CNS 1 Flashcards

1
Q

Parts of nervous system

A
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2
Q

Central nervous system

A

Brain and spinal cord

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3
Q

peripheral nervous system

A

Autonomic and somatic

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4
Q

sympathetic nervous system

A
  • part of autonomic nervous system
  • fight or flight
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5
Q

parasympathetic

A

rest and digest

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6
Q

somatic

A
  • part of peripheral nervous system
  • voluntary control of skeletal muscles
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7
Q

white matter

A

high density of myelin covering axon pathways (and very few neurons)

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8
Q

gray matter

A

high density of neurons and dendrites (axons also present)

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9
Q

nucleus

A

cluster of neurons within the CNS

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10
Q

ganglion

A

cluster of neurons outside of the CNS

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11
Q

cortex

A

dense layers of neurons

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12
Q

tract

A

axons within the CNS traveling as a group/usually named based on region of origin and termination

i.e. spinocerebellar tract

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13
Q

pathway

A

similar to tract however it relates more to synaptically connected neurons performing a function

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14
Q

spinal cord function

A
  • associated nerves: Dorsal and ventral roots
  • primary function:
    • sensory input
    • reflex circuits
    • somatic and autonomin motor output
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15
Q

dorsal root

A
  • posterior
  • sensory
  • afferent (towards the brain)
  • joins with the ventral root to form the spinal nerve
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16
Q

ventral root

A
  • anterior
  • efferent (exiting the brain)
  • motor
  • joins with dorsal root to form spinal nerve
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17
Q

brainstem

A
  • medulla, pons, and midbrain
  • 12 associated cranial nerves
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18
Q

reticular formation

A
  • part of brainstem
  • receives a summary of much of the information that enters the spinal cord and brain stem.
    • filters information and excludes irrelevent stimuli
  • regulates arousal
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19
Q

medulla

A
  • Associated nerves:
    • cranial VIII-XII
  • functions:
    • subconscious CV and respiratory control
    • early relay nuclei in auditory, balance/equilibrium, taste
    • head and neck control
    • brainstem reflexes
    • sets baseline tone for blood vessels
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20
Q

Pons

A
  • Associated nerves:
    • Cranial nerves V-VIII
  • functions:
    • respiratory control
    • urinary control
    • motor control of the eye
    • sensation and motor control of the face
    • ventral:
      • pontine nuclei relay movement and sensation info from cortex to cerebellum
    • dorsal:
      • taste and sleep
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21
Q

pontine nuclei

A
  • ventral (motor) part of pons- relays movement and sensation information from cortex to cerebellum
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22
Q

Midbrain

A
  • Associated nerves:
    • Cranial nerves III-IV
  • functions:
    • acoustic relay and mapping (processing hearing)
    • eye movement, lens, and pupil reflex
    • pain modulation
    • contains nuclein and relay pathways critical for motor coordination
      • i.e. substantia nigra
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23
Q

Cerebellum

A
  • Associated nerves:
    • cranial nerve VIII
  • function:
    • coordination and equilibrium
      • helps make smooth, coordinated muscles
    • motor learning
    • sensory association/language
  • **found to not be necessary for life
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24
Q

thalamus

A
  • associated nerves:
    • cranial nerve II
  • functions:
    • sensory and motor relay/coordination btw cerebral hemispheres and lower CNS regions
    • sensory modulation and gating
    • regulation of cortical activation (attention and consciousness)
      • without thalamus engaged, we can’t be conscious
    • visual input
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25
hypothalamus
* primary functions: * autonomic/endocrine control * controls all pituitary secretions * superchiasmatic nucleus * circadian rhythms (hormones for day/night) * motivated behavior * reward centers
26
basal ganglia
* functions: * receives fibers from substantia nigra * shaper patterns of thalamocortical motor inhibition * keeps movements smooth * controls fine motor
27
amygdala
* function * social behavior and expression of emotion
28
hippocampus
* primary functions: * memory
29
cerebral cortex
* associated nerves: * CN I * dependent on lower brain for "wakefulness" * functions: * fine tune lower brain functions * sensory perception * cognition * learning * large "memory storehouse" * motor planning and voluntary movement * language * planning, personality
30
Cerebral cortex Frontal lobe
* planning and carrying out motor behavior * speech generation (Broca's area) * personality and emotional behavior
31
Cerebral Cortex Parietal lobe
* sensory perception and processing * interconnectal with frontal lobe * to connect what is being sensed with motor function * Werkicke's area- understanding speech
32
Occipital lobe Cerebral cortex
* visual perception and processing * controls eye movements, pupil constriction
33
temporal lobe cerebral cortex
* sound and balance * difficult visual processing (i.e. facial recognition) * emotional behavior * ANS regulation * learning and memory
34
circle of willis
connection of vessels that supply blood to brain \*\*lots of collateralization
35
Artery of Adamkiewicz
* supplies blood to lower two thirds of spinal cord * comes off of main artery at a different spot on every person with wide variety * can be a problem when clamping arter and losing blood flow to most of spine.
36
spinal cord blood supply
* anterior spinal artery * only one, no backup * supplies anterior 2/3 * during spinal surgeries we check for motor to check integrity of anterior spinal artery to make sure cord is still being perfused. * posterior spinal arteries * there are two * supply posterior one third
37
cerebral blood volume
* CBV = 3-5ml/100g brain tissue * cerebral flow influences total cerebral volume * consider arterial flow **and** venous drainage * obstruction to outflow can increase CBV * obstruction can be position, vent with high PIP
38
intracranial pressure
* normal 8-12 mmHg * measured in lateral ventricles
39
cranial vault fixed volume
* brain (cellular and ICF) = 80% * fixed, can't manipulate the brain * Blood (arterial and venous) = 12% * we can manipulate this * CSF = 8% * can also manipulate (ventric, lumbar drains) * don't do this in OR very often
40
ICP curve
* once compensation abilities is maxed out, ICP will increase significantly * high ICP decreases CPP * herniation
41
Intracranial Elastance (compliance)
* determined by the change in ICP after a change in intracranial volume * compensatory mechanisms are: * displacement of CSF from cranial to spinal compartment * Increased CSF absorption * Decreased CSF production * Decreased CBV (mostly venous)
42
CPP
* CPP = MAP-ICP (or CVP, whichever is greater) * normal is 80-100
43
Cerebral Blood flow
* Normal Adult 50ml/100g/min = 750 ml/min * grey matter: 80 ml/100g * white matter: 20 ml/100g * flow is closely linked with metabolism * increased activity, increased metabolism, increased flow
44
Important factors impacting CBF during anesthesia
1. anesthetic agents- cause dilation but decrease activity 2. level of arousal 3. metabolic by-products- Ca, K, CO2, NO, lactate; important in regulating vessels 4. blood viscosity--thicker wont flow as well 5. temperature- change electrophysiology req 6. Concentration of CO2 and H ions 7. O2
45
effect of CO2 on CBF
* increased CO2, increased CBF * Most powerful tool we have to quickly change ICP in OR * only lasts for about 6 hours before HCO3 normalized pH * useful with volatile anesthetics * CO2 + H2O = carbonic acid * carbonic acid disassociates into H+ * for each 1 mmHg change in PaCO2: * CBF changes 1-2 ml/100g/min * CBV changes 0.5 ml/100g brain tissue
46
Brain metabolism
* only 2% of total body mass, 15-20% of total body metabolism and cardiac output
47
Cerebral metabolic rate (CMRO2)
3-3.8 ml/100g/min = 50 ml/min of O2
48
Pediatric Cerebral Metabolic Rate (CMRO2)
5.2 ml/100g/min
49
brain glucose consumption
5.5 mg/100g/min
50
Brain tissue O2 use
3.5 ml O2/100g brain tissue \*\*stays within narrow range except in case of intense brain activity
51
Autoregulation of CBF
Between MAP of 70-150, no change to blood flow occurs.
52
Outside of Autoregulation of CBF concens
* outside of auto-regulation for CBF range * below normal range: * worry about ischemia * above normal range: * worry about bleeds
53
Cerebral blood flow graph
* as O2 concentration drops below about 60 mmhg, CBF increases * As MAP increases, CBF increases (outside of autoregulation) * As CO2 increases, CBF increases * this is best tool to control CBF
54
Temperature and CBF
* CBF changes 5-7% per 1 degree C of temp change * hypothermia decreases CBF and CMRO2 * hyperthermia increases CBF and CMRO2 \*\*evidence does NOT support the use of hypothermia \<35 degrees C without CP bypass
55
CMRO2
cerebral metabolic rate
56
Viscosity and CBF
* decrease in HCT will increase CBF but decrease O2 carrying capacity of the blood
57
Cerebral spinal fluid (CSF) information
* CNS "lymphatic system" and protection from mechanical force * Formed from choroid plexuses at 0.35 ml/min * complete turnover 3-4 times per day * about 500 ml per day * reabsorbed by arachnoid villi * these function like one way valves; with increased CVP, decreased ability to absorb CSF
58
CSF electrolytes
* Na 148 * K 2.9 * Cl 120-130 * Glucose 50-75 * protein 15-45 * pH 7.3
59
flow of CSF
1. Fluid from lateral ventricles passes through **intraventricular foramina** to the third ventricle 2. Additional fluid is added and then it flows downward along the **Aqueduct of Sylvius** into 4th ventricle 3. More fluid added and then it passes through three small openings ( **two lateral foramna of Luschka and a midline foramen of Magendie**) and enters the **Cisterna Magna** (a large fluid space that lied behind the medulla and is part of the subarachnoid space)
60
Blood brain barrier
* exists in tissue capillary membranes in all parts of the blood except hypothalamus, pituitary, and area postrema * Large molecules and charged ions can't get through * tight junctions between CNS capillary and endothelial cells * wholes are much smaller than in other areas * astrocytes restrict movement by taking up potassium ions