Heart Anatomy PDF

Heart The heart, which is a hollow, muscular pump that propels blood through the vessels, is located in the thoracic cavity between the lungs in a space known as the **mediastinum**. The heart is about the size of a fist. The superior aspect of the heart, or the base, is the origin of most major b...

Heart The heart, which is a hollow, muscular pump that propels blood through the vessels, is located in the thoracic cavity between the lungs in a space known as the **mediastinum**. The heart is about the size of a fist. The superior aspect of the heart, or the base, is the origin of most major blood vessels. The inferior aspect of the heart is the apex. Walls of the Heart The walls of the heart are made up of three layers: - Pericardium - Myocardium - Endocardium This is the thickest layer of the heart wall. Remember, my/o means muscle. The myocardium needs a continuous supply of oxygen to function, and this layer keeps blood flowing. The coronary arteries and veins surround the heart and supply the myocardium with oxygen and nutrients. The coronary arteries branch off the aortic arch. The heart is divided into two halves by a septum (sept/o). The right half collects blood from the systemic system and passes it on to the pulmonary system. The left half collects blood from the pulmonary system and forwards it to the systemic vessels. The left side is more muscular than the right side is because the left side has to propel blood farther. Each half of the heart is further divided into two, creating four **chambers**: - **Upper chambers (Atria)** - The left atrium and right atrium are divided by the interatrial septum - **Lower chambers (Ventricles)** - The left ventricles and right ventricles are divided by the interventricular septum - Pulse - There are two phases to the heartbeat: the diastole when the tricuspid and mitral valves are open as the blood enters the ventricles; and the systole in which the pulmonary and aortic valves are open as the blood is pumped to the pulmonary artery and aorta. - The **sinoatrial node (SA)** is the pacemaker of the heart. The current electricity generated by the pacemaker causes the walls of the atria to contract and force blood into the ventricles. - After each heartbeat, a pressure wave passes along the arteries. The arterial walls bulge, then contract. You can feel the pulse at various points on the body.  The **atrioventricular node (AV)** receives the electrical signal and forwards it to the ventricles. Blood pressure is the measurement of the amount of force exerted by the blood against arterial walls. It consists of two measurements: systolic and diastolic. **Combining Form** **Meaning** ------------------------- ------------- Cardi/o; Coron/o Heart Vascul/o; Vas/o; Angi/o Vessel Arter/o; Arteri/o Artery Venul/o Venule Ven/o; Ven/i; Phleb/o Vein Pulmon/o Lungs **Combining Form** **Meaning** Thorac/o Chest Abdomin/o Abdomen My/o Muscle Sept/o Septum Atri/o Atrium Ventricul/o Ventricle **Prefix / Suffix** **Meaning** --------------------- --------------------------------- Endo- In; within Peri- Surrounding Epi- Above; upon Inter- Between Tri- Three Bi- Two -ole Small; little -logist Specialist; someone who studies