Heart, Circulation & Blood Vessels: Basic Information

2023 Author: Wallace Forman | [email protected]. Last modified: 2023-08-25 11:04

Heart, circulation & blood vessels: basic information

The heart is a muscle the size of a fist. It beats about 80 times a minute and in 80 years of life transports more than 200 million liters of blood through the vessels. This makes a total of at least three billion heartbeats. The heart has a stimulus generation and conduction system that is independent of the nervous system and that stimulates the muscles of the heart. However, influencing signals can be given via the vegetative nervous system. For example, fear, panic or joy make the heart beat faster.

navigation

• Continue reading
• more on the subject
• Advice, downloads & tools
• The four layers of the heart
• The blood supply to the heart
• The pumping function of the heart
• The heart - our "engine"

The four layers of the heart

Anatomically, the heart lies behind the breastbone between the two lungs in a connective tissue bag called the pericardium. This is followed by a layer (epicardium) that lies directly on the heart. Between the pericardium and the epicardium there is a gap filled with fluid, which enables the heart to move with little friction in the pericardium. The coronary arteries run under the epicardium, embedded in a protective layer of fat. The next layer is the heart muscle tissue (myocardium), and then comes the innermost layer, called the endocardium.

The blood supply to the heart

The blood supply must be guaranteed so that the heart muscle is adequately supplied with oxygen and nutrients. This is ensured by the so-called coronary arteries. These vessels enclose the heart in the form of a wreath, hence the name coronary vessels.

Two vessels are responsible for the blood supply to the heart muscle from the outside:

• left coronary artery (arteria coronaria sinistra)
• right coronary artery (arteria coronaria dextra)

Each of the coronary arteries branches into a large number of other arteries and thus supplies the entire heart muscle.

The pumping function of the heart

The heart consists of four chambers that alternately contract and slacken and two halves that both work as independent pumps. The right half of the heart receives the deoxygenated blood through the vena cava and pumps it through the pulmonary artery into the lungs. The left half of the heart collects the oxygen-rich blood that comes from the lungs through the pulmonary veins and pumps it into the body through the main artery (aorta). In terms of its biological function, the heart is a pump with a cavity in which blood is collected and then pressed into the lungs and body.

At rest, around five liters of blood per minute are pumped into the circulation, thus supplying the body with nutrients and energy. During exertion, the heart can increase this volume four to five times.

The heart - our "engine"

Basically, the heart consists of the stimulus generation and conduction system and the actual working muscles. In order for the heart to pump blood into the body, countless muscle cells in the atria and chambers of the heart have to contract and relax at the same time. This community action is coordinated by electrical impulses. The normal heartbeat begins in the right atrium in special heart muscle cells that form the sinus node the size of an olive nucleus. In addition to the sinus node as the central clock generator, the stimulation system also consists of the atrioventricular node (AV node) and subordinate centers in the atrial septum in the transition to the chamber.

The electrical signals regularly generated in the sinus node are known as sinus rhythm and are distributed over the entire heart by the conduction system, which also consists of special heart cells: First, both atria are stimulated to contract the muscles. Then the excitation wave passes through the AV node. The conduction system (His bundle) then divides into two fiber strands ("Tawara legs"), the smallest fibers (Purkinje fibers) of which extend into the muscles of the heart chambers. This path and the chronological sequence must be precisely adhered to so that the heart beats and pumps efficiently.