Exam 3 · Week 5 · BIO 280 Pathophysiology
M5 · Mental Health & Neurological Disorders
The neurotransmitters behind psychiatric illness, and the neurological emergencies where minutes decide the outcome.
▸M5Mental Health & Neurological DisordersWeek 5
💡 The one idea
Psychiatric illness is chemistry and circuitry, not character. Almost every drug in this module works by nudging one of four neurotransmitters — and almost every side effect is that same nudge landing somewhere you did not want it.
Too little serotonin → depression. Too much dopamine → psychosis. Too little dopamine → Parkinson.
🧪 The four neurotransmitters
| Chemical | Too little | Too much |
|---|---|---|
| Serotonin | Depression, anxiety, OCD | Serotonin syndrome |
| Dopamine | Parkinson, flat affect, the negative symptoms of schizophrenia | The positive symptoms — hallucinations, delusions |
| Norepinephrine | Depression, poor concentration | Anxiety, mania, hypervigilance |
| GABA | Anxiety, seizures — GABA is the brake | Sedation |
Acetylcholine is the other one worth holding: low in Alzheimer, and blocking it gives the anticholinergic picture — dry as a bone, red as a beet, blind as a bat, mad as a hatter, hot as a hare.
🧵 The major disorders
- Major depression — low mood or anhedonia most of the day, most days, for 2 weeks or more, plus sleep, appetite, energy, concentration and worth changes.
- Bipolar — depression plus at least one manic episode.
Mania is
≥1 weekof elevated or irritable mood with grandiosity, reduced need for sleep, pressured speech, flight of ideas and risky behavior. - Schizophrenia — positive symptoms are things added (hallucinations, delusions, disorganized speech); negative symptoms are things taken away (flat affect, avolition, alogia, anhedonia). Negative symptoms respond far less well to medication and predict the worse outcome.
- Anxiety disorders — GAD, panic disorder, phobias, OCD, PTSD. The physical symptoms are sympathetic activation, which is why they mimic cardiac and thyroid disease.
🚨 Delirium is not dementia
Delirium is an acute medical emergency with an underlying cause. Treating it as dementia means missing the infection, the hypoxia or the drug that caused it.
| Delirium | Dementia | |
|---|---|---|
| Onset | Hours to days | Months to years |
| Course | Fluctuates — worse at night | Steady, progressive |
| Attention | Impaired — the defining feature | Preserved until late |
| Consciousness | Altered | Clear until late |
| Reversible | Yes, if the cause is found | No |
Common causes: infection (especially UTI and pneumonia), hypoxia, electrolytes, dehydration, pain, medication, withdrawal, and sleep deprivation.
🧠 Stroke — the two kinds and the clock
| Ischemic (~87%) | Hemorrhagic | |
|---|---|---|
| Cause | Thrombus or embolus blocks a vessel | A vessel ruptures — hypertension, aneurysm, AVM |
| Onset | Sudden deficit, often on waking | Sudden worst headache of my life, vomiting, rapid decline |
| Treatment | Thrombolysis if within the window | Thrombolytics are absolutely contraindicated |
A non-contrast CT comes before any thrombolytic, every time. The two strokes look identical at the bedside and the treatment for one kills the other.
BE FAST — Balance, Eyes, Face droop, Arm drift, Speech, Time. Left hemisphere → right-sided weakness and aphasia; right hemisphere → left-sided weakness, neglect and impulsiveness.
A TIA resolves completely within 24 hours and leaves no infarct — but it is a warning shot, not a reassurance.
⭐ Raised intracranial pressure & seizures
The skull is a fixed box. Brain, blood and CSF share it; if one grows, another must shrink or the pressure rises (Monro–Kellie).
- Earliest sign of rising ICP is a change in level of consciousness. Not the pupils, not the vital signs.
- Cushing triad is late and ominous: rising systolic with a widening pulse pressure, bradycardia, and irregular respirations.
- Nursing: head of bed
30°, head midline, avoid neck flexion, cluster care, prevent coughing and straining.
Seizures: focal starts in one area; generalized involves both
hemispheres from the outset. Status epilepticus is continuous or repeated seizing
>5 min — an emergency because the brain's oxygen demand outruns supply.
During a seizure: protect the head, turn them on their side, time it, loosen clothing. Never restrain them and never put anything in the mouth.
🎯 Module quiz
Questions for this module.
Nothing here yet — drop it in when you have it