Overview of the Structures & Functions of Nervous System

MEDICAL SURGICAL

Abby Tabuena

Overview of the Structures & Functions of Nervous System

Central NSPNSANS

Brain & spinal cord 31 spinal & cranial sympathetic NS

ParasypathaticNS

Somatic NS

C- 8

T- 12

L- 5

S- 5

C- 1

ANS (or adrenergic of parasympatholitic response)

SNS involved in fight or aggression responseEffects of SNS (anti-cholinergic/adrenergic)

1. Dilate pupil – to aware of surroundings

Release of norepinephrine (adrenaline – cathecolamine) - medriasis

Adrenal medulla (potent vasoconstrictor)2. Dry mouth

Increases body activitiesVS = Increase3. BP & HR= increased

Except GIT – decrease GITmotility bronchioles dilated to take more oxygen

4. RR increased

* Why GIT is not increased = GIT is not important!5. Constipation & urinary retention

Increase blood flow to skeletal muscles, brain & heart.

I. Adrenergic Agents – Epinephrine (adrenaline)

SE: SNS effect

II. PNS: Beta adrenergic blocking agents (opposite of adrenergic agents) (all end in –‘lol’)

-Blocks release of norepinephrine.

-Decrease body activities except GIT (diarrhea)

Ex. Propanolol, Metopanolol

SE:

B – broncho spasm (bronchoconstriction)

E – elicits a decrease in myocardial contraction

T – treats HPN

A – AV conduction slows down

Given to angina & MI – beta-blockers to rest heart

Anti HPN agents:

1. Beta blockers (-lol)
2. Ace inhibitors (-pril) ex ENALAPRIL, CAPTOPRIL
3. Calcium antagonist

ex CALCIBLOC or NEFEDIPINE

Peripheral nervous system: cholinergic/ vagal or sympatholitic responseEffect of PNS: (cholinergic)

-Involved in fly or withdrawal response1. Meiosis – contraction of pupils

-Release of acetylcholine (ACTH)2. Increase salivation

-Decrease all bodily activities except GIT (diarrhea)3. BP & HR decreased

4. RR decrease – broncho constriction

I Cholinergic agents5. Diarrhea – increased GI motility

ex 1. Mestinon6. Urinary frequency

Antidote – anti cholinergic agents Atropine Sulfate – S/E – SNS

S/E- of anti-hpn drugs:

1. orthostatic hpn
2. transient headache & dizziness.

-Mgt. Rise slowly. Assist in ambulation.

CNS (brain & spinal cord)

I. Cells – A. neurons

Properties and characteristics

1. Excitability – ability of neuron to be affected in external environment.
2. Conductivity – ability of neuron to transmit a wave of excitation from one cell to another
3. Permanent cells – once destroyed, cant regenerate (ex. heart, retina, brain, osteocytes)

Regenerative capacity

A. Labile – once destroyed cant regenerate

- Epidermal cells, GIT cells, resp (lung cells). GUT

B. Stable – capable of regeneration BUT limited time only ex salivary gland, pancreas cells cell of liver, kidney cells

C. Permanent cells – retina, brain, heart, osteocytes can’t regenerate.

3.) Neuroglia – attached to neurons. Supports neurons. Where brain tumors are found.

Types:

1. Astrocyte
2. Oligodendria

Astrocytoma – 90 – 95% brain tumor from astrocyte. Most brain tumors are found at astrocyte.

Astrocyte – maintains integrity of blood brain barrier (BBB).

BBB – semi permeable / selective

-Toxic substance that destroys astrocyte & destroy BBB.

Toxins that can pass in BBB:

1. Ammonia-liver cirrhosis.
2. 2. Carbon Monoxide – seizure & parkinsons.
3. 3. Bilirubin- jaundice, hepatitis, kernicterus/hyperbilirubenia.
4. 4. Ketones –DM.

OLIGODENDRIA – Produces myelin sheath – wraps around a neuron – acts as insulator facilitates rapid nerve impulse transmission.

No myelin sheath – degenerates neurons

Damage to myelin sheath – demyellenating disorders

DEMYELLENATING DSE

1.)ALZHEIMER’S DISEASE– atrophy of brain tissue due to a deficiency of acetylcholine.

S&Sx:

A – amnesia – loss of memory

A – apraxia – unable to determine function & purpose of object

A – agnosia – unable to recognize familiar object

A – aphasia –

- Expressive – brocca’s aphasia – unable to speak

- Receptive – wernickes aphasia – unable to understand spoken words

Common to Alzheimer – receptive aphasia

Drug of choice – ARICEPT (taken at bedtime) & COGNEX.

Mgt: Supportive & palliative.

Microglia – stationary cells, engulfs bacteria, engulfs cellular debris.

II. Compositions of Cord & Spinal cord

80% - brain mass

10% - CSF

10% - blood

MONROE KELLY HYPOTHESIS: The skull is a closed vault. Any increase in one component will increase ICP.

Normal ICP: 0-15mmHg

Brain mass

1. Cerebrum – largest - Connects R & L cerebral hemisphere

- Corpus collusum

Rt cerebral hemisphere, Lt cerebral hemisphere

Function:

1. Sensory
2. Motor
3. Integrative

Lobes

1.) Frontal

a. Controls motor activity

b. Controls personality development

c. Where primitive reflexes are inhibited

d. Site of development of sense of umor

e. Brocca’s area – speech center

Damage - expressive aphasia

2.) Temporal –

a. Hearing

b. Short term memory

c. Wernickes area – gen interpretative or knowing Gnostic area

Damage – receptive aphasia

3.) Parietal lobe – appreciation & discrimation of sensory imp

- Pain, touch, pressure, heat & cold

4.) Occipital - vision

5.) Insula/island of reil/ Central lobe- controls visceral fx

Function: - activities of internal organ

6.) Rhinencephalon/ Limbec

- Smell, libido, long-term memory

Basal Ganglia – areas of gray matte located deep within a cerebral hemisphere

-Extra pyramidal tract

-Releases dopamine-

-Controls gross voluntary unit

Decrease dopamine – (Parkinson’s) pin rolling of extremities & Huntington’s Dse.

Decrease acetylcholine – Myasthenia Gravis & Alzheimer’s

Increased neurotransmitter = psychiatric disorder Increase dopamine – schizo

Increase acetylcholine – bipolar

MID BRAIN – relay station for sight & hearing

Controls size & reaction of pupil 2 – 3 mm

Controls hearing acuity

CN 3 – 4

Isocoria – normal size (equal)

Anisocoria – uneven size – damage to mid brain

PERRLA – normal reaction

DIENCEPHALON- between brain

Thalamus – acts as a relay station for sensation

Hypothalamus – (thermoregulating center of temp, sleep & wakefulness, thirst, appetite/ satiety center, emotional responses, controls pituitary function.

BRAIN STEM- a. Pons – or pneumotaxic center – controls respiration

Cranial 5 – 8 CNS

MEDULLA OBLONGATA- controls heart rate, respiratory rate, swallowing, vomiting, hiccups/ singutus

Vasomotor center, spinal decuissation termination, CN 9, 10, 11, 12

CEREBELLUM – lesser brain

- Controls posture, gait, balance, equilibrium

Cerebellar Tests:

a.) R – Romberg’s test- needs 2 RNs to assist

- Normal anatomical position 5 – 10 min

(+) Romberg’s test – (+) ataxia or unsteady gait or drunken like movement with loss of balance.

b.) Finger to nose test –

(+) To FTNT – dymetria – inability to stop a movement at a desired point

c.) Alternate pronation & supination

Palm up & down . (+) To alternate pronation & supination or damage to cerebellum – dymentrium

Composition of brain - based on Monroe Kellie Hypothesis

-Skull is a closed container. Any alteration in 1 of 3 intracranial components = increase in ICP

Normal ICP – 0 – 15 mmHg

Foramen Magnum

C1 – atlas

C2 – axis

(+) Projectile vomiting = increase ICP

Observe for 24 - 48 hrs

CSF – cushions the brain, shock absorber

Obstruction of flow of CSF = increase ICP

Hydrocephalus – posteriorly due to closure of posterior fontanel

CVA – partial/ total obstruction of blood supply

INCREASED ICP – increase ICP is due to increase in 1 of the Intra Cranial components.

Predisposing factors:

1.)Head injury

2.)Tumor

3.)Localized abscess

4.)Hemorrhage (stroke)

5.)Cerebral edema

6.)Hydrocephalus

7.)Inflammatory conditions - Meningitis, encephalitis

B. S&Sxchange in VS = always late symptoms

Earliest Sx:

a.) Change or decrease LOC – Restlessness to confusion Wide pulse pressure: Increased ICP

- Disorientation to lethargyNarrow pp: Cardiac disorder, shock

- Stupor to coma

Late sign – change in V/S

1. BP increase (systolic increase, diastole- same)
2. Widening pulse pressure

Normal adult BP 120/80 120 – 80 = 40 (normal pulse pressure)

Increase ICP = BP 140/80 = 140 – 80= 60 PP (wide)

1. RR is decreased (Cheyne-Stokes = bet period of apnea or hyperpnea with periods of apnea)
2. Temp increase

Increased ICP: Increase BPShock – decrease BP –

Decrease HRIncrease HRCUSHINGS EFFECT

Decrease RRIncrease RR

Increase TempDecrease temp

b.) Headache

Projectile vomiting

Papilledima (edema of optic disk – outer surface of retina)

Decorticate (abnormal flexion) = Damage to cortico spinal tract /

Decerebrate (abnormal extension) = Damage to upper brain stem-pons/

c.) Uncal herniation – unilateral dilation of pupil. (Bilateral dilation of pupil – tentorial herniation.)

d.) Possible seizure.

Nursing priority:

1.) Maintain patent a/w & adequate ventilation

a. Prevention of hypoxia – (decrease tissue oxygenation) & hypercarbia (increase in CO2 retention).

Hypoxia – cerebral edema - increase ICP

Hypoxia – inadequate tissue oxygenation

Late symptoms of hypoxia – B – bradycardia

E – extreme restlessness

D – dyspnea

C – cyanosis

Early symptoms – R – restlessness

A – agitation

T – tachycardia

Increase CO2 retention/ hypercarbia – cerebral vasodilatation = increase ICP

Most powerful respiratory stimulant increase in CO2

Hyperventilate decrease CO2 – excrete CO2

Respiratory Distress Syndrome (RDS) – decrease Oxygen

Suctioning – 10-15 seconds, max 15 seconds. Suction upon removal of suction cap.

Ambu bag – pump upon inspiration

c. Assist in mechanical ventilation

1. Maintain patent a/w

2. Monitor VS & I&O

3. Elevate head of bed 30 – 45 degrees angle neck in neutral position unless contra indicated to promote venous drainage

4. Limit fluid intake 1,200 – 1,500 ml/day

(FORCE FLUID means:Increase fluid intake/day – 2,000 – 3,000 ml/day)- not for inc ICP.

5. Prevent complications of immobility

6. Prevent increase ICP by:

a. Maintain quiet & comfy environment

b. Avoid use of restraints – lead to fractures

c. Siderails up

d. Instruct patient to avoid the ff:

-Valsalva maneuver or bearing down, avoid straining of stool

(give laxatives/ stool softener Dulcolax/ Duphalac)

- Excessive cough – antitussive

Dextrometorpham

-Excessive vomiting – anti emetic (Plasil – Phil only)/ Phenergan

- Lifting of heavy objects

- Bending & stooping

e. Avoid clustering of nursing activities

7. Administer meds as ordered:

1.) Osmotic diuretic – Mannitol./Osmitrol promotes cerebral diuresis by decompressing brain tissue

Nursing considerations: Mannitol

1. Monitor BP – SE of hypotension
2. Monitor I&O every hr. report if < 30cc out put
3. Administer via side drip
4. Regulate fast drip – to prevent formation of crystals or precipitate

2.) Loop diuretic - Lasix (Furosemide)

Nursing Mgt: Lasix

Same as Mannitol except

- Lasix is given via IV push (expect urine after 10-15mins) should be in the morning. If given at 7am. Pt will urinate at 7:15

Immediate effect of Lasix within 15 minutes. Max effect – 6 hrs due (7am – 1pm)

S/E of Lasix

Hypokalemia (normal K-3.5 – 5.5 meg/L)

S&Sx

1. Weakness & fatigue
2. Constipation
3. (+) “U” wave in ECG tracing

Nursing Mgt:

1.)Administer K supplements – ex Kalium Durule, K chloride

Potassium Rich food:

ABC’s of K

Vegetables Fruits

A - asparagusA – apple

B – broccoli (highest)B – banana – green

C – carrotsC – cantalope/ melon

O – orange (highest) –for digitalis toxicity also.

Vit A – squash, carrots yellow vegetables & fruits, spinach, chesa

Iron – raisins,

Food appropriate for toddler – spaghetti! Not milk – increase bronchial secretions

Don’t give grapes – may choke

S/E of Lasix:

1.)Hypokalemia

2.)Hypocalcemia (Normal level Ca = 8.5 – 11mg/100ml) or Tetany:

S&Sx

weakness

Paresthesia

(+) Trousseau sign – pathognomonic – or carpopedal spasm. Put bp cuff on arm=hand spasm.

(+) Chevostek’s sign

Arrhythmia

Laryngospasm

Administer – Ca gluconate – IV slowly

Ca gluconate toxicity: Sx – seizure – administer Mg SO4

Mg SO4 toxcicity– administer Ca gluconate

B – BP decrease

U – urine output decrease

R – RR decrease

P – patellar reflexes absent

3.)Hyponatremia – Normal Na level = 135 – 145 meg/L

S/Sx – Hypotension

Signs of Dehydration: dry skin, poor skin turgor, gen body malaise.

Early signs – Adult: thirst and agitation / Child: tachycardia

Mgt: force fluid

Administer isotonic fluid sol

4.) Hyperglycemia – increase blood sugar level

P – polyuria

P – polyphagia

P – polydipsia

Nsg Mgt:

1. Monitor FBS (N=80 – 120 mg/dl)

5.) Hyperurecemia – increase serum uric acid. Tophi- urate crystals in joint.

Gouty arthritis kidney stones- renal colic (pain)

Cool moist skin

Sx joint pain & swelling usually at great toe.

Nsg Mgt of Gouty Arthritis

a.) Cheese (not sardines, anchovies, organ meat)

(Not good if pt taking MAO)

b.) Force fluid

c.) Administer meds – Allopurinol/ Zyloprim – inhibits synthesis of uric acid – drug of choice for gout

Colchicene – excretes uric acid. Acute gout drug of choice.

Kidney stones – renal colic (pain). Cool moist skin

Mgt:

1.)Force fluid

2.)Meds – narcotic analgesic

Morphine SO4

SE of Morphine SO4 toxicity

Respiratory depression (check RR 1st)

Antidote for morphine SO4 toxicity –Narcan (NALOXONE)

Naloxone toxicity – tremors

Increase ICP meds:

3.) Corticosteroids - Dexamethsone – decrease cerebral edema (Decadrone)

4.) Mild analgesic – codeine SO4. For headache.

5.) Anti consultants – Dilantin (Phenytoin)

Question: Increase ICP what is the immediate nsg action?

1. Administer Mannitol as ordered
2. Elevate head 30 – 45 degrees
3. Restrict fluid
4. Avoid use of restraints

Nsg Priority – ABC & safety

Pt suffering from epiglotitis. What is nsg priority?

1. Administer steroids – least priority
2. Assist in ET – temp, a/w
3. Assist in tracheotomy – permanent (Answer)
4. Apply warm moist pack? Least priority

Rationale: Wont need to pass larynx due to larynx is inflamed. ET can’t pass. Need tracheostomy only-

Magic 2’s of drug monitoring

Drug N range Toxicity Classification Indication

D – digoxin.5 – 1.5 meq/L 2cardiac glycosides CHF

L - lithium.6 – 1.2 meq/L 2antimanic bipolar

A – aminophylline10 – 19 mg/100ml 20bronchodilator COPD
D – Dilantin10 -19 mg/100 ml 20anticonvulsant seizures
A – acetaminophen 10 – 30 mg/100ml 200narcotic analgesic osteoarthritis

Digitalis – increase cardiac contraction = increase CO

Nursing Mgt

1. Check PR, HR (if HR below 60bpm, don’t giveDigoxin)

Digitalis toxicity – antidote - Digivine

1. Anorexia -initial sx.
2. n/v GIT
3. Diarrhea
4. Confusion
5. Photophobia
6. Changes in color perception – yellow spots

(Ok to give to pts with renal failure. Digoxin is metabolized in liver not in kidney.)

L – lithium (lithane) decrease levels of norepinephrine, serotonine, acetylcholine

Antimanic agent

Lithium toxicity

S/Sx -

a.)Anorexia

b.)n/s

c.)Diarrhea

d.)Dehydration – force fluid, maintain Na intake 4 – 10g daily

e.)Hypothyroidism

(CRETINISM– the only endocrine disorder that can lead to mental retardation)

A – aminophyline (theophylline) – dilates bronchioles.

Take bp before giving aminophylline.

S/Sx : Aminophylline toxicity:

1. Tachycardia
2. Hyperactivity – restlessness, agitation, tremors

Question: Avoid giving food with Aminophylline

1. Cheese/butter– food rich in tyramine, avoided only if pt is given MAOI
2. Beer/ wine -
3. Hot chocolate & tea – caffeine – CNS stimulant tachycardia
4. Organ meat/ box cereals – anti parkinsonian

MAOI – antidepressant

m AR plan
n AR dilcan lead to CVA or hypertensive crisis
p AR nate

3 – 4 weeks - before MAOI will take effect

Anti Parkinsonian agents – Vit B6 Pyridoxine reverses effect of Levodopa

D – dilatin (Phenytoin) – anti convulsant/seizure

Nursing Mgt:

1. Mixed with plain NSS or .9 NaCl to prevent formation of crystals or precipitate

-Do sandwich method

-Give NSS then Dilantin, then NSS!

1. Instruct the pt to avoid alcohol – bec alcohol + dilantin can lead to severe CNS depression

Dilantin toxicity:

S/Sx:

G – gingival hyperplasia – swollen gums

1. Oral hygiene – soft toothbrush
2. Massage gums

H – hairy tongue

A - ataxia

N – nystagmus – abnormal movement of eyeballs

A – acetaminophen/ Tylenol – non-opoid analgesic & antipyretic – febrile pts

Acetaminophen toxicity :

1. Hepato toxicity
2. Monitor liver enzymes

SGPT (ALT) – Serum Glutamic Piruvate Tyranase

SGOT- Serum Glutamic Acetate Tyranase

1. Monitor BUN (10 – 20)

Crea (.8-1)

Acetaminophen toxicity can lead to hypoglycemia

T – tremors, Tachycardia

I – irritability

R – restlessness

E – extreme fatigue

D – depression (nightmares) , Diaphoresis

Antidote for acetaminophen toxicity – Acetylcesteine = causes outporing of secretions. Suction.

Prepare suctioning apparatus.

Question: The following are symptoms of hypoglycemia except:

1. Nightmares
2. Extreme thirst – hyperglycemia symptoms
3. Weakness d. Diaphoresis

PARKINSONS DSE (parkinsonism) - chronic, progressive disease of CNS char by degeneration of dopamine producing cells in substancia nigra at mid brain & basal ganglia

-Palliative, Supportive

Function of dopamine: controls gross voluntary motors.

Predisposing Factors:

1. Poisoning (lead & carbon monoxide). Antidote for lead = Calcium EDTA

2. Hypoxia

3. Arteriosclerosis

4. Encephalitis

High doses of the ff:

a. Reserpine (serpasil) anti HPN, SE – 1.) depression - suicidal 2.) breast cancer

b. Methyldopa (aldomet) - promote safety

c. Haloperidol (Haldol)- anti psychotic

d. Phenothiazide- anti psychotic

SE of anti psychotic drugs – Extra Pyramidal Symptom

Over meds of anti psychotic drugs – neuroleptic malignant syndrome char by tremors (severe)

S/Sx: Parkinsonism –

1. Pill rolling tremors of extremities – early sign
2. Bradykinesia – slow movement
3. Over fatigue
4. Rigidity (cogwheel type)
5. Stooped posture
6. Shuffling – most common
7. Propulsive gait
8. Mask like facial expression with decrease blinking eyes
9. Monotone speech
10. Difficulty rising from sitting position
11. Mood labilety – always depressed – suicide

Nsg priority: Promote safety

1. Increase salivation – drooling type
2. Autonomic signs:

-Increase sweating

-Increase lacrimation

-Seborrhea (increase sebaceous gland)

-Constipation

-Decrease sexual activity

Nsg Mgt

1.)Anti parkinsonian agents

-Levodopa (L-Dopa), Carbidopa (Sinemet), Amantadine Hcl (Symmetrel)

Mechanism of action

Increase levels of dopa – relieving tremors & bradykinesia

S/E of anti parkinsonian

-Anorexia

-n/v

-Confusion

-Orthostatic hypotension

-Hallucination

-Arrhythmia

Contraindication:

1. Narrow angled closure glaucoma
2. Pt taking MAOI (Parnate, Marplan, Nardil)

Nsg Mgt when giving anti-parkinsonian

1. Take with meals – to decrease GIT irritation
2. Inform pt – urine/ stool may be darkened
3. Instruct pt- don’t take food Vit B6 (Pyridoxine) cereals, organ meats, green leafy veg

-Cause B6 reverses therapeutic effects of levodopa

Give INH (Isoniazide-Isonicotene acid hydrazide.) SE-Peripheral neuritis.

2.)Anti cholinergic agents – relieves tremors

Artane mech – inhibits acetylcholine

Cogentin action , S/E - SNS

3.)Antihistamine – Diphenhydramine Hcl (Benadryl) – take at bedtime

S/E: adult– drowsiness,– avoid driving & operating heavy equipt. Take at bedtime.

Child – hyperactivity CNS excitement for kids.

4.) Dopamine agonist

Bromotriptine Hcl (Parlodel) – respiratory depression. Monitor RR.

Nsg Mgt – Parkinson

1.) Maintain siderails

2.) Prevent complications of immobility

- Turn pt every 2h

Turn pt every 1 h – elderly

3.)Assist in passive ROM exercises to prevent contractures

4.)Maintain good nutrition

CHON – in am

CHON – in pm – to induce sleep – due Tryptopan – Amino Acid

5.)Increase fluid in take, high fiber diet to prevent constipation

6.)Assist in surgery – Sterotaxic Thalamotomy

Complications in sterotaxic thalmotomy- 1.) Subarachnoid hemorrhage 2.) aneurism 3.) encephalitis

MULTIPLE SCLEROSIS (MS)

Chronic intermittent disorder of CNS – white patches of demyelenation in brain & spinal cord.

-Remission & exacerbation

-Common – women, 15 – 35 yo cause – unknown

Predisposing factor:

1. Slow growing virus
2. Autoimmune – (supportive & palliative treatment only)

Normal Resident Antibodies:

Ig G – can pass placenta – passive immunity. Short acting.

Ig A – body secretions – saliva, tears, colostrums, sweat

Ig M – acute inflammation

Ig E – allergic reactions

IgD – chronic inflammation

S & Sx of MS: (everything down)

1. Visual disturbances

a. Blurring of vision

b. Diplopia/ double vision

c. Scotomas (blind spots) – initial sx

2. Impaired sensation to touch, pain, pressure, heat, cold

a. Numbness

b. Tingling

c. Paresthesia

3. Mood swings – euphoria (sense of elation )

4. Impaired motor function:

a. Weakness

b. Spasiticity –“ tigas”

c. Paralysis –major problem

5. Impaired cerebellar function

Triad Sx of MS

I – intentional tremors

N – nystagmus – abnormal rotation of eyes Charcots triad

A – Ataxia

& Scanning speech

6. Urinary retention or incontinence

7. Constipation

8. Decrease sexual ability

Dx – MS

1. CSF analysis thru lumbar puncture

- Reveals increase CHON & IgG

2. MRI – reveals site & extent of demyelination

3. Lhermitte’s response is (+). Introduce electricity at the back. Theres spasm & paralysis at spinal cord.

Nsg Mgt MS

-Supportive mgt

1.) Meds

a. Acute exacerbation

ACTH – adenocorticotopic

Steroids – to reduce edema at the site of demyelination to prevent paralysis

Spinal Cord Injury

Administer drug to prevent paralysis due to edema

a. Give ACTH – steroids

b. Baclopen (Lioresol) or Dantrolene Na (Dantrene)

To decrease muscle spasticity

c. Interferone – to alter immune response