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53 terms

Blood Supply, Venous Drainage, and Innervation of th Heart (Chp 3)

What arteries supply blood to the heart?
right and left coronary artery
What does the right coronary artery supply blood to?
right atrium, including the SA and AV nodes and posterior parts of interventricular septum
What are the branches of the right coronary artery?
SA-nodal artery, right marginal artery, posterior interventricular artery, and AV-nodal artery
What does the SA-nodal artery supply blood to?
the SA node and the pulmonary trunk
What does the right marginal artery supply blood to?
right ventricle and apex of the heart
What does the posterior interventricular artery supply blood to?
both ventricles, including posterior and inferior walls of left ventricle, and posterior part of the interventricular septum
What does the AV-nodal artery supple bood to?
AV node in 80% of people
What does the left coronary artery supply blood to?
most of left atrium, left ventricle, interventricular septum, AV bundles of conductive system, and SA node in some people
What are the branches of the left coronary atery?
anterior interventricular artery, circumflex branch, and left marginal artery
What does the anterior interventricular artery supply blood to?
both ventricles and the anterior two-thirds of the interventricular septum
What does the circumflex branch supply blood to?
left atrium,left surface of the heart, and left ventricle
What is the left marginal artery and what does it supply blood to?
a branch of the circumflex artery and supplies blood to the left ventricle
What are coronary arteries and therefore, what do they not have?
functional end arteries, they dont have large precapillary anastomosis (a connection between adjacent blood vessels) to provide alternative blood supply to a part of the myocardium if the main artery is blocked
What may happen if there is a sudden blockage of the coronary vessels or their major branches and why?
it may lead to myocardial infarction and death because they dont have anastomatic connections
What may a heart attack be a result of?
blockage of the smaller coronary arteries
What are the few anastomoses that exist in the coronary arteries?
the connection between the anterior and posterior interventricular aretroles or connection between the right coronary artery and the circumflex artery
What are the three major cardiac veins?
great cardiac vein, small cardiac vein, and middle cardiac vein
What do the main cardiac veins drain into?
coronary sinus
Where are the branches of the great cardiac vein?
one branch runs along the anterior interventricular groove (accompanied by ant. interventricular a.) and the other branch runs along the left coronary sulcus (accompanied by left coronary a.)
What does the middle cardiac vein do?
drains most of the blood supplied by the right coronary artery
What are other veins of the heart?
left posterior ventricular vein, left marginal vein, oblique vein of the left atrium, anterior cardiac vein, and smallest cardiac vein
What does the left posterior ventricular vein drain into?
coronary sinus
What is the oblique vein of the left atrium?
a remnant of the left superior vena cava, which disappears during gestation; it is seen on the posterior aspect of the left atrium and drains into the great cardiac vein
Where do the anterior cardiac veins enter?
directly into the right atrium
Where do the smallest cardiac veins go and what do they do?
go directly into the heart chambers (mainly atria) and they carry blood to the myocardium
What does the coronary sinus receive?
receives majority of the blood returning from the heart and drains it into the right atrium
What is atherosclerosis of the coronary vessels and what can it lead to?
when plaques of fatty material form in the lumen of the coronary arteries causing the blood supply of the heart to be compromised and leads to chest pain or angina pectoris (chest pain caused from lack of blood to the heart), and also lead to narrowing of the lumen
How can the lumen narrowings be detected in atherosclerosis?
by angiography in which you inject a contrast medium
How is angiography done?
by injecting contrast medium/ catheter into the femoral or brachial artery and is guided toward the origin of the aorta into the coronary vessels (through the arch of aorta backward into the ascending aorta)
What happens in percutaneous transluminal coronary angioplasty?
when you reach the arterial narrowing, a balloon is inflated close to the tip of the catheter at the site of the narrowing, it then stretches the arterial wall and squashes the atherosclerotic plaque, which then restores the blood supply to the affected part of the myocardium
When do you use a stent, where do you put it, and why?
you use it after you do the angioplasty and you place into the lumen of the coronary artery to function for a long time and keep it open to prevent plaque from occluding (blocking) the vessel
What are other preventative methods of atherosclerosis?
nonsteriodal anti-inflammatroy drugs (NSAIDs) and thrombolytic medication
What is the innervation of the heart?
sympathetic nerve and parasympathetic nerve
What does the sympathetic nerve originate from?
it originates from the preganglionic neurons in the intermediolateral gray column of 5-6 upper thoracic segments and synapse in the sympathetic chain, icluding the stellate and middle cervical sympathetic ganglia
Where do the postsynaptic fibers (cardiopulmonary splanchnic nerves) reach the cardiac plexus and end?
close to the bifurcation of the trachea and end on the SA and AV nodes, the myocardium, and the coronary vessels
What does the sympathetic nerve do in the heart?
increases the heart rate, contraction force, and impulse conduction of the heart acting on the beta1- receptor
What does the sympathetic nerve do in the coronary arteries?
it leads to dilation by acting on the beta2-receptor to meet the demand for blood and oxygen when myocardial contractility increases
How is the sensory information of the heart transmitted?
through the sympathetic nerves to the upper thoracic (T1-T5) spinal cord and conveys (carrys) the pain information to the higher brain centers
Where is referred pain of the angina pectoris typically felt and why?
in the left shoulder and arm, due to the sensory termination in spinal levels that the brachial plexus (C5-T1) is also associated with
What is the parasympathetic nerve?
vagus nerve axons (preganglionic fibers) that terminate on many small ganglia on the heart
What do the postganglionic fibers innervate?
the heart and vessels through muscarinic receptors
What does the parasympathetic nerve do?
decreases the heart rate and force, and is a vasoconstrictor (constricts blood vessels which increase blood pressure) to the coronary arteries
What are the lymphatics of the heart drained by?
the subpericardial plexus, which receives lymph from the myocardial and the subendocardial lymphatic plexus
What does the subpericardial plexus merge with?
right and left cardiac-collecting trunks into the bronchomediastinal trunk which drains into the left venous angle at the junction between the left subclavian and internal jugular veins
What are the two phases in a cardiac cycle?
systole and diastole
What happens during the systole phase?
the blood-filled ventricles are emptied by contraction of the ventricles
What happens during the diastole phase or relaxation phase?
the ventricles become filled with blood
What is the systole phase characterized by?
isovolumetric contraction and the ejection period
What happens in isovolumetric contraction during the systole phase?
at the beginning of systole all valves are closed; pressure then rises in the ventricles and when the intraventricular pressure equals the pressure in the aorta, the aortic valve opens
What happens in the ejection period during the systole phase?
the aortic valve opens and about 70 mL of blood is ejected into the aorta (cardiac output) and the pressure rises in the aorta to about 120 mmHg (in pulmonary trunk it reaches about 20 mmHg); the intraventricular pressure then falls below that of the aorta, which results in closure of the aortic valve
What is the diastole phase characterized by?
isovolumetric relaxation and filling time
What happens in isovolumetric relaxation during the diastole phase?
the atrioventricular and aortic valves are closed, with approximately 70 mL of blood already inside the ventricle; as a result the intraventricular pressure drops below that of the atrium
What happens in filling time during the diastole phase?
the atrioventricular valve opens and blood enters the ventricle; at the end of this period atrial systole (contraction) takes place