heart, coronary vessels and conduction system Flashcards
what is the coronary circulation?
the vessels that supply and drain the heart
what are the 2 main coronary arteries which branch to supply the heart?
the left and right coronary arteries
where do the left and right coronary arteries arise from?
the left and right aortic sinuses within the aorta (small dilations or pockets located just above the aortic valve )
what are the aortic sinuses?
small openings found within the aorta behind the left and right flaps of the aortic valve
what are the branches of the left coronary artery?
-anterior interventricular artery / left anterior descending artery
-left marginal artery
-left circumflex artery
-in some individuals, the left circumflex artery contributes to the posterior inter ventricular artery
what are the branches of the right coronary artery?
-right marginal artery
-posterior inter ventricular branch - in 80-855 of individuals
- AV nodal branch
-atrail-sinoatrial branch
what is ischemic heart disease / coronary heart disease & what is this caused by?
- reduced blood flow to the heart muscle
-reduction of blood flow is usually caused by a build up of fatty deposits in the coronary arteries - leading to atherosclerosis
what structure is involved in the venous drainage of the heart?
a large venous structure located o the posterior aspect of the heart called the coronary sinus
describe the great cardiac vein
- great cardiac vein (anterior inter ventricular vein) - originates at the apex of the heart and ascends - enlarges to form the coronary sinus
Describe the middle cardiac vein
- also called the posterior inter ventricular vein
-begins at the apex of the heart and ascends in the posterior inter ventricular groove to empty into the coronary sinus
describe the small cardiac vein
-located on the anterior surface of the heart in a groove between the RA and RV
-travels within this groove onto the posterior surface of the heart where it empties into the coronary sinus
what is regurgitation with valves?
- a condition in which one or more heart valves do not close properly during the cardiac cycle
-this leads to backward flow or leakage of blood - can occur in the mitral and aortic valve
what are the functions of the cardiac skeleton?
-maintenance of the integrity of the openings
-separates the atrial and ventricular musculature
-electrically isolates the atria from the ventricles
what is the cardiac skeleton?
-fibrous skeleton of the heart - dense, fibrous connective tissue framework that gives structural support to the heart
what are the right and left fibrous trigones?
-specific regions within the cardiac fibrous skeleton
-right fibrous trigone forms the boundary between the RA & RV
-left fibrous trigone forms the boundary between the LA and LV
what is the function of the cardiac conduction system?
it initiates and coordinates the contraction of the myocardium
what are the components of the cardiac conduction system?
- SA node
-AV node
-bundle of his
-purkinke fibres
what is the SA node?
collection of pacemaker cells in the upper wall of the RA
it functions to spontaneously generate electrical impulses - which spreads via gap junctions across both atria and ventricles
what is the AV node?
-located in the atrioventricular septum near opening of coronary sinus
-acts to delay the impulses by 120ms to ensure the atria have enough time to fully inject the blood into the ventricles before ventricular systole
what are cardiac arrhythmias?
abnormalities of the electrical impulses of the heart
what are examples of cardiac arrthymias?
-atrial fibrillation
-bradycardia
-ventricular fibrillation
-ventricular tachycardia
what is Wolff Parkinson white?
cardiac arrhythmia characterised by the presence of an extra electrical pathway in the heart
what system innervates the heart?
the autonomic NS
describe the conducting pathway in the heart
- SA node initiates the electrical impulse
- then spreads across the atria - causing the atria to contract and eject blood into ventricles
-AV node delays the impulse to allow time to fill ventricles - impulses travel down the bundle of His after the AV node
-bundle of his then branch into purkinje fibres which rapidly conduct electrical pulses to the muscles of the ventricles
where is the superficial cardiac plexus located?
-inferior to the aortic arch between the aortic arch and pulmonary trunk
where is the deep cardiac plexus located?
-between the aortic arch and tracheal bifurcation
