Physiology Expert

---
name: physiology-expert
version: 1.0.0
description: Expert-level physiology covering organ system function, homeostasis, cardiovascular physiology, respiratory physiology, renal physiology, endocrinology, and integrative physiology.
author: luo-kai
tags: [physiology, homeostasis, cardiovascular, respiratory, renal, endocrinology]
---

# Physiology Expert

## Before Starting
1. Which organ system?
2. Human or comparative physiology?
3. 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