Nervous system pathophysiology

What is the blood brain barrier?

Specialised interface between blood vessels in brain and brain tissue

What is the function of the blood brain barrier?

Limits movement of substances between blood and brain

What are the two adaptations of the capillary endothelial cells in brain capillaries?

Tight junctions with adjacent cells to reduce cell wall permeability, forming thick basement membrane

Astrocyte foot processes extend and wrap around capillaries

What is meningitis?

Inflammation of meninges

What happens during meningitis?

Infection invades subarachnoid space and travels in CSF along spinal cord and brain, spreading around the body

What are two common causes of viral meningitis?

Cranial fracture

Contamination

What are the two types of meningitis?

Non infective

Viral

What is non infective advanced meningitis?

Brain tissues attacked by autoimmune processes or invaded by tumours

What are the two consequences of swelling and compromising blood flow?

Hypoxia

Ischemia

What is a consequence of slow blood flow?

Triggers clotting, forming microthrombi

What are consequences of increased pressure and inflammation in the brain?

Compresses brain tissue and cranial nerves, and causes pus formation causing obstruction s

What is multiple sclerosis?

Autoimmune disorder in which inflammatory demyelination of CNS disrupts nerve signal transmission

What is the 5 step process of multiple sclerosis disease?

Myelination sheath is destroyed by inflammatory episodes

Remission periods occur

Repeated episodes cause permanent scarring

Plaques caused by scarring are infiltrated by inflammatory cells

Causes a progressive inflammatory cycle, eventually exposing nerve axons to the inflammatory process

What cells are central to multiple sclerosis myelin destruction?

Autoreactive T cells targeting myelin are activated in peripheral tissue by prexisting infection and cross into the CNS

What is Alzheimer’s disease?

Neurodegenerative disorder caused by wide spread brain cell degeneration

What is the three step process of Alzheimer’s disease involving beta amyloid protein?

Atrophy of cerebral cortex and neuronal loss

Insoluble bet amyloid protein plaques develop

Cause local neuronal damage and trigger inflammation

What is the function of beta amyloid proteins?

Part of synaptic plasticity and memory processes at low levels

What are two precursors believed to produce beta amyloid protein?

Amyloid precursor protein and tau protein

What is tau protein?

Thread like proteins in neurones that hold the intracellular network of micro tubules together

What is the two step process of Alzheimer’s disease involving tau proteins?

Become tangled and causes microtubule system to fall apart

stopping all transmission of impulses in that area

What hormone may be preventative against Alzheimer’s?

Oestrogen

What are the most common features of central nervous system tumours?

Often secondary from glial or support cells and mostly occur in brain not spinal cord

What effects could benign brain tumours have?

Increased intracranial pressure, oedema, seizures and neurological deficits

What are gliomas?

Group of primary brain tumours arising from glial cells

What is an atrocytoma?

Most common gliomas

What are glioblastomas?

High grade astrocytoma which is incurable and aggressive

What is cerebral palsy?

A group for permanent movement and posture disorders resulting from non progressive brain injury during early development

What is encephalitis?

Inflammation of the brain, commonly due to infection, leading to altered consciousness, seizures and neurological deficits

What is a medulloblastoma?

Malignant primary brain tumours, originating in cerebellum

What is a meningioma?

Slow growing tumour arising from meninges

What is polio?

Viral infection that can damage motor neurones, leading to muscle weakness, paralysis and respiratory failure

What is rabies?

Fatal viral disease affecting the CNS, causing acute encephalitis through an animal bite

What is a stroke?

Sudden interruption of cerebral blood supply, causing neurological deficits