The heart


Lub


bicuspid and tricuspid valves close


Dub


pulmonary and aortic semi-lunar valves close


Cardiac conduction system


contraction of the atria and ventricles occur automatically as a result of electrical impulses that originate in and are conducted by heart tissues.


What four things happen as a result of the sinoatrial node?


1. Depolarization spreads in the myocardium2. lft and rgt atria contract3. atria empty and ventricles fill4. impulse picked up by conduction fibers that stimulate #2


Where is the Atrioventricular node found?


on the floor of the rght atrim near septum


Where is the atrioventricular bundle found and what does it split into?


found in the upper part of the interventricular septum. Splits into the lft and right bundle fibers


What is step four in the cardiac conduction system and where is it located?


Right and left bundle fiber. Found in the septum


What happens as a result of the Purkinje Fibers?


the ventricular muscle fibers depolarize and the ventricles contract.


How are the ventricular muscle fibers arranged as a result of the Purkinje Fibers?


the ventricle muscles are arranged in whorls that "wring" the ventricles dry.


In the Electrocardiogram what happens during the P Wave?


atrial depolarization


In the electrocardiogram, what happens during the QRS complex?


ventricular depolarization and atrial repolarization


In the Electrocardiogram, what happens during the T Wave?


Ventricular repolarization


What is special abou the QRS complex?


The atrial repolarization is not seen because overshadowed by the QRS complex.


Cardiac Cycle


this is the sequence of events in the heart b/w the start of one contraction and the start of the next.


Cardiac output


the amount of blood pumped out by each ventricle in 1min.


Cardiac Output Equation


Cardiac Output=Stroke Volume*Heart Rate


Stroke Volume


the amount of blood pumped out by one ventricle w/ each beat.~70 ml/beat


What five things is stroke volume regulated by?


SA node, Autonomic Nervous System, temp, hormones, and ions


SA node produces how many beats per min?


75 beats per min


Parasympathetic nervous sys


inhibits heart rate


sympathetic ner. sys.


inc. heart rate


Temperature


with inc in temp there is an inc in heart rate


The hormone epinephrine given off by the adrenal medulla will...


stimulate inc. HR


What is the name of the heart rate that will enhance the effects of the epinephrine and norepinephrine on the heart?


Thyroxin(T4) from the thyroid gland


K+


because inc or dec K+ alters the polarized state.


Hyperakalemia


slows down HR


hypoakalemia


slows up HR


Ca+


needed for contraction of the cardiac muscle tissue


Hypercalcemia


speeds up HR


hypocalcemia


slows down HR


Tachycardia


fast beats over 100/min


bradycardia


slow beat <60/min


Flutter


chamber contracts regularly but very fast 250-350 beats/min


Fibrillation


rapid but uncoordinated contractions


During fibrillation


not all areas contract together


During fibrillation, during atrial fibrillation


one can survive


During fibrillation, during ventricular fibrillation


it can be fatal


Arrhythmias


due to conduction disorders. Any interference or block in cardia impulse conduction may be the cause.


Pericardium


the CT covering of the heart-made up of 2 layers


Name four characteristics of visceral pericardium.


1. inner most layer2. very thin, serous membrane3. puts out fluid4. forms the epicardium


Parietal pericardium


is the outermost layer


Name four characteristics of the parietal pericardium.


1. outermost layer2. thick3. forms the pericardial sac4. pericardial cavity


pericardial cavity


is the space b/w the 2 pericardial layers. It is fluid filled. For protection.


The heart wall is composed of 3 layers


1. Epicardium2. Myocardium3. Endocardium


Epicardium


outer layer, thin, serous


Myocardium


thickest, middle layer, cardiac muscle


Endocardium


serous, thin, innermost layer of the heart...gives rise to the Purkinje Fibers that are specialized muscle fibers in the endocardium. Covers valves.


Atria and auricles


receive blood. Rt from body, left from lungs


Ventricles


pump bld out. Rt to lungs, left to body


Atrioventricular sulcus (coronary sulcus)


grooves b/w atria and ventricles, encircles the heart


Interventricular sulci


anterior and posterior, found b/w ventricles


Systemic circuit (left side of the heart)


left atrium->thru bicuspid valve-left ventricle-thru aortic semilunar valves-ascending aorta-aortic arch-descening aorta-arteries-arterioles-cap-venules-veins-superior or inferior vena cava-right atrium


pulmonary circuit(right side of the heart)


right atrium->thru tricuspid valve-right ventricle-thru pulmonary semilunar valves-pulmonary trunk-pulmonary arteries-pul.arterioles- pul. cap in lungs where gas exchange occurs-pul venules-pul. veins-left atrium


Right coronary artery has two main branches


posterior interventricular artery, marginal artery


posterior interventricular artery


feed the two ventricles


marginal artery


feeds the right atrium and right ventricles


left coronary artery has 2 main branches


circumflex artery, anterior interventricular artery


circumflex artery


feeds the left atrium and left ventricles


anterior interventricular artery


fees both ventricles


The cardiac veins run parallel to the arteries. They empty into what?


the coronary sinus that empties into the right atrium


Three vessels contribute to the coronary sinus.


1. Great Cardiac Vein2. Middle Cardiac Vein3. Small Cardiac Vein


Great cardiac vein


found in the anterior interventricular sulcus


Middle cardiac vein


found in the posterior interventricular sulcus


small cardiac vein


found in the inferior margin of the heart on the right