Body Fluids and Circulation: Key Notes
💓 Electrocardiogram (ECG)
- An ECG uses 3 electrical leads (attached to wrists and left ankle) to track heart activity.
- Each peak in an ECG has a letter that shows a specific heart action:
- P-wave = Atria excitation (makes atria contract)
- QRS complex = Ventricles excitation (starts ventricular contraction → systole begins)
- T-wave = Ventricles relaxing (end of T-wave = end of systole)
- 💡 Heart rate = Count QRS peaks over time!
- ⚠️ Unusual ECG shapes may signal heart problems.
🩸 Blood Vessel Structure
All arteries and veins have 3 layers:
| Layer | Composition | Fun Fact |
|---|---|---|
| Tunica intima | Squamous endothelium (inner lining) | Innermost layer |
| Tunica media | Smooth muscle + elastic fibers | Thinner in veins |
| Tunica externa | Fibrous connective tissue | Outermost layer |
🚀 Double Circulation System
Two pathways work together:
1. Pulmonary Circulation (Lungs) 🔁
Pathway:
Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium
💨 Deoxygenated → Oxygenated blood!
2. Systemic Circulation (Body) 🌍
Pathway:
Left ventricle → Aorta → Arteries → Capillaries (in tissues) → Veins → Vena cava → Right atrium
✨ Delivers O2 & nutrients → Removes CO2 & waste
🌟 NEET Must-Knows
- ECG wave meanings (P-wave = atrial depolarization, QRS = ventricular depolarization)
- Blood vessel layers (Tunica intima/media/externa differences)
- Pulmonary vs. systemic circulation (pathways & blood oxygenation)
- Systole timing (starts at QRS complex → ends at T-wave)
- Systemic circulation function (O2/nutrient delivery & waste removal)
Keep practicing these pathways – you’ve got this! 👍
Next up: We’ll explore that special digestive-liver connection mentioned at the end!
