신경계(Nervous System)

• 중추신경계(Central nervous system, CNS)– 뇌(Brain)

– 척수(Spinal cord)

• 수막(Meninges: surrounding membranes)신경구성세포:

- 신경세포(Neurons, nerve cells)

- 신경아교세포(Neuroglia, supporting cells)

– 감각성 또는 구심성 신경(Sensory or afferent nerve): →신경계로 신경신호를 전달

– 운동성 또는 원심성 신경(Motor or efferent nerve):

→뇌와 척수의 신호를 근육으로 전달• 신경섬유의 전달은 신경전달물질로 전달:

신경전달물질: Acetylcholine, norepinephrine, dopamine

중추신경계질환의특징

1. Tropographically localized and regionally distributedSpecific disease of specialized tissues:

- Neurodegenerative and Demyelinating disease

** 선택적취약성(Selective vulnerability) **Infectious disease: poliomyelitis, herpes simplex, rabiesDemyelinating disease: multiple sclerosisDegenerative disease: Alzheimer’s & Parkinson’s disease Vascular diseases: Berry aneurysmBrain tumors

2. Age affected

신경계 구성 세포Neuronal cells (신경세포) and Glial cells(아교세포)

Type of Glial cells(아교세포의 유형)

1. Astrocyte(별아교세포):

2. Oligodendrocytes(희소돌기아교세포)

- production & maintainence of CNS myelin3. Ependyma(뇌실막세포): Regulates fluid transport- specializes focally to form choroid plexus4. Microglia(미세아교세포)- mesodermal origin (BM), serve as a fixed macrophage

system(CD4+)

수막(Meninges)- 경막(Dura):

- 단단하고, 섬유질의 바깥쪽 막- 거미막(Arachnoid): 거미줄 모양

– 거미막밑공간(Subarachnoid space):

• CSF (cerebrospinal fluid)

- 연질막(Pia):

- 얇은 막, 뇌실질 막

Stroke(뇌졸증): Cerebrovascular Accident

• Any injury to brain tissue from disturbance of blood supply to brain

• Types of stroke– Cerebral thrombosis: most common; thrombosis of

cerebral artery narrowed by arteriosclerosis– Cerebral embolus: occurs less frequently; blockage of

cerebral artery by fragment of blood clot from an arteriosclerotic plaque or from heart

– Cerebral hemorrhage: most serious type of stroke; usually from rupture of a cerebral artery in person with hypertension

• Predisposing Factors– Mural thrombus formed on wall of left ventricle adjacent to

a healing myocardial infarction– Thrombus formed on rough surface of diseased mitral or

aortic valve– Small thrombus in left atrium of person with atrial

fibrillation• Ischemic infarct: no blood leaks into brain• Hemorrhagic infarct: blood leaks into damaged brain tissue• Arteriosclerosis of extra-cranial arteries

– Sclerosis of a major artery from aorta that supplies brain– Common affected site: carotid artery in neck;

arteriosclerotic plaque may narrow lumen and reduce cerebral blood flow

Congenital aneurysm of circle of Willis(Berry aneurysm)– Congenital weakness in arterial wall allows lining to protrude– Weakness is congenital but aneurysm develops in adult life– Size dependent (over 10mm : 50% risk of rupture)– Rupture causes subarachnoid hemorrhage– Treatment: aneurysm occluded surgically

감염증(Infections)• Three types

– Bacterial– Viral

• Meningitis: infection affecting meninges• Encephalitis: infection of brain tissue• Meningoencephalitis: affects both meninges and

brain tissue

Meningitis from Bacteria and Virus

• E. Coli • Meningococcus (Neisseria meningiditis)• Pneumococcus (Streptococcus pneumoniae)• Hemophilus influenzae

• Measles• Mumps• Herpes simplex virus• Cytomegalovirus• Poliomyelitis virus

크로이체필트-야곱병(Creutzfeldt-Jakob Disease)

• Caused by small protein particle produced as a result of gene mutation– Normal form of protein: “good prion” designated as

PrPc– Abnormal form: “bad prion” designated as PrPsc

• Mad cow disease(광우병)– Prion disease affecting cows– Cows become infected from animal feed mixed with

protein-rich tissue from sheep infected with scrapie– Eating infected beef causes variant Creutzfeldt-Jakob

disease in humans

A photomicrograph of cerebral tissue from patient with Creutzfeldt-Jakob disease.

알쯔하이머병(Alzheimer Disease)• Characteristics

– Progressive mental deterioration– Emotional disturbances

• Anatomic and biochemical features:• Cerebrum: frontal, temporal, parietal lobe

– Neurofibrillary tangles: thickening of neurofilaments– Neurotic plaques: clusters of thick, broken neurofilaments– Biochemical abnormalities and brain enzyme deficiencies:

acetylcholine and acetylcholine synthesizing enzyme• No specific treatment; some drugs may temporarily improve

cerebral function

Alzheimer DiseaseThickened neurofilaments forming

neurofibrillary tangles

다발성경화증(Multiple Sclerosis)• Probably an autoimmune disease in generally predisposed

individual• Random foci of demyelination followed by glial scarring• Neurologic symptoms depend on location of plaques• Probably initiated by a viral infection in a genetically

predisposed person• Manifestations

– Activated T lymphocytes, monocytes target myelin proteins, destroy myelin

• Treatment– MRI demonstrates plaques in CNS

Coronal section of brain illustrating areas of gilial scarring (arrows) adjacent to ventricle in multiple

sclerosis.

파킨슨병(Parkinson Disease)• Most cases unknown etiology• Some develop subsequent to viral infection of nervous

system or toxic drugs• Manifestations

– Progressive loss of neurons in substantia nigra of midbrain

– Rigidity of voluntary muscles– Tremors of fingers and extremities– Decreased dopamine in CNS

• Treatment: relieved by L-dopa– Embryonic stem cells may be key to successful

treatment; possible to induce stem cells to differentiate into dopamine-producing neurons to treat disease

운동신경침범하는퇴행성질환(Degenerative Disease of Motor Neurons)

• Affects both upper and lower motor neurons• From degeneration of neurons• Causes: weakness, paralysis, respiratory problems• No specific treatment• Amyotrophic lateral sclerosis(근위축성축삭경화증, ALS)

– Affects upper and lower motor neurons– Flaccid paralysis of muscles– Respiratory problems

뇌종양(Brain Tumors)1) Incidence is low: about 5% in all tumor

1/3 primary, 1/3 secondary, and 1/3 non-glial cell tumor

2) Occur in all age groups, 20 % of all cancers of childhood

• Primary tumors– Astrocytoma(별아교세포종)– Glioblastoma(아교모세포종)– Oligodendroglioma(희소돌기아교세포종)– Ependymoma(뇌실막세포종)– Lymphoma(림프종)– Medulloblastoma(수질모세포종) – Meningioma(수막종)– Schwannoma(신경집종)

척수종양(Spinal Cord Tumors)

• Same types of tumors that arise in brain• Tumors in spinal vertebrae may extend from

vertebrae to compress or invade spinal cord– Bone metastasis: breast cancer, prostate cancer– Multiple myeloma(다발성골수종):

- Plasma cell neoplasm