Lecture 17: Circulatory System Heart Flashcards
Circulatory System
Distributes oxygen and nutrients to body, and picks up waste materials to be eliminated by respiratory and urinary system
Includes heart and blood vessels
Mediastinum borders
Anterior border: sternum, costal cartilage
Lateral border: lungs
Posterior border: thoracic vertebrae
Superior border: manubrium of of sternum, ribs 1, T1
Inferior border: diaphragm
Contains heart, large vessels, esophagus, trachea, thoracic aorta
Parts of the mediastinum
Transverse plane through sternal angle at TIV, and TV divide it to superior and inferior mediastinum
Inferior mediastinum divided into 3 regions: anterior (in front of heart, between sternum and pericardium), middle (heart, surrounding membranes, pericardium), posterior (behind heart, between pericardium and vertebrae of TV-TXII)
Superior mediastinum
Contains:
Arch of aorta and branches (brachiocephlic artery, L common carotid artery, L subclavian artery)
R/L brachiocephalic veins, inferior part of superior vena cava, end of azygus vein
R/L phrenic and vagus nerve
Trachea, esophagus, thymus gland, thoracic duct
Anterior mediastinum
Contains:
thymus gland
Over age 25 - becomes loose connective tissue and fat
Middle mediastinum
Contains: Heart and pericardium Ascending aorta, pulmonary trunk, pulmonary veins R/L phrenic nerves Main bronchi
Posterior mediastinum
Contains: Descending aorta, azygus, hemiazygus veins R/L vagus nerve Sympathetic chains and splachnic nerve Thoracic duct and esophagus
Heart
Muscular pump in middle mediastinum (size of fist)
Superior and inferior collects venous/deoxygenated blood to body and sends it to R atrium -> R ventricle -> lungs (pulmonary circulation)
L atrium receives oxygenated blood from lungs via pulmonary vein -> L ventricle -> body (systemic circulation)
Surface anatomy of heart
Upper L corner: L 2nd intercostal space, 1 inch away from midline
Upper R corner: R 3rd costal cartilage, 1 inch away from midline
Lower R corner: R 6th costal cartilage, 1 inch away from midline
Lower L corner: L 5th intercostal space, 3-4 inches away from midline
Heart sulci
Coronary sulcus
Anterior interventricular sulci
Posterior interventricular sulci
Coronary sulcus / Atrial-ventricular sulcus
Encircles heart
Separates atria and ventricles
Contains coronary artery
Interventricular sulci
2 of them
Separates ventricles on anterior and inferior surface
Heart surfaces
Anterior/sternocostal surface
Inferior/diaphragmatic surface
Left pulmonary surface
Right pulmonary surface
Anterior / Sternocostal surface
In touch with sternum and 2-6 costal cartilages
Consists of R ventricle, R atrium, L ventricle
Inferior / diaphragmatic surface
Leans on diaphragm
Consists of L ventricle and R ventricle
Has posterior interventricular sulcus
Contains superior and inferior vena cava, pulmonary veins (2 per side)
L/R pulmonary surface
L - related to L lung, has L ventricle and L atrium
R - related to R lung, has R atrium
Base of heart
Faces posteriorly
Formed by L atrium and R atrium
Apex of heart
L ventricle
Directed anteriorly, inferiorly, to the L
Sits in 5th intercostal space on L, 3 inches away from sternum
Heart borders
Superior border - R/L atria and auricles
R border - R atrium
L border - L ventricle and L auricle
Inferior border - R ventricle and L ventricle (separates anterior and inferior surface)
R atrium
Get venous blood from superior vena cava, inferior vena cava, and coronary sinus
Pectinate muscles lines anterior part and extends to R auricle
Fossa ovalis
R atrioventricular/tricuspid valve - guards R atrioventricular opening that connects to R ventricle
Fossa ovalis
In interatrial septum
Remnant of embryonic foramen ovalis that used to connect R/L atrium
In embryonic stage, blood was oxygenated in R atrium by placenta, and the moment the baby cries, the connection is cut (due to pressure change)
R ventricle
Walls are thicker than R atrium
Trabeculae carneae (muscle fibers)
Papillary muscles (3)
Pulmonary artery from superior part
Pulmonary/semilunar valve that prevents blood flowing back
Interventricular septum (separates L/R ventricle)
Papillary muscles
Group of trabeculae carneae
Finger like projections from walls of ventricles that insert into tricuspid/bicuspid valve via chorda tendinae
L atrium
Receives oxygenated blood from R/L pulmonary veins
Pectinate muscles in L auricle
L atrioventricular/bicuspid/mitral valve guards L atrioventricular opening connecting to L ventricle
L ventricle
Thickest walls Trabeculae carneae Papillary muscles (2) Aorta from superior part Aorta/semilunar valve that prevents blood flowing back
Pericardial sac
Surrounds the heart
Composed of fibrous pericardium (outer) and serous pericardium (inner)
Fibrous pericardium
Dense connective tissue
Attaches to central tendon of diaphragm inferiorly, and great vessels of heart superiorly
Mechanically protects the heart
Serous pericardium
2 layers to secrete serous fluid
Parietal layer lines inner fibrous pericardium
Visceral layer (epicardium) attaches to heart
Pericardial cavity
Space between parietal and visceral layers of serous pericardium
Filled with serous fluid
Lubricates heart to facilitate movement
Conducting system of heart
Sinuatrial (SA) node
Atrioventricular (AV) node
Atrioventricular bundle (bundle of his)
Electrical impulses from modified myocardial cells start at SA node, propagates and contracts atrial walls before AV node. Impulse passes ventricular walls via bundle of His and Purkinje fibers to ventricular contraction via myocytes. Will give rise to a heart rate at a lower rate
Sinuatrial node
Heart pacemaker
R atrial wall close to superior vena cava opening
Atrioventricular node
R side of interatrial septum close to opening of coronary sinus
Atioventricular bundle
Starts at AV node -> interventricular septum -> L/R branches -> Purkinje fibers -> R/L ventricular walls
ANS and heart rate
Preganglionic sympathetic fibers from T1-T5 lateral horn to paravertebral sympathetic ganglion to cardiac plexus under aortic arch; increases heart rate
Preganglionic parasympathetic fibers from vagus nerve in medulla to cardiac plexus; decreases heart rate
Visceral afferent of cardiac plexus
Fibers with parasympathetic system (vagus nerve) - detect change in blood pressure/chemical content, and cardiac reflex
Fibers with sympathetic system return to upper 4-5 thoracic segments and conduct pain sensation from heart
R coronary artery
From R ascending aorta to R coronary sulcus
Supplies R atrium and R ventricle
R marginal artery (when passing R side)
Terminal branch, posterior interventricular artery, runs in posterior interventricular sulcus and supplies to posterior aspect of ventricles
L coronary artery
From L ascending aorta
Branches to anterior interventricular artery and circumflex artery
Anterior interventricular artery (left anterior descending artery) runs in anterior interventricular sulcus and supplies to anterior aspect of ventricles
Circumflex artery follows coronary sulcus to L side supplying to L atrium and L ventricle
Venous Drainage of heart
3 major veins
Great cardiac vein (anterior interventricular sulcus)
Middle cardiac vein (posterior interventricular sulcus)
Small cardiac vein (R coronary sulcus; follows R marginal artery)
All drain into coronary sinus in coronary sulcus on inferior surface, which drains into R atrium
