Understanding the Cardiovascular System
Cardiovascular System
The cardiovascular system is the network of channels through which blood flows and consists of:
- The heart
- Blood vessels
In anatomy, the heart is the principal organ of the circulatory system. It is a striated muscle that acts as a suction pump and impeller, which aspirates blood flowing through the veins into the atria and drives it from the ventricles into the arteries.
Heart Anatomy
Location: The heart is situated practically in the middle of the chest (mediastinum), between the two lungs, above the diaphragm, in front of the thoracic spine vertebrae (separated by the esophagus and aorta), and behind the sternum and costal cartilages. The heart is held in this position by the large vessels that run to and from it, and by the pericardium.
Shape and Orientation: The heart is shaped like a triangular pyramid or cone, whose apex is directed downward toward the left and forward, and the base is directed to the right, upward, and slightly backward.
Volume and Weight: The volume of the heart differs by gender and age. The total volume varies between 500 to 800 ml, but the stroke volume of the left ventricle is more important. It weighs around 275 grams in men and 250 grams in women.
Parts of the Heart
The heart is divided into two lateral halves:
- Right Heart: It consists of the right atrium and right ventricle, separated by the tricuspid valve. Venous blood flows through the right heart.
- Left Heart: It consists of the left atrium and left ventricle, separated by the mitral valve. Arterial blood flows through the left heart.
Types of Blood Vessels
The vessels are classified into three groups:
Arteries: Carry blood from the heart to the body, carrying oxygen and nutrients. This blood is called oxygenated blood and has a deep red color.
Major Arteries of the Human Body
- Carotid
- Aorta
- Radial
- Brachial
- Humeral
- Subclavian
- Femoral
Veins: Carry blood from organs and tissues to the heart and then to the lungs, where carbon dioxide is exchanged for oxygen in the inspired air. This is called venous blood and is darker in color.
Major Veins of the Human Body
- Pulmonary veins
- Portal vein
- Superior vena cava
- Inferior vena cava
- Femoral vein
- Jugular vein
Diseases of the Veins
- Varices
- Phlebitis
- Deep vein thrombosis
- Superior vena cava syndrome
- Renal vein thrombosis
Capillaries: Originate in the progressive division of the arteries into ever-smaller branches until reaching the capillaries, which have very thin walls. Blood cells, respiratory gases, nutrients, and other substances carried by the blood pass through these walls.
There are two types of capillaries:
- Venous Capillaries: Responsible for carrying deoxygenated blood to the heart through the venules, which connect to the veins. This blood is then pumped to different parts of the body.
- Arterial Capillaries: Responsible for processing the blood and then passing it to the venous capillaries, exchanging waste products in the blood (carbon dioxide) for oxygen.