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637 terms

A&P Test3 B

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absolute refractory period
In this period, the neuron cannot respond to a stimulus no matter how strong.
depolarization
In this period, the interior of the cell becomes less negative due to an influx of sodium ions.
repolarization
In this period, potassium ions diffuse out of the neuron due to a change in membrane permeability.
action potential
Also called a nerve impulse transmitted by axons.
relatively refractory period
In this period, an exceptionally strong stimulus can trigger a response.
Temporal summation
Numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect.
Spatial summation
Stimulation of a postsynaptic neuron by many terminals at the same time.
Subthreshold stimulus
An insufficient stimulus.
Threshold stimulus
Any stimulus below this intensity will result in no response in a neuron.
trigger zone
Area where nerve impulse is generated.
receptive region
Receives stimuli.
conducting region
Plasma membrane exhibits voltage-gated Na+ and K+ channels.
secretory region
Plasma membrane exhibits voltage-gated Ca2+ channels.
secretory zone
Axon terminals release neurotransmitters.
receptive region
Plasma membrane exhibits chemically gate ion channels.
diverging circuit
One incoming fiber triggers responses in ever-increasing numbers farther and farther along the circuit.
parallel after-discharge circuit
May be involved in complex, exacting types of metal processing.
reverberating circuit
Involved in control of rhythmic activities such as breathing.
diverging circuit
Involved in activating fibers of a skeletal muscle such as the biceps muscle.
converging circuit
Different types of sensory input can have the same ultimate effect.
histamine
Increases acid secretion in the stomach; blocked by cimetidine.
norepinephrine
"Feel-good" neurotransmitter.
substance p
Mediates pain.
glycine
Principal inhibitory neurotransmitter of the spinal cord.
endorphins
Natural opiates that inhibit pain; effect mimicked by morphine.
E. provide the defense for the CNS
Which of the following is NOT a function of astrocytes?
A. support and brace neurons
B. anchor neurons to blood vessels
C. guide the migration of young neurons, synapse formation, and helping to determine capillary permeability
D. control the chemical environment around neurons
E. provide the defense for the CNS
motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle and glands
Describe the ANS.
ependymal cells
What are ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid?
neurilemma
The sheath of Schwann.
in the retina of the eye
Bipolar neurons are commonly found
acetylcholine
An excitatory neurotransmitter secreted by motor neurons innervating the skeletal muscle.
analyzes sensory information, stores information, makes decisions
Describe the integrative function of the nervous system.
absolute refractory period
The period after an initial stimulus when a neuron is not sensitive to another stimulus.
c. they are mitotic
Which of the following is NOT a special characteristic of neurons?
A. they conduct impulses
B. they have extreme longevity
C. they are mitotic
D. they have an exceptionally high metabolic rate
axon
The part of a neuron that conducts impulses away from its cell body.
voltage-gated channel
An ion channel that opens in response to a change in membrane potential and participates in the generation and conduction of action potentials.
synapse
An impulse from one nerve cell is communicated to another nerve cell via the ___.
destroy ACh a brief period after its release by the axon endings
What is the role of acetylcholinesterase?
D. innervation of skeletal muscle
Which of the following is NOT a function of the autonomic nervous system?
a. innervation of smooth muscle of the digestive tract
b. innervation of cardiac muscle
c. innervation of glands
d. innervation of skeletal muscle
ganglia
Collections of nerve cell bodies outside the central nervous system.
neurotransmitter
The substance released at axon terminals to propagate a nervous impulse.
association neuron
A neuron that has as its primary function the job of connecting other neurons.
the myelin sheath
Saltatory conduction is made possible by ___.
e. nucleic acid
Which of the following is NOT a chemical class of neurotransmitters?
a. acetylcholine
b. amino acid
c. biogenic amine
d. ATP and other purines
e. nucleic acid
b. a nerve impulse occurs if the excitatory in inhibitory effects are equal
Which of the following is false or incorrect?
a. an excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold.
b. a nerve impulse occurs if the excitatory in inhibitory effects are equal.
c. an inhibitory postsynaptic potential occurs if the inhibitory effect is greater than the excitatory, causing hyper polarization of the membrane.
d. the synaptic cleft prevents an impulse from being transmitted directly from one neuron to another
Select the correct statement regarding synapses.
a. cells with interconnected cytoplasm are chemically coupled
b. the release of neurotransmitter molecules gives cells the property of being electrically coupled
c. neurotransmitter receptors are located on the axons of cells
d. the synaptic cleft prevents an impulse from being transmitted directly from one neuron to another
help to circulate the cerebrospinal fluid
Ependymal cells ___.
astrocytes
Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters.
oligodendrocytes
Schwann cells are functionally similar to ___.
potassium
Immediately after an action potential has peaked, which cellular gates open?
are crucial for the development of neural connections
Nerve cell adhesion molecules (N-CAMs) ____.
hyperpolarization
An inhibitory postsynaptic potential (IPSP) is associated with ____.
a single type of channel will open, permitting simultaneous flow of sodium and potassium
What occurs when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?
generator potential
When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ___.
c. they increase amplitude as they move away from the stimulus point
Which of the following is not true of graded potentials?
a. they are short-lived
b. they can form on receptor endings
c. they increase amplitude as they move away from the stimulus point
d. they can be called postsynaptic potentials
b. some ions are prevented from moving down their concentration gradients by ATP-driven pumps
Which of the following is true about the movement of ions across excitable living membranes?
a. ions always move actively across membranes through leakage channels
b. some ions are prevented from moving down their concentration gradients by ATP-driven pumps
c. sodium gates in the membrane can open in response to electrical potential changes
d. the bulk of the solutions inside a cell are negatively charged
the membrane potential has been reestablished
A second nerve impulse cannot be generated until ___.
the interior is negatively charged and contains less sodium
In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment?
the impulse would spread bidirectionally
If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of an axon...
group c fibers are not capable of saltatory conduction
How are group c neuron fibers classified?
spinal reflexes
What is an example of serial processing?
somatic
That part of the nervous system that is voluntary and conducts impulses from the CNS to the skeletal muscles is the ___ nervous system.
astrocytes
___ are found in the CNS and and bind axons and blood vessels to each other.
node of ranvier
A gap between Schwann cells in the peripheral system.
ATP-dependent "motor" proteins such as kinesin, dynesin, and myosin.
What mechanism is responsible for axon transport?
electrical synapse
The synapse more common in embryonic nervous tissue than adults is the ___.
parallel processing
When information is delivered within the CNS simultaneously by different parts of the neural pathway.
graded
___ potentials are short-lived, local changes in membrane potential that can be either depolarized or hyper polarized.
multiple sclerosis
___ is a disease that gradually destroys the myelin sheaths of neurons in the CNS, particularly in young adults.
temporal
When one or more presynaptic neurons fire in rapid order it produces a much greater depolarization of the postsynaptic membrane than would result from a single EPSP; this event is called ___ summation.
Foramen magnum
The spinal cord begins at the level of the
Cauda equina
The nerves arising from the inferior lumbosacral enlargement form the
Subarachnoid space
What area of the spinal cord contains cerebrospinal fluid?
Filum terminale and denticulate ligaments
What structures help to anchor the spinal cord within the subarachnoid space?
Three horns
The gray matter of each halve of the spinal cord is divided into
Sensory and has a ganglion
The dorsal spinal nerve root is
Lateral gray horns
The cell bodies of motor neurons to autonomic effectors are located in the
Withdrawal
Pulling the arm back from a hot pan is an example of a ______ reflex.
Endoneurium
The connective tissue wrap around an axon and its Schwann cell sheath is the
Perineurium
The connective tissue wrap that surrounds many axons to form a fascicle is the
Epineurium
The connective tissue wrap the surrounds many fascicles to form a nerve is the
C. Lumbar plexus - T10 to L5
Which plexus is NOT correctly matched to its spinal nerve makeup? A. Cervical plexus - C1 to C4, B. Brachial plexus - C5 to T1, C. Lumbar plexus - T10 to L5, D. Sacral plexus - L4 to S4, E. Coccygeal plexus - S5 to Co
D. 5 roots, 3 trunks, 6 divisions, 3 cords, 5 nerves
Which of the following is the correct sequence of branching of the brachial plexus? A. 5 roots, 5 nerves, 3 trunks, 6 divisions, 3 cords / B. 5 nerves, 3 cords, 6 divisions, 3 trunks, 5 roots / C. 6 divisions, 5 roots, 5 nerves, 3 cords, 3 trunks / D. 5 roots, 3 trunks, 6 divisions, 3 cords, 5 nerves
B. Phrenic
Which of the following is NOT a main nerve of the brachial plexus? A. Median, B. Phrenic, C. Musculocutaneous, D. Ulnar, E. Radial
Cervical
The phrenic nerve is the major nerve from the ______ plexus.
Anterior thigh and leg
The major nerves from the lumbar plexus serve the
Sacral
The sciatic nerve comes from the _________ plexus.
A. Thalamus
Which of the following is NOT part of the brainstem? A. Thalamus / B. Pons / C. Medulla oblongata / D. Midbrain
B. Auditory relay center
Which of the following is NOT a function of the medulla oblongata? A. Regulate heart rate / B. Auditory relay center / C. Regulate blood vessel diameter /D. Regulate breathing
D. Visual relay center
Which of the following is NOT a function of the pons? A. Controls chewing and salivation / B. Aides the medulla oblongata in controlling breathing, swallowing and balance / C. Relay between the cerebellum and cerebrum / D. Visual relay center
Reticular activating system
What structure plays a major role in consciousness and sleep-wake cycles?
Arbor vitae
The white matter of the cerebellum is called the
C. Origin of impulses to skeletal muscle
Which of the following is NOT a function of the cerebellum? A. Controls balance and eye movements / B. Controls posture, locomotion and fine motor coordination / C. Origin of impulses to skeletal muscle / D. Planning, practicing and learning complex movements
B. Midbrain
Which of the following is NOT part of the diencephalon? A. Hypothalamus / B. Midbrain / C. Thalamus / D. Subthalamus
Thalamus
All sensory impulses except for smell are relayed through the
D. Control of the autonomic nervous system
Which of the following is NOT a function of the thalamus? A. Regulation of skeletal muscles / B. Limbic system and emotions / C. Perception of pain / D. Control of the autonomic nervous system
Habenular
What part of the diencephalon is involved with emotional and visceral responses to odors?
D. All of the choices are correct
Which of the following is NOT a function of the hypothalamus? A. Body temperature control / B. Autonomic nervous system control / C. Mood and emotions / D. All of the choices are correct
Mammillary bodies
What part of the hypothalamus are involved in emotional responses to odors, olfactory reflexes and memory?
Longitudinal fissure
What divides the cerebrum into right and left hemispheres?
Central
What structure separates the frontal from the parietal lobe?
Cerebral medulla
The white matter of the cerebrum is the
Commissural fibers
What type of fibers connect one hemisphere to the other?
Projection fibers
What type of fibers are continuations of the fibers in the spinal cord?
C. Mammillary bodies
Which of the following is NOT a basal nucleus? A. Substantia nigra / B. Caudate nucleus / C. Mammillary bodies / D. Lentiform nucleus
Limbic system
What system is involved in basic survival functions and emotions?
Cerebral aqueduct
What structure connects the third and fourth ventricles?
Cerebrospinal fluid
What is found in the subarachnoid space?
Choroid plexuses
What produces cerebrospinal fluid?
Arachnoid granulations into the dural sinuses
Where does cerebrospinal fluid return to the blood supply?
A. Trigeminal
Which cranial nerve is NOT involved with taste? A. Trigeminal / B. Glossopharyngeal / C. Vagus / D. Facial
Trigeminal
Which cranial nerve is the major sensory nerve from the face?
Facial
Which cranial nerve is the major motor nerve for facial expressions?
Vagus
Which cranial nerve leaves the head and neck region to supply the internal viscera?
Trigeminal
Tic douloureux is caused by a lesion to the ____________ nerve.
Mandibular branch of the trigeminal nerve
What nerve is generally used for dental anesthesia of the lower jaw?
Pons
The corneal reflex is mediated by the
Medulla oblongata
The gag reflex is mediated by the
D. CNS - always excitatory; ANS - always inhibitory
Which of the following differences between the central nervous system and the autonomic nervous system is incorrect? A. CNS - one neuron to effector; ANS - two neurons to effector / B. CNS - innervates skeletal muscle; ANS - innervates smooth and cardiac muscles and glands / C. CNS - axons myelinated; ANS - preganglionic axons myelinated, postganglionic axons unmyelinated / D. CNS - always excitatory; ANS - always inhibitory
Preganglionic
The _______________ neuron runs from the CNS and the autonomic ganglion.
Thoracolumbar division
Another name for the sympathetic division is the
Lateral gray horns of T1 through L2 region of the spinal cord
The cell bodies of the sympathetic preganglionic neurons are in the
Alongside the vertebral column from cervical through sacral regions
The sympathetic chain ganglion are located
Short and myelinated and the postganglionic neuron is long and nonmyelinated
In the sympathetic division, the preganglionic neuron is
Skeletal muscle B. Smooth muscle and glands in the skin
Sympathetic postganglionic nerves that run with spinal nerves will serve
Organs in the thoracic cavity
Sympathetic postganglionic nerves that form sympathetic nerves supply
Organs in the abdominal cavity
The sympathetic splanchnic nerves serve
Adrenal medulla
Splanchnic nerves that do not synapse in either the chain ganglion nor the collateral ganglion will synapse with specialized neurons in the
Brain stem and lateral gray horns of the sacral area of the spinal cord
The cell bodies of the parasympathetic preganglionic neurons are found in the
Long and myelinated and the postganglionic neuron is short and nonmyelinated
In the parasympathetic division, the preganglionic neuron is
C. Somatic motor neurons that connect the CNS to the digestive tract
The nerve plexuses of the enteric nervous system receive contributions from all of the following except A. Enteric neurons of the enteric plexuses / B. ANS neurons that connect the CNS to the digestive tract / C. Somatic motor neurons that connect the CNS to the digestive tract / D. Sensory neurons that connect the digestive tract to the CNS
Norepinephrine
Nerve fibers that are considered adrenergic secrete ____ as the neurotransmitter.
Nicotinic receptors
Cholinergic receptors on skeletal muscles and postganglionic neurons in the ANS are called
Muscarinic receptors
Cholinergic receptors on ANS effectors are called
Inhibitory or excitatory
Acetylcholine binding to muscarinic receptors has a/an ______ effect, depending on the effector.
Alpha or beta receptors
Adrenergic receptors on effectors are called
C. All sympathetic postganglionic neurons
Which of the following does NOT release acetylcholine? A. All sympathetic preganglionic neurons / B. All parasympathetic preganglionic neurons / C. All sympathetic postganglionic neurons / D. All parasympathetic postganglionic neurons
D. Blood vessels
Which of the following effectors are NOT cholinergic? A. Sweat glands / B. Heart / C. Large intestines / D. Blood vessels
Blood pressure, Heart rate, Digestion
Autonomic reflexes are used by the body to help regulate
Parasympathetic reduction of heart rate and sympathetic dilation of blood vessels
A sudden increase in blood pressure detected by baroreceptors in the walls of large arteries near the heart will cause
Sympathetic
In general, stimulation of the posterior hypothalamus produces ____ responses.
Arrector pili muscle
Which organs receive sympathetic innervation, but NOT parasympathetic?
Dilate the pupil
What is the function of the sympathetic division?
Constriction of airways
What is the function of the parasympathetic division?
Increase digestive functions
In general, the parasympathetic division will
Sympathetic
Which division of the ANS has a more generalized effect in the body?
One preganglionic neuron synapses with many postganglionic neurons; The secretion of epinephrine and norepinephrine can effect many organs
Why does the sympathetic division of the ANS have a more generalized effect in the body?
C. Increased secretions in the digestive tract
Which of the following is NOT a typical "flight or fight" response by the sympathetic division of the ANS? A. Vasoconstriction of abdominal blood vessels / B. Dilation of air passageways / C. Increased secretions in the digestive tract / D. Increased fat break down for energy
Calcium and sodium
What ion channels are opened to produce an action potential in olfactory neurons?
Bitter
Which primary odor serves to protect from poisons?
B. Hypoglossal nerve
Which of the following cranial nerves does NOT carry taste impulses to the brain? A. Facial nerve / B. Hypoglossal nerve / C. Glossopharyngeal nerve / D. Vagus nerve
Eyebrows
Which accessory structure of the eyes protect the eyes by preventing perspiration from getting into the eyes?
Lacrimal apparatus
What structure produces tears?
Killing bacteria
What is the function of lysozyme in the eyes?
B. Vascular
Which of the following is NOT a characteristic of the cornea? A. Transparent / B. Vascular / C. Refracts light / D. Allows light to enter the eye
Optic disc
What area of the retina contains the least amount of photoreceptors?
Vitreous humor
What is found in the vitreous chamber of the eye?
Visible light
The part of the electromagnetic spectrum that can be detected by the human eye is
Refraction
The process of bending light rays is called
Accommodation
The process of adjusting the thickness of the lens for near vision is called
Convergence
The rotation of the eyes medially to view a close object is called
B. Pigment cells
Which of the following is NOT part of the neural layer of the retina? A. Bipolar neurons / B. Pigment cells / C. Photoreceptors / D. Ganglionic neurons
Rods
Which photoreceptors are responsible for low-light and noncolor vision?
Retinal
What visual pigment is found combined with opsin in cones?
Binocular vision
The ability to perceive depth and judge distance is due to
Myopia
Which eye disorder results in clear vision of close objects and blurry vision of distant objects?
Behind the retina
The result of hyperopia is an image focused
Convex lens
Hyperopia can be corrected with
Tympanic membrane
What structure separates the outer ear from the middle ear?
B. Cochlea
Which of the following is NOT an auditory ossicle? A. Incus, B. Cochlea, C. Stapes, D. Malleus
Equalizes pressure on tympanic membrane in the middle ear
What is the function of the auditory tube?
Scala vestibuli
Which cochlear chamber is connected to the oval window into the middle ear?
Cochlear duct
What is found between the vestibular membrane and the basilar membrane of the cochlea?
Tectorial membrane
The longest stereocilia of the outer hair cells are embedded in the
Stops the sound waves from reflecting back toward the cochlear canal
What is the function of the round window?
Potassium
What ion produces depolarization in the stereocilia of the macula?
Ampulla of the semicircular canals
What structure is associated with dynamic balance?
Cataracts
The most common visual problem of older persons that requires medical treatment is
Somatic general senses
What type of senses are found in the skin, muscles and joints?
Nociceptors
What type of receptors respond to painful stimuli?
Thermoreceptors
What type of receptors respond to temperature changes?
Free nerve endings
What type of general sense receptors are the simplest and most common?
Ipsilateral cerebellum
The spinocerebellar tracts carry unconscious proprioception to the
Occipital
The visual cortex is located in the _______ lobe.
Insula
The taste cortex is located in the _____ lobe.
Prefrontal area
Forethought, motivation and emotional regulation occurs in the
Internal capsule
The ________ contains projection fibers that connect the cerebrum to other parts of the brain.
Reticulospinal
Which descending tract carries impulses for posture adjustment and walking?
A. Vestibulospinal
Which of the following descending tracts is NOT a direct pathway to muscles for conscious, skilled movements? A. Vestibulospinal / B. Anterior corticospinal / C. Corticobulbar / D. Lateral corticospinal
Wernicke's area
Which cortical area is necessary for understanding and formulating coherent speech?
Electroencephalogram
A record of the electrical activity of the brain is called a/an
Beta
What type of brain waves are observed when a person is mentally very active?
Sensory memory
What type of memory lasts for less than a second while the brain is receiving and evaluating input?
central nervous system
The integrating and command center of the nervous system.
peripheral nervous system
What system is outside the central nervous system?
sensory (or afferent)
Which division of the peripheral nervous system carries impulses toward the central nervous system from sensory receptors located throughout the body?
motor (efferent)
Which division of the peripheral nervous system carries impulses from the central nervous system to effector organs, which are muscles and glands?
somatic nervous system
Which nervous system consists of somatic nerve fibers that conduct impulses from the CNS to skeletal muscles?
somatic nervous system
Which nervous system allows conscious control of motor activities?
autonomic nervous system
Which nervous system is an involuntary system?
autonomic nervous system
Which nervous system consists of visceral motor nerve fibers that regulate the activity of smooth muscle, cardiac muscle, and glands?
neuroglia (glial cells)
What are closely associated with neurons, providing a protective and supportive network?
astrocytes
Glial cells of the CNS that regulate the chemical environment around neurons and exchange between neurons and capillaries.
microglia
Glial cells of the CNS that monitor health and perform defense functions for neurons.
ependymal cells
Glial cells of the CNS that line the central cavities of the brain and spinal cord and help circulate cerebrospinal fluid.
oligodendrocytes
Glial cells of the CNS that wrap around neuron fibers, forming myelin sheaths.
satellite cells
Glial cells of the PNS whose function is largely unknown. They are found surrounding neuron cell bodies within ganglia.
schwann cells (neurolemmocytes)
Glial cells of the PNS that surround nerve fibers, forming the myelin sheath.
neurons
Specialized cells that conduct messages in the form of electrical impulses throughout the body.
neurons
What function optimally for a lifetime, are mostly amitotic, and have an exceptionally high metabolic rate requiring oxygen and glucose?
neuron cell body (perikaryon or soma)
The major biosynthetic center containing the usual organelles except for centrioles.
dendrites
Cell processes that are the receptive regions of the cell.
generates and conducts nerve impulses away from the cell body to the axon terminal
What is the purpose of the single axon of neurons?
myelin sheath
What is a whitish, fatty, segmented covering that protects, insulates, and increases conduction velocity of axons?
multipolar, bipolar, unipolar
What are the three structural classes of neurons?
multipolar neurons
Which structural class of neuron has three or more processes?
bipolar neurons
Which structural class of neuron have a single axon and dendrite?
unipolar neurons
Which structural class of neuron have a single process extending from the cell body that is associated with receptors at the distal end?
sensory (afferent), motor (efferent), interneurons (association neurons)
What are the three functional classes of neurons?
sensory (afferent)
Which functional class of neuron conduct impulses toward the CNS from receptors?
motor (efferent)
Which functional class of neuron conduct impulses from the CNS to effectors?
interneurons (association neurons)
Which functional class of neuron conduct impulses between sensory and motor neurons, or in CNS integration pathways?
voltage
A measure of the amount of difference in electrical charge between two points.
potential difference
The amount of difference in electrical charge between two points.
current
The flow of electrical charge from point to point.
current
What is dependent on voltage and resistance?
the movement of ions across cellular membranes
What are electrical currents due to in the body?
the cell
What has many gated ion channels?
chemically gated (ligand-gated) channels
What channels open when the appropriate chemical binds?
voltage-gated channels
What channels open in response to a change in membrane potential?
mechanically gated channels
What channels open when a membrane receptor is physically deformed?
ions diffuse across the membrane, creating electrical currents
What happens when ion channels are open?
neuron cell membrane
What is polarized, being more negatively charged inside than outside?
resting membrane potential
Degree of difference in electrical charge inside and outside a neuron.
resting membrane potential
What is generated by differences in ionic makeup of intracellular and extracellular fluids, and differential membrane permeability to solutes?
changes in membrane potential
What do neurons use as communication signals?
depolarizations; hyperpolarizations
Changes in membrane potential relative to resting membrane potential can either be ___ or ___.
depolarization
The interior of the cell becomes less negative.
hyperpolarization
The interior of the cell becomes more negatively charged.
graded potentials
Short-lived, local changes in membrane potentials.
graded potentials
Can either be depolarizations or hyperpolarizations, and are critical to the generation of action potentials.
action potentials (nerve impulses)
Occur in axons and are the principle way neurons communicate.
A transient increase in Na+ permeability, followed by restoration of Na+ impermeability, and then a short-lived increase in K+ permeability.
Generation of an action potential involves
propagation (transmission) of an action potential
Occurs as the local currents of an area undergoing depolarization cause depolarization of the forward adjacent area.
repolarization
Restores resting membrane potential.
repolarization
Follows depolarization along the membrane.
critical minimum (threshold) depolarization
Defined by the amount of influx of Na+ that at least equals the amount of efflux of K+.
action potentials
What are all-or-none phenomena?
stimulus intensity
What is coded in the frequency of action potentials?
the refractory period of an axon
What is related to the period of time required so that a neuron can generate another action potential?
axons with larger diameters
Which axons conduct impulses faster:
axons with larger diameters, or axons with smaller diameters?
unmyelinated axons
Which axons conduct impulses relatively slowly?
myelinated axons
Which axons have a high conduction velocity?
synapse
A junction that mediates information transfer between neurons or between a neuron and an effector cell.
presynaptic cells
Neurons conducting impulses toward the synapse.
postsynaptic cells
Neurons carrying impulses away from the synapse.
electrical synapses
These have neurons that are electrically coupled via protein channels and allow direct exchange of ions from cell to cell.
chemical synapses
Specialized for release and reception of chemical neurotransmitters.
Degradation by enzymes from the postsynaptic cell or within the synaptic cleft; reuptake by astrocytes or the presynaptic cell; or diffusion away from the synapse.
In what three ways are neurotransmitter effects terminated?
synaptic delay
What is related to the period of time required for release and binding of neurotransmitters?
temporal and spatial summation
In what two ways is summation by the postsynaptic neuron accomplished?
temporal summation
Occurs in response to several successive releases of neurotransmitter.
spatial summation
Occurs when the postsynaptic cell is stimulated at the same time by multiple terminals.
synaptic potentiation
What results when a presynaptic cell is stimulated repeatedly or continuously?
an enhanced release of neurotransmitter
What results after synaptic potentiation occurs?
presynaptic inhibition
What results when another neuron inhibits the release of excitatory neurotransmitter from a presynaptic cell?
neuromodulation
What occurs when a neurotransmitter acts via slow changes in target cell metabolism, or when chemicals other than neurotransmitter modify neuronal activity?
neurotransmitters
What is one of the ways neurons communicate?
neurotransmitters
What has several chemical classes?
whether the effects are excitatory or inhibitory, and whether the effects are direct or indirect
What do functional classifications of neurotransmitters consider?
channel-linked receptors and g protein-linked receptors
What are two main types of neurotransmitter receptors?
channel-linked receptors
These receptors mediate direct transmitter action and result in brief, localized changes.
g protein-linked receptors
These receptors mediate indirect transmitter action resulting in slow, persistent, and often diffuse changes.
neuronal pools
Functional groups of neurons that integrate incoming information from receptors.
divirging (amplifying) circuits
Circuits common in sensory and motor pathways.
divirging (amplifying) circuits
Characterized by an incoming fiber that trigger responses in ever-increasing numbers of fibers along the circuit.
converging circuits
Circuits common in sensory and motor pathways.
converging circuits
Characterized by reception of input from many sources, and a funneling to a given circuit, resulting in strong stimulation or inhibition.
reverberating (oscillating) circuits
Characterized by feedback by axon collaterals to previous points in the pathway, resulting in ongoing stimulation of the pathway.
parallel after-discharge circuits
May be involved in complex activities, and are characterized by stimulation of several neurons arranged in parallel arrays by the stimulating neuron.
serial processing
Exemplified by spinal reflexes, and involves sequential stimulation of the neurons in a circuit.
parallel processing
Results in inputs stimulating many pathways simultaneously, and is vital to higher level mental functioning.
three weeks
During which week of gestation does the endoderm form the neural plate*?

*which invaginates, forming the neural groove, flanked on either side by neural folds.
fourth week
By which week of pregnancy does the neural groove fuse, giving rise to the neural tube, which rapid idly differentiates into the CNS?
the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain)
The neural tube develops constrictions that divide into which three primary brain vesicles?
basic pattern of the CNS
What consists of a central cavity surrounded by a gray matter core, external to which is white matter?
cerebrum and cerebellum
In the brain, the ____ and ____ have an outer gray matter layer, which is reduced to scattered gray matter nuclei in the spinal cord.
ventricles
The ___ of the brain are continuous with one another, and with the central canal of the spinal cord.
ventricles
Lined with ependymal cells, and are filled with cerebrospinal fluid.
paired lateral ventricles
Lie deep within each cerebral hemisphere, and are separated by the septum pellucidum.
third ventricle
Lies within the diencephalon, and communicates with the lateral ventricles via two inter ventricular foramina.
fourth ventricle
Lies in the hindbrain and communicates with the third ventricle via the cerebral aqueduct.
cerebral hemispheres
Form the superior part of the brain, and are characterized by ridges and groves called gyri and sulci.
longitudinal fissure
Cerebral hemispheres are separated along the midline by the
transverse cerebral fissure
Cerebral hemispheres are separated from the cerebellum along the
frontal, parietal, temporal, occipital, insular
Five lobes of the brain separated by specific sulci.
cerebral cortex
Location of the conscious mind, allowing us to communicate, remember, and understand.
cerebral cortex
Has several motor areas located in the frontal lobes, which control voluntary movement.
primary motor cortex
Allows conscious control of skilled voluntary movement of skeletal muscles.
premotor cortex
The region controlling learned motor skills.
broca's area
A motor speech area that controls muscles involved in speech production.
frontal eye field
Controls eye movement
pons
Contains fiber tracts that complete conduction pathways between the brain and spinal cord.
medulla oblongata
The location of several visceral motor nuclei controlling vital functions such as cardiac and respiratory rate.
cerebellum
Processes inputs from several strutters and coordinates skeletal muscle contraction to produce smooth movement.
anterior and posterior lobes
coordinate body movements
flocculonodular lobes
adjust posture to maintain balance
cerebellar peduncles
communicate between the cerebellum and the brain stem
cerebellar processing
follows a functional scheme in which the frontal cortex communicates the intent to initiate voluntary movement to the cerebellum
cerebellum
collects input concerning balance and tension in muscles and ligaments
functional brain systems
consist of neurons that are distributed throughout the brain but work together
limbic system
involved with emotions, and is extensively connected throughout the brain, allowing it to integrate and respond to a wide variety of environmental stimuli.
reticular formation
extends through the brain stem, keeping the cortex alert via the reticular activating system, and dampening familiar, repetitive, or weak sensory inputs.
normal brain functions
results from continuous electrical activity of neurons
normal brain functions
can be recorded with an electroencephalogram, or EEG
brain waves
patterns of electrical activity
alpha, beta, theta, delta
What are 4 types of brain waves?
consciousness
encompasses conscious perception of sensations, voluntary initiation and control of movement, and capabilities associated with higher mental processing.
sleep
a state of partial unconsciousness from which a person can be aroused, and has two major types that alternate through its cycle.
four
how many stages are in non-rapid eye movement sleep (NREM)?
rapid eye movement (REM) sleep
In sleep, when does most dreaming occur?
hypothalamus
What are sleep patterns regulated by?
NREM (non-rapid eye movement) sleep
What type of sleep is considered restorative?
REM (rapid eye movement) sleep
What type of sleep allows the brain to analyze events or eliminate meaningless information?
memory
the storage and retrieval of information
short-term (working) memory
allows the memorization of a few units of information for a short period of time.
primary somatosensory cortex
allows spatial discrimination and the ability to detect the location of stimulation.
somatosensory association cortex
integrates sensory information and produces an understanding of the stimulus being felt.
primary visual cortex and visual association area
allow reception and interpretation of visual stimuli.
primary auditory cortex and auditory association area
allow detection of the properties and contextual recognition of sound.
olfactory cortex
allows detection of odors
gustatory cortex
allows perception of taste stimuli
vestibular cortex
responsible for conscious awareness of balance
prefrontal cortex
involved with intellect, cognition, recall, and personality, and is closely linked to the limbic system.
wernicke's area, broca's area, the lateral prefrontal cortex, and the lateral and ventral parts of the temporal lobe
the language areas involved in comprehension and articulation
posterior association area
receives input from all sensory areas, integrating signals into a single thought.
visceral association area
involved in conscious visceral sensation.
left
which hemisphere of the brain often dominates language abilities, math, and logic?
right
which hemisphere of the brain often dominates visual-spatial skills, intuition, emotion, and artistic and musical skills?
cerebral white matter
responsible for communication between cerebral areas and the cerebral cortex and lower CNS centers.
basal nuclei
consist of a group of subcortical nuclei, which play a role in motor control and regulating attention and cognition.
diencephalon
a set of gray matter areas, and consists of the thalamus, hypothalamus, and epithalamus.
thalamus, hypothalamus, epithalamus
the diencephalon consists of
thalamus
plays a key role in mediating sensation, motor activities, cortical arousal, learning, and memory
hypothalamus
the control center of the body, regulating ANS activity, such as emotional response, body temperature, food intake, sleep-wake cycles, and endocrine function.
epithalamus
includes the pineal gland, which secretes melatonin and regulates the sleep-wake cycle.
the brain stem
produces rigidly programmed, automatic behaviors necessary for survival.
midbrain, pons, medula oblongata
what 3 parts does the brain stem consist of?
midbrain
comprised of the cerebral peduncles, corpora quadrigemina, and substantia nigra
long-term memory
allows the memorization of potentially limitless amounts of information for very long periods
a high emotional state, repetition, association of new information with old, or the automatic formation of memory while concentrating on something else.
transfer of information from short-term to long-term memory can be affected by
declarative memory
entails learning explicit information, is often stored with the learning context, and is related to the ability to manipulate symbols and language.
nondeclarative memory
entails motor skills, is often stored without details of the learning context, and is reinforced through performance.
learning
causes changes in neuronal RNA, dendritic branching, deposition of unique proteins at LTM synapses, increase of presynaptic terminals, increase of neurotransmitter, and development of new neurons in the hippocampus.
meninges
three connective tissue membranes that cover and protect the CNS, protect blood vessels, and enclose venous sinuses, contain cerebrospinal fluid, and partition the brain.
dura mater
the most durable, outermost covering that extends inward in certain areas to limit movement of the brain within the cranium.
arachnoid mater
the middle meninx that forms a loose brain covering
pia mater
the innermost layer that clings tightly to the brain
cerebrospinal fluid
the fluid found within the ventricles of the brain and surrounding the brain and spinal cord
cerebrospinal fluid
gives buoyancy to the brain, protects the brain and spinal cord from impact damage, and is a delivery medium for nutrients and chemical signals.
blood-brain barrier
a mechanism that helps maintain a protective environment for the brain.
concussion, contusion, and subdural or subarachnoid hemorrhage
traumatic head injuries can lead to which brain injuries
cerebrovscular accidents (CVAs) or strokes
occur when blood supply to the brain is blocked, resulting in tissue death
alzheimer's disease
a progressive degenerative disease that ultimately leads to dementia
parkinson's disease
results from deterioration of dopamine-secreting neurons of the substantia nigra, and leads to a loss in coordination of movement and a persistent tremor
huntington's disease
a fatal hereditary disorder that results from deterioration of the basal nuclei and cerebral cortex
sensory receptors
specialized to respond to changes in their environment called stimuli
mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, nociceptors
receptors may be classified according to their location or location of stimulus, and include
simple or complex
receptor may be classified according to structural complexity and may be
simple receptors
general senses, and may be unencapsulated or encapsulated dendritic endings
unencapsulated dendritic endings
free, or naked, nerve endings, and detect temperature, pain, itch, or light touch
encapsulated dendritic endings
consist of a dendrite enclosed in a connective tissue capsule and detect discriminatory touch, initial, continuous, and deep pressure, and stretch of muscles, tendons, and joint capsules
somatic sensory system
the part of the sensory system serving the body wall and limbs
somatic sensory system
involves the receptor level, the circuit level, and the perpetual level
receptor level
processing at this level involves a stimulus that must excite a receptor in order for sensation to occur
circuit level
processing at this level is involved with delivery of impulses to the appropriate region of the cerebral cortex for stimulus localization and perception
perceptual level
processing at this level involves interpretation of sensory input in the cerebral cortex
perception of pain
protects the body from damage, and is stimulated by extremes of pressure and temperature, as well as chemicals released from damaged tissues
nerve
a cordlike organ consisting of parallel bundles of peripheral axons enclosed by connective tissue wrappings
ganglia
collections of neuron cell bodies associated with nerves in the PNS
cut or compressed axons can regenerate
if damage to a neuron occurs to the axon and the cell body remains in tact
12
how many pairs of cranial nerves originate from the brain?
olfactory nerves (cranial nerve I)
nerves that detect odors
optic nerves (cranial nerve II)
nerves that are responsible for vision
oculomotor, trochlear, and abducens nerves (cranial nerves III, IV, and VI)
nerves that allow movement of the eyeball
trigeminal nerves (cranial nerve V)
nerves that allow sensation to the face, and motor control of chewing muscles
facial nerves (cranial nerve VII)
nerves that allow movements of muscles creating facial expression
vestibulocochlear nerves (cranial nerve VIII)
nerves that are responsible for hearing and balance
glossopharyngeal nerves (cranial nerve IX)
nerves that control the tongue and pharynx
vagus nerves (cranial nerve x)
nerves that control several visceral organs
accessory nerves (cranial nerve XI)
nerves that have a relationship with the vagus nerves
hypoglossal nerves (cranial nerve XIII)
nerves that innervate muscles of the tongue
31
How many pairs of mixed spinal nerves arise from the spinal cord and serve the entire body except the head and neck?
dorsal root and a ventral root
each spinal nerve connects to the spinal cord by a
rami
lie distal to and are lateral branches of the spinal nerves that carry both motor and sensory fibers
dorsal rami
the back is innervated by the ______, with each innervating the muscle in line with the point of origin from the spinal column
thorax
only here are the ventral rami arranged in a simple segmental pattern corresponding to that of the dorsal rami
cervical plexus
formed by the ventral rami of the first four cervical nerves
brachial plexus
situated partly in the neck and partly in the axilla and gives rise to virtually all the nerves that innervate the upper limb
sacral and lumbar plexuses
plexuses that overlap
lumbar plexuses
contribute to the sacral plexus via the lumbosacral trunk
sacral and lumbar plexuses
also referred to as the lumbosacral plexus
dermatome
the area of skin innervated by the cutaneous branches of a single spinal nerve
hinton's law
states that any nerve serving a muscle that produces movement at a joint also innervates the joint and the skin over the joint
peripheral motor endings
the PNS element that activates effectors by releasing neurotransmitters.
terminals of the somatic motor fibers that innervate voluntary muscles
form elaborate neuromuscular junctions with their effector cells and they release the neurotransmitter acetylcholine
junctions between autonomic motor endings and the visceral effectors
involve varicosities and release either acetylcholine or epinephrine as their neurotransmitter
segmental level
the lowest level on the motor control hierarchy and consists of the spinal cord circuits
projection level
has direct control of the spinal cord
precommand level
made up of the cerebellum and the basal nuclei and is the highest level of the motor system hierarchy
reflexes
unlearned, rapid, predictable motor responses to a stimulus, and occur over highly specific neural pathways
reflex arcs
the highly specific neural pathways of reflexes
spinal reflexes
somatic reflexes mediated by the spinal cord
stretch reflex
in this reflex, the muscle spindle is stretch and excited by either an external stretch or an internal stretch.
golgi tendon reflex
produces muscle relaxation and lengthening in response to contraction
flexor (withdrawal) reflex
initiated by a painful stimulus and causes automatic withdrawal of the threatened body part from the stimulus
crossed-extensor reflex
a complex spinal reflex consisting of an ipsilateral withdrawal reflex and a contralateral extensor reflex
superficial reflexes
elicited by gentle cutaneous stimulation
the developing spinal cord and adjacent neural crest
the spinal nerves branch from
the forming vertebrae
the spinal nerves exit between
cranial nerves
innervate muscles of the head in a similar way
sensory receptors
atrophy to some degree with age, and there is a decrease in muscle tone in the face and neck; reflexes occur a bit more slowly
vision
our dominant sense
70%
what percent of our body's sensory receptors are found in the eye
eyebrows
short, coarse hairs overlying the supraorbital margins of the eye that shade the eyes and keep perspiration out
eyelids (palpebrae), eyelashes, and their associated glands
help to protect the eye from physical danger as well as from drying out
conjunctiva
a transparent mucous membrane that lines the eyelids and the whites of the eyes
conjunctiva
produces a lubricating mucus that prevents the eye from drying out
lacrimal apparatus
consists of the lacrimal gland, which secretes a dilute saline solution that cleanses and protects the eye as it moistens it, and ducts that drain excess fluid into the nasolacrimal duct
the movement of each eyeball
controlled by six extrinsic eye muscles that are innervated by the abducens and trochlear nerves
3
how many layers form the wall of the eyeball?
fibrous tunic
the outermost coat of the eye and is made of a dense avascular connective tissue
sclera and cornea
two regions of the fibrous tunic
vascular tunic (uvea)
the middle layer of the eyeball
choroid, ciliary body, iris
three regions of the vascular tunic
retina
the inner layer of the eye
outer pigmented layer, inner neural layer
two regions of the retina
outer pigmented layer
region of the retina that absorbs light
inner neural layer
region of the retina that contains millions of photoreceptors (rods, cones) that transduce light energy
posterior segment (cavity)
filled with a clear gel called vitreous humor that transmits light, supports the posterior surface of the lens, holds the retina firmly against the pigmented layer, and contributes to intraocular pressure
anterior segment (cavity)
filled with aqueous humor that supplies nutrients and oxygen to the lens and cornea while carrying away wastes
lens
an avascular, biconcave, transparent, flexible structure that can change shape to allow precise focusing of light on the retina
electromagnetic radiation
includes all energy waves from long waves to short waves, and includes the visible light that our eyes see as color
refraction of a light ray
occurs when it meets the surface of a different medium at an oblique angle rather than a right angle
three
how many times is light bent when entering/leaving the cornea and lens?
far point of vision
that distance beyond which no change in lens shape is required (about 6 meters or 20 feet)
accommodation of the lens, constriction of the pupils, and convergence of the eyeballs
three adjustments demanded by the focusing for close vision
myopia (nearsightedness)
occurs when objects focus in front of the retina and results in seeing close objects without a problem but distant problems are blurred
hyperopia (farsightedness)
occurs when objects are focused behind the retina and results in seeing distant objects clearly but close objects are blurred
photoreception
the process by which the eye detects light energy
photoreceptors
modified neurons that structurally resemble tall epithelial cells
rods
highly sensitive and are best suited to night vision
cones
less sensitive to light and are best adapted to bright light and color vision
photoreceptors
contain a light-absorbing molecule called retinal
rhodopsin
the visual pigment of rods, formed and broken down within the rods (same for cones)
pigment breakdown
exposure of the photoreceptors to light causes
light adaptation
occurs when we move from darkness into bright light
dark adaptation
occurs when we go from a well-lit area into a dark one
retinal ganglion cells
merge in the back of the eyeball to become the optic nerve, which crosses at the optic chiasma to become the optic tracts
optic tracts
send their axons to neurons within the lateral geniculate body of the thalamus
axons from the thalamus
project through the internal capsule to form the optic radiation of fibers in the cerebral white matter
visual processing
occurs when the action of light on photoreceptors hyper polarizes them, which causes the bipolar neurons from both rods and cones to ultimately send signals to their ganglion cells
receptors for taste and smell
chemoreceptors that respond to chemicals in solution
olfactory epithelium
the organ of smell located in the roof of the nasal cavity
olfactory receptors
bipolar neurons with a thin apical dendrite that terminates in a knob with several olfactory cilia
volatile, and it must be dissolved in the fluid coating the olfactory epithelium that stimulates the olfactory receptors
to smell a particular odorant, it must be
olfactory transduction
an odorant binds to the olfactory receptor, a g protein, and the secondary messenger of cyclic AMP.
taste buds
the sensory receptor organs for taste
taste buds
located in the oral cavity, with the majority located on the tongue
sweet, sour, bitter, salty, umami
five basic taste sensations
dissolved in saliva, move into the taste pore, and contact a gustatory hair
for a chemical to be tasted it must be
taste sensation
each has its own special mechanism for transduction
afferent fibers carrying taste information from the tongue
found primarily in the facial nerve and glossopharyngeal cranial nerves
vagus nerve
taste impulses from the few taste buds found on the epiglottis and the lower pharynx are conveyed via the
taste
strongly influenced by smell and stimulation of thermoreceptors, mechanoreceptors, and nociceptors.
anosmias
olfactory disorders resulting from head injuries that tear the olfactory nerves, nasal cavity inflammation, or aging.
uncinate fits
olfactory hallucinations
taste disorders
less common but may be caused by respiratory tract infections, head injuries, chemicals, medications, or head and neck radiation.
auricle (pinna) and the acoustic meatus
the external ear consists of the
middle ear (tympanic cavity)
a small, air-filled, mucosa-lined cavity in the petrous portion of the temporal bone; spanned by the auditory ossicles
bony labyrinth, membranous labyrinth
two divisions of the internal ear
vestibule
central cavity of the body labyrinth with two membranous sacs suspended in the perilymph, the saccule and the utricle
semicircular canals
project from the posterior aspect of the vestibule, each containing an equilibrium receptor region called a crista ampullaris
spiral, snail-shaped cochlea
extends from the anterior part of the vestibule and contains the cochlear duct
cochlear duct
houses the spiral organ (of corti), the receptors for hearing
sound
a pressure disturbance produced by a vibrating object and propagated by the molecules of the medium
frequency
the number of waves that pass a given point in a given time
amplitude (height)
reveals a sound's intensity
tympanic membrane
airborne sound entering the external acoustic meatus strikes the _____ ____ and sets it vibrating.
resonance of the basilar membrane
processes sound signals mechanically before they ever reach the receptors
transduction of sound stimuli
occurs after the trapped stereo cilia of the hair cells are deflected by localized movements of the basilar membrane
perception of pitch, detection of loudness, and localization of sound
auditory processing involves
deafness
any hearing loss, no matter how slight
tinnitus
a ringing or clicking sound in the ears in the absence of auditory stimuli
meniere's syndrome
a labyrinth disorder that causes a person to suffer repeated attacks of vertigo, nausea, and vomiting
equilibrium sense
responds to various head movements and depends on input from the internal ear, vision, and information from stretch receptors of muscles and tendons
maculae
sensory receptors for static equilibrium
crista ampullaris
receptor for dynamic equilibrium
crista ampullaris
found in the ampulla of the semicircular canals and activated by head movement
directly to reflex centers in the brain stem
information from the balance receptors goes ___________________________, rather than to the cerebral cortex.
somatic nervous system
stimulates skeletal muscles
autonomic nervous system
innervates cardiac an smooth muscle and glands
somatic nervous system
the cell bodies of the neurons are in the spinal cord and their axons extend to the skeletal muscles they innervate
autonomic nervous system
consists of a two-neuron chain
acetylcholine
neurotransmitter released by the somatic motor neurons
epinephrine and acetylcholine
neurotransmitters released by the autonomic nervous system; both may have either an excitatory or an inhibitory effect
overlap
there is _____ between the somatic and autonomic nervous systems
skeletal muscle activity and visceral organ responses
most body responses to changing internal and external stimuli involve both ____ and ____
parasympathetic division
keeps body energy use as low as possible while directing digestion and elimination activities
sympathetic division
prepares the body to respond to an energy or threatening situation (or vigorous exercise)
preganglionic axons
extend from the CNS nearly all the way to the structures to be innervated, where they synapse with ganglionic neurons in the terminal ganglia
cranial outflow
consists of preganglionic fibers that run in the oculomotor, facial, glossopharyngeal, and vagus cranial nerves
sacral outflow
the rest of the large intestine and pelvic organs are served by the
sacral outflow
arises from neurons located in the lateral gray mater of the spinal cord segment S2-S4
sympathetic division
supplies the visceral organs in the internal body cavities but also all visceral structures in the somatic part of the body
gray rami communicantes
when synapses are made in chain ganglia, the postganglionic axons enter the ventral (or dorsal) ramus of the adjoining spinal nerves by way of communicating branches called
preganglionic fibers from t5 down
enter and leave the sympathetic chains without synapsing
thoracic splanchnic nerves; adrenal cortex
some fibers of the ___________ terminate by synapsing with the hormone-producing medullary cells of the _________.
visceral sensory neurons
the first link in autonomic reflexes, sends information concerning chemical changes, stretch, and irritation of the viscera
B. sensory neuron-delivers signals to control sensory organs such as eye movement
Which is NOT a correct association of structure and function?
A. axons-outgoing signals
B. sensory neuron-delivers signals to control sensory organs such as eye movement
C. cell body-nucleus and organelles
D. dendrites-incoming signals
E. interneuron-sums up input before sending signals to muscle or gland
dendrites
carry impulses toward a cell body
the nerve contained both sensory and motor neurons
carpal tunnel results in damage to one medial nerve that results in lack of control to the wrist and also numbness. this indicates that
axons
When a finger or other appendage is severed in an accident, it is possible to surgically rejoin most tissues (bone, skin, etc.) and most will grow back together. However, in a cut through an appendage nerve, it is currently more difficult to reconnect what are primarily severed _____.
away from the cell body
in the axon, the nerve impulses travel
they are mostly myelin sheath made of lipid or fat molecules
in dissection, most nerve fibers appear gray to white because
e. cell walls
which of the following does not pertain to neurons?
a. sodium pumps
b. schwann cells
c. myelin
d. nodes of rangier
e. cell walls
d. it decreases the speed of nerve impulse conduction
which of the following is not true about the myelin sheath?
a. it is composed of layers of cellular membrane containing myelin around nerve fibers
b. it gives nerve fibers their white glistening appearance
c. it provides a pathway for new fiber growth if the axon is severed
d. it decreases the speed of nerve impulse conduction
e. it is formed from schwann cells
nerve impulse
a change in the difference in positive and negative ions on the outer and inner surfaces of the neuron membrane, a change that opens adjacent channels and propagates its flow
the action potential jumps from node to node
"Saltatory" conduction occurs when
the speed with which sodium ion can be pumped back outside the neuron membrane
how fast a person can type or play the piano is ultimately limited by the number of impulses a person can send to their fingers per second. this in turn is limited by
synaptic vesicles fuse with the presynaptic membrane, and neurotransmitters diffuse across the synaptic cleft
in order for transmission across the synapse to occur
either excite or inhibit the postsynaptic neuron
neurotransmitters are molecules that cross the synaptic cleft and
acetylcholine
the enzyme that breaks down acetylcholine within the synaptic cleft is
e. cholinesterase
which of the following is not a neurotransmitter?
a. gaba
b. norepinephrine
c. acetylcholine
d. dopamine
e. cholinesterase
both sensory and motor fibers
spinal nerves contain
reflex actions and communication between the brain and spinal nerves
the primary functions of the spinal cord involve
nerve
composed of the long fibers of long axons
reflex action
an automatic, involuntary response
motor neuron
part of a simple relax that takes the message away from the CNS
tracts
bundles of nerve fibers traveling up or down the white matter of the spinal cord
cauda equina
bundle of nerve roots within vertebrae L2-S5 which innervate the pelvic organs and legs
dorsal horn
all somatic sensory fibers from the neck down enter a region of gray matter of the spinal cord called the
sciatic
the thick ___ nerve of the lower limb is actually two nerves enclosed in a common fibrous sheath
dura mater
this meninx lies closest to the surrounding bone
afferent fibers
nerve fibers that conduct sensory signals to the central nervous system
epineurium
fibrous sheath enclosing a nerve
corticospinal tracts
descending tracts that carry signals from the cerebral cortex for precise coordinated limb movements
mixed
name of a type of nerve that transmits both sensory and motor information
reflexes
coordinators of simple, repeated actions
neurilemma
an individual peripheral nerve axon is covered by Schwann cells which produce a
somatic
nerve fibers that innervate the skin and skeletal muscles
the ventral horn of the spinal cord
the upper motor neurons that control the skeletal muscles are found in
coticospinal tracts
the signals that control you handwriting travel down the spinal cord in
the dorsal horns of the spinal cord
most lower motor neurons are located in
adipose tissue
the epidural space in the spinal column is occupied by
endoneurium
the neurilemma is covered by the loose connective tissue called the
b. touch
which of the following sensory functions involve neurons in the dorsal root ganglia?
a. smell
b. touch
c. hearing
d. taste
e. vision
the ventral horn of the spinal cord
nerve fibers that stimulate the skeletal muscles of your foot have their somas in
phrenic nerves
if the ___ of the cervical plexus were severed, it would have a life-threatening effect, whereas severance of any other would be less serious.
sciatic nerve
two nerves inclosed in a common fibrous sheath
cervical, thoracic, lumbar, sacral
the spinal cord is divided into what regions
coccygeal ligament
this structure anchors the spinal cord to L2
intercostal nerve
most important in relaying motor signals bringing about ventilation
chickenpox
this viral infestation can remain viable with the dorsal root ganglia for many years
cervical
sensory only nerve
central pattern generators
walking is controlled by groups of neurons in the spinal cord called
L1
spinal cord ends at about which vertebra?
lumbar
nerves to the pelvic region and lower limbs arise from an area of the spinal cord called the
cauda equina
a bundle of nerve roots that occupy the canal of vertebrae L2 to S5
epidural
anesthetics and anti-inflammatory drugs are introduced into this space in the spinal cord
subarachnoid space
majority of cerebrospinal fluid in the spinal cord is found here
pia matter
the innermost meninx around the spinal cord
terminal filum
the pia matter extends beyond the medullary cone as
spina bofida
a congenital defect resulting from the failure of one or more vertebrae to form a complete vertebral arch for enclosure of the spinal cord
epidural space, dura matter, arachnoid, subarachnoid space
you were going to have a spinal tap to remove some cerebrospinal fluid for analysis. starting from outside of the spinal cord, what would be the correct order of spaces and meninges through which the syringe would pass?
dorsal root > dorsal horn > ventral horn > ventral root > spinal nerve
you are following the signals from a sensory neuron to the spinal cord where it synapses with a motor neuron that leaves the spinal cord and synapses on a skeletal muscle the route would be
gracile fasciculus; medulla oblongata
sensory information about deep touch or visceral pain in the lower limbs are carried in ____ tracts, which decussate, or cross over, in the _____.
thalamus
second-order neurons synapse with neurons in the
amyotrophic lateral sclerosis
this disease is marked by degeneration of motor neurons, and in most cases, neurons are destroyed by the inability of astrocytes to reabsorb glutamate, which allows this neurotransmitter to reach toxic levels
motor; sensory
the ventral root carries ____ neurons, while the dorsal root carries ____ neurons.
sciatic
the most vulnerable nerve in the body
sensory; shingles
this virus remains for life in the dorsal root ganglion but can travel down neurons from the dorsal root ganglion by fast axonal transport and cause a painful trail of skin discoloration along the path of the neurons. this virus travels down ____ neurons and causes ____.
sacral; lumbar
the sciatic nerve comes from the ___ plexus, while the femora nerve comes from the ____ plexus
stretch reflex
you begin to nod off as you are reading this question. your head starts to lower a bit but this reflex causes your head to rise
above level c5
quadriplegia, or paralysis of all four limbs, results from spinal cord lesions
brain; spinal cord
the central nervous system consists of the ___ and ___.
neuroglia
nervous tissue is composed of neurons and supporting cells called ___.
threshold
whether or not a neuron fires depends on whether it is depolarized to a voltage called its ___.
nodes of ranvier
in the peripheral nervous system, myelin sheaths have gaps called ___ about 1 mm apart.
synapse
the junction where one neuron meets another
all-or-none
neurons follow the ___ law, meaning they either fire at a maximum voltage or not at all
dendrite
the portion of the neuron that receives signals from other neurons
alzheimer disease
neurofibrillary tangles and the destruction of parts of the hippocampus are characteristics of
norepinephrine
a neurotransmitter whose function depends on a second messenger
microglia
macrophages of the central nervous system
glycine
an inhibitory neurotransmitter is known as
synapse
the gap between one neuron and the next
oligodendrocytes
the brain's counterpart to the schwann cells
summation
the process of adding up postsynaptic potentials and responding to their net effect
facilitation
process in which one presynaptic neuron makes it easier for another one to stimulate a postsynaptic neuron
soma
nissl bodies are located in the ____ of a neuron
axon hillock
the trigger zone of a neuron includes
diverging
in a ___ neuronal circuit, input to one neuron leads to output from multiple neurons
voltage-regulated Na+ gates open
when a neuron is depolarized to threshold
endoneurium
because of the absence of an _____, damaged nerve fibers in the CNS cannot regenerate.
nerve signals pass from neuron to neuron over junctions called synapses
the neuron doctrine refers to the fact that
diverging circuits
because of ___, one motor neuron of the brain can ultimately cause thousands of muscle fibers to contract
axon hillock
summation occurs in the ____ of a neuron
nerve signals
travel fastest in large myelinated fibers
endothelium
the blood brain barrier consists of tight junctions in the
help form the blood brain barrier
one role of the astrocytes is to
ependymal cells
____ line the ventricles of the brain
gland
an effector
interneurons
the integrative function of the nervous system i associated especially with
central
the brain and spinal cord constitute the ___ nervous system
the threshold potential
a neuron fires only when its membrane reaches
substance p
long-term memories occur when there are more of these receptors
na+ is entering the neuron
during the rising phase of an action potential
neurilemma
the bodies of the schwann cells
self-propogating
unlike local potentials, action potentials are
calcium ions enter the synaptic knob
the first event when a nerve reaches a synaptic knob
astrocytes
blood capillaries of the brain are enveloped by
rough endoplasmic reticulum
the nissl bodies of a neuron consist of
one axon and one dendrite arising from the soma
a bipolar neuron has
+35 mv
a typical neuron will have a membrane voltage of about ___ at the time when sodium gates close and potassium ions begin rapidly leaving the cell.
with their nerve cell bodies in the PNS and their synaptic knobs in the CNS
unipolar neurons are found
undergo mitosis
mature neurons lack centrioles. you would expect these neurons to be unable to
astrocyte
the most abundant cell in the nervous system
central nervous system; form the myelin sheath
the oligodendrocyte is found in the ___ and functions to ___________.
astrocytes
the glial cells that contribute to the blood-brain barrier in the CNS
had been damaged by infection, trauma, or stroke
in an autopsy, a pathologist found an area of brain tissue with very high concentration of microglia. that area of the brain most likely
ependymal cells
glial cells which resemble a cuboidal epithelium without the basement membrane and produce cerebrospinal fluid (CSF)
glial cells; blood-brain barrier
most adult brain tumors are composed of ____ cells and cannot be treated by chemotherapy because of the _____.
large; myelinated
neurons that send impulses to skeletal muscles have a ____ diameter and are ____.
multiple sclerosis
in this disorder, oligodendrocytes and myelin sheaths of the CNS deteriorate and are replaced by hardened scar tissue
dopamine
parkinson's disease is caused by degeneration of neurons that release
serotonin
prozac (fluoxetine) is an antidepressant that blocks the synaptic reuptake of