chap 23 - nervous system

Question 1

neurons

Answer 1

send signals

Question 2

glia

Answer 2

supporting cells
- astrocytes, oligodendrocytes, ependymal, microglia, schwann cells

Question 3

astrocytes

Answer 3

help to form the blood brain barrier

Question 4

oligodendrocytes

Answer 4

wrap their “arms” around the axons and neurons to myelinate neurons (which speeds up transmission)

Question 5

ependymal cells

Answer 5

found in ventricles of the brain

Question 6

microglia

Answer 6

type of white blood cells that decrease bacteria in the brain

Question 7

schwann cells

Answer 7

similar to oligodendrocytes but located in PNS

Question 8

components of the brain

Answer 8

cerebrum, cerebellum brain stem
- sensory and motor contralateral
- one side dominant

Question 9

vascular supply of CNS

Answer 9

Interconnections at base of brain
Lack of interconnections elsewhere
Structure of brain capillaries
Blood brain barrier
Only small, fat soluble molecules move across

Question 10

meninges

Answer 10

dura mater, arachnoid mater, subarachnoid space, and pia mater

Question 11

cerebrospinal fluid

Answer 11

Made by choroid plexus
Arachnoid granulations - CSF exit to blood
Components
Clear
Small amount protein
Glucose 50-80 mg/dl
Gives buoyancy to the brain, shock absorber for the brain as well, chemical buffer to large changes in the chemicals circulating
Needs to be able to circulate

Question 12

most frequent and serious problems

Answer 12

Headaches
Cerebrovascular accidents - brain attack
Traumatic injuries
Infections
Degenerative disease
Neoplasms

Question 13

common signs and symptoms

Answer 13

Headaches
Weakness - one sided → hemiparesis
Nausea and vomiting
Motor disturbances, stiff neck or back, rigid muscles, seizures, convulsions, paralysis
Sensory disturbances, especially vision or speech
Drowsiness, stupor, or coma
Mood swings
Intellectual disturbances - loss of critical thinking skills
Memory capabilities

Question 14

common tests

Answer 14

Analysis of cerebrospinal fluid
- Examined for presence of leukocytes (indication of infection in brain), red blood cells, neoplastic cells, and microorganisms
Electroencephalogram (EEG) - brain activity
Radiologic procedures
- Skull x-rays to detect fractures
- Angiography is used to: (looks at blood vessels)
- Look for abnormal distribution or distortion of vessels in the region of a lesion
-Demonstrate vessel occlusion in patients with CVA and to find the site of rupture of an intracranial aneurysm
Neurologic examination includes:
-Examination of motor and sensory systems
-Observing gait, posture, and symmetry of muscle mass
-Testing muscle strength, coordination, and reflexes
Testing of cognitive function
-Eliciting a careful history of abnormal sensations
-Testing for diminished or absent sensory perception
- Knee-jerk reflex

Question 15

genetics/developmental disease

Answer 15

Deleterious forces acting within first half of gestation
Due to
Genetics
Infection
Traumatic insult to brain
Examples
Down syndrome - trisomy 21
Neural tube defects

Question 16

neural tube defects

Answer 16

Incomplete development of brain, spinal cord, and/or meninges
Neural tube is the precursor to the spinal cord
Common = 2 per 1,000 births in U.S
Types
Spina bifida - affects spinal cord
Anencephaly = without brain
Many related to deficiency in what vitamin? Folate or folic acid (a B vitamin)
Diagnosis
Ultrasound
Amniocentesis

Question 17

hydrocephalus

Answer 17

Accumulation of excess CSF
Result from:
Obstruction to flow of CSF
Over production of CSF
Inability of arachnoid granulations to restore water of CSF back into circulation
Children vs. adults
Children, enlargement of skull

Question 18

signs and symptoms of hydroencephalus

Answer 18

Dilated pupils
Increased blood pressure
Headache
nausea/vomiting
Seizures
drowsiness/altered consciousness

Question 19

treatment of encephalus

Answer 19

Eliminate the cause
Reduce the pressure
Hydrocephalus = intracranial shunts
Edema = osmotic agents
Craniotomy
Steroid therapy
Medially induced coma
Hypothermia = slow brain metabolism

Question 20

inflammatory diseases

Answer 20

Numerous infectious diseases involve the brain preferentially:
Meningitis
Encephalitis
polio

Question 21

meningitis

Answer 21

Inflammation of the meninges
Most often caused by bacteria
Bacteria gains access to brain and spinal cord via the blood
Onset is usually abrupt
Major signs and symptoms
Fever
Headache
Neck rigidity
Diagnosis
treatment

Question 22

encephalitis

Answer 22

Enceph = the brain
Diffuse inflammation of the brain
Usually caused by viral infections
Many are mosquito-borne
West nile encephalitis
Symptoms and signs are generalized - lots of parts of the brain are affected
Irritability, drowsiness and headache
Diagnosis
Depends on culture and identification of viral infections
Spinal tap
No specific treatment
Patients die, recover fully, or recover with variable neurologic deficit

Question 23

poliomyelitis

Answer 23

Caused by poliovirus, type of enterovirus (intestinal)
Pathogenesis
Transmitted by fecal-hand-oral contamination
Infects the spinal horn of the vertebrae which is where motor neurons and spinal nerves are located which is why some cases result in paralysis
Outcomes
95% asymptomatic
4-8% minor specific illness
Malaise or headache
1-2% nonparalytic aseptic meningitis
Less than 1% paralytic

Question 24

cerebrovascular accident

Answer 24

Sudden neurologic deficit caused by vascular occlusion
Leads to infarcts
The brain can only last 5 minutes without oxygen, the lowest of any organ
Fourth leading cause of death in U.S
Types of stroke
Cerebral thrombosis: most common, thrombosis of cerebral artery narrowed by atherosclerosis
Abnormal blood clot
Cerebral embolus: occurs less frequently; blockage of cerebral artery by fragment of blood clot from an arteriosclerotic plaque or from heart
Traveling blood clot
Cerebral hemorrhage: most serious type of stroke; usually from rupture of a cerebral artery in person with hypertension
Burst aneurysm → severe bleeding in the brain
May also be due to ruptured blood vessel, ruptured aneurysm
Risk factors
Hypertension
Weakened vessel

Question 25

cerebral thrombus

Answer 25

Vascular occlusions results in infarcts in brain tissue supplied by affected vessel Damaged brain tissue Loses function within minutes Becomes soft and necrotic within a few days Tissue is lost from the area

Question 26

CVAs caused by brain hemorrhage

Answer 26

Signs and symptoms depend on location and size Up to half of patients die within hours because accumulation of blood: Displaces adjacent tissue Rapidly elevates intracranial pressure - because the brain is enclosed in the skull swelling has no where to go

Question 27

Strokes may occur suddenly or preceded by

Answer 27

transient ischemic attacks (TIA)

Question 28

transient ischemic attacks

Answer 28

Temporary often recurrent episodes of impaired neurological activity resulting from insufficient blood flow to a part of the brain Mini stroke Warning for impending stroke speed is important for treatment

Question 29

CVA signs and symptoms

Answer 29

Impaired speech or consciousness Hemiparesis Poor coordination Confusion

Question 30

CVA outcomes

Answer 30

⅓ die within first two weeks ⅓ recover with neurological deficit ⅓ recover with no deficit Dissolve embolus Largely dependent on area of brain affected and size When the brain is damaged by ischemia following a cerebrovascular accident Neurons and oligodendroglia readily die Neurons cannot regenerate themselves - scar tissue is formed in place Astrocytes proliferate rapidly and repair the injury structurally by forming a scar

Question 31

traumatic brain injury

Answer 31

Serious public health concern Occurs when the brain collides with the inside of the skull - basically bruising the brain Causes bleeding, bruising, and tearing of nerve fibers A traumatic insult to the brain possibly producing physical, intellectual and emotional changes May be due to Transportation accidents Falls Sports-related event Violence Range in severity Mild serious

Question 32

CNS trauma

Answer 32

Direct or indirect Coup - where the actual impact occurred Contrecoup - rebound of the brain and shifting in the skull Results Fracture Intraparenchymal injury - within the brian Vascular injury Consequences depend on location and size of lesion

Question 33

cerebral concussion

Answer 33

Description Most common head injury Immediate loss of consciousness for seconds to minutes - but not noticeable in all cases, especially in a mild concussion Etiology Blunt force impact to head Brain strikes and rebounds from skull Disrupts normal brain activity

Question 34

types of hemorrhages in the brain

Answer 34

epidural, subdural, and subarachnoid

Question 35

epidural hemmorhage

Answer 35

artery - fatal within 24 hours - forms quickly

Question 36

subdural hemorrhage

Answer 36

slow venous bleeding

Question 37

subarachnoid hemorrhage

Answer 37

Not as commonly due to trauma, but may be Arterial bleeding Typically from circle of willis Blood in subarachnoid space - most likely to be due to an aneurysm

Question 38

treatment for TBI

Answer 38

Mild TBI = bed rest and analgesic - want to limit brain activity - no reading, school, work, etc. Severe TBI = diuretics (want to decrease any extra pressure), anti seizure and coma-inducing medications, surgery to remove clots, repair fractures, or create an opening to provide space for the brain to swell

Question 39

CNS degenerative disorders

Answer 39

Degeneration of cortical neurons Alzheimer disease Degeneration of basal ganglia neurons Parkinson’s disease Huntington’s disease Degeneration of motor neurons

Question 40

neurodegenerative disorders etiology

Answer 40

Several factors combined are implicated Genetic predisposition Environmental toxins Oxidative stress Aging

Question 41

dementia

Answer 41

Global, irreversible deterioration of cerebral cortex Not normal part of aging Losses Orientation Memory Language Judgment Decision making

Question 42

alzheimer's disease

Answer 42

Most common form of dementia Irreversible, progressive, chronic Unknown etiology Atrophy of cortical parts of frontal and temporal parts of the brain Characteristics Dementia; progressive loss of cognitive functions, memory Emotional disturbances 1 in 10 over age 65 Anatomic and biochemical features Amyloid-beta protein-forming plaques - the brain can't clear them and this disrupts communication between neurons Neurofibrillary tangles Decreased acetylcholine production Risk factors Age Chronic hypertension Head injury adults are three times more likely to develop alzheimer's disease

Question 43

multi-infarct vascular dementia

Answer 43

Cumulative brain damage from small strokes Second most common cause of dementia Treated by addressing underlying cause, such as hypertension

Question 44

parkinson's disease

Answer 44

Subcortical neurodegenerative disorder - Basal ganglia: important for modifying movement Cause unknown Decreased number of dopaminergic neurons in substantia nigra - these neurons make dopamine Disturbances of movement, rigidity, bradykinesia, pill rolling tremor, postural instability Treated with drugs that increase dopaminergic activity, with dopamine

Question 45

amyotrophic lateral scelrosis

Answer 45

Rare age-associated neurodegenerative disease Death of alpha motor neurons Affects upper and lower motor neurons Atrophy Paralysis of muscles Respiratory problems No treatment or cure Cause unknown Two forms Sporadic Familial

Question 46

neoplasia

Answer 46

Small, slow-growing tumors that would be benign elsewhere can readily disrupt vital functions in strategic locations and kill the patient Other benign tumors may occur in inoperable locations Metastatic tumors more common than primary tumors Primary tumors Glioma: Mostly poor prognosis with deep location in brain; surgery, radiation, chemotherapy Astrocytoma Oligodendroglioma Lymphoma Meningioma

Question 47

brain neoplasms

Answer 47

Most common signs and symptoms: Increased pressure because of mass lesion Accompanying edema Generalized symptoms such as headaches, vomiting, blurred vision, and seizures - the brain has no where to swell

Question 48

organ failure

Answer 48

Brain death Patient often considered legally dead if two successive electroencephalograms taken 24 hours apart both show complete absence of electrical activity in the brain

Question 49

seizures

Answer 49

sudden transient alteration or brain function caused by an abrupt, explosive, disorderly discharge of cerebral neurons

Question 50

epilepsy

Answer 50

present when 2 or more unprovoked seizures occur at an interval greater than 24 hours apart

Question 51

causes of provoked seizures

Answer 51

fever, electrolyte imbalances (hypocalcemia, alkalosis), hypoglycemia, hypoxia, arthemia, CNS infection or damage, head trauma

Question 52

causes of unprovoked seizures

Answer 52

idiopathic - strong genetic basis

Question 53

types of seizures

Answer 53

partial seizures, simple, complex, generalized, convulsive, nonconvulsive, absence (petit mal), atonic, myoclonic, clonic, tonic, grand mal

Question 54

simple seizure

Answer 54

without loss of consciousness

Question 55

complex seizure

Answer 55

loss of consciousness

Question 56

absence (petit mal) seizure

Answer 56

brief loss of consciousness

Question 57

atonic seizure

Answer 57

loss of muscle tone

Question 58

myoclonic seziure

Answer 58

muscles contract

Question 59

clonic seizure

Answer 59

repetitive jerking movements

Question 60

tonic seizure

Answer 60

muscle stiffness, rigidity

Question 61

grand mal seizure

Answer 61

muscle contractions and loss of consciousness

Question 62

diagnosis of seizures

Answer 62

electroencephalogram, MRI/CT

Question 63

treatment of seizures

Answer 63

avoidance of precipitant, anticonvulsants (reduce electrical activity of the brain), surgery (removal of seizure focus

Question 64

huntington's disease

Answer 64

autosomal dominant neurodegenerative disease - characterized by chorea = involuntary but conscious, gyrating movements, progressive dementia - atrophy of cortex, subcortical nuclei, most prominently in caudate putamen - late onset - high rate of suicide

Question 65

glioma

Answer 65

most poor prognosis with deep location in brain, surgery, radiation, chemotherpay

Question 66

menigioma

Answer 66

arise from meninges, benign in a biological sense, but the location needs to be considered to determine the severity

Question 67

diseases of peripheral nerves

Answer 67

axon vs schwann cells motor vs sensory types - autoimmune, inflammatory - toxic - trauma - vascular, especially diabetes - high blood glucose tumors neuropathy = loss of sensation

Question 68

amyotrophic lateral scleorsis

Answer 68

aka lou gehrig's - rare age-associated neurodegenerative disease - death of alpha motor neurons - affects upper and lower motor neurons - atrophy - paralysis of muscles - respiratory problems no treatment or cure, cause is unknown two forms: sporadic and familial

Question 69

guillain-barre syndrome

Answer 69

polyneuropathy = many nerves in different parts of body - rare: 1 in 100,000 symptoms - weakness and tingling autoimmune - immune system attacks peripheral nerves, leading to inflammation, progressive weakness from extremities towards trunk - can become life-threatening due to breathing issues - rare cases, death - often preceded by viral or bacterial "flu-like" infection - most recover, but some may have permanent nerve damage

Question 70

bell palsy

Answer 70

idiopathic unilateral facial nerve paralysis - temporary symptoms - inability to control facial muscles on affected side - twitching, weakness, drooping eyelid, drooling prognosis = good, symptoms recede within 2 weeks after initial onset, and complete recovery within 3-6 months

Question 71

headache

Answer 71

Diffuse pain occurring in any portion of the head Primary: tension, migraine, cluster headaches Secondary: underlying structural problems No pain receptors in brain Result of vasodilation Thus treatment may include vasoconstrictors