HUMAN HEART Learn the following structures on the heart models. The human heart has four chambers that consist of the right atrium, left atrium, right ventricle, and left ventricle. The atria are smaller chambers situated on the upper part of the heart and receive blood from the veins of the body. The lower and larger ventricles are powerful pumps that deliver blood to the arteries and then to the organs of the body. The superior vena cava, inferior vena cava, and coronary sinus drain blood into the right atrium. The right ventricle pumps blood out the pulmonary trunk and to the lungs by way of the right and left pulmonary arteries. Oxygenated blood, from the lungs, flows into the right and left pulmonary veins and then enters the left atrium. The left ventricle pumps blood into the ascending aorta that curves into the aortic arch and then curves downward into the descending aorta. The aortic arch has three asymmetrical branches coming off starting with the brachiocephalic (innominate) trunk, then the left common carotid, and finally the left subclavian artery. The ligamentum arteriosum, located between the pulmonary trunk and aortic arch, is a connective tissue remnant of the ductus arteriosus. The heart s surface contains sulci, shallow grooves that contain coronary blood vessels and fat. The anterior interventricular sulcus and posterior interventricular sulcus divide the ventricles externally while the coronary sulcus separates the atria from the ventricles. Two small coronary arteries
branch off the beginning of the aortic arch. The right coronary artery contains the marginal branch and posterior interventricular branch. The left coronary artery divided into the circumflex and anterior interventricular branches. These branches deliver blood to the heart muscle. The heart is drained by the great cardiac vein, posterior cardiac vein, middle cardiac vein, and small cardiac vein. These veins drain into the coronary sinus located on the posterior wall of the heart between the atria and ventricles. The coronary sinus flows into the right atrium. Internally the two atria are separated by the interatrial septum whose right wall indentation is the fossa ovalis. The interventricular septum separates the two ventricles. The valves of the heart direct the flow of blood between the chambers and out the arteries. The valves found between the atria and ventricles are the atrioventricular valves with the tricuspid valve on the right side and the mitral valve (bicuspid) located on the left side. These valves contain cord-like chordae tendineae that connect the flaps or cusps to the papillary muscles attached to the inner wall of the ventricles. The semilunar valves separate the ventricles from the arteries. The pulmonary valve is located between the right ventricle and pulmonary trunk and the aortic valve is located between the left ventricle and aorta.
The heart s electrical excitation and synchronization of its chambers is achieved by the following structures. The pacemaker of the heart is the sinoatrial node located in the upper wall of the right atrium. Impulses from the sinoatrial node eventually excite the atrioventricular node that delivers impulses along the bundle branches within the interventricular septum to the hearts apex. From here the impulses are spread throughout the ventricles by the purkinje (conduction myofibers) fibers. SHEEP HEART Learn the following structures on the sheep heart. The outer thin epicardium can be observed when pulled away from the heart. The myocardium makes up the bulk of the heart chambers while the endocardium is a thin layer that lines the inner surface. Right atrium Left atrium Right ventricle Left ventricle Superior vena cava Inferior vena cava Pulmonary trunk (artery) Pulmonary veins (if present) Aorta Tricuspid valve Pulmonary valve Mitral (bicuspid) valve Aortic valve Papillary muscles Chordae tendineae
ARTERIES The major arteries of the systemic circuit start with the ascending aorta coming off the left ventricle. It then curves forming the aortic arch. The first branch is the brachiocephalic trunk that divides into the right common carotid and right subclavian artery. The next branch coming off the arch is the left common carotid and finally the left subclavian artery. The common carotids split in the neck into the external and internal carotid arteries sending blood to the head and brain respectively. The subclavian arteries each have a small vertebral artery that travels through the transverse foramina of the cervical vertebrae to the base of the brain where the two form the basilar artery. The basilar artery and internal carotids feed the brain. The subclavian changes into the axillary artery as it enters the armpit and then becomes the brachial artery as it reaches the arm. The brachial divides into the lateral radial artery and medial ulnar artery. They rejoin forming the palmar arches that feed into the digital arteries within the fingers.
The aortic arch continues to bend becoming the descending aorta. Above the diaphragm the descending aorta is the thoracic aorta and below the diaphragm the abdominal aorta. The first major branch of the abdominal aorta is the short celiac trunk that immediately branches into the left gastric artery, hepatic artery, and splenic artery delivering blood to the stomach, liver, and spleen respectively. The superior mesenteric artery delivers blood to the intestines and branches off the abdominal aorta just inferior to the celiac. The paired renal arteries come off the aorta and send blood to the two kidneys. Smaller adrenal (suprarenal) arteries come off the renal arteries on their way to the adrenal glands situated upon the kidneys. A pair of gonadal arteries (testicular or spermatic in males and ovarian in females) branch off the abdominal aorta followed by a singular inferior mesenteric artery. The abdominal aorta bifurcates into two common iliac arteries that become the external iliac arteries after the internal iliac arteries branches off the vessels. The external iliac continues within the abdominopelvic cavity and becomes the femoral artery as it leaves the cavity and courses along the thigh. The femoral artery has a medial deep femoral branch and a lateral circumflex branch. The femoral artery continues within the thigh and changes into the popliteal artery behind the knee. Further along on the leg the anterior tibial artery and posterior tibial artery branch. The anterior tibial becomes the dorsalis pedis on the dorsum of the foot. The fibular (peroneal) artery is a lateral vessel coming off the posterior tibial.
VEINS Systemic veins drain the same organs their namesake arteries feed. However, there are more veins draining the organs then arteries feeding them, especially in the appendages. The radial and ulnar veins of the forearm drain into the brachial vein that flows into the axillary vein. Superficial veins of the upper extremity also drain the arm. A medial basilic vein joins with the brachial vein becoming the axillary vein in the armpit, while the cephalic vein courses along the forearm and lateral arm before emptying into the subclavian vein where the axillary vein joins. Lateral to the cephalic vein on the forearm is the accessory cephalic vein. A short median cubital vein connects the cephalic vein with the basilic vein. The external jugular vein from the head and neck joins the subclavian vein. The union of the subclavian vein and the internal jugular vein forms the brachiocephalic vein. The two brachiocephalic veins, one from each side, become the superior vena cava. Two posterior veins collect blood from the thorax. Blood from the left side is collected by the hemiazygos vein that drains into the azygos vein. The azygos vein drains into the superior vena cava.
The lower extremities collect blood from the posterior tibial vein, fibular (peroneal) vein, anterior tibial vein, lateral circumflex vein, deep femoral vein, and femoral vein. These vessels run along side their artery counterparts. The lower extremities also collect blood from two superficial vessels, the small saphanous vein and great saphanous vein. The femoral vein becomes the external iliac vein and is joined by the internal iliac vein to become the common iliac vein. The two common iliac veins form the inferior vena cava. Vessels from the abdomiopelvic cavity flow into the inferior vena cava. The paired gonadal veins connect with the lower inferior vena cava while the adrenal veins join the renal veins before joining the central inferior vena cava. Vessels from the digestive organs flow into the liver before the hepatic veins join the upper inferior vena cava. The spleen is drained by the splenic vein, the stomach the left gastric vein, and the intestines the superior and inferior mesenteric veins. These four vessels drain blood into the hepatic portal vein that sends blood to the liver. The pulmonary circuit includes pulmonary arteries that deliver blood to the lungs while the pulmonary veins drain the lungs and send blood to the left atrium.
HUMAN HEART right atrium left atrium right ventricle left ventricle superior vena cava inferior vena cava pulmonary trunk right & left pulmonary arteries right & left pulmonary veins ascending aorta aortic arch descending aorta brachiocephalic trunk left common carotid left subclavian artery ligamentum arteriosum ductus arteriosus anterior interventricular sulcus posterior interventricular sulcus coronary sulcus right coronary artery marginal branch posterior interventricular branch left coronary artery circumflex branch anterior interventricular branche great cardiac vein posterior cardiac vein middle cardiac vein small cardiac vein coronary sinus interatrial septum fossa ovalis interventricular septum right atrioventricular valve (tricuspid) left atrioventricular vavlve (bicuspid or mitral) chordae tendineae papillary muscles pulmonary valve aortic valve sinoatrial node atrioventricular node bundle branches purkinje fibers. SHEEP HEART epicardium myocardium endocardium Right atrium Left atrium Right ventricle Left ventricle Superior vena cava Inferior vena cava Pulmonary trunk (artery) Pulmonary veins (if present) Aorta Tricuspid valve Pulmonary valve Mitral (bicuspid) valve Aortic valve Papillary muscles Chordae tendineae ARTERIES ascending aorta aortic arch brachiocephalic trunk right common carotid right subclavian artery left common carotid left subclavian artery external and internal carotid arteries vertebral artery basilar artery axillary artery brachial artery radial artery ulnar artery palmar arches digital arteries descending aorta thoracic aorta abdominal aorta celiac trunk left gastric artery hepatic artery splenic artery superior mesenteric artery renal arteries
adrenal (suprarenal) arteries gonadal arteries (spermatic or ovarian) inferior mesenteric artery common iliac arteries external iliac arteries internal iliac arteries femoral artery deep femoral lateral circumflex branch popliteal artery anterior tibial artery posterior tibial artery dorsalis pedis fibular (peroneal) artery VEINS radial vein ulnar vein brachial vein axillary vein basilic vein cephalic vein subclavian vein accessory cephalic vein median cubital vein external jugular vein subclavian vein internal jugular vein brachiocephalic vein superior vena cava hemiazygos vein azygos vein posterior tibial vein fibular (peroneal) vein anterior tibial vein lateral circumflex vein deep femoral vein femoral vein small saphanous vein great saphanous vein external iliac vein internal iliac vein common iliac vein. inferior vena cava gonadal veins adrenal veins renal veins hepatic veins splenic vein left gastric vein superior and inferior mesenteric veins hepatic portal vein pulmonary arteries pulmonary veins
HISTOLOGY Blood Vessels Slide # 1. Page 573. Find the artery and vein on the slide then identify the tunica intima, tunica media, and tunica externa on each vessel. Blood Smear Slide # 2. Pages 540 and 544. Identify the erythrocytes, neutrophils, lymphocytes, monocytes, eosinophils, basophils, and platelets (thrombocytes). Lymph Nodes Slide # 3. Identify the capsule, trabeculae, cortex with its lymphatic nodules, and the medulla with its medullary cords.