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353 Cards in this Set

  • Front
  • Back
Peripheral nervous system is made up of what types of nerves?
Spinal nerves
Cranial nerves
Autonomic nerves
Peripheral nervous system can be subdivided into what two major branches?
Somatic and Autonomic
The Somatic branch of the peripheral nervous system does what?
Is both sensory and motor, and carries sensory nerve impulses to and motor impulses from the CNS from skin and skeletal muscle fibers
The Autonomic Nervous system innervates:
Smooth muscle, cardiac muscle, glands
How many nerves are there in the CNS? Is most of their activity sensory or motor?
Over 100 billion, most activity is sensory (input receiving)
What do astrocytes do?
1. provide for rapid transport for nutrients and metabolites
2. believed to form an essential component of the blood-brain barrier
3. appear to be the scar-forming cells of the CNS, which may be the foci for seizures
4. may play a role in segregating postsynaptic receptor surfaces from other regions
What do Oligodendroglia do?
Deposit myelin within the CNS
What do Schwann Cells do?
Form the myelin sheath and neurilemma outside of the CNS (in the PNS)
Microglia: what do they do?
Phagocytic properties; they clear away cellular debris
Ependymal cells: where are they and what do they do?
Serve as a lining for the cerebral ventricles and chroid plexuses (which are responsible for CSF production)
What are 6 other names for the sensory (afferent) system within the CNS?
1. Dorsal
2. Spinothalamic
3. Anterolateral
4. Dorsolateral Spinal
5. Somatosensory
6. Post central gyrus
What are 3 other names for the motor (efferent) system within the CNS?
1. Ventral
2. Alpha Motor
3. Corticospinal
What is a bipolar neuron, and where might you find it?
spindle-shaped neuron with a dendrite at one end and an axon at the other, found in light-sensitive retina of the eye
_______ neurons comprise 99% of all neurons, and are the major type found in the CNS
Multipolar
The _______ insulates nerve axons to prevent electrical loss and speed conduction.
Myelin sheath
The _______ are 2-3 micrometer sized gaps in the myelin sheath that allow the process of ______ conduction
Nodes of Ranvier allow saltatory conduction
Schwann cells wrap around the axons of nerves to form a fatty myelin insulator. This insulation is so tight that it prevents the movement of Na and K ions except at the ______. This allows the electrical signal to "jump" from Node to node down the axon, and is much _______
Nodes of Ranvier, much faster (saltatory conduction)
A Alpha Fibers: myelinated? diameter, speed, location/transmits:
Myelinated, fastest conduction (60-120 m/s); largest diameter (10-18 micrometers)
Located/transmission: somatic motor fibers, muscle propricepors
A Beta fibers: myelinated? Diameter, speed, Transmits:
Myelinated, diameter 5-10 micrometers, conductance: 38-70 m/s
Transmits: rapid sensory touch, pressure, kinesthesia
A Gamma fibers: myelinated? Diameter, speed, transmits?
Myelinated, diameter 1-5 micrometers, conductance 15-45 m/s,
Transmits: motor to muscle spindle, rapid sensory (touch, pressure)
A Delta fibers: myelinated? Diameter, speed, transmits?
Myelinated,2-5 micrometer diameter, conductance 5-30 m/s, Transmits: Pain, temperature, pressure
B Fibers: myelinated, diameter, speed, transmits
Thinly myelinated, diameter 3 micrometers, conductance 3-15 m/s, Transmits: Autonomic preganglionic transmission
Autonomic preganglionic transmissions are carried by what type of fibers?
B fibers
sympathetic postganglionic transmissions are carried by ____ fibers.
C
C fibers: myelinated? diameter, speed, transmission
No; 1-3 micrometers (smallest fibers), 5+ m/s conductance, Transmits: sympathetic postganglionic; slow pain
Are sympathetic postganglionic nerve fibers myelinated?
No
What is an example of a mechanoreceptor?
Carotid sinus baroreceptor
What is are two examples of chemoreceptors?
Carotid and aortic bodies (sense partial pressure of oxygen); supraoptic nuclei (sense serum osmolality)
The Dorsal-column medial lemniscal tracts carry information regarding what 6 sensations?
Touch-high localization
Touch-fine gradients
Vibration
Movement against skin
Position sense (joints)
Pressure
The anterolateral tracts carry information regarding what 5 sensations?
Pain
Temperature
Crude touch and pressure with crude localization
Tickle and itch
Sexual sensations
Dorsal Column medial lemniscal tract neurons decussate:
In the medulla (second order neuron begins in medulla and crosses over to contralateral side from where impulse sensed)
Anterolateral tract neurons decussate?:
Immediately upon entering the dorsal horn
Anterolateral tracts: where do the first, second, and third order neurons go?
First order neuron enters through the dorsal horn, meets the second order neuron which immediately crosses over to the contralateral side and travels up the anterior or lateral portions of the spinal cord white matter through the medulla, meets the third order neuron in the ventrobasal and intralaminal nuclei of the thalamus, and ascends to the somatosensory area of the post central gyrus
Describe the first, second, and third order neuron locations and destinations in dorsal column medial lemniscal tract?
First order neuron enters through the dorsal root, travels into the dorsal horn, ascends through this DCML tract to the medulla where it meets the second order neuron. The second order neuron in the medulla immediately decussates to contralateral side, and ascends to ventrobasal region of the thalamus where it meets the third order neuron. The third neuron carries this information to the somatosensory area of the post central gyrus
Enkephalins are _______; the increase the threshold needed to create an action potential
Inhibitory on the presynaptic side
Enkephalins cause less _____ and ______ to be released from the axon terminal
less Glutamate and substance P are released
Spinoreticular tract: what does it do?
terminates in centers responsible for blood pressure, motor control, and descending inhibition of pain- causes less glutamate and substance P to be released at the level of the spinal cord and thereby decreases pain
Spinomesencephalic tract: what does it do?
terminates in centers for integrated motor, autonomic, and antinociceptive responses such as orienting, defense, and confrontation
Spinolimbic tract: what does it do?
terminates in hypothalamus and amygdala- creates an emotional response to pain or other stimulus
Threshold: definition

What factors influence this?
The voltage that must be exceeded before depolarization will occur;

Influenced by: pH, temperature, and oxygen
Summation: What is it?
A series of sub-threshold stimuli may additively create enough of stimulus to generate an action potential (think of lots of neurons sending low voltage stimuli regarding the same event to one axon; individually, each of these stimuli is not strong enough to generate an action potential, but together, they decrease the membrane potential to its threshold level and thus trigger impulse conduction
accommodation:
the ability of nerve tissue to adjust to a constant source and intensity of stimulation so that some change in either intensity or duration of the stimulus is necessary to elicit a response beyond the initial reaction. Accommodation is probably caused by reduced sodium ion permeability, which results in an increased threshold intensity and subsequent stabilization of the resting membrane potential; when a stimulus causes the membrane potential to change very slowly, the nerve is not as likely to create an action potential
All or none law:
If a stimulus is strong enough to initiate an impulse, it will do so to its fullest extent; if a stimulus is strong enough to generate an action potential, it will travel down the entire length of the axon or not at all
Refractory period:
For a short time after the development of an action potential, it is not responsive to further stimuli; The absolute refractory period places a limit on the rate at which a neuron can conduct impulses, and the relative refractory period permits variation in the rate at which a neuron conducts impulses. Such variation is important because it is one of the ways by which our nervous system recognizes differences in stimulus strength,
The resting membrane potential of a nerve is:
-90 mv
When a stimulus changes the resting membrane potential of a nerve by a few mv, it causes the _____ channels to open
Voltage gated Sodium channels (remember: Stimulus- Sodium); as the sodium enters the cell, it overshoots to + 35mv and this change in voltage shuts down the voltage gated sodium channels so no more sodium can enter the cell membrane
The Sodium channels close very quickly after stimulation, and then the ______ open more slowly to restore the membrane potential
Potassium channels open as the sodium channels close- remember "slow K channels"
Threshold for an action potential is:
-65 mv
What serves to restore the concentrations of potassium inside the cell and sodium outside the cell?
The sodium-potassium pump: pumps 3 Na molecules out for every 2 K that it pumps in; this requires ATP
How do local anesthetics work?
They act directly on the sodium channels, decreasing their excitability and impeding their ability to generate an action potential
Myasthenia Gravis is caused by:
How is it treated?
Autoimmune destruction of the postsynaptic Ach receptors (resulting in an inability to respond to Ach). It is treated with neostygmine which deactivates acetylcholinesterase and therefore causes Ach to accumulate within the NMJ
Fatigue of synaptic transmission occurs with ______, ______ firing.
Repeated, rapid firing (this may partly explain why seizures eventually stop even without intervention)
Alkalosis ______ neuronal excitability
Increases; it is easier to get neurons to conduct
What three factors greatly decrease neuronal excitability?
Acidosis, hypoxia, and anesthetic and other drugs (increase the threshold necessary or firing)
Why does unconsciousness follow cardiac arrest?
Brain cells stop firing within 3-7 seconds following cardiac arrest because they cannot transmit impulses in a hypoxic environment
What are the two major types of synapses?
Chemical and electrical
Neurotransmitter release is _____ dependent
Calcium
Another name for facilitation:

Another name for inhibition
EPSP (excitatory postsynaptic potential)

IPSP: Inhibatory Postsynaptic potential (hyperpolarizes the cell membrane)
What class of neurotransmitter is acetylcholine? What is its role?
Ester;
Nicotinic: Fast synaptic transmission at NMJ and autonomic ganglia
 
Muscarinic: Excitatory/inhibitory slow synaptic transmission r/t tissue
What class of neurotransmitter is NE? What is its role?
Monoamine; Works on alpha and beta receptors; Slow synpatic transmission in CNS and smooth muscle
Corticospinal tracts are _____. They come together in the _____ to form pyramids
Descending; join in the medulla to form pyramidal tracts
What percent of corticospinal tracts decussate in the medulla?
75% decussate in medulla, remaining 25% do not
Motor neurons NOT traveling in the pyramidal tracts descend in the ____
anterior horn motor neuron
Extrapyramidal motor neuron tracts are responsible for
Coordination of routine muscle movements; Plays a crucial role in producing larger, more automatic movements; brings about contraction of muscles in sequence or simultaneously (swimming, walking), and all normal voluntary movements (the "riding a bike effect"- things you don't think about); also regulates ingrained emotional expressions (smiles, frowns, etc)
The adrenal medulla is innervated by:
preganglionic adrenergic neurons (nicotinic receptor- releases Ach and causes adrenal gland to release Epi and NE)
Skeletal muscle is innervated by _____ arising from
Skeletal muscle innervated by myelinated efferent motor nerve fibers (α motor neurons) arising from cell body in ventral horn of spinal gray matter
Motor nerves divide and end on
Individual muscle fibers
Motor Unit
Motor nerve + multiple innervated fibers
Skeletal muscle neurotransmitter
Ach (nicotinic)
Motor end plate
Post junctional membrane at neuromuscular junction
post junctional receptors on the motor end plate
alpha (2), beta, gamma, delta
What is acetylcholine synthesized from?
What is it broken down into? By what?
synthesized by enzyme choline acetyltransferase from the compounds choline and acetyl-CoA
Broken down by acetylcholinesterase into acetate and choline
How is acetylcholine released into NMJ?
Action potential causes fast and slow calcium channels to open and release calcium. Calcium binds to nerve plasma membrane and causes it to expel Ach into NMJ.
What are inhibitors of Ach release?
Mg²
Aminoglycosides
Calcium channel blockers
What causes the fast Ca channels to open? The slow channels?
Fast calcium channels are voltage gated (activated by voltage change from action potential propagation), slow are opened using cAMP
Where does acetylcholinesterase live?
In the spongy connective tissue within the synaptic cleft
The cerebrum is structured
Outer gray holding cell bodies; inner white matter consisting of fiber tracts
How thick is the cerebral cortex?
2-3 mm
What is the most basic way of describing the functions of the cerebrum?
Storage of experience (memory)
Exchange of impulses with other cortical areas (association)
What does the frontal lobe do? What are the associated landmarks?
Concerned with intellectual function such as
Reasoning, abstract thinking
Aggression
Sexual behavior
Olfaction (smell)
Articulation of meaningful sound (speech)
Voluntary movement;
Landmarks: Central sulcus separates frontal lobe from parietal lobe
Parietal lobe functions:
Body sensory awareness
Taste (postcentral gyrus)
Use of symbols for communication (language)
Abstract reasoning (math)
Body imaging
What does the temporal lobe do? What does it do in conjunction with the limbic system?
Non-limbic portion
Interpretation of language
Awareness, discrimination of sound
Major memory processing area
In conjunction with the limbic system:
Formation of emotions
Love
Anger
Aggression
Compulsion
Sexual behavior
Occipital lobe functions:
Receiving, interpreting, discriminating visual stimuli from optic tract
Associating visual impulses with other cortical areas
What does the limbic system do?
Incorporates parts of frontal, temporal, parietal lobe
Oldest part of cortex in evolutionary terms
Center for emotional behavior
What cerebral hemisphere is responsible for speech?
Left only
What does the left cerebral hemisphere primarily do?
Left hemisphere deals with higher functions
Mathematical
Analytical
Verbal
What is the right hemisphere primarily responsible for?
Visual and musical orientations
The idea of cerebral dominance is
controversial
The basal ganglia are
Collections of grey matter deep in substance of cerebral hemispheres
Structures associated with basal ganglia functionality are
Subthalamic nucleus
Substantia nigra
What does the basal ganglia do (what is its function)?
Planning, programming voluntary muscle movement
Parkinson's disease is a disorder of the _______ caused by
Basal ganglia; Degenerative disease of CNS with loss of dopaminergic fibers present in basal ganglia; Depletion of dopamine, the neurotransmitter that inhibits rate of firing of neurons controlling extrapyramidal motor system
Parkinson's disease is manifest by:
Decreased spontaneous movements
Rigidity of extremities
Facial immobility
Shifting gait
Rhythmic resting tremor
Parkinson's disease is treated by
 ↑ dopamine in CNS or ↓ neuronal effect of Ach
Patients with Parkinson's disease should _____ on the day of surgery. Why?
continue L-dopa including day of surgery; half-life is short, interruption for 6-12 hrs can result in loss of benefits
What side effects might you see from L-dopa? What happens if you stop it abruptly?
orthostatic hypotension, cardiac dysrhythmia, hypertension may occur with use; abrupt d/c might cause severe muscle rigidity
Patients with Parkinson's disease may exhibit a _____ response to Ketamine
Exaggerated SNS response; avoid use
Is succinylcholine safe in patients with Parkinson's disease?
Should be, only one reported case of hyperkalemia (perhaps r/t patient being bedridden, severe Parkinsons)
hunting tons chorea is a degenerative disease of the CNS affecting _____
Basal ganglia
Caudate nucleus
Putamen
Globus pallidus
Huntington's chorea results in
Deficiencies of Ach and GABA basal ganglia
S/S of Huntington's Chorea
Progressive dementia
Chorea first symptom
What response might a patient with Huntington's Chorea exhibit to succinylcholine?
Decreased plasma cholinesterase prolongs response to succinylcholine
Patients with Huntington's Chorea are prone to ______
Prone to aspiration due to involvement pharyngeal muscles
The diencephalon is made up of what 4 structures?
Epithalamus
Thalamus
Hypothalamus
Subthalamus
Where is the epithalamus located and what does it do?
Forms roof of 3rd ventricle, most superior portion of diencephalon
It connects with and is closely associated with functions of limbic system
Hormones of pineal body influence reproductive activity
Secretion of melatonin (circadian rhythm)
Where is the thalamus and what does it do?
Largest part of diencephalon; surrounds third ventricle
Major integrating center for afferent impulses to cerebral cortex
Relay station for information from basal ganglia, cerebellum that is sent on to appropriate portions of motor area
Crude appreciation of touch, pain, temperature, may occur here
The _____ forms the base of the diencephalon; what are its two generic functions?
Hypothalamus;

Maintains a constant internal environment
Maintains behavioral patterns
The hypothalamus is ______ to the limbic system
Focal structure of limbic system; limbic system + hypothalamus performs role in overall behavior and emotional expression
What are the specific functions of the hypothalamus?
Visceral, somatic responses
Afferent responses
Hormone synthesis
Autonomic nervous system activity
Temperature regulation
Feeding responses
Physical expression of emotions
Sexual behavior
Pleasure-punishment centers
Awareness
The cerebellum is the _____ largest part of the brain. Where is it located?
Second largest; Located just below posterior portion of cerebrum and is partially covered by it
How is the tissue of the cerebellum arranged?
Gray matter makes up outer portion, white matter in interior
Two cerebellar hemispheres; central section called vermis (resembles a worm coiled on itself)
What does the cerebellum do?
Coordinates signals from muscle, joint, visual, auditory and equilibrium receptors with instructions from cortex
What three structures make up the brain stem?
Medulla, Pons, and midbrain
Medulla: location and function
Forms lower portion of brainstem
Contains centers controlling heart rate, blood vessels, respiration, coughing, sneezing, swallowing, vomiting
Contains nuclei of VIII, IX, X, XI, XII cranial nerves
Contains pyramidal tracts
Where is the Pons located? What is its function?
Below midbrain
Primary function is transmission of information from cerebellum to brainstem and between two cerebellar hemispheres
Important center for control of respiration
Groups of neurons form sensory nucleus of V and VI, VII CN
Midbrain: function
Superior and inferior colliculi  are centers for visual and auditory reflexes
Tegmentum contains red nucleus and substantia nigra which help to control skilled muscular movements
Contains nuclei of III, IV CN
Reticular Formation (RAS): function
Controls level of excitability of brain neurons and helps maintain consciousness and the waking state
Inhibition of the RAS leads to sleep or coma
Red Nucleus
Primal control of movement- controls crawling in babies and arm swinging
What connects medulla, pons, midbrain with each other and spinal cord, thalamus, cortex
Reticular formation
Preganglionic fibers: (type)
B fibers
Postganglionic fibers (type)
C fibers
NO is occasionally a neurotransmitter in the ___ system
Parasympathetic
Another name for the PNS
Craniosacral
Another name for the SNS
Thoracolumbar
What is are catecolamines made of? Where are they produced?
Tyrosine produced in liver then transported to catecholamine-secreting neurons where a series of reactions convert it to dopamine, to norepinephrine and finally to epinephrine
For every SNS preganglionic fiber,
there are _____ postganglionic
fibers
20-30
Alpha 1 fibers of SNS: function
constrict blood vessels, inhibit insulin sec
Alpha 2 Fibers of the SNS
Receptors presynaptic. Some vasodilation (negative feedback)
Beta 1 fibers:
Inc. HR, contractility, conduction. Lipolysis
What parts make up the basal ganglia
Claustrum
Corpus stratum
Lentiform nucleus
Globus pallidus
Putamen
Caudate nucleus
Which has a wider distribution: the SNS or the PNS?
SNS;
SNS- distributed throughout body
Transmitters: Ach, NE
PNS- limited distribution. Ganglia near organs
Transmitters: Ach, Ach (& occas, NO)
Dopa 1 Receptors
Dilate splanchnic blood vessels, increase GFR
Dopa 2 receptors
Inhibit Norepi release
What effects can Neurotransmitters produce?
Change in membrane permeability (ions)
Activating/inactivating enzyme
 
2nd messengers
Amplification
Control
Specificity
Receptors of the SNS are sensitive to levels of _________
circulating catecholamines; up regulate number of in times of sparse catecholamines, down regulate when lots of catecholamine floating around
Alpha 1-adrenergic stimulation causes _______ which causes arteriole vasoconstriction in the skin and GI tract and venous vasoconstriction increasing preload
an increase in intracellular Ca
Stimulation of Alpha 2 causes what reaction at peripheral presynaptic sites?
Decreases synthesis and release of NE by negative feedback
Vasodilation
Stimulation of Alpha 2 at central post synaptic sites does what?
Postsynaptic alpha-2 receptors found in brainstem inhibits outflow of SNS
Vasodilation
Sedation
Where are beta 1 adrenergic receptors found?
Heart, kidneys, adipose
What does beta 2 stimulation cause?
Dilation of smooth muscle of lungs and vasculature, liver and glands
Promotes hyperglycemia & hypokalemia (stimulation of beta 2 activates the Na-K pump)
Beta 3 stimulation causes
Negative inotropy
What cells in the adrenal medulla release Epi and NE when stimulated by presynaptic sympathetic acetylcholine receptors?
chromaffin cells
What percentage of catecholamines released from the adrenal medulla is Epi? NE? What is each of their intrinsic rates?
80% Epi, 0.2 mcg/kg/min
20% NE; 0.05 mug/kg/min
NE stimulates:
Alpha and beta fibers A>B
Epi stimulates
Alpha and Beta, A=B and results in greater metabolic stimulation than NE
D1 increases_____
Increases cAMP via adenylate cyclase
D2 functions by _____
Increases phosphodiesterase activity to decrease cAMP
What effect does stimulation of muscarinic receptors have?
Heart: Decrease HR, contractility, conduction
Lungs:  Bronchoconstriction, secretions
stimulate GI
(SLUDGEM- Salivation, lacrimation, urinanation, defecation, GI motility, emesis, Meiosis)
Parasympathetic nervous system fibers exit
Out through CN III, V, IX, X, and Sacral nerves S2-S4
What happens when Nicotinic receptors are stimulated?
opens an ion pore allowing Na+ and Ca+ influx and K+ efflux from postsynaptic tissue
Where are Nicotinic receptors found?
Autonomic ganglia (preganglionic neurotransmitter of PNS and SNS)
MNJ
Adrenal chromaffin cells
What happens when muscarinic receptors on cardiac tissue are stimulated? Why?
These receptors lie on presynaptic sympathetic nerve terminals; Stimulation decreases NE release leading to ↓ HR and contractility
What does NO do?
Nitric oxide activates 2nd messenger cGMP to promote bronchodilation and vasodilation
Prevertebral ganglia- what are they?
Sympathetic ganglia that lie between the sympathetic chain and the organ of supply
What do the pre vertebral ganglia consist of?
Prevertebral ganglia consist of pre- and postganglionic sympathetic fibers and parasympathetic fibers and the ganglia cell bodies
What is the Vasoconstrictor area of the Vasomotor Center?
Anterolateral of upper medulla that stimulates preganglionic vasoconstricting neurons
Lateral portions ↑ heart rate & contractility
What is the Vasodilator area of the Vasomotor Center?
Anterolateral lower half of medulla that inhibits vasoconstrictor area
What does the dorsal motor nuclei of the vagus do?
Receive input from medial vasomotor center to ↓ heart rate and contractility
What cranial nerves help regulate blood pressure through the vasomotor center of the medulla?
IX (glossopharyngeal) and X (Vagus
Where is the vasomotor center located? What does it do?
a collection of cell bodies in the medulla oblongata of the brain that regulates or modulates blood pressure and cardiac function
Information from Baroreceptors, Chemoreceptors, GI receptors is all processed in ______
Vasomotor center
How does the baroreceptor reflex work?
Initiated by baroreceptors in the carotid sinus via Hering’s nerve to CN IX and the aortic arch via CN X to the tractus solarius of the medulla to inhibit the vasoconstricting area and excite the vagus PNS area
What is the effect of stimulating the baroreceptor reflex? How long will this reaction last?
Net effects: vasodilation and decreased heart rate & contractility
Not effective long term, can be reset in 1-2 days
How does the chemoreceptor reflex work?
Decreased O2 (and to lesser extent increased CO2 and H+) stimulate Carotid bodies in carotid bifurcation (CN IX)
Aortic bodies in aortic arch (CN X)
Transmit to vasomotor center via Hering’s nerves and cause excitation, resulting in increased BP
How does the oculocardiac reflex work?
Traction on the extracocular muscles stimulates afferent CN V with reflexive efferent CN X resulting in
Bradycardia
Decreased SVR/BP
Arrhythmias
What is the celiac reflex?
Traction or pressure on structures within peritoneal/thoracic cavities
Bradycardia
Hypotension
Apnea
What are the Atrial & Pulmonary Artery Reflexes?
Stretched atria (volume overload) results in slight reflex vasodilation of peripheral arterioles, stimulates hypothalamus to decrease ADH (causing increased UOP), Increased HR- Bainbridge reflex —> offload fluid from heart, Reflex dilation of afferent arterioles of kidneys to ↑ GFR, release of atrial natriuretic peptide to promote Na+ and thus water excretion
What is the CNS ischemic response?
Stimulated by ABP <60 mm Hg; most potent activator of vasoconstricting system
Cushing reaction: when high ICP ↓ cerebral perfusion (HTN & bradycardia)
What is the net result of the renin angiotensin Aldosterone system?
Kidneys secrete renin in response to decreased blood flow, which results in aldosterone and ADH release causing increased sodium and water retention, and NE release (ACE inhibitors work here)
In pediatric patients, CO is dependent on
HR
At birth, the ______ is less developed
SNS
Name 4 common changes to the ANS in the geriatric population?
Impaired quality of adrenergic receptors in the heart
More dependent on atrial kick
Greater incidence of shivering
HTN common
Autonomic neuropathy occurs in ____ of diabetics, and results in ______
40%; vagal denervation
Autonomic dysreflexia occurs in 85% of spinal cord injuries above the level of _____
T5
What is autonomic dysreflexia?
Vasoconstriction via ANS mass reflex below lesion in response to noxious stimuli (full bladder, defecation, skin incision)
What are S/S of autonomic dysreflexia?
Paroxysmal hypertension
Bradycardia
Cardiac dysrhythmias
Vasodilation above lesion (flushing)
How do you treat autonomic dysreflexia?
Remove noxious stimulant
Direct vasodilators
Cranial Nerves
Oh, Oh, Oh, To Touch And Feel Virgin Girl's Vaginas- AH
olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal
CN 1: Name and function
Olfactory, Sensory, Smell
CN 2: Name and function
Optic: Sensory: Vision
CN 3: name and function
Oculomotor: Motor: eye movements, pupillary constriction, Parasympathetic input to the ciliary ganglion to constrict pupil,
Damage manifests as blown pupil
CN 4: Name and Function
Trochlear: Motor: eye movement
CN 5: Name and Function
Trigeminal; Mixed, Somatosensory information from the face and head; muscles for chewing
CN 6: Name and Function
Abducens, Motor, eye movement
CN 7: Name and Function
Facial; Mixed: Taste (anterior 2/3 of tongue); somatosensory information from ear; controls muscles used in facial expression; Paralysis of the facial nerve causes a facial droop. it carries Parasymapathetic input to the salivary and lacrimal glands; damage to this nerve is manifest as facial droop
CN 8: Name and Function
Vestibulocochlear; Sensory, hearing, balance
CN 9: Name and Function
Glossopharyngeal; Mixed, Taste (posterior 1/3 of tongue); Somatosensory information from tongue, tonsil, pharynx; controls some muscles used in swallowing; parasympathetic innervation to parotid gland
CN 10: Name and Function
Vagus; Mixed: supplies general sensory and motor function to the larynx and pharynx; Parasympathetic input to the heart and lungs and gastro intestinal tract
CN 11: Name and Function
Spinal accessory;Motor: Controls muscles used in head movement.
CN 12: Name and Function
hypoglossal; Motor: Controls muscles of tongue
Mnemonic for CSF production and flow
*Lady *Monroe has *3 *Aquaducts that lead to *4 *Luscious and *Magical *Subarachnoid places (Lateral, Foramen of Monroe, 3rd Ventricle, Aqueduct of Sylvus, 4th Ventricle, Foramen of Luschka, Foramen of Magendie into cerebellar cisterns and into subarachnoid space
CSF is reabsorbed by _____ in the _____
Arachnoid villi in the subarachnoid space into the venous sinuses
What are the % constituents of the contents of the cranium
80% Brain & Water
12% Blood
8% CSF
What is the cerebral blood flow rate to the brain?
45-50 ml/100 g brain/min
What are the two major arteries that supply the brain?
Internal Carotid and Basilar arteries
At any given time, the intracranial blood volume is _____
100-150 ml
The anterior cerebral artery supplies what structures within the brain?
Basal ganglia; corpus callosum; medial surface of cerebral hemispheres; superior surface of frontal and parietal lobes
What would a stroke (occlusion) in the anterior cerebral artery manifest as?
Hemiplegia on the contralateral side of the body, greater in the lower than in the upper extremities
What structures does the Middle cerebral artery supply?
Frontal lobe, parietal lobe; temporal lobe (primarily the cortical surfaces)
What would an occlusion of the middle cerebral artery manifest as?
Aphasia in dominant hemisphere
What structures does Posterior cerebral artery serve?
Part of the diencephalon and temporal lobe; occipital lobe
What would an occlusion of the posterior cerebral artery manifest as?
Contralateral hemiplegia greater in the face and upper extremities than in the lower extremities; sensory loss; visual loss
Dura Mater
Hard mother, tough, nonstretchable membrane with 2 layers; outer dura periosteum of skull
Arachnoid Mater
Thin, avascular membranewhich skips from crest to crest; subarachnoid below contains CSF, large blood vessels
Pia Mater
Tender mother, intimately attached to brain and cord; vascular layer through which vessels pass to nourish neural tissue
CSF is manufactured in the _______ of which ventricles?
Choroid plexuses of the lateral ventricle and the roofs of the 3rd, 4th
What is the choroid plexus>?
Networks of capillaries that project out from the pia mater into the ventricles
What is the composition of CSF?
Composition is same as extracellular fluid; free communication between brain, ECF spaces, ventricles, SAS
How much CSF is produced each day? How much is present at any given time?
600-800 ml/day, 125-150 present at one time
What pressure does the CSF exert within the brain and spinal cord
12 mm Hg
What is the purpose of CSF
Cushions and protects brain and spinal cord
What is the main "brain drain" vein?
Internal jugular- occludes with improper positioning and head has decreased venous return
What percent of the cardiac output goes to the brain?
15%
What percentage of the CBF goes to gray matter? To white matter?
80% gray, 20% white
CBF is auto regulated within a range of
MAP 50-150 (Miller says 65-150)
What 5 areas are outside of the blood brain barrier?
–Pineal gland
–Neurohypophysis
–Area postrema
–Supraoptic crest
–Subfornical organ
Premature babies have an ______ BBB
immature; kernicterus can be a problem because of this
What factors make the BBB more permeable?
tumors, trauma, hypoxia, severe changes in CO2
What is useful for stabilizing the BBB?
Cortisone
What is the cerebral metabolic rate for oxygen (CMRO2)?
3.0 ml/100 g/min
What is the cerebral metabolic rate for glucose (CMRg)?
4.5 ml/100 g/min
In a normal (uninjured) brain, what is the major determinant of Cerebral perfusion?
MAP
In response to increased MAP, the auto regulation mechanisms of the brain cause
Vasoconstriction; maintains constant CBF
Time to autoregulation
30-120 seconds
What is the effect of a MAP > 150?
Cerebral edema
Normal CPP
100
EEG will be flat at normothermia at what CPP
25-40
Irreversible tissue damage to the brain occurs at a CPP of _____ at normothermia
<20
Myogenic theory of cerebral auto regulation:
Smooth muscle contracts in response to stretch, so when blood vessels stretched by increased BP, they vasoconstrict
Metabolic Theory of cerebral autoregulation
Tissue produces acid metabolites in response to hypoxia, and the increased acid causes cerebral vasodilation
When cerebral auto regulation is lost, there is a _____ relationship between BP and CBF
linear
What 5 factors can lead to a loss of cerebral auto regulation?
•Hypoxemia
•Ischemia
•Hypercapnia
•Trauma
•Some anesthetic agents
What effect does beach chair position have on cerebral hemodynamics?
•MAP,  CVP,  PAOP, SV, CO, and PaO2 decrease
•CPP decreases by ~15% in non-anesthetized
Anesthesia blunts normal compensatory responses
To accurately measure the CBF to the head with an art-line, you can
Level the transducer at the tragus instead of the phlebostatic axis
Cerebral blood flow varies linearly with CO2 ______
20-80 (other source says 25-70)
_______ profoundly affects CBF
PaCO2 (and spinal cord blood flow)
Increases in CBF do not occur until PaO2 < _______
50 mm Hg
•Hyperoxia (80-100% inhaled O2) in normal person associated with _______
10-12% decrease in CBF
The autonomic nervous system (SNS, PNS) appears less important in maintaining CBF except at
The upper and lower limits of cerebral autoregulation
Decreased body temperature decreases CBF by how much?
5% per degree centigrade drop
increasing body temperature increases _______
CBF and metabolism
There are no ____ stores in the brain; consciousness is lost at _____
no O2 stores; consciousness lost at PaO2 30
Hct affects CBF by altering blood viscosity; changes are not seen with Hct between
30-50%
In the brain, more than 90% glucose is _______
aerobic- brain does not use glucose well in hypoxic states
What classes of drugs offer neuroprotection?
•Barbiturates- mainstay
–Propofol
–Etomidate
–Benzodiazepines
–Volatiles
ICP- definition
supratentorial CSF pressure or pressure in a lateral ventricle or SAS
Which two agents increase both the CMRO2 and the cerebral blood flow?
Ketamine and N20
TIVA is offers what advantages over volatiles in neurosurgery?
Improved CPP, Better preservation of cerebral autoregulation vs. volatile, less interference with SSEP, MEP, AEP; potential neuroprotective effects via antioxidant properties.
Uncoupling effect:
High dose volatile increases CBF but decreases CMRO2
N20 is a ______ and therefore ______ ICP
Vasodilator, increases CBF and therefore raises ICP
Increases in ICP with N2O can be attenuated by
pretreatment with Benzo or thiopental
What 5 factors need to be considered in choosing anesthetic agents for neurosurgery?
1. Cerebral elastance (slack brain)
2. Control of cerebral blood flow and metabolism
3. Brain protection
4. Early neurological assessment
5. Hemodynamically stable emergence
Analgesic and premedicant doses of narcotics have little effect on CBF or ICP unless ______
unless PaCO2 increases secondary to respiratory depression
Ketamine is only contraindicated in neurosurgery in the case of _____
known high ICP
Name 4 situations where TIVA is specifically indicated:
–Tight brain
–Unplanned TIVA
•Progression of response to poor brain conditions
–Neurotrauma
_Neurological monitoring necessitates minimal influence of anesthetics
What is lost in brain before permanent damage is done? How can you measure this?
Nerve function lost before cellular integrity is lost; Electrical changes (EEG) shows ischemia by showing decreased electrical activity
What is the downside of EEG for neurologic monitoring?
Not very specific as to areas of damage or ischemia
What 4 characteristics would an ideal intraoperative neurological monitor have?
•Used continuously during period of risk
•Sensitive to at-risk damage
•Specific to at-risk damage
•There is an intervention available to respond to detected problems
What are 3 types of sensory evoked potentials?
1. Somatosensory EP
2. Brain stem ep
3. Visual EP
What are two types of motor EP?
1. Motor EP
2. EMG
What are somatosensory evoked potentials used for?
Used to evaluate the integrity of the spinal cord or nerves during procedures when blood supply to cord or actual tissue of cord in potential danger of being damaged
Somatosensory waveforms are examined for ____ and _____. what do these measures tell you?
Latency and amplitude: increased latency and decreased amplitude signify a problem (damage to the neuronal pathway being monitored)
Neuro anesthesia relies heavily on _____ for the bulk of pharm management
opioid
General intravenous anesthetics and volatile agents do what to SSEP?
decrease the amplitude and increase latency in proportion to the dose
What is the 0.4, 0.4, 0.4 approach?
.4 MAC Iso, 0.4 mcg/kg Sufentanil infusion, (??? maybe 40% Nitrous?)
The order than things are knocked out under anesthesia (4 A's)
Amnesia
Analgesia
Akinesia
Autonomics
The anesthetic goal of amnesia is achieved by affecting what part of the body? How much volatile is required to do this?
Cortex, 0.4 MAC, in neurosurgery, this is usually the only purpose of your volatile
The anesthetic goal of analgesia is achieved by affecting what part of the body? How much volatile is required to do this?
Thalamus; 0.8 MAC; in neurosurgery, this is the role of opiod (not volatile)
The anesthetic goal of akinesia is achieved by affecting what part of the body? How much volatile is required to do this?
Spinal Cord Reflex; 1 MAC;
How much volatile is typically required to knock out the autonomic reflexes? What system influences this?
1.5 MAC; Endocrine system
What is the 60/60 club in neuro anesthesia
Dose opioid until HR 60, MAP 60
According to the Monroe Kelly Doctrine, what 4 steps does the brain take to decrease ICP?
1. CSF translocation
2. Decrease CSF production
3. Decrease CBF (blood translocation)
4. Brain herniation
Supratentorial refers to:
Infratentorial?
Anything above the cerebellum
Infratentorial is the cerebellum
The tentorium separates:
The cerebrum from the cerebellum (also supports occipital lobes)
Which is more common: supratentorial or infratentorial lesions?
Supratentorial
What are symptoms of supratentorial lesions?
•Seizures
•Hemiplegia
•Aphasia
•Ataxia
•Syncope
•Decorticate rigidity
Supratentorial lesions are more common in _____ and infratentorial lesions are more common in ______
adults- supratentorial
Children- infratentorial (think infant-tentorial)
What are two characteristics of skull masses?
–May be highly vascular
–Rarely elevates ICP
What is the most common type of brain mass? How does it usually present?
Glioma (aka astrocytoma)- often presents as seizures, very poor prognosis
Tumors of the meninges are called _____. Name two important features.
Meningioma;
–Seizures Common
–May be highly vascular
Where do Vestibular Schwannomas arise? What cranial nerves might they involve?
Arise at CN VIII (vestibulocochlear), –Also affects 5, 7,8,9,10,11
–9 & 10 involvement may depress airway reflexes.
Infratentorial lesions may result in what 2 broad categories of symptoms? Name the symptoms
Cerebellar dysfunction
•Ataxia
•Nystagmus
•Dysarthria
Brainstem Compression
•Cranial nerve palsies
•Altered LOC
•Altered respiratory patterns
•Decerebrate rigidity
Signs of infratentorial compression may also be caused by
herniation of a supratentorial lesion into the infratentorial space
Loss of ability to think rapidly and clearly; impaired judgment and decision-making
Confusion
Beginning loss of consciousness; disorientation to time followed by disorientation to place and impaired memory; lost last is recognition of self
Disorientation
Limited spontaneous movement of speech; easy arousal with normal speech or touch; may or may not be oriented to time, place, or person
Lethargy
Mild to moderate reduction in arousal (awakeness) with limited response to the environment; falls asleep unless stimulated verbally or tactiley; questions answered with minimum response
Obtundation
What is a potential drawback to use of meperidine
Normeperidine accumulation and cardiac depression
When choosing fluids for a neurosurgical patient, what should you avoid?
–Glucose containing solutions
–Hypoosmolar solutions (LR)
–Albumin
Ventilatory considerations for neurosurgery patients
•Mild to moderate hypocapnia (EtCO2 25-30)
•Low intrathoracic pressures
•PEEP?
What are the benefits and drawbacks to early emergence in neurosurgical patients?
–Immediate assessment and intervention
–Less HTN or catecholamine surge
–Anesthesia provider is present
–Hypoxia or hypercapnia
–Monitoring critical during transport and recovery
What are the benefits and drawbacks to letting a neuro patient wait to wake up after surgery (late emergence/extubation)
–Less risk for hypercapnia or hypoxia
–Confident respiratory and hemodynamic control
–Controlled transfer to ICU
–Continued benefits of anesthetics
–Unable to monitor neuro status
–Greater hemodynamic and catecholamine response
How does venous air embolism occur?
•Subatmospheric pressure in an opened vein
–Air entrained into venous circulation
Most common in sitting position, can happen with any surgery where surgical site is more than 5 cm above level of r. atrium
What is the gold standard for Venous air embolism detection?
TEE
What methods can be used to detect Venous air embolism?
Precordial doppler (most specific non-invasive method), PA catheter (rising PA pressures, but not specific for air), ET Nitrogen (detects earlier than ETCO2, specific for air), ETCO2 (abrupt decrease d/t increased dead space), TEE
What are symptoms of Venous Air Embolism?
•Decreased ETCO2
•ET Nitrogen
•Increasing PA pressures
•Dysrhythmias
•Hypoxemia
•Murmurs
•RV failure
What are the treatment modalities, priorities when a VAE has been detected?
•Notify Surgeon
–Flood field
–Apply bone wax
•D/C N2O
•Increase O2 delivery
•Aspirate RA catheter
•Change position
•Jugular vein compression
•ACLS
Place on left side, head up position
What are the general, overall goals of treatment when a VAE has occurred?
–Stop further entry
–Remove air already present (can be done with CVL/PA catheter)
–Correct hypocapnia, hypotension, hypoxemia
Epidural hematomas arise from what vessels?
–Middle Meningeal Artery (90%)
–Dural Venous Sinus(10%)
Superior spinocerebellar tract
Sends information from cerebellum to midbrain by way of red nucleus
Middle spinocerebellar tract
Relays information from Pons to cerebellum
Lower spinocerebral tract
Relays info from Medulla to cerebellum
salutatory conduction increases the velocity by _____ and decreases the number of ions used
5-50 times; by 100 times
Size of the synaptic cleft
200-300 angstroms
GABA and glycine work by:
Binding to and making Cl ions go into the cell and hyper polarize the cell so that it cannot respond as easily
GABA- A
GABA-B
Class of neurotransmitter?
Fast inhibitory in the CNS
Slow inhibatory in the CNS
Amino acid
Glycine
Inhibitory in the Spinal cord
Excitatory neurotransmitters
Serotonin, acetylcholine, glutamate, ATP, Substance P
Monamines are broken down by
MAO in the cleft, COM-t in the liver
Ach is broken down in the blood by
plasmacholinesterase
Temporal:
TALP: taste, abstract thinking (math), language, proprioception
Frontal:
I MISS: Intellectual, movement, inhibition, speech, smell
Wernickes area
Area in posterior temporal lobe responsible for understanding spoken language; input zone; say what? Hear but don't understand
Broca's area
Speech formation (expressive): frontal lobe
Temporal functions
MEAL: memory, emotion, awareness of sound and language
Ventromedial nucleus
Satiety center- damage leads to inability to ever feel full
paraventricular nucleus
Cause oxytocin secretion
Lateral hypothalamic nucleus
Thirst center (some hunger, too)
Supraoptic nuclei
Stimulates Posterior pituitary to secrete ADH, and thereby increases body water
Amino acid neurotransmitters:
GABA, Glutamate, Glycine
Glutamate: Class of neurotransmitter
Type of receptor? and action
Amino Acid
AMPA- fast excitatory in CNS
NMDA- slow excitatory in CNS
Metabotropic: neuromodulation
Purines: what neurotransmitters does this include?
adenosine, ATP
Adenosine- receptor and type of action
A1- neuromodulation
ATP- receptor types and type of action
PAX- Fast excitatory in CNS

PAV- neuromodulation
Acetylcholine is an _____ neurotransmitter; what are its effects?
Ester
Nicotinic- fast excitatory at at NMJ and autonomic ganglia
Muscarinic- slow excitatory or inhibitory depending on the innervated tissue
What are the monoamine neurotransmitters?
NE, Serotonin, Dopamine
Serotonin- class, receptors, and method of transmission
Monoamine, 5HT3 receptors, in CNS, smooth muscle, and gut (fast or slow)
Dopamine: class, receptors, and method of transmission
Monoamine, D1 and D2, slow synaptic transmission in CNS, blood vessels, and gut
Peptides: what neurotransmitters fall into this category?
Substance P, Enkephalins, Endorphins
Substance P- receptor, location, and method of transmission
Receptors unknown, Slow excitation of smooth muscle and neurons in CNS
Enkaphalins: Receptors, location, and method of transmission
mu and (?) opioid receptors, Slow  synaptic signaling (reduction in excitability). Decrease in gut motility. Promotes analgesia
B-Endorphin: receptors, location, and method of transmission
Κ-opioid receptors, Slow synaptic signaling analgesia
Inorganic gas: example, receptor, and method
Nitric oxide, Guanylyl cyclase receptor, results in synaptic modulation
What are 4 names for white matter within the brain and spinal cord
Fasciculus
Peduncle
Column
Lemniscus
What are 5 other names for white matter outside of the brain and spinal cord
Nerve
Nerve fiber
Root
Nerve trunk
Ramus
Glutamate (and other excitatory neurotransmitters) cause ______ to be released from the cell and ______ the membrane potential
Calcium- causes the membrane to become hypopolarized (less negative) and therefore easier to create an action potential
Glyicine (and other inhibatory neurotransmitters) may cause ion pores for _______ to be opened, and cause _________
Chloride, hyperpolarization
Barbiturates work by ______
opening chloride channels, making nerves less excitable
Calcium is a very common and active ______ system
Second messenger system
Anesthetics are_____ mimetic
GABA
Cell bodies for sensory neurons reside:
In the dorsal route ganglia
Where are you trying to affect with local anesthetics?
The dorsal roots of the nerves (cell bodies located in dorsal route ganglia)
Central sulcus separates:
motor cortex from somatosensory area (pre central gyrus (motor) from post central gyrus (sensory))
Another name for the midbrain
Mesencephalon
What percent of the anterolateral tracts do not decussate immediately? What is the clinical significance of this?
Approx. 10% do not decussate immediately, so if you have a partial spinal cord transection, you may still feel some pain
Spinal nerve = (other names)
Second motor neuron = lower motor neuron = alpha motor neuron
Spinal nerves are ______ type
A alpha
Gamma motor neurons
smaller than alpha, keep general muscle tone
Sympathetic nervous system is more diffuse because
All of the cell bodies are linked through the paravertebral ganglia (sympathetic chain); stimulating one nerve can send impulses up/down the chain to the whole body very quickly
choline acetyltransferase
Manufactures acetylcholine
The vasoconstrictor zone of the vasomotor center is responsible for ______
Vasomotor tone; spinal cord transection causes loss of this tone and therefore lower blood pressure
Nitrous oxide causes ______ in response to______
Vasodilation in response to tension on vessel walls; cgmp is second messenger in this reaction
Cannot give _____ to Parkinson's patients
Reglan- dopamine antagonist