Overview
This lecture introduces the cardiovascular system, focusing on the heart's location, coverings, wall structure, and the function of the cardiac skeleton.
Cardiovascular System Overview
- The cardiovascular system consists of the heart and blood vessels.
- The heart acts as a double pump and separates oxygen-rich and oxygen-poor blood.
- Humans have a closed circulatory system, which is efficient at transporting blood.
Heart Location and Orientation
- The heart is located in the thoracic cavity, specifically in the mediastinum (middle space).
- It sits obliquely, slightly to the left of the body's midline, and rests on the diaphragm within the cardiac notch of the left lung.
Coverings of the Heart
- The heart is surrounded by the pericardium, a type of serous membrane.
- The pericardium has two main components: the fibrous pericardium (outer, tough, anchoring) and the serous pericardium (double-layered, friction-reducing).
- The fibrous pericardium anchors and protects the heart, preventing overfilling.
- The serous pericardium includes a parietal layer (lining cavity wall), visceral layer (covering heart surface), and the pericardial cavity (filled with pericardial fluid for cushioning).
Heart Wall Structure
- The heart wall has three layers:
- Epicardium (outermost; same as visceral layer of serous pericardium)
- Myocardium (middle, muscular layer of cardiac muscle)
- Endocardium (innermost, thin, smooth lining)
Cardiac Skeleton
- The cardiac skeleton is dense connective tissue bands within the heart.
- It stabilizes heart valves, prevents overexpansion, provides elasticity, and acts as an electrical barrier between atria and ventricles.
Key Terms & Definitions
- Pericardium — double-layered membrane surrounding the heart.
- Fibrous Pericardium — tough outer layer anchoring the heart.
- Serous Pericardium — thin, double-layered membrane reducing friction.
- Parietal Layer — serous pericardium layer lining the cavity wall.
- Visceral Layer (Epicardium) — serous pericardium layer covering the heart.
- Pericardial Cavity — fluid-filled space between parietal and visceral layers.
- Epicardium — outer heart wall layer (visceral serous pericardium).
- Myocardium — muscular middle layer of the heart wall.
- Endocardium — thin, inner lining of heart chambers and vessels.
- Cardiac Skeleton — connective tissue framework stabilizing and insulating heart structures.
Action Items / Next Steps
- Review diagrams of heart coverings and wall layers.
- Practice naming all heart layers and their functions.
- Prepare for further discussion on heart valves and electrical conduction.