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Lecture

BIOB32H3 Lecture Notes - Sympathetic Nervous System, Autonomic Nervous System, Interventricular Septum


Department
Biological Sciences
Course Code
BIOB32H3
Professor
Kenneth Welch

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The Cardiovascular System: The Heart
Heart Anatomy
Approximately the size of your fist
Location
Superior surface of diaphragm
Left of the midline
Anterior to the vertebral column, posterior to the sternum
Heart Covering
Pericardial physiology
Protects and anchors heart
Prevents overfilling
Heart Covering
Pericardial anatomy
Fibrous pericardium
Serous pericardium (separated by pericardial cavity)
Epicardium (visceral layer)
Heart Wall
Epicardium visceral layer of the serous pericardium
Myocardium cardiac muscle layer forming the bulk of the heart
Fibrous skeleton of the heart crisscrossing, interlacing layer of connective tissue
Endocardium endothelial layer of the inner myocardial surface
External Heart: Major Vessels of the Heart (Anterior View)
Returning blood to the heart
Superior and inferior venae cavae
Right and left pulmonary veins
Conveying blood away from the heart
Pulmonary trunk, which splits into right and left pulmonary arteries
Ascending aorta (three branches) brachiocephalic, left common carotid, and subclavian
arteries
External Heart: Vessels that Supply/Drain the Heart (Anterior View)
Arteries right and left coronary (in atrioventricular groove), marginal, circumflex, and
anterior interventricular
Veins small cardiac vein, anterior cardiac vein, and great cardiac vein
External Heart: Major Vessels of the Heart (Posterior View)
Returning blood to the heart
Right and left pulmonary veins
Superior and inferior venae cavae
Conveying blood away from the heart
Aorta
Right and left pulmonary arteries
External Heart: Vessels that Supply/Drain the Heart (Posterior View)
Arteries right coronary artery (in atrioventricular groove) and the posterior interventricular
artery (in interventricular groove)
Veins great cardiac vein, posterior vein to left ventricle, coronary sinus, and middle
cardiac vein
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Gross Anatomy of Heart: Frontal Section
Frontal section showing interior chambers and valves
Major vessels leading to and from the heart
Gross Anatomy of Heart: Frontal Section
Atria of the Heart
Atria are the receiving chambers of the heart
Each atrium has a protruding auricle
Pectinate muscles mark atrial walls
Blood enters right atria from superior and inferior venae cavae and coronary sinus
Blood enters left atria from pulmonary veins
Ventricles of the Heart
Ventricles are the discharging chambers of the heart
Papillary muscles and trabeculae carneae muscles mark ventricular walls
Right ventricle pumps blood into the pulmonary trunk
Left ventricle pumps blood into the aorta
Pathway of Blood through the Heart and Lungs
Right atrium tricuspid valve right ventricle
Right ventricle pulmonary semilunar valve pulmonary arteries lungs
Lungs pulmonary veins left atrium
Left atrium bicuspid valve left ventricle
Left ventricle aortic semilunar valve aorta
Aorta systemic circulation
Coronary Circulation
Coronary circulation is the functional blood supply to the heart
Collateral routes insure blood delivery to heart even if major vessels are occluded
Heart Valves
Heart valves insure unidirectional blood flow through the heart
Atrioventricular (AV) valves lie between the atria and the ventricles
AV valves prevent backflow into the atria when ventricles contract
Chordae tendineae anchor AV valves to papillary muscles
Aortic semilunar valve lies between the left ventricle and the aorta
Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk
Semilunar valves prevent backflow of blood into the ventricles
Microscopic Heart Muscle Anatomy
Cardiac muscle is striated, short, fat, branched, and interconnected
Connective tissue endomysium acts as both tendon and insertion
Intercalated discs anchor cardiac cells together and allow free passage of ions
Heart muscle behaves as a functional syncytium
Cardiac Muscle Contraction
Heart muscle:
Is stimulated by nerves and self-excitable (automaticity)
Contracts as a unit
Has a long (250 ms) absolute refractory period
Cardiac muscle contraction is similar to skeletal muscle contraction
Heart Physiology: Intrinsic Conduction System
Autorhythmic cells:
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