & emotional responses
direct pathway
projection of axons from striatum to globus pallidus internal segment & substantia nigra pars reticulata
indirect pathway
projection of axons from striatum to globus pallidus external segment to subthalamic nucleus and then to GPi/SNr
disinhibition
inhibition of one cell on a target cell that then inhibits first cell
substantia nigra pars compacta
switch between two pathways; projects into striatum & releases neurotransmitter dopamine
cerebral cortex
outer portion of cerebrum composed of grey matter
diencephalon
brain, spinal cord, PNS send info to cerebrum through here except olfaction; any region w/ “thalamus” in name;
thalamus
relay info between cerebral cortex & periphery, spinal cord, brain stem
cerebellum
“little brain”;
axons entering dorsal nerve root of the vertebral column transmit signals from
sensory input
main connection between cerebellum & brain stem is
pons
ganglion
group of neuron cell bodies in the periphery; sensory or autonomic ganglia
dorsal (posterior) root ganglion
in skin; extend into CNS through dorsal nerve root
autonomic ganglia
divided into sympathetic & parasympathetic nervous systemsq
acronym for remembering cranial nerves (12)
on old olympus towering tops/a finn and german viewed some hops ; olfactory nerve I, Optic nerve II, oculomotor nerve III, trochlear nerve IV, trigeminal nerve V, abducens nerve VI, Facial nerve VII, Glossopharyngeal nerve IX, Vagus Nerve X, accessory nerve XI, hypoglossal nerve XII
olfactory/optic nerve
sense of smell & vision
oculomotor nerve
eye movements; upper eyelid & pupillary constriction
trochlear nerve & abducens nerve
responsible eye movement by controlling extraocular muscles
trigeminal nerve
cutaneous sensations of face & controlling muscles of mastication
facial nerve
muscles in facial expressions; taste & production of saliva
vestibulocochlear nerve
sense of hearing & balance
glossopharyngeal nerve
controlling muscles in oral cavity & upper throat
vagus nerve
contributing to homeostatic control of organs of thoracic & upper abdominal cavities
spinal accessory nerve
controlling muscles of neck, along cervical spinal nerves
hypoglossal nerve
controlling muscles of lower throat & tongue
how many spinal nerves are there
31; 8 pairs of cervical nerves, 12 thoracic nerves, 5 pairs of lumbar nerves, five pairs of sacral nerves; 1 coccxygal nerves
cervical plexus
composed of axons from spinal nerves C1 through C5 & branches into nerves in the posterior neck & head
lumbar plexus
arises from lumbar spinal nerves & enervates to pelvic region & anterior leg
femoral nerve
major nerve from lumbar plexus; gives rise to saphenous nerve as branch that extends through anterior lower leg
sacral plexus
lower lumbar & sacral nerves; sciatic nerve comes form here
anosmia
loss of sense of smell; olfactory nerve being severed
association of spinal nerves C4 through T1 known as
brachial plexus
functions of the nervous system
sensation, integration, response
somatic nervous system
responsible for conscious perception & voluntary motor responses (contraction of skeletal muscle)
autonomic nervous system
responsible for involuntary control of body (for sake of homeostasis)
enteric nervous system
describes functional responses (controlling nervous system) & smooth muscle & glandular tissue in digestive system; not dependent on CNS; large part of PNS
integration & association areas of the nervous system function to
combine sensory perceptions w/ higher cognitive functions in order to produce a response
central processing of sensory stimuli into a meaningful pattern is termed
perception
