BSC 216 Lecture Notes - Lecture 6: Atrial Flutter, Heart Valve, Atrial Fibrillation
21 Feb 2018
School
Department
Course
Professor
Heart & Blood Vessels
• Interpret electrocardiogram waveforms for various dysrhythmias
o Sinus bradycardia:
▪ “Brady” = slow
▪ Probably explanations, increased parasympathetic tone
o Sinus tachycardia:
▪ “Tachy” = fast
▪ Response to exercise or congestive heart failure
▪ POTS!!
o Atrial flutter:
▪ Heart block at AV node or AV bundle
▪ Requires pacemaker if severe
o Atrial fibrillation:
▪ Irregular, chaotic atrial activation
▪ Hard to distinguish from flutter sometimes
▪ No P-wave shape
▪ Dendrites require many local action potentials to get other action
potentials started
o Ventricular Fibrillation:
▪ Irregular, chaotic ventricular activation
▪ Extremely serious (no pumping) cardiac arrest
▪ Requires CPR and defibrillation
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o Atrial can be life threatening but usually isn’t. Ventricular is extremely life
threatening.
• Describe the cardiac cycle and explain how the heart valves and pressure changes
result in one-way blood flow
o Heart beat:
▪ Coordination contraction of cardiac cells in a “wringing” motion that
generate pressure changes in the chambers
o Cardiac cycle:
▪ Sequence of events that take place between one heart beat and the next
▪ 1. Ventricular filling: filling blood into the ventricles; starts with
ventricles in diastole, pressure would be higher in atria, pulmonary trunk
and aorta. Semilunar valves closed and tricuspid and mitral valves are
open. AKA: Non-semilunar valves are open during this stage. Blood
drains from atria into ventricles. Atrial systole begins somewhere in the
middle of this stage.
▪ 2. Isovolumetric contraction: Pressure gradient is non-existent, not big
enough to open or close the valves; Ventricular systole begins.
Atrioventricular valves close (S1). Pressure not high enough yet to open
semilunar valves. Atrial diastole begins
▪ 3. Ventricular ejection: More pressure in ventricles than pulmonary artery
and aorta – opens pulmonary and aortic valve; ventricular systole
continues, pressure in ventricles exceeds pressure in pulmonary trunk and
aorta. Atria diastole continues
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▪ 4. Isovolumetric relaxation: All valves are closed; Ventricular diastole
begins. Pressure not high enough yet to open AV valves. Atria diastole
continues
o Diastole
▪ Period of relaxation for a heart chamber
o Systole
▪ Period of contraction for a heart chamber
▪ Atrial v. Ventricular
• What are the common structural components of blood vessels?
o Efferent pathways: taking blood away from the heart & into body
▪ 1. Heart
▪ 2. Elastic arteries
▪ 3. Muscular arteries
▪ 4. Arterioles
▪ 5. Capillaries
o Afferent pathways: taking blood back to the heart
▪ 1. Venules
▪ 2. Small veins
▪ 3. Large veins
▪ 4. Heart
o Only capillaries and venules exchange gas and nutrients with tissues
o Tunica externa (adventitia):
▪ Made of dense, irregular collagenous connective tissue
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find more resources at oneclass.com
Document Summary
Irregular, chaotic atrial activation: hard to distinguish from flutter sometimes, no p-wave shape, dendrites require many local action potentials to get other action potentials started, ventricular fibrillation: Irregular, chaotic ventricular activation: extremely serious (no pumping) cardiac arrest, requires cpr and defibrillation, atrial can be life threatening but usually isn"t. Ventricular filling: filling blood into the ventricles; starts with ventricles in diastole, pressure would be higher in atria, pulmonary trunk and aorta. Semilunar valves closed and tricuspid and mitral valves are open. Aka: non-semilunar valves are open during this stage. Atrial systole begins somewhere in the middle of this stage: 2. Isovolumetric contraction: pressure gradient is non-existent, not big enough to open or close the valves; ventricular systole begins. Pressure not high enough yet to open semilunar valves. Ventricular ejection: more pressure in ventricles than pulmonary artery and aorta opens pulmonary and aortic valve; ventricular systole continues, pressure in ventricles exceeds pressure in pulmonary trunk and aorta.
