6 Cardiovascular System – Heart
Learning Objectives
- Apply the rules of medical language to build, analyze, spell, pronounce, abbreviate, and define terms as they relate to the cardiovascular system
- Identify meanings of key word components of the cardiovascular system
- Use terms related to the cardiovascular system
Cardiovascular System – Heart Word Parts
Click on prefixes, combining forms, and suffixes to reveal a list of word parts to memorize for the cardiovascular system – Heart.
Introduction to the Heart
The heart is a fist-sized vital organ that has one job: to pump blood. If one assumes an average heart rate of 75 beats per minute, a human heart would beat approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan. At rest, each of the major pumping chambers of the heart ejects approximately 70 mL blood per contraction in an adult. This would be equal to 5.25 liters of blood per minute and approximately 14,000 liters per day. Over one year, that would equal 10,000,000 liters of blood sent through roughly 100,000 km of blood vessels. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart.
Watch the video: The Heart, Part 1 – Under Pressure: Crash Course Anatomy & Physiology #25 (10 minutes)
Cardiovascular System – Heart Medical Terms
Anatomy of the Heart
Location
The human heart is located within the thoracic cavity, between the lungs in the space known as the mediastinum. Figure 6.1 shows the position of the heart within the thoracic cavity. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the pericardial cavity. The great vessels, which carry blood to and from the heart, are attached to the superior surface of the heart, which is called the base. The base of the heart is located at the level of the third costal cartilage. The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs.
Concept Check
- On the diagram below (Figure 6.1), locate the mediastinum, the pericardial cavity, the base of the heart and the apex of the heart.
- Locate the largest vein in the body superior vena cava.
Membranes and Layers of the Heart Walls
The heart and the roots of the great vessels are surrounded by a membrane known as the pericardium or pericardial sac. The pericardium consists of two distinct sub layers:
- The sturdy outer fibrous pericardium is made of tough, dense connective tissue that protects the heart and holds it in position.
- Separated by the pericardial cavity and containing pericardial fluid the inner serous pericardium consists of two layers:
- the outer parietal pericardium, which is fused to the fibrous pericardium.
- the inner visceral pericardium, or epicardium, which is fused to the heart and forms the o