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ap2 chp 12-14
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260
Anatomy
Undergraduate 1
01/25/2012

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Term
Sensory
Definition
sensory receptors detect internal and external stimuli and carry information to brain and spinal cord
Term
Integrative
Definition
process of sensory information and determining response
Term
Motor-responding to infromation
Divisions
Definition
Central Nervous System (CNS)
Peripheral nervous system (PNS)
Term
– Afferent system
Definition
sensory
Term
Efferent system
Definition
motor
Term
• Somatic nervous system
Definition
skeletal muscles
Term
• Autonomic nervous system
Definition
- impulses to smooth muscle, cardiac muscle, and glands (involuntary control); sympathetic and parasympathetic divisions
Term
• Enteric nervous system
Definition
impulses to digestive tract
Term
• Neuroglia
Definition
connective tissue cells in nervous system organs
Term
• Neurons
Definition
Nerve cells
Term
Astrocytes
Definition
Large, star-shaped
Found at blood-brain barrier
Help in metabolism of neurotransmitters
Maintain balance of K+ for generation of nerve impulses
Term
Fibrous astrocytes
Definition
- long unbranched processes; mainly in the white matter
Term
Protoplasmic astrocytes
Definition
short branching processes; found in gray matter
Term
Astrocytes-functions
Definition
contain microfilaments giving strength to support neurons
processes wrapped around blood capillaries help create a blood-brain barrier restricting movement of substances between blood and interstitial fluid of CNS
In embryo, secrete chemicals that regulate growth, migration, and interconnection of neurons in brain
Help maintain proper chemical environment for nerve impulse generation
May play role in learning and memory by influencing formation of neural synapses
Term
• Oligodendrocytes
Definition
– Fewer processes
– Support neurons
– Produce myelin sheath around nerve fibers in brain and cord
Term
• Microglia
Definition
– Small cells
– Enlarge and move about in inflamed brain tissue
– Phagocytic
Term
• Ependyma
Definition
– Single layer of epithelial cells with cilia and microvilli
– Line ventricles of brain and central canal
– Form cerebrospinal fluid (CSF) and assist in circulation
Term
• Schwann cells (Neurolemmocytes)
Definition
– Produce myelin sheath around PNS neurons
-Each cell myelinates a single axon
Term
• Satellite cells
Definition
– Support neurons in ganglia of PNS
Surround cell bodies of neurons of PNS ganglia
Regulate exchange of materials between neuronal cell bodies and IF
Term
• Most axons surrounded by
Definition
multilayered lipid and protein covering called myelin sheath
Term
Myelination Function
Definition
insulates axon and increases speed of impulse conduction
Term
• Schwann cells produce
Definition
myelin sheath during fetal development and 1st year of life
Term
• Schwann cells form
Definition
multiple layers around axon and contain an outer neurolemma (sheath of Schwann) which encloses myelin sheath (neurolemma aids regeneration of injured nerve axon)
Term
• Myelin sheath has gaps at intervals called
Definition
nodes of Ranvier or neurofibral nodes
Term
• Oligodendrocytes deposit myelin sheath without
Definition
forming neurolemma and have fewer neurofibral nodes
Term
• Soma or perikaryon
Definition
cell body
Term
• Nissl bodies (Chromatophilic substance )
Definition
layered fragments of RER; synthesize proteins for maintaining and regenerating neuron processes and renewing neurotransmitters
Term
• Neurofibrils
Definition
fine fibers extending through dendrites, cell bodies, and axons
Term
• Dendrites
Definition
branching process from cell body (are not myelinated)
Term
• Receptors
Definition
distal ends of dendrites of sensory neurons
Term
• Nerve fibers
Definition
axons or dendrites
Term
• Axon
Definition
- single process but may have collateral branches
Term
Axon background!
Definition
– Originates from cell body at axon hillock
– Impulses arise at junction of axon hillock and initial segment called trigger zone
– Axon terminals (telodendria) - fine filaments branching from axon and ending in synaptic end bulbs; contain synaptic vescicles with neurotransmitter substance
Term
– Synapse is junction of two
Definition
neurons or neuron and effector (muscle or gland)
Term
– Neuromuscular junction is
Definition
synapse between neuron and muscle; neuroglandular junction is between neuron and gland
Term
– Neurotropins (proteins) regulate
Definition
normal growth and development of neurons--include nerve growth factor (NGF), brain-derived neurotropic factor, and neurotropins 3, 4, and 5
Term
• Nerves
Definition
bundles of myelinated fibers located outside brain and cord
Term
• Ganglia
Definition
nerve cell bodies in PNS
Term
• Tracts
Definition
bundles of myelinated fibers located in CNS
Term
• White matter
Definition
myelinated fibers
Term
• Gray matter
Definition
neuron cell bodies and unmyelinated fibers
Term
– Sensory or afferent functional classification
Definition
carry information to CNA
Term
– Motor or efferent functional classification
Definition
carry innrmation away fo SCS
Term
– Association (connecting or internuncial)
Definition
conduct from sensory to motor; located entirely within CNS
Term
– Multipolar
Definition
Numerous
Term
– Bipolar
Definition
found in retina, inner ear, asnd olfactory area of brain
Term
– Unipolar (pseudounipolar)
Definition
one process comes off neuron cell body but divides almost immediately into one axon and one dendrite
Term
• Ion channels
Definition
pores that may be open or closed in plasma membranes
Term
• Threshold of stimulation
Definition
potential that triggers impulse conduction
Term
• Potential difference
Definition
- difference in electrical charge or voltage
Term
• Polarized membrane
Definition
one whose outer and inner surfaces bear different electrical charge
Term
• Depolarized membrane
Definition
one with zero potential difference across its membrane
Term
• Leakage (nongated) channels
Definition
always open - allow materials to move across membrane primarily by diffusion
Term
• Gated channels open and close in response to
Definition
some stimulus
Term
– Mechanically gated ion channel
Definition
respond to mechanical vibration or pressure such as sound waves or pressure of touch
Term
– Voltage-gated (regulated) ion channel
Definition
opens in response to direct change in membrane potential; gives nerve and muscle plasma membranes property of excitability (irritability)
Term
– Ligand-gated ion channel
Definition
responds to specific chemical stimulus such as neurotransmitters, hormones and ions such as H+ or Ca2+; may operate directly (NT and ions) or via second messenger (hormones and some NTs)
Term
• Chemical and mechanical gated allow for
Definition
graded potential
Term
graded potential
Definition
responses are larger or smaller depending on how many gated ion channels are opened and for how long
Term
• Resting Potential
Definition
potential across nonconducting neurons’ plasma membrane (-70 mV)
Term
– Sodium pump transports sodium out of ICF into
Definition
surrounding ECF and membrane is not very permeable to sodium
Term
– Potassium remains within neuron’s ICF due to
Definition
potassium equilibrium potential and pull of negative ions
Term
– Cell membrane relatively impermeable to
Definition
intracellular negative ions so number of negative ions diffusing out is less than number of positive ions diffusing out;
Term
minute excess of negative ions inside neuron cell membrane and minute excess of positive ions outside it
Definition
produces resting potential
Term
• Action Potential
Definition
- potential across membrane of an active (conducting) neuron; also known as nerve impulse; involves depolarization and repolarization
Term
– Graded potential causes membrane to reach threshold (-55 mV)
Definition
opening voltage-gated sodium channels
Term
– Rapid inward diffusion of sodium causes membrane’s inner surface to become
Definition
positive to outer surface (+30 mV)
Term
– Voltage-gated sodium channels have two gates
Definition
activation gate and inactivation gate
Term
in resting membrane inactivation gates open but
Definition
activation gates closed; at threshold activation gates open followed shortly by closing of inactivation gates
Term
– Reverse potential causes
Definition
current flow to adjacent region where it acts as stimulus, causing process to be repeated to axon terminals
Term
• Repolarization
Definition
- replacement of action potential by resting potential
Term
– Threshold opens voltage-gated K+ channels
Definition
but at slower rate than Na+ channels
Term
– Plasma membrane becomes
Definition
relatively impermeable to sodium (due to gate closure) but highly permeable to potassium (because gates are open)
Term
– More positive potassium ions move out through membrane than move in --
Definition
restores resting potential
Term
– Gates may stay open long enough to result in
Definition
hyperpolarization (polarization more negative than resting potential) (-90mV)
Term
• Refractory Period
Definition
• Cell cannot generate another action potential
Term
• Absolute refractory period
Definition
follows action potential
Term
neuron will not respond to any strength stimulus
Definition
neuron will not respond to any strength stimulus
Term
– Large diameter axons absolute refractory period of
Definition
0.4 msec (2500 impulses/sec)
Term
– Smaller diameter have
Definition
4 msec absolute refractory period (250 impulses/sec)
Term
• Relative refractory period follows
Definition
absolute period
Term
neuron will respond to strong stimulus;
Definition
corresponds to period of increased potassium permeability
Term
• All-or-none principle
Definition
– If stimulus generates an action potential, impulse is conducted through entire neuron (propagation)
Term
• Saltatory conduction
Definition
– Occurs in myelinated fibers; action potential moves from one node of Ranvier to the next instead of point to point
Term
• Speed of impulse conduction
Definition
- related to diameter of axon, myelinization, and temperature(warm would speed up, cold slow down)
Term
– A fibers
Definition
largest diameter, myelinated; fastest impulse conduction; touch, pressure, joint position, temp., impulses to skeletal muscles (If converted to mph-it’s be like 200mph-very fast!)
Term
– B fibers
Definition
smaller diameter, myelinated; impulses from viscera to CNS and general visceral efferent neurons (Slower than A Fibers)
Term
– C fibers
Definition
smallest diameter, unmyelinated, longest absolute refractory period; some impulses for pain, touch, pressure, temperature from skin and pain from viscera and visceral efferent fibers from autonomic ganglia (1-4mph, much slower-the slowest one. It’s good, since it’s for pain)
Term
• Synaptic end bulbs
Definition
– tiny distensions at presynaptic neuron’s axon terminals
– bulbs contain numerous vescicles with neurotransmitter substance
Term
• Synaptic cleft -
Definition
– space between a synaptic bulb and a postsynaptic neuron’s dendrite or cell body
Term
• Postsynaptic neuron’s plasma membrane
Definition
– protein molecules embedded in membrane function as neurotransmitter receptors and as enzymes (pick up that information from presynaptic neuron)
Term
– Electrical
Definition
(Are only going to be in a few location) (pg. 473-difference between and chemical and electrical synapse)
Term
• Ionic current spreads directly from one cell to
Definition
another through gap junctions
Term
• Each gap junction contains tubular, protein structures called
Definition
connexons forming tunnels to connect cytosol of two cells (NO SYNAPTIC CLEF! They’re right next to each other so ion can move into other cell very quickly) much faster response, clef causes dely
Term
Electrical synapse found
Definition
• Found in visceral smooth muscle, cardiac muscle, and developing embryo
Term
– Advantage of electrical synapse
Definition
• Faster communication
• Synchronize activity of group of neurons
• Allow two-way transmission of impulses (With the chemical it’s just with axon, not the dendrite, with electrical because they’re together the cells and stimulate one another due to connections, and chemical is unable to do such.)
Term
– Chemical synapse -
Definition
• Neurons do not touch and neurotransmitter crosses cleft and acts on receptors in postsynaptic neuron (pg 472 table: action potential and greater potential (more up by dendrites))
Term
– When action potential reaches axon terminals voltage-gated Ca2+ channels
Definition
are opened allowing Ca2+ to enter (Ca into axon terminals)
Term
are opened allowing Ca2+ to enter (Ca into axon terminals)
Definition
to be released from synaptic bulb vesicles
Term
– Neurotransmitters diffuse across cleft and bind to neurotransmitter receptors in
Definition
postsynaptic membrane (When you bind to receptor you open whatever channel the receptor is associated with-some excitatory some inhibatory)
Term
– Binding of neurotransmitter to receptors
Definition
opens channels and allows ions to flow across membrane
Term
– Depending on channels opened ionic flow causes
Definition
depolarization or hyperpolarization (less negative-depolarization, causes to move through threshold. Hyperpolarization-move towards more negative.) (pg. 474-summary of this! )
Term
– If threshold is reached
Definition
action potential is generated
Term
• Excitatory Postsynaptic Potentials (EPSP)
Definition
Depolarizes postsynaptic membrane (If you want to depolarize you would open sodium channels, because it’s what is exchange for action potential. Hyperpolarize opens the potassium channels, because if potassium goes out the inside will be more negative. The other thing to hyperpolarize you can also open the chloride receptor, it’s a negative ion, so chloride would come in. If you depolarize it is easier to generate an impulse. Hyperpolarize is harder to generate an impulse.)
Term
• (Brings membrane closer to threshold) [Excitatory postsynaptic potential-closer threshold=closer to generating an impulse]
Definition
Opens Sodium Channels
Term
• Opens Na+ channels through which sodium ions diffuse into
Definition
interior of neuron (one neuron opens one neuron. (Towards end of chapter-we’ll hit them in Chp 14)
Term
• Inhibitory Postsynaptic Potentials
Definition
• * Causes hyperpolarization of postsynaptic membrane
Term
• Inhibitory Postsynaptic Potentials
Definition
• (Increases negativity of postsynaptic neuron’s membrane potential above its resting potential); inhibits impulse conduction (more negative, makes it more difficult to generate an impulse, leading it to be inhibitory for the impulse conduction)
Term
• Results from opening of chemically gated Cl- or K+
Definition
(Chloride to move in, Potassium moves out=inhibitory!!!!)
Term
• Neurotransmitter activity (If it stays in the neuron it may be generating impulses that are
Definition
not needed-and needs to be terminated)
Term
• NT terminated at synapse by
Definition
–Diffuse out of synaptic cleft
–Inactivation by enzymes (ex) Neurotransmitter released-neurotransmitters broken down by enzymes, and sometimes are picked up in order to be reused.)
– Uptake by presynaptic neuron by neurotransmitter transporters (The neuron might have more than one impulses coming towards it, and it has to respond to all the impulses. Summation next point)
Term
• Adding together of effects of excitatory and inhibitory NTs
Definition
released from various knobs that synapse with a single postsynaptic neuron (spatial summation pg 478-both 477)
Term
• Buildup of neurotransmitter released by
Definition
by a single presynaptic end-bulb firing 2 or more times in rapid succession (temporal summation pg 477)
Term
• Facilitation (subthreshold EPSP)
Definition
– Decrease in negativity of postsynaptic neuron’s potential to level below its resting potential but above its threshold of stimulation (
Term
Effect of NTs may be either
Definition
facilitation, impulse conduction, or inhibition of postsynaptic neuron
Term
• Ganglia
Definition
– Grouping of nerve cell bodies outside CNS
Term
• Tract
Definition
– Bundle of fibers(axons or dendrites) within CNS
Term
• Ascending tracts
Definition
– Sensory impulses sent up cord to brain
Term
• Descending tracts
Definition
– Motor tracts carrying impulses down cord
Term
• Nucleus
Definition
– Mass of unmyelinated nerve cell bodies and dendrites within CNS (analysis to the ganglia-Nucleus in CNS)
Term
• Horns
Definition
– Major areas of gray matter within spinal cord
Term
• Dura mater
Definition
white fibrous tissue outer layer
Term
• Arachnoid
Definition
cobwebby, delicate middle layer
Term
• Pia mater
Definition
transparent, fibrous membrane; adheres to outer surface of cord and brain; contains blood vessels (nutritive layer)
Term
• Epidural space
Definition
between dura mater and vertebral canal
Term
• Subdural space
Definition
- between dura mater and arachnoid--contains serous (watery) fluid
Term
• Subarachnoid space
Definition
between arachnoid and pia mater -- contains cerebrospinal fluid
Term
• Denticulate ligaments
Definition
thickenings of pia mater in spinal cord; project laterally and fuse with dura mater between ventral and dorsal nerve roots of spinal nerves (pg494-495)
Term
Spinal Cord
• Structure
Definition
about 45 cm long
– Two enlargements: cervical and lumbar
Term
– Below lumbar enlargement
Definition
spinal cord tapers to conical portion (conus medullaris) between 1st and 2nd lumbar
Term
– Filum terminale arises from
Definition
conus medullaris (extension of pia mater
Term
– Cauda equina
Definition
- tail-like collection of roots of spinal nerves at inferior end of cord (pg 495)
Term
– Two deep grooves, anterior median fissure and posterior median sulcus,
Definition
incompletely divide cord into right and left symmetrical halves
Term
• Anterior median fissure deeper
Definition
and wider than posterior groove
Term
– Gray matter
Definition
shaped like 3-D letter H
Term
• Gray commissure
Definition
cross bar of H, contains central canal (joining piece\connecting piece)
Term
• Anterior gray horns, posterior gray horns, and lateral gray horns make up
Definition
remainder of H
Term
– White matter (myelinated fibers)
Definition
• Present in columns--anterior, lateral, and posterior
Term
• Each column divided into tracts
Definition
(fasciculi) which are ascending and descending (Different locations for each track)
Term
Spinal Cord Function
Definition
– Sensory tracts conduct to brain from peripheral nerves; motor tracts conduct from brain to peripheral nerves
– Synapses and association neurons in gray matter function as reflex centers for spinal reflexes
– Sensory information carried over spinothalamic and posterior column tracts
Term
• Spinothalamic tracts carry impulses for
Definition
pain, temperature, crude touch, and deep pressure
Term
• Posterior column tracts (fasciculus gracilis and fasciculus cuneatus) carry impulses for
Definition
proprioception, discriminating touch, two-point discrimination, pressure and vibrations
Term
– Motor information carried via
Definition
pyramidal and extrapyramidal tracts
Term
• Pyramidal tracts (corticospinal and corticobulbar) convey
Definition
impulses for precise voluntary movements of skeletal muscles
Term
• Extrapyramidal tracts (rubrospinal, tectospinal, and vestibulospinal) carry impulses for
Definition
automatic movements, tone and posture, equilibrium, coordinate body movements with visual stimuli
Term
• Reflexes
Definition
reflex is fast response to changes (stimuli) in internal or external environment allowing the body to maintain homeostasis
Term
• Somatic reflexes
Definition
result in contraction of skeletal muscle
Term
• Visceral (autonomic) reflexes
Definition
- cause contraction of smooth or cardiac muscle
Term
• Spinal reflexes
Definition
carried out by spinal cord alone
Term
• Cranial reflexes
Definition
involve brain and cranial nerves
Term
• Reflex arc
Definition
two or more neurons that conduct impulses from periphery to spinal cord or brain stem and back to periphery
Term
– Impulse begins in
Definition
receptors and ends in effectors
Term
– Receptors
Definition
distal ends of sensory neurons
Term
– Effectors
Definition
muscle or glandular cells
Term
• Two-neuron or monosynaptic reflex arc
Definition
simplest arc possible
Term
– One sensory neuron and one motor neuron
Definition
(ex. Stretch reflex)
Term
– Initiated when muscle is stretched stimulating muscle spindles which
Definition
which send impulse into spinal cord
Term
– Sensory neuron synapses with
Definition
motor neuron which sends impulse to skeletal muscle causing contraction
Term
• Polysynaptic reflex arc
Definition
– At least one sensory neuron, synapse, association neuron, synapse, and motor neuron (ex. Withdrawal reflex)
– May involve intersegmental reflex arc due to activation of several association neurons to stimulate more than one effector
Term
• Contralateral reflex arcs exist
Definition
such as crossed extensor reflex
Term
• Reflexes of significance
Definition
• Patellar reflex
• Achilles reflex
• Babinski sign
• Abdominal reflex
• Spinal Nerves
Term
• Number of spinal nerves
Definition
31 pairs
Term
• Originate by anterior and posterior roots from cord
Definition
emerge through intervertebral foramina; spinal ganglion on each posterior root
Term
• Spinal nerves are mixed
Definition
both sensory and motor fibers
Term
– Endoneurium
Definition
connective tissue covering individual fibers
Term
– Fascicles
Definition
groups (bundles) of fibers
Term
groups (bundles) of fibers
Definition
covering of fascicles (bundles)
Term
– Epineurium
Definition
outermost covering which fuses with meninges
Term
• Distribution
Definition
branches distributed to skin, mucosa, skeletal muscles
Term
• After passing through intervertebral foramen spinal nerve divides
Definition
into several branches
Term
– Dorsal ramus
Definition
- serves deep muscles and skin of dorsal surface of trunk
Term
– Ventral ramus
Definition
serves muscles and structures of upper and lower extremities and lateral and ventral trunk
Term
– Meningeal branch
Definition
reenters spinal canal and supplies vertebrae, vertebral ligaments, blood vessels of cord and meninges
Term
– Rami communicantes
Definition
- involved with autonomic nervous system
Term
• Plexuses
Definition
ventral rami
Term
– Cervical plexus
Definition
ventral rami of first 4 cervical nerves (contributions from C5) and supply skin and muscles of head, neck, and upper part of shoulders (phrenic)
Term
– Brachial plexus
Definition
ventral rami of spinal nerves C5-C8 and T1; nerve supply for upper extremities and shoulder region (median, ulnar, radial)
Term
– Lumbar plexus
Definition
ventral rami of spinal nerves L1-L4; supplies anterolateral abdominal wall, external genitalia, and part of lower extremity (femoral, obturator)
Term
– Sacral plexus
Definition
- ventral rami of spinal nerves L4-L5 and S1-S4; supplies buttocks, perineum, and lower extremities (sciatic)
Term
• Dermatomes
Definition
skin segment supplied by dorsal root of a spinal nerve
Term
• Plexuses Functions
Definition
• Conduct impulses both to cord from periphery and from cord to periphery
• Nerves need to know: phrenic, musculocutaneous, median, ulnar, radial, axillary, femoral, obturator, sciatic, tibial, common peroneal
Term
• Glutamic (glutamate) and aspartic acids (aspartate) are most common
Definition
excitatory transmitters at brain synapses
Term
• GABA is most common
Definition
inhibitory transmitter in brain (opens chloride channels) (Valium enhances action of GABA)
Term
• Glycine is
Definition
inhibitory transmitter in cord (opens chloride channels)
Term
• Dopamine
Definition
- inhibitory; involved in emotional responses, addictive behaviors, and pleasurable experiences; and subconscious movements of skeletal muscles (Parkinson’s muscular stiffness due to degeneration of neurons releasing dopamine)
Term
• Substance P
Definition
found in sensory nerves, spinal cord pathways, and parts of brain associated with pain; enhances perception of pain
Term
• Enkephalins and endorphin are transmitters
Definition
that serve as pain-killers – suppress release of substance P
Term
• Acetylcholine (ACh)
Definition
excitatory neurotransmitter at neuromuscular junctions; may be inhibitory at some synapses (opens potassium channels in heart); Neurotransmitter of parasympathetic system (Helps to slow the heart rate down)
Term
• Norepinephrine (NE)
Definition
excitatory neurotransmitter outside CNS; Neurotransmitter of sympathetic system; within brain may be related to arousal, dreaming, and regulation of mood
Term
• Serotonin
Definition
excitatory in brain; may be involved in inducing sleep, sensory perception, temperature regulation, and control of mood, appetite, and induction of sleep
Term
• Brain stem
Definition
• Medulla
• Pons
• Midbrain
Term
• Falx cerebri
Definition
separates two hemispheres of cerebrum
Term
• Falx cerebelli
Definition
separate two hemispheres of cerebellum
Term
• Tentorium cerebelli
Definition
separates cerebrum from cerebellum
Term
• Ventricles and cerebral aqueduct inside brain
Definition
4 cavities inside brain
Term
• 1st and 2nd (lateral) ventricles
Definition
large cavities one in each cerebral hemisphere; connected to 3rd ventricle by Foramen of Monro (interventricular foramen)
Term
• 3rd ventricle
Definition
- vertical slit in cerebrum beneath corpus callosum and longitudinal fissure
Term
• 4th ventricle
Definition
• diamond-shaped space between cerebellum and medulla and pons
• expansion of central canal of cord
• connected to 3rd ventricle by cerebral aqueduct
• 3 openings (median aperture of Magendie and 2 lateral apertures of Luschka) lead from 4th ventricle to subarachnoid space
Term
• Cerebrospinal fluid
• Formation
Definition
• Formed by plasma filtering from network of capillaries (choroid plexus) in each ventricle; pass through ependymal layer which with choroid plexus forms blood-brain barrier; allows for selective passage of materials into interior of brain
Term
• Circulation
Definition
• Circulates from lateral ventricles → 3rd ventricle → cerebral aqueduct → 4th ventricle (& central canal) → median and lateral apertures → subarachnid space of cord and brain → arachnoid villi → venous sinuses (especially superior sagittal sinus)
Term
• Cerebrospinal fluid
• Composition of CSF -
Definition
glucose, proteins, lactic acid, urea, cations and anions, some wbc
Term
• Mechanical protection
Definition
shock-absorbing medium
Term
• Chemical protection
Definition
- provides optimum chemical environment for neuronal signaling
Term
• Circulatory
Definition
- provides nourishment and removes wastes
Term
• Medulla
Definition
• Enlargement of cord as it enters cranial cavity through foramen magnum
Term
• Consists of white matter (ascending and descending tracts) and
Definition
mixture of gray and white matter (reticular formation)
Term
• Motor tracts of pyramids undergo
Definition
decussation (cross)
Term
• Contains nucleus gracilis and nucleus cuneatus and
Definition
vestibular nucleus complex and nuclei of cranial nerves VIII-XII
Term
• Pons
Definition
• Lies above medulla
• Ascending and descending tracts make up white matter
• Contains reticular formation (functions in consciousness and arousal from sleep)
• Nuclei include pneumotaxic area and apneustic area and nuclei of cranial nerves V- VIII
Term
• Midbrain
Definition
• Lies above pons, below diencephalon and cerebrum
• Contains ascending/descending tracts and reticular formation
• Cerebral peduncles connect pons to cerebrum (tracts)
Term
• Corpora quadrigemina
Definition
2 superior and 2 inferior colliculi - rounded eminences on dorsal surface of midbrain
Term
• Midbrain
Definition
• Red nucleus and substantia nigra are prominent nuclei
• Cerebral aqueduct is fluid space in midbrain
• Medial lemniscus extends through medulla, pons, and midbrain
Term
midbrain function
Definition
Two-way conduction between cord and brain
Term
• Medulla
Definition
• Cardiac, vasomotor, and respiratory centers in medulla vital in control of heartbeat, blood pressure, and respiration
• Centers for reflexes of swallowing, vomiting, coughing, sneezing, and hiccuping
• Important for maintaining equilibrium
• Centers for cranial nerves VIII-XII
Term
Functions of Pons
Definition
• Centers for cranial nerves V-VIII
• Contain pneumotaxic and apneustic centers for respiration
• Has transverse fibers connecting opposite sides of cerebellum and longitudinal fibers connecting medulla with other parts of brain
Term
Function of Midbrain
Definition
• Centers for cranial nerves III and IV (pupillary reflexes and eye movements)
• Centers for movements of head and trunk in response to auditory stimuli (corpora quadrigemina)
• Helps coordinate muscular movements
Term
• Netlike arrangement of small areas of gray matter among white matter of brainstem
Definition
and extending into spinal cord and diencephalon
Term
• Reticular activating system
Definition
(part of reticular formation with fibers projecting to cerebral cortex) responsible for maintaining consciousness and awakening from sleep
Term
• Cerebellum
Definition
• Center section (vermis) lies between two hemispheres
• Surface is grooved with sulci and has slightly raised, slender convolutions
• Internal white matter in leaflike pattern (arbor vitae)
• Attached to brain stem by 3 tracts (cerebellar peduncles) - inferior, middle, and superior
Term
Cerebellum Functions
Definition
• Synergic control of skeletal muscles
• Mediates postural and equilibrium reflexes
Term
• Thalamus
Definition
• Large rounded mass of gray matter, one in each hemisphere of cerebrum, lateral to 3rd ventricle
• Includes medial geniculate, lateral geniculate, and ventral posterior nuclei
Term
• Hypothalamus
Definition
• Includes gray matter around optic chiasma, pituitary stalk, posterior lobe of pituitary gland, mammillary bodies and adjacent regions
• Prominent nuclei are supraoptic and paraventricular
• Tracts connect diencephalon with cerebral cortex, basal ganglia, brain stem and cord
Term
• Thalamus Functions
Definition
• Relays sensory impulses from cord to cerebral cortex
• Registers crude sensations of pain, temperature, and touch
• Emotions of pleasantness or unpleasantness associated with sensations
• Part of pathway for arousal or alerting and for complex reflex movements
Term
• Hypothalamus
Definition
major regulator of homeostasis
Term
• Higher center for both sympathetic and parasympathetic divisions of autonomic system,
Definition
regulating and coordinating them and thus integrating responses by visceral effectors
Term
• Link between psyche and soma (mind-over-body) by
Definition
relaying impulses from cerebral cortex to autonomic centers
Term
• Hypothalamus Function
Definition
• Supraoptic and paraventricular nuclei synthesize posterior pituitary hormones
• Synthesize and secrete releasing hormones that regulate secretion by anterior pituitary gland
• Part of pathways for arousal and alerting (rage and aggression) and for regulating appetite, temperature, and thirst
• One of centers that maintains waking state and sleep patterns
Term
• Cerebrum
Definition
• Longitudinal fissure divides cerebrum into 2 hemispheres, connected only by corpus callosum; each cerebral hemisphere divided by fissures into 5 lobes--frontal, parietal, temporal, occipital, and insula (island of Reil)
Term
• Cerebral cortex
Definition
- outer gray matter arranged in ridges called convolutions or gyri
Term
• Cerebral tracts
Definition
bundles of axons compose white matter in interior of cerebrum
Term
• Commissural tracts transmit from one hemisphere to other
Definition
(includes corpus callosum, anterior and posterior commissure)
Term
• Association tracts transmit from one convolution (gyri)
Definition
to another in same hemisphere
Term
• Basal ganglia (cerebral nuclei)
Definition
• Masses of gray matter embedded deep inside white matter in interior of cerebrum
• Largest is corpus striatum which consists of caudate nucleus and lentiform nucleus
• Lentiform nucleus is subdivided into putamen and globus pallidus
Term
• Limbic system
Definition
• On inner border of cerebrum and floor of diencephalon
• Made up of limbic lobe (with hippocampus, parahippocampal and cingulate gyri), dentate gyrus, septal neuclei, amygdaloid body, mammillary bodies, anterior nucleus of thalamus, olfactory bulbs, and axons
Term
• Sensory
Definition
sensory areas of cortex compare, evaluate, and integrate sensations to form total perceptions
Term
• Motor
Definition
- control voluntary (skeletal muscle) movements
Term
• Integrative functions
Definition
• Consciousness, Memory, and Emotions
Term
Consciousness
Definition
state of awareness of one’s self, one’s environment and other beings; depends on excitation of cortical neurons by impulses from reticular activating system; normal variations in degree of level of consciousness (waking, REM sleep, deep sleep); also several kinds of altered states of consciousness (ASC) (anesthesia, coma, and yoga)
Term
Memory
Definition
several parts of cortex (temporal, parietal, occipital lobes) store memories and limbic system (“emotional brain”) and protein synthesis play key roles in memory; protein synthesis crucial for long-term memory
Term
Emotions
Definition
both subjective experience and objective expression of emotions involve limbic system
Term
• Language functions
Definition
depends on widespread integrated cortical processes; regions called speech centers in several lobes serve as focal points for integration of speech processes; speech defects (aphasias) of different kinds result from lesions of different speech centers
Term
• Generalizations about cerebral functions
Definition
• Cerebral activity goes on as long as life itself; EEGs are records of cerebrum’s electrical activity (brain waves)
Term
• Alpha waves
Definition
moderately fast, moderately high-voltage waves - dominate in relaxed nonattentive state
Term
• Beta waves
Definition
- fast, low-voltage waves - dominate in attentive waking state
Term
• Delta waves
Definition
- very slow, high-voltage waves characteristic of deep sleep; normal in awake infant, indicate brain damage in awake adult
Term
• Theta waves
Definition
moderately slow, low-voltage waves that appear as drowsiness descends; occur in children and in adults experiencing emotional stress
Term
• Left hemisphere
Definition
specializes in language functions and in control of skilled movements and gesturing movements of right hand
Term
• Right hemisphere
Definition
specializes in perception of nonspeech sounds and in locating objects in space; may also function better in tactual perception and in visualizing spatial relationships
Term
• Functional areas of cerebral cortex
Definition
• Sensory areas
• Primary somatic sensory area - crucial for experiencing general sensations (heat, cold, touch, proprioception, and pain)
• Primary visual area - crucial for vision
• Primary auditory area - crucial for auditory sensations
• Primary gustatory area - important for taste
• Primary olfactory area - crucial for smell
Term
• Motor areas
Definition
• Primary somatic motor area - dominates control of somatic effectors (skeletal muscles)
• Language areas (motor speech area or Broca’s area) - control muscles of larynx, pharynx, and mouth; involves coordination with other areas
Term
• Association areas
Definition
connect motor and sensory areas and large parts of cortex
Term
• Somatosensory association area
Definition
integrate and interpret sensations; store memories of past sensory experiences
Term
• Visual association area
Definition
relates present to past visual experiences with recognition and evaluation of what is seen
Term
• Frontal eye field area
Definition
voluntary scanning movements of eyes
Term
• Auditory association area
Definition
determines if sound is speech, music, or noise
Term
• Wernicke’s area
Definition
interprets meaning of speech by recognizing spoken words
Term
• Gnostic area (common integrative area) -
Definition
integrates sensory inputs from other association areas so common thought can be formed
Term
• Premotor area
Definition
causes specific group of muscles to contract in specific sequence; memory bank for learned skilled movements
Term
• Early development (of Nectoderm)
Definition
by 4th week
• Prosencephalon - forebrain
• Mesencephalon - midbrain
• Rhombencephalon - hindbrain
Term
5th week developement
Definition
• Later - after 5th week
• Telencephalon - cerebrum
• Diencephalon - thalamus an hypothalamus
• Mesencephalon
• Metencephalon - cerebellum
• Myelencephalon - medulla oblongata
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