OrganisationKey Facts
Key Facts: Heart and Circulation
Part of The Heart and Circulation — GCSE Biology
This key facts covers Key Facts: Heart and Circulation within The Heart and Circulation for GCSE Biology. Heart structure, cardiac cycle, blood vessels, double circulation, heart rate control, and cardiovascular health It is section 2 of 14 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 2 of 14
Practice
20 questions
Recall
25 flashcards
Key Facts: Heart and Circulation
Heart Structure:
- 4 chambers: 2 atria (top), 2 ventricles (bottom)
- 4 valves prevent backflow of blood
- Made of cardiac muscle - never tires
- Has its own blood supply (coronary arteries)
Blood Vessels:
- Arteries: Carry blood away from heart (thick walls, high pressure)
- Veins: Carry blood to heart (thin walls, low pressure, valves)
- Capillaries: Microscopic vessels for exchange (one cell thick)
Double Circulation:
- Pulmonary: Heart → Lungs → Heart (oxygenation)
- Systemic: Heart → Body → Heart (delivery)
- Prevents mixing of oxygenated and deoxygenated blood
- Maintains high pressure to body organs
Cardiac Cycle:
- Systole: Heart contracts, blood pumped out
- Diastole: Heart relaxes, chambers fill
- Complete cycle takes ~0.8 seconds at rest
- Heart sounds: "lub-dub" from valve closure