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Lub
bicuspid and tricuspid valves close
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Dub
pulmonary and aortic semi-lunar valves close
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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.
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What four things happen as a result of the sinoatrial node?
- 1. Depolarization spreads in the myocardium
- 2. lft and rgt atria contract
- 3. atria empty and ventricles fill
- 4. impulse picked up by conduction fibers that stimulate #2
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Where is the Atrioventricular node found?
on the floor of the rght atrim near septum
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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
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What is step four in the cardiac conduction system and where is it located?
Right and left bundle fiber. Found in the septum
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What happens as a result of the Purkinje Fibers?
the ventricular muscle fibers depolarize and the ventricles contract.
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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.
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In the Electrocardiogram what happens during the P Wave?
atrial depolarization
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In the electrocardiogram, what happens during the QRS complex?
ventricular depolarization and atrial repolarization
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In the Electrocardiogram, what happens during the T Wave?
Ventricular repolarization
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What is special abou the QRS complex?
The atrial repolarization is not seen because overshadowed by the QRS complex.
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Cardiac Cycle
this is the sequence of events in the heart b/w the start of one contraction and the start of the next.
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Cardiac output
the amount of blood pumped out by each ventricle in 1min.
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Cardiac Output Equation
Cardiac Output=Stroke Volume*Heart Rate
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Stroke Volume
the amount of blood pumped out by one ventricle w/ each beat.~70 ml/beat
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What five things is stroke volume regulated by?
SA node, Autonomic Nervous System, temp, hormones, and ions
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SA node produces how many beats per min?
75 beats per min
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Parasympathetic nervous sys
inhibits heart rate
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sympathetic ner. sys.
inc. heart rate
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Temperature
with inc in temp there is an inc in heart rate
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The hormone epinephrine given off by the adrenal medulla will...
stimulate inc. HR
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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
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K+
because inc or dec K+ alters the polarized state.
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Hyperakalemia
slows down HR
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Ca+
needed for contraction of the cardiac muscle tissue
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Hypercalcemia
speeds up HR
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hypocalcemia
slows down HR
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Tachycardia
fast beats over 100/min
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bradycardia
slow beat <60/min
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Flutter
chamber contracts regularly but very fast 250-350 beats/min
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Fibrillation
rapid but uncoordinated contractions
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During fibrillation
not all areas contract together
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During fibrillation, during atrial fibrillation
one can survive
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During fibrillation, during ventricular fibrillation
it can be fatal
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Arrhythmias
due to conduction disorders. Any interference or block in cardia impulse conduction may be the cause.
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Pericardium
the CT covering of the heart-made up of 2 layers
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Name four characteristics of visceral pericardium.
- 1. inner most layer
- 2. very thin, serous membrane
- 3. puts out fluid
- 4. forms the epicardium
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Parietal pericardium
is the outermost layer
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Name four characteristics of the parietal pericardium.
- 1. outermost layer
- 2. thick
- 3. forms the pericardial sac
- 4. pericardial cavity
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pericardial cavity
is the space b/w the 2 pericardial layers. It is fluid filled. For protection.
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The heart wall is composed of 3 layers
- 1. Epicardium
- 2. Myocardium
- 3. Endocardium
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Epicardium
outer layer, thin, serous
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Myocardium
thickest, middle layer, cardiac muscle
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Endocardium
serous, thin, innermost layer of the heart...gives rise to the Purkinje Fibers that are specialized muscle fibers in the endocardium. Covers valves.
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Atria and auricles
receive blood. Rt from body, left from lungs
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Ventricles
pump bld out. Rt to lungs, left to body
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Atrioventricular sulcus (coronary sulcus)
grooves b/w atria and ventricles, encircles the heart
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Interventricular sulci
anterior and posterior, found b/w ventricles
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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
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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
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Right coronary artery has two main branches
posterior interventricular artery, marginal artery
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posterior interventricular artery
feed the two ventricles
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marginal artery
feeds the right atrium and right ventricles
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left coronary artery has 2 main branches
circumflex artery, anterior interventricular artery
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circumflex artery
feeds the left atrium and left ventricles
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anterior interventricular artery
fees both ventricles
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The cardiac veins run parallel to the arteries. They empty into what?
the coronary sinus that empties into the right atrium
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Three vessels contribute to the coronary sinus.
- 1. Great Cardiac Vein
- 2. Middle Cardiac Vein
- 3. Small Cardiac Vein
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Great cardiac vein
found in the anterior interventricular sulcus
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Middle cardiac vein
found in the posterior interventricular sulcus
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small cardiac vein
found in the inferior margin of the heart on the right
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