Introduction[edit | edit source] Show
The heart is a muscular organ that serves to collect deoxygenated blood from all parts of the body, carries it to the lungs to be oxygenated and release carbon dioxide. Then, it transports the oxygenated blood from the lungs and distributes it to all the body parts[1]
This 10 minute video is a good summary of the heart.[3] Anatomy[edit | edit source]The heart is a conical hollow muscular organ situated in the middle mediastinum and is enclosed within the pericardium. It is positioned posteriorly to the body of the sternum with one-third situated on the right and two-thirds on the left of the midline. The heart measures 12 x 8.5 x 6 cm and weighs ~310 g (males) and ~255 g (females). It pumps blood to various parts of the body to meet their nutritive requirements. The Greek name for the heart is cardia from which we have the adjective cardia. [4] Relations
Layers of the Heart Walls[edit | edit source]The heart wall consists of three layers enclosed in the pericardium[1][6][7]:
The rest of the heart is composed mainly of the subepicardial and subendocardial layers. Structure and Function[edit | edit source]The heart is subdivided by septa into right and left halves, and a constriction subdivides each half of the organ into two cavities, the upper cavity being called the atrium, the lower the ventricle. The heart, therefore, consists of four chambers:
Heart Valves[edit | edit source]The valves of the heart maintain unidirectional flow of the blood and prevent its regurgitation in the opposite direction. There are two pairs of valves in the heart, a pair of atrioventricular valves and a pair of semilunar valves. Apart, it has four valves. All four valves of the heart have a singular purpose: allowing forward flow of blood but preventing backward flow.[8] The outflow of each chamber is guarded by a heart valve: Atrioventricular valves between the atria and ventricles
Semilunar valves which are located in the outflow tracts of the ventricles
See also Cardiac Valve Defects Blood Supply[edit | edit source]The heart is supplied by two coronary arteries:
2. Right coronary artery: branches supply the right ventricle, right atrium, and left ventricle's inferior wall. Coronary arteries and veins course over the surface of the heart. Most coronary veins coalesce into the coronary sinus that runs in the left posterior atrioventricular groove and opens into the right atrium. Other small veins, called thebesian veins, open directly into all four chambers of the heart.[8] Image: Overview of the coronary arteries and cardiac veins - anterior and posterior views[9] See also Coronary Artery Disease Venous drainage and Lymphatics[edit | edit source]Venous drainage is via the variable coronary veins and the coronary sinus[5]. The lymphatic vessels drain mainly into:
Nerve Supply[edit | edit source]The main control of the heart resides with the medulla oblongata. There is an area called the cardioacceleratory centre, or pressor centre, in the upper part of the medulla oblongata, and an area called the cardioinhibitory centre, or depressor centre, in the lower part. Together they are called the cardioregulatory centre, since they interact to control heart rate, etc. The nervous supply to the heart is autonomic, consisting of both sympathetic and parasympathetic parts. The sympathetic fibres arise from the pressor centre, while the parasympathetic fibres arise in the depressor centre. See also Vagal Tone
Heart Conduction System[edit | edit source]An electrical conduction system regulates the pumping of the heart and timing of contraction of various chambers. Heart muscle contracts in response to the electrical stimulus received system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood. Among the major elements in the cardiac conduction system are the sinus node, atrioventricular node, and the autonomic nervous system.
Relevance to Physiotherapy[edit | edit source]
2. See our many pages on heart related health issues eg Cardiac Rehabilitation; Myocardial Infarction; Atrial Fibrillation; Acute Coronary Syndrome; Physical Activity and Cardiovascular Disease. Videos[edit | edit source]References[edit | edit source]
Which part of the cardiac conduction system acts as an electrical gateway to the ventricles quizlet?The AV node, located near the right AV valve at the lower end of the interatrial septum. This node acts as an electrical gateway to the ventricles.
Which of the following is the electrical gateway to the ventricles?The AV (atrioventricular) node
It is the “gateway” between the atria and the ventricles. The AV node channels the signal into the ventricles.
What part of the heart's electrical conduction system plays a role in ventricular?The subendocardial surface is part of the endocardium, the inner layer of tissue that lines your heart's chambers. When the Purkinje fibers deliver electrical signals to your ventricles, the ventricles contract.
Which part of the electrical conduction system Innervates the ventricles?Located in the interatrial septum, the AV node conducts electrical impulses from the SA node to the heart ventricles. This is achieved via atrioventricular bundles (a.k.a. bundle of His) and subendocardiac conducting network/Purkinje fibers located in the ventricle walls.
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