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Biology · Quick Reference
Lesson 7 — Circulatory System Cheat Sheet
In one line: 4 chambers, 4 valves, systole pumps out, diastole fills, and cardiac output = heart rate × stroke volume.
Key Ideas
1Heart: 4 chambers (RA, RV, LA, LV), 4 valves.
2Systole = contraction (blood out); diastole = relaxation (heart fills).
3Artery = away from heart, thick; vein = to heart, has valves; capillary = 1 cell thick, exchange.
4Blood: 55% plasma, 45% RBCs, plus WBCs and platelets.
5Bohr effect: ↑CO2 → ↑O2 release to tissues.
Formulas
Cardiac Output = HR × Stroke Volume
CO = 72 bpm × 70 mL ≈ 5 L/min
Normal BP
120/80 mmHg
120 (systolic)
Ventricle contracting
80 (diastolic)
Ventricle relaxed