Nervous system disorders — A/L Biology

What must I remember about Nervous system disorders?

• Alzheimer's Disease is a progressive neurodegenerative disorder marked by memory loss, cognitive decline, and personality changes, characterized histopathologically by extracellular amyloid-beta plaques and intracellular neurofibrillary tau tangles.
• Parkinson's Disease is a movement disorder caused by the degeneration of dopamine-producing neurons in the Substantia Nigra of the midbrain, presenting with resting tremors, muscular rigidity, bradykinesia (slowness of movement), and postural instability.
• Stroke (Cerebrovascular Accident) occurs when blood supply to a brain region is disrupted, either by ischemia (arterial thrombosis or embolism, ~85% of cases) or hemorrhage (ruptured aneurysm), resulting in rapid neuronal hypoxia, tissue infarction, and localized neurological deficits.
• Meningitis is an inflammation of the meninges surrounding the brain and spinal cord, caused by bacterial (e.g., Neisseria meningitidis, Streptococcus pneumoniae) or viral infections, characterized by severe headache, high fever, and neck stiffness (nuchal rigidity).
• Spinal Cord Injuries disrupt ascending sensory and descending motor pathways, leading to permanent loss of sensation and voluntary movement below the level of the lesion (paraplegia from thoracic/lumbar injury, tetraplegia/quadriplegia from cervical injury).

Test yourself (1 minute)

1. Stroke warning signs (FAST protocol)

   Facial drooping, Arm weakness, Speech difficulty, Time to call emergency services immediately; thrombolytic window is critical within 3-4.5 hours.

2. Neurotransmitter deficits

   Alzheimer's is linked with Acetylcholine deficiency in hippocampus; Parkinson's is linked with Dopamine deficiency in striatum.

3. Blood-Brain Barrier (BBB) vulnerability

   Astrocytic foot processes normally seal brain capillaries; inflammation during bacterial meningitis disrupts BBB, permitting toxic extravasation.

Practise Nervous system disorders questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 5

What should I study first?

What comes next?

Next in the syllabus

Where does Nervous system disorders fit in the syllabus?

Year 2 · Term 1