Final Flashcards
a network of cells that sense and respond to stimuli in ways that maintain homeostasis
the nervous system
What two cell types are neural tissue composed of?
Neurons and neuroglia
specialized cells that read to physical and chemical changes in their surroundings
neurons
small cellular processes (arms) that receive input; typicaly highly branched, providing receptive surfaces with which processes from other neurons communicate
dendrites
contains granular cytoplasm, mitochondria, lysosomes, glory apparatus, microtubules; also neurofilaments ad chromatophilic substance
cell body
longer process (arm) or nerve fiber that carries information away from the cell in the form of impulses
axon
a bioelectric signal or action potential which allows the neuron to communicate with other neurons and with cells outside the nervous system
impulse
What are bundles of axons called in the PNS?
Nerves
What are bundles of axons called in the CNS?
Tracts (brain and spinal cord)
nourish neurons; send and receive chemical messages; fill spaces and surround or support neurons; create blood-brain barrier and forms the capillaries
neuroglia
the small space between a neuron and the cells with which it communicates
synapse
biological messenger molecules that convey electrochemical messages
neurotransmitter
3 general functions of the nervous system
receiving information, deciding what to do, and acting on decisions
structures at the ends of neurons in the PNS that provide the sensory function of the nervous system gather information by detecting changes side and outside the body; convert information into impulses -> PNS -> CNS
sensory receptors
communicate voluntary (conscious) instructions originating in the CNS to skeletal muscles, causing contraction
somatic nervous system
communicates instructions from the CNS that control viscera, which are involuntary subconscious actions
autonomic nervous system
neurons that conduct impulses from the NS to these responsive structures that carry out motor functions of the nervous system; muscles and/or glands
effectors
Two systems that are part of the motor portion of the PNS
somatic and autonomic nervous system
a network of fine threads that extends into the axon and supports it
neurofilaments
(Nissl bodies) many membranous packets which consists mainly of touch E.R.
chromatophilic substance
the place from which the axon arises from the cell boy as a cone-shaped thickening
axon hillock
space between axon terminal (synaptic knob and receptive surface of another cell
synaptic cleft
neuroglia that encase the large axons of peripheral neurons in lipid-rich sheaths
Schwann cells
a specialized end of an axon that has many fine extensions that ends as a synaptic knob
axon terminal
consists of several types of lipids and proteins; gives the cell membranes of Schwann cells higher proportion of lipid
myelin
surrounds the myelin sheath; only on axons of PNS, not in CNS; regeneration requires the presence of this
neurilemma
narrow gap in the myelin sheath between Schwann cells; responsible for rapid impulse movement
nodes of Ranvier
What color matter would be myelinated axons?
WHITE MATTER
neuron that haas many processes (dendrites) arising from its cell body
multipolar neeuron
specialized masses of nerve tissue that are located outside the brain and spinal cord
ganglia
neuron that only has 2 processes, one arising from either end (nose, ears, eyes)
bipolar neuron
neuron with simple process extending from its cell body
unipolar neuron
neurons that conduct impulses from peripheral body parts into the brain and spinal cord; detect changes in the outside world; mostly unipolar; afferent; sensory receptors trigger impulses that travel on these axons to CNS
sensory neurons
neurons that lie within brain and spinal cord; multipolar; relay information from one part of the brain or spinal cord to another; may conduct incoming sensory information to appropriate regions of processing and interpreting
interneurons
interneurons aggregate in these specialized masses of nervous tissue; similar to ganglia, but in CNS
nuclei
neurons that are multipolar; conduct impulses from the brain or spinal cord out to effectors - muscles or glands; efferent
motor neurons
star shaped cells between neurons and blood vessels; they are for structural support, scar tissue formation, substance transport between blood vessels and neurons, communication between neurons, clean up excess ions, induce synapse formation
astrocytes
shaped like astrocytes but wit fewer cellular processes, in rows along axons; form myelin sheaths in the brain and spinal cord, proceed nerve growth factors
oligodendrocytes
small cells with few cellular processes and found throughout the CNS; structural support and phagocytosis (immune protection)
microglia
cuboidal and columnar cells in the lining of the ventricles of the brain and central canal of the spinal cord; form a porous layer through which substances diffuse between the interstitial fluid of the brain and spinal cord and the cerebrospinal fluid
ependyma
cells with abundant, lipid-rich membrane that wrap tightly around the axon of peripheral neurons; form myelin sheaths of PNS
schwann cells
small, cuboidal cells that surround cell bodies of neurons in ganglia; support ganglia
satellite cells
neuroglia of CNS
astrocytes, oligodendrocytes, microglia, ependyma
neuroglia of PNS
Schwann cells, satellite cells
Which nervous system lacks the neurilemma?
CNS
the neuron conducting an impulse to the synapse; the sender of the text message
presynaptic neuron
the neuron accepting/receiving input at the synapse (could be an effector [muscle or gland])
postsynaptic neuron
a gap that separates two cells that are connected functionally
synaptic cleft
the process by which the impulse in the presynaptic neuron signals the postsynaptic neuron; result is that the presynaptic cell stimulates or inhibits a postsynaptic cell; a one way process carried out by neurotransmitters
synaptic transmission
a series of events that fuses the synaptic vesicles with cell membrane and neurotransmitters are released by exocytosis
impulse
Which ions pass more readily through resting neuron cell membranes?
Potassium
Where is there a higher concentration of potassium ions? Inside or outside the cell membrane?
Inside!!!!!!
-70mV; where large numbers of negatively charged ions on the inside of the cell; they cannot diffuse through the cell membrane; in this state, more positive ions leave the cel than enter it, causing the inside of the cell membrane to develop a negative charge than outside the cell
resting potential
What is the ratio to potassium and sodium ions entering/leaving the cell?
3 sodium ions leave for every 2 potassium ions that come in
the mechanism of active transport by which sodium is extruded from a cell and potassium is brought in, so as to maintain the low concentration of sodium and high concentration within the cell with respect to the surrounding medium
sodium/potassium pump
a rapid change in membrane potential, first in a positive direction, then in a negative direction, returning to the resting potential
action potential
this is located at the axon hillock or initial segment, because it contains many voltage-gated sodium channels
trigger zone
reaching this (-55mV) will result in an action potential
threshold potential
this occurs for an instant when is released out of the cell, then repolarizated
hyperpolarization
when the axon’s voltage-gated channels are temporarily not responsive at all and the axon cannot be stimulated; limits how many action potentials may be generated in a neuron in a given period
refractory period
where action potentials only occur at the nodes in myelinated neurons, and it is initiated at the trigger zone; the action potentials appear to jump from node to node
saltatory conduction
local potentials in chemically gated channels which enable one neuron to affect another
synaptic potentials
lasts for about 15 milliseconds; when a neurotransmitter binds to a postsynaptic receptor and opens sodium ion channels and they diffuse inwards, depolarizing the membrane and could trigger an action potential
excitatory postsynaptic potential
an action potential is less likely to occur due to potassium ions diffusing out the the cell due to the effect of a neurotransmitter
inhibitory postsynaptic potential
chains of amino acids; endorphins
neuropeptides
CNS - controns sksletal muscle actions; PNS - stimulates skeletal muscle contractio at neuromuscular junctions
acetylcholine
CNS - creates a sense of wellbeing, low levels may lead to depression; PNS - may excite or inhibit autonomic nervous system actions, depending on receptors
norepinephrine
CNS - creates a sense of wellbeing, deficiency in some brain areas associated with Parkinson disease; PNS - Limited actions in autonomic nervous system; may cite or inhibit, depending on receptors
Doapmine
within CNS, primarly inhibitory; leads to sleepiness; action is blocked by LSD, antidepressant drugs
serotonin
CNS; release in hypothalamus promotes alterness
histamine
CNS, generally inhibitory
GAA
CNS, generally excitatory
glutamate
axons originating from different neurons leading to the same postsynaptic neuron
convergence
a neuron has a single axon, but axons may branch at several points and reach several neurons
divergence
membranes that protect the brain and spinal cord
meninges
he three meaning layers from outside to inside
dura mater, arachnoid mater, pia mater
outermost layer; thickest; primarily composed of of tough, white, dense connective tissue and contain many blood vessels and nerves; over entire CNS, can have double thickness in some areas; tough mother
dura mater
thin, weblike membrane that does not have blood vessels and is located between dura and pia maters; supplies to brain and spinal cord
arachnoid mater
between arachnoid/pia maters that contain CSF that completely surrounds brain/spinal cord
subarachnoid space
clear watery fluid that protects the brain and spinal cord by absorbing forces that might otherwise jar and damage the delicate tissues
cerebrospinal fluid
thin; contains many nerves as well as blood vessels that nourish the underlying cells of the brain and spinal cord - right up against cerebrum and cerebellum; third layer of meninges and innermost
pia mater
four interconnected cavities the CSF forms that lie in the cerebral hemispheres and brainstem
ventricles
in the left cerebral hemisphere, the same size as its twin, extends anteriorly and posteriorly into the cerebral hemispheres
first ventricle, as well as second ventricle (lateral)
in the midline of the brain beneath the corpus callous, which is a bridge of axons that links the two cerebral hemispheres; communicates with the lateral ventricles trough openings
third ventricle
is in the brainstem, just anterior of the cerebellum a cerebral aqueduct is connecting two ventricles together; continuous with the central canal of the spinal cord and has openings in its roof that lead into the subarachnoid space of the meninges
fourth ventricle (third is connected via cerebral aqueduct)
tiny, reddish, cauliflower like masses of specialized capillaries form the pia mater, covered by a single layer of ependymal cells that block the passage of water-soluble substances between blood-CSF layer; secretes CSF
choroid plexuses
contains neural centers associated with sensory function and is response for sensations and perceptions; also contains neural centers and pathways that coordinate muscular movements, and other that regulate visceral activities
brain
arachnoid membrane that bulges through the dura mater; a way for CSF to get into venous circulation
arachnoid granulations
root with which impulse enters spinal cord
dorsal root
root with which impulse exits and heads toward effectors
ventral root
sensitive to a specific type of internal or external change; the receptor end of a dendrite or a specialize receptor cell in a sensory orgran
receptor
dendrite, cell body, and axon of a sensory neuron; conducts an impulse from the receptor into the brain and spinal cord
sensory neuron
dendrite, cell body, and axon of a neuron within the brain and spinal cord; serves as processing center; conducts an impulse from the sensory neuron to its synapse with a motor neuron
interneuron
dendrite, cell body, nd axon of these neuron; conducts an impulse from the brain or spinal cord out to the synapse with an effector
motor neuron
a muscle of gland; responds to stimulation by the motor neuron and produces the reflex or behavioral action
effector
prosencephalon; divides into anterior and posterior portions (telencephalon and diencephalon)
forebrain
mesencephalon; contains bundles of myelinated nerve fibers that join lower parts of the brain stem to higher centers of brain; also contains several masses of gray matter that serve as reflex centers for vision; maintains posture
midbrain
largest part of brain; two hemispheres connected by the corpus callous; controls higher brain functions, including interpreting sensory impulses, initiating muscular movements, storing memory, reasoning, and intelligence
cerebrum
two large masses within the cerebrum that are essentially mirror images of each other
cerebral hemispheres
a broad, flat, bundle f axons that connect the cerebral hemispheres
corpus callosum
many ridges or convolutions that are separated by grooves that mark the cerebrum’s surface
gyri
a shallow, somewhat deep groove; divide each hemisphere into lobes
sulcus
a very deep groove (longitudinal and transverse)
fissure
association areas that carry on higher intellectual processes for concentrating, planning, complex problem solving, and judging the consequences of behavior; motor areas control movements of voluntary skeletal muscle; “executive”
frontal lobes
sensory areas provide sensations of temperature, touch, pressure, and pain involving skin; association areas function in understanding speech and in using words to express thoughts or feelings
parietal lobes
sensory areas are responsible for hearing; association areas interpret sensory experiences and remember visual scenes, music, and other complex sensory patterns
temporal lobes
sensory areas are responsible for vision; association areas combine visual images with other sensory experiences
occipital lobes
motor areas involved with the control of voluntary muscles
pre central gyrus
sensory areas involved with cutaneous and other senses
post central gyrus
a thin layer of gray matter that constitutes the outermost portion of the cerebrum; contains nearly 75% of all the neuron cel bodies in the nervous system; the boys ultimate control and information processing center
cerebral cortex
receive and interpret impulses from sensory receptors, producing feelings and sensations
sensory areas
neither primarily sensory nor motor; connect with each other and with other brain structures; analyze and interpret sensory experiences and help provide memory, reasonings, verbalizing, judgment, and emotions
association areas
provides motor instructions for written or spoken communication; left frontal
Broca’s area
general interpretive area; left temporal
Wernicke’s area
ver rapid repeated stimulation of the same neurons increases the number of postsynaptic neurotransmitter receptors and causes physical changes at the synapse that makes synaptic transmission effective
long-term potentiation
memories are stored in various parts of cerebral cortex; hippocampus
memory consolidation
masses of gray matter deep within the cerebral hemispheres; produces dopamine; responsible for movement and reward; interacts with motor cortex, thalamus, and cerebellum
basal nuclei
three parts of basal nuclei
caudate nucleus, putamen, and globus pallidus
contains thalamus, hypothalamus, optic chiasma, infundibulum, posterior pituitary gland, mammillary bodies, and pineal gland
diencephalon
relay station for sensory impulses ascending from other parts of the nervous system to the cerebral cortex; a dense mass; synchronizes action potentials, filters out information
thalamus
helps maintain homeostasis by regulating visceral activities an by linking the nervous and endocrine systems; regulates many bodily functions such as heart rate, BP, temperature, water and electrolyte balance
hypothalamus
allows us to have 3D image, were optic nerves cross
optic chiasma
two rounded structures behind the infundibulum (pituitary stalk); important for memory
mammillary bodies
motor fibers that run down each side of the spinal cord
pyramidal tracts
produces melatonin, maintains circadian rhythm and regulates reproductive hormones
pineal land
controls emotional experience and expression and can modify the way a person acts, producing such feelings as anger, fear, pleasure, and sorrow; hypothalamus, thalamus, basal nuclei, amygdala, hippocampus
limbic system
fight or flight
amygdala
memory processing
hippocampus
responsible for autonomic survival functions; connects the cerebrum to spinal cord; mid brain, pons, medulla oblongata
brainstem
a bulge on the underside of the brainstem the contains masses of gray matter and nerve fibers; relay impulses between the medulla oblongata and cerebrum; helps regulate rate and depth of breathing; relay impulses to cerebellum
pons
an enlarged continuation of spinal cord that extends from the foramen magnum to the pons and contains masses of gray matter and nerve fibers; conducts vasomotor, cardiac, and respiratory control centers and across nonmetal control centers
medulla oblongata
“filers incoming sensory impulses, arousig the cerebral cortex into wakefulness in response to meaningful impulses; “wakes up” the cerebrum when sensory input arrives; programs us to wake up at certain time
reticular formation (reticular activating system) RAS
a large mass of tissue inferior to the cerebrum and posterior to the brainstem; includes two lateral hemispheres connected by the vermis; equilibrium; communicates with other parts of the CNS by tracts; position of body parts; coordinates muscle activities and maintains posture
cerebellum
connects ponds to cerebellum
cerebellar peduncles
a slender column of nervous tissue that is continuous with the brain and extends downward through the vertebral column; white matter surrounds core of gray matter
spinal cord
automatic, subconscious responses to changes; help maintain homeostasis
reflex
conduct motor impulses to brain
ascending tracts
conduct mortar impulses to muscles andor glands
descending tracts
bundles of axons
nerves
nerve fiber
axon
consists of the nerves that branch form the cNS, connecting it to other body parts; includes the cranial nerves from brain and spinal nerves from spinal cord
PNS (peripheral nervous system)
What are the two subdivisions of the PNS
somatic and autonomic
consists of the cranial and spinal nerve fibers the connect the CNS to the skin and skeletal muscles; plays a role in sensuous activities
somatic nervous system
includes fibers that connect the CNS to viscera such as the heart, stomach, intestines, and various glands; controls subconscious actions
autonomic nervous system
nerves with one fibers of sensory neurons, conducting impulses into the brain and spinal cord
sensory nerves
nerves that have only fibers involved with motor control
motor nerves
nerves that include both sensory and motor fibers (most nerves)
mixed nerves
nerves originating from the brain that communicate with other body part; 12 pairs in total
cranial nerves
sensory; sense of smell
I. olfactory
sensory; sense of vision
II. optic
primarily motor; motor=raise eyelids, move the eyes, adjust amount of life entering the eyes, focus the lenses; sensory=proprioceptors
III. oculomotor
primarily motor; motor=move eyes; sensort=proprioceptrs; the smallest cranial nerve
IV. trochlear
mixed; largest with 3 divisions. Sensory: surface of eyes, tear glands, scalp, forehead, upper eyelids; upper teeth and gum, lining of palate, skin of face; scalp, skin of jaw, lower teeth and lip. Motor: mastication, muscles of mouth floor
V. trigeminal
primarily motor, motor=muscles that move eyes. Sensory=proprioceptors
VI. abducens
mixed; sensory=taste w/ anterior tongue. motor=muscles of facial expression, tear glands, and salivary glands
VII. facial
sensory; two branches. sensory with equilibrium and hearing
VIII. vestibulocochlear
mixed; sensory=pharynx, tonsils, posterior tongue, carotid arteries. motor=salivary glands, muscles of pharynx used in swallowing
IX. glossopharyngeal
mixed; longest; sensory=pharynx, larynx, esophagus, viscera of thorax&abdomen; somatic motor=muscles with speech&swallowing; autonomic motor=viscera of thorax and abdomen
X. vagus
primarily motor; 2 branches (cranial and spinal); cranial=motor-muscles of soft palate, pharynx, larynx. Spinal=motor-muscles of neck&back; sensory=proprioceptor input
XI. accessory
primarily motor; motor=muscles that move tongue; sensory=some proprioceptor input
XII. hypoglossal
mass of neuron cell bodies outside CNS
ganglion
cerebral cortex will give proportional space to motor functions that are critical
homunculus theory
the process by which the CNS receives input from the environment via sensory neurons; bottom-up processing
sensation
the process by which the brain interprets and organizes sensory information; top-down processing
perception
