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NR 340 Exam 3 Studyguide, Chapter 13 to 20, (Latest 2021) 100% Correct Study Guide
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NR 340 Exam 3 Studyguide, Chapter 13 to 20, (Latest 2021) 100% Correct Study Guide
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NR340 Exam 3 Chapters: 13, 14, 17, 8, 20 Page 1 of 43NR 340 Exam 3
Nervous System Alterations
Anatomy and Physiology
o Cells of the nervous system
Neurons
Basic functional unit
Neuroglia
Supportive structures
o Transmission of impulses
Dendrites
Axon
Synaptic knob
Releases neurotransmitters
Bind to receptors on nerve or muscle cell to continue trasmission
o Cerebral circulation
Receives 15% to 20% of cardiac output
Circle of Willis joins anterior and posterior circulation
Assures blood is evenly distributed through brain
Carotid arteries (anterior circulation)
Vertebral arteries (posterior circulation)
Cerebral veins empty into venous sinuses to jugular then into Superior venacava to right atrium
LOC good indicator of adequate blood flow
o Brain metabolism
Neurons cannot store glucose/ O2 – needs constant supply
Cerebral glucose < 70 mg/dL = confusion
Cerebral glucose < 20 mg/dL = damage
Varies from person to person
o Cerebral blood flow
Auto regulation
Ability for cerebral blood vessels to change in diameter to control blood volume
Changes in pressure
Changes in CO2
CO2 most potent agent
CO2↑45 (hypoventilate) causes vessels to dilate -- ↑ICP
CO2↓35 (hyperventilate) causes vessels to constrict
o Blood-brain barrier
Protects the brain by being selectively permeable to substances
Does not allow things to pass into brain and CSF
o Brain
,NR340 Exam 3 Chapters: 13, 14, 17, 8, 20 Page 2 of 43
Cerebrum
Right and Left Hemisphere
5 Lobes
Frontal: Conscious thoughts, abstract thinking, judgement, voluntary movement, affect, memory,
concentration
Parietal: Processing, association and interpretation of sensory information
Temporal: Processing, association and interppration of autidtory information, memory and social
behavior
Occipital: Visual processing and interpretation
Basal ganglia: Motor control of fine body movements
Diencephalon:
Connects brain stem and cerebrum and midbrain
4 Regions: thalamus, hypothalamus, subthalamus and epithalamus
Thalamus integrates all sensations except smell
Brainstem
Controls vital functions
3 major divisions:
Midbrain
Pons
Medulla
Regulates basic rhythm of respiration, rate and strength of pulse, and vasomotor activity
Reflexes: Sneezing, swallowing, coughing and vomitting
Cerebellum
Fine movements
Equilibrium
Muscle tone
Balance and Coordination
Limbic System
Primitive control of emotional responses and arousal
Reward and Fear stimuli
Long term memory
Attention and Cognition
Sleep wake cycle
Decreased arousal – coma
o Cranial Nerves
Assessing Cranial Nerves in Critically Ill
I –Olfactory: Smell
-Pupils react to light? (2 & 3)
II – Optic: Visual Acuity -Dolls Eyes (4 & 6)
III – Oculomotor: Movement of eyes, Pupillary Constriction -Corneal Reflex (5 & 7)
and Accommodation -Cold Chloric (8)
-Suction elicits Gag Reflex (9 & 10)
IV – Trochlear: Movement of eyes
V – Trigeminal: Chewing, Sensation of scalp, face and teeth
VI – Abducens: Movement of Eyes
VII – Facial: Facial expression, Lacrimation, Salvation, Taste (anterior tongue)
VIII – Auditory: Hearing and Equilibrium
IX – Glossopharyngeal: Swallowing, Taste (posterior tongue)
,NR340 Exam 3 Chapters: 13, 14, 17, 8, 20 Page 3 of 43
X – Vagus: Swallowing and Laryngeal control
XI – Spinal Accessory: Movement of head and shoulders
XII – Hypoglossal: Movement of tongue
o Spinal Nerves
Sympathetic Nervous System
Origninating in thoracic and lumbar regions
Neurotransmitter – Norepinephrine
Vasoconstriction in skin and viscera
Vasodilation in muscles
Fight/Flight
Parasmpathetic Nervous System
Originating in crainosacral region
Neurotransmitter – Acetylcholine
Returns to normal state of functioning
Rest/Digest
Dermatomes
Inervation of skin from each spinal nerve
Sensory function of skin
7 areas arise from 7 nerves
Intracranial Pressure (ICP)
o Normal ICP: 0 – 15 mmHg
o Composed of Blood, Brain and CSF
o Normal CPP (Cerebral Profusion Pressure): 60 – 100 mmHg
Calculated by: MAP – ICP = CPP
MAP: (Systolic + 2(Diastolic)) / 3
o Increased Intracranial Pressure
Associated with many problems
Monro-Kellie Doctrine
Increase in any component requires reduction in one or both other components to sustain
normal ICP
Changes in LOC is first sign of Increased ICP
Complications:
Herniation
Occurs when ICP is sustained at 20 mmHg or higher for 5 minutes or longer
Cause depends on underlying issue
Interventions
↑HOB
Promote Oxygenation
Causes of ↑ICP
Increased Brain Volume
Cytotoxic: Intracellular swelling or Hypoxia/Hypoosmality
Vasogenic: Increased capillary permeability or Tumors/Meningitis
, NR340 Exam 3 Chapters: 13, 14, 17, 8, 20 Page 4 of 43
Increased Blood Volume
Loss of Autoregulation
Decreased Oxygenation, Hypercapnia (Vasodilation)
Increased metabolic Demands
Obstruction of venous outflow
Increased CSF
Hydrocephalus – Blockage of normal flow, obstruction of normal reabsorption or excess
production
Goal: ↓ICP and Profuse Brain
Keep ICP between 0 – 15 mmHg
Keep CPP ≥ 70 (Normal between 60 – 100)
Intracranial Pressure Monitoring
o Indications
GCS score 3-8 (comatose)
Assess consciousness and arousal
Not always accurate GCS
Looking for motor response
Worse Score: 3 Best Score: 15
Get one point for “showing up”
Hard to assess ICP
o Purpose
Assess response to therapy
Augment neurological assessment
o Transducer system
Fluid filled
Normal saline – no preservatives
No pressurized flush system
Assess ICP
Microchip
Advanced computer technology
Fiberoptic catheter
Don’t want to damage neurons
COMPLICATIONS
Infection
Meningitis
Hematoma
Bleeding
o Cerebral Oxygenation Monitoring
Jugular Oxygen Saturation (Jugular vein SvO2)
Monitored via a fiberoptic catheter
More accurate than CPP
Internal jugular vein/jugular venous bulb
Normal value 60%-70%
Does not insure adequate profusion to brain
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