Term papers writing service


The description of the action of the heart in terms of collecting blood

Print Anatomy of the Heart The heart is the hollow, muscular organ in the thoracic cavity chest that maintains the circulation of blood throughout the body. It is surrounded by a membrane called the pericardium.

  1. Thin walls so that nearby muscles can help push blood towards the heart.
  2. The right ventricle pumps the blood to the lungs, where it absorbs oxygen.
  3. Thick outer layer of longitudinal collagen and elastic fibres prevents leaks and bulges.

The pericardium consists of a layer of fibrous connective tissue and a layer of thin, serous i. This fluid prevents friction between the pericardium and the heart. The heart wall consists of the epicardium inner layerthe myocardium middle layer comprised of cardiac muscle tissueand the endocardium lining of the myocardium that covers the heart valves.

The heart has a right side and a left side. Each side has a relatively thin-walled chamber that receives blood returning to the heart atrium and a muscular chamber that pumps blood out of the heart ventricle.

Anatomy of the Heart

Blood Flow The flow of blood through the heart is controlled by the opening and closing of valves and the contraction and relaxation of the myocardium. Heart valves are controlled by pressure changes within each chamber and contraction and relaxation are controlled by the heart's conduction system.

This blood flows through the tricuspid valve into the right ventricle.

  • This rise in pressure first causes the atrioventricular valves to close preventing back flow of blood into the atria;
  • When the atria contract the blood flows through the atrioventricular valves which are open, into the ventricle;
  • They have a thick wall which is essential to withstand the high pressures;
  • Phagocytes can also pass through pores;
  • The electrical impulse is conducted through the AV node and wire-like pathways Purkinje fibers to the ventricles, signaling the ventricles to contract and pump blood into the lungs and throughout the body.

The right ventricle pumps the blood to the lungs, where it absorbs oxygen. Blood passes from the left atrium through the mitral valve and into the left ventricle.

The left ventricle, the largest and most muscular of the four chambers, is the main pumping chamber of the heart. When the left ventricle contracts, blood is pumped through the aortic valve into the main artery of the body aorta. The aorta supplies blood to smaller arteries that travel to the head, arms, abdomen, and legs. These arteries supply oxygen-rich blood to the organs and tissues of the body, which require oxygen to function. The coronary arteries supply oxygen-rich blood to the tissues of the heart.

Oxygen-poor blood travels from organs and tissues to the heart through veins. The vena cava is the major vein that returns blood to the right atrium of the heart. The vena cava superior returns blood from the head, neck, upper extremities, and chest. The vena cava inferior returns blood from the lower extremities, the pelvis, and the abdomen. The coronary sinus drains blood from the coronary arteries into the right atrium.

Blood Flow

Conduction System An electrical impulse travels through the heart and initiates contractions of the chambers. The heart's "spark plug" is an area of specialized heart tissue called the sinoatrial node SA nodewhich is located in the right atrium. Each time the SA node "fires," an electrical impulse is generated that travels through the right and left atria, signaling these chambers to contract and pump blood into the ventricles.

The impulse then travels into another area of specialized heart tissue called the atrioventricular node AV nodewhich is located between the atria and the ventricles.

The electrical impulse is conducted through the AV node and wire-like pathways Purkinje fibers to the ventricles, signaling the ventricles to contract and pump blood into the lungs and throughout the body.

Heart Anatomy & Blood Flow

The normal sequence of electrical activation of the chambers of the heart is called sinus rhythm. It occurs each time the heart beats, usually about 60 to 80 times every minute.

  • Each side has a relatively thin-walled chamber that receives blood returning to the heart atrium and a muscular chamber that pumps blood out of the heart ventricle;
  • When the ventricles contract during a heartbeat, the blood on the left side is forced into the aorta;
  • When the ventricle contracts, the blood is pushed into the pulmonary artery that branches into two main parts;
  • Atria collect blood from veins;
  • Afterwards, the heart muscle relaxes, allowing blood to flow in from the veins and fill the atria again;
  • This largest artery of the body is an inch wide.

In a normal heartbeat, the atria contract simultaneously while the ventricles relax. Then, the ventricles relax and the atria contract. The term systole refers to contraction and the term diastole refers to relaxation.

  1. Ventricle contracts, atrioventricular valves close and semilunar valves open. The aorta supplies blood to smaller arteries that travel to the head, arms, abdomen, and legs.
  2. The aorta supplies blood to smaller arteries that travel to the head, arms, abdomen, and legs.
  3. Then, the ventricles relax and the atria contract. Finally, adrenaline epinephrine is carried by the blood and once it reaches the pacemaker it signals it to increase the beating of the heart.
  4. The pericardium consists of a layer of fibrous connective tissue and a layer of thin, serous i.
  5. One nerve carries messages from the medulla of the brain to the pacemaker and speeds up the beating of the heart. When the ventricles contract during a heartbeat, the blood on the left side is forced into the aorta.

A heartbeat consists of the systole and diastole of the atria and the systole and diastole of the ventricles.