Cardiorespiratory System: Heart, Vascular, and Lymphatic Anatomy
The Cardiorespiratory System: Function and Anatomy
Function of the Cardiorespiratory System
The cardiorespiratory system is responsible for oxygenating and distributing oxygenated blood throughout the body.
Anatomy of the Cardiovascular System
Anatomy of the Heart
The heart is an organ of involuntary contraction, located in the mediastinum. It is formed by four cavities: atria (right and left) and ventricles (right and left). The atrioventricular groove, located between the atrial and ventricular surfaces, contains the coronary arteries, which are responsible for irrigating the heart.
Heart Chambers and Blood Flow
Blood vessels enter and leave the heart as follows:
- Into the right atrium enter the superior and inferior vena cava (either alone or in a common trunk) and the coronary sinus.
- Into the left atrium enter the four pulmonary veins.
- From the right ventricle exits the pulmonary artery.
- The aorta exits the left ventricle.
The heart rests on the diaphragm and is located posteriorly. A partition called the septum separates the two functional halves of the heart, known as the right and left heart.
Heart Septa
Interatrial Septum
This septum separates the two atria and is composed of two segments that typically fuse at birth. If this fusion does not occur, it can lead to blood pathologies due to exchange between the two atria.
Interventricular Septum
This septum is unique to the ventricles.
Heart Valves
Atrioventricular Valves
These valves divide into two main types:
- Tricuspid valve
- Mitral valve
Arterial Valves
Also called semilunar or sigmoid valves, these are regulated by a muscular system.
Papillary Muscles and Chordae Tendineae
Papillary muscles (named for their elongated shape) pull the connective tissue fibers called chordae tendineae. These chordae are attached to the edge of the valves, allowing their opening and closing.
Pericardium
The pericardium has two layers:
- Outer layer (parietal layer): a hard, fibrous consistency.
- Inner layer (visceral layer): a serous layer.
Between both layers, there is a virtual space containing minimal amounts of pericardial fluid, whose mission is to lubricate and cushion the friction of the heart during its contraction and relaxation movements.
Heart Wall Layers
The heart wall is composed of three layers:
- Epicardium
- Myocardium
- Endocardium
Anatomy of the Vascular System
This system consists of a network that carries blood from the heart to all body cells and collects waste products, returning them to the heart.
Arterial System
Arteries leave the heart and carry oxygenated blood to the tissues. Arteries possess smooth muscle, allowing for contraction.
Venous System
Veins transport deoxygenated blood back to the heart. The venous system contains valves that prevent the backflow of blood.
Anatomy of the Lymphatic System
This system is responsible for returning the lymph to the blood, along with substances that have been absorbed. Lymph is a fluid consisting of fats absorbed during food digestion in the small intestine and excess extracellular fluid. This fluid is transported by lymphatic vessels, which converge into major ducts like the thoracic duct.
Lymphatic vessels pass through nodes (lymph nodes) that are responsible for eliminating toxic substances and germs before they reach the bloodstream. An increase in lymph nodes is called adenopathy.