THE HUMAN HEART I. HUMAN HEART MODELS. A. Introduction
THE HUMAN HEART I.
HUMAN HEART MODELS A.
Introduction You cannot understand the heart by studying only models; you must study a real heart. However,...
Introduction You cannot understand the heart by studying only models; you must study a real heart. However, heart models are useful to get the “lay of the land,” and you will enjoy the sheep heart dissection much more if you are familiar with the models. Our models have no keys, but the text illustrations will serve as keys.
B.
External structures (Fig. 20.55) Use the heart models. Keep in mind that when the vessel’s name is “pulmonary,” the color of the blood within is opposite the usual. Always use “left” and “right” as given below. Right atrium [plural is atria] Right ventricle Left atrium Left ventricle Right auricle Left auricle (not shown on illustrations) Pulmonary trunk Right pulmonary artery Left pulmonary artery Aorta Superior vena cava Inferior vena cava Right pulmonary veins Left pulmonary veins Coronary sulcus (groove that separates atria from ventricles) Anterior interventricular sulcus Posterior interventricular sulcus
C.
Internal structures (Fig. 20.7) Study the heart models. Right atrium Coronary sinus Tricuspid valve Papillary muscles Right ventricle 22
23 Left Atrium Bicuspid valve (mitral valve) Left ventricle Chordae tendineae Interventricular septum Pulmonary semilunar valve Aortic semilunar valve D.
Remnants of fetal structures. These structures were open to blood flow before birth; they closed shortly after. They are not well shown on the illustrations, but are easily seen on most heart models. Fossa ovalis Ligamentum arteriosum
E.
Heart wall and serous membranes (Fig. 20.3, 20.4) Use models except as noted. Parietal pericardium (illustration only) Epicardium (Visceral pericardium) Myocardium Endocardium
F.
Blood flow through the heart (Fig. 20.10) Trace the pathway of blood through these structures using a heart model. Know this sequence. 1.
Deoxygenated (“blue”) blood flows from Superior and inferior vena cava and coronary sinus to Right atrium, through Tricuspid valve to Right ventricle, through Pulmonary semilunar valve to Pulmonary trunk [artery] to Alveoli of lungs
2.
Oxygenated (red) blood flows from Alveoli of lungs to Pulmonary veins (4) to Left atrium, through Bicuspid (mitral) valve to Left ventricle, through Aortic semilunar valve to Aorta, to entire body except __________ ___ _________.
24 G.
Vessel definitions Artery: takes blood away from the heart, no matter the color of the blood Vein: carries blood toward the heart, no matter the color Systemic arteries: carry red blood to all parts of the body except the alveoli of the lungs Systemic veins: carry “blue” blood toward the heart from all parts of the body except the alveoli of the lungs Pulmonary arteries: carry “blue” blood from the right heart toward the lungs. The pulmonary trunk is an artery Pulmonary veins: carry red blood from lungs toward the left heart Sinus: a large, thin-walled vein. All sinuses are found in the systemic circulation; for example, the superior sagittal sinus of the brain, or the coronary sinus of the heart.
25 II.
CORONARY CIRCULATION A.
Introduction This is the vital circulation to the heart muscle itself. The illustrations show the vessels on the anterior and posterior side at once, as if it were a transparent glass heart. The lighter color shows more posterior vessels. The coronary arteries are the ones that are replaced during “bypass” surgery. Use the heart models to study these vessels. Our lab has only one model which opens to show the left coronary artery, which is hidden because it runs behind the pulmonary trunk. (Fig. 20.6)
B.
Left coronary artery and its two main branches: Anterior interventricular artery Circumflex artery
C.
Right coronary artery and its two main branches: Posterior interventricular artery Right marginal artery
D.
Coronary sinus and the main branches which form it. These drain blood from the capillaries of the heart and return the “blue” blood to which chamber? Great cardiac vein Middle cardiac vein Small cardiac vein
E.
Pairings of the arteries and veins of the heart. It is typical for arteries, veins, and nerves to run side-by-side throughout the body. In the heart, which veins run along side the arteries listed below? Anterior interventricular artery
