luokai0 Physiology Expert
Before Starting
- Which organ system?
- Human or comparative physiology?
- Normal function or pathophysiology?
Core Expertise Areas
Homeostasis
Negative feedback: response opposes perturbation — thermoregulation, blood glucose. Positive feedback: response amplifies stimulus — parturition, blood clotting. Set point: target value maintained by control system. Effectors: organs/tissues that implement corrective response.
Cardiovascular Physiology
Cardiac cycle: systole, diastole, pressure-volume relationships. Cardiac output: CO = HR x SV. Starling law: SV increases with preload. Blood pressure: BP = CO x TPR. Autoregulation of blood flow. Electrocardiogram: P wave (atrial), QRS (ventricular), T wave (repolarization). Frank-Starling mechanism: greater stretch -> greater force of contraction.
Respiratory Physiology
Mechanics: compliance, resistance, work of breathing, spirometry values. Gas exchange: Fick principle, alveolar gas equation, V/Q matching. Hemoglobin: oxygen dissociation curve, Bohr effect, 2,3-BPG. Control of breathing: chemoreceptors (central CO2, peripheral O2), Hering-Breuer reflex.
Renal Physiology
Nephron function: filtration (GFR ~120 mL/min), reabsorption, secretion. Sodium balance: proximal tubule (67%), loop of Henle, distal/collecting duct (aldosterone). Acid-base: bicarbonate buffer, renal compensation, Henderson-Hasselbalch. Renin-angiotensin-aldosterone system: blood pressure and volume regulation.
Endocrinology
Hormone classes: peptides (fast, membrane receptors), steroids (slow, nuclear receptors). Feedback axes: hypothalamus -> pituitary -> target gland -> feedback. Key axes: HPA (stress), HPT (thyroid), HPG (reproductive). Insulin/glucagon: glucose homeostasis, anabolic vs catabolic balance. Stress response: catecholamines (fast), cortisol (slow) — fight or flight.
Key Patterns
Best Practices
- Always consider compensatory mechanisms when analyzing disorders
- Use systematic approach: primary disorder -> compensation -> diagnosis
- Distinguish acute from chronic adaptations in organ function
- Consider species differences in comparative physiology
- Integrate multiple systems — they rarely act in isolation
Common Pitfalls
| Pitfall | Fix |
|---|---|
| Ignoring compensation in acid-base | Always identify both primary disorder and compensation |
| Confusing preload and afterload | Preload is filling pressure, afterload is resistance to ejection |
| Forgetting Bohr effect in O2 transport | Acidosis shifts O2 curve right, reducing affinity |
| Oversimplifying hormone feedback | Many axes have ultra-short, short, and long feedback loops |
Related Skills
- cell-biology-expert
- biochemistry-expert
- neuroscience-expert
- endocrinology within this skill