heart, coronary vessels and conduction system

Question 1

what is the coronary circulation?

Answer 1

the vessels that supply and drain the heart

Question 2

what are the 2 main coronary arteries which branch to supply the heart?

Answer 2

the left and right coronary arteries

Question 3

where do the left and right coronary arteries arise from?

Answer 3

the left and right aortic sinuses within the aorta (small dilations or pockets located just above the aortic valve )

Question 4

what are the aortic sinuses?

Answer 4

small openings found within the aorta behind the left and right flaps of the aortic valve

Question 5

what are the branches of the left coronary artery?

Answer 5

-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

Question 6

what are the branches of the right coronary artery?

Answer 6

-right marginal artery
-posterior inter ventricular branch - in 80-855 of individuals
- AV nodal branch
-atrail-sinoatrial branch

Question 7

what is ischemic heart disease / coronary heart disease & what is this caused by?

Answer 7

• 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

Question 8

what structure is involved in the venous drainage of the heart?

Answer 8

a large venous structure located o the posterior aspect of the heart called the coronary sinus

Question 9

describe the great cardiac vein

Answer 9

• great cardiac vein (anterior inter ventricular vein) - originates at the apex of the heart and ascends - enlarges to form the coronary sinus

Question 10

Describe the middle cardiac vein

Answer 10

• 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

Question 11

describe the small cardiac vein

Answer 11

-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

Question 12

what is regurgitation with valves?

Answer 12

• 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

Question 13

what are the functions of the cardiac skeleton?

Answer 13

-maintenance of the integrity of the openings
-separates the atrial and ventricular musculature
-electrically isolates the atria from the ventricles

Question 13

what is the cardiac skeleton?

Answer 13

-fibrous skeleton of the heart - dense, fibrous connective tissue framework that gives structural support to the heart

Question 14

what are the right and left fibrous trigones?

Answer 14

-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

Question 15

what is the function of the cardiac conduction system?

Answer 15

it initiates and coordinates the contraction of the myocardium

Question 16

what are the components of the cardiac conduction system?

Answer 16

• SA node
  -AV node
  -bundle of his
  -purkinke fibres

Question 17

what is the SA node?

Answer 17

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

Question 18

what is the AV node?

Answer 18

-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

Question 19

what are cardiac arrhythmias?

Answer 19

abnormalities of the electrical impulses of the heart

Question 20

what are examples of cardiac arrthymias?

Answer 20

-atrial fibrillation
-bradycardia
-ventricular fibrillation
-ventricular tachycardia

Question 21

what is Wolff Parkinson white?

Answer 21

cardiac arrhythmia characterised by the presence of an extra electrical pathway in the heart

Question 22

what system innervates the heart?

Answer 22

the autonomic NS

Question 23

describe the conducting pathway in the heart

Answer 23

• 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

Question 24

where is the superficial cardiac plexus located?

Answer 24

-inferior to the aortic arch between the aortic arch and pulmonary trunk

Question 25

where is the deep cardiac plexus located?

Answer 25

-between the aortic arch and tracheal bifurcation