2nd degree AV block:
is a disease of the electrical conduction system of the heart. It refers to a conduction blockbetween the atria and ventricles.
The presence of second-degree AV block is diagnosed when one or more (but not all) of the atrial impulses fail to conduct to the ventricles due to impaired conduction.
**for every ventricular contraction your having two atrial contractions hence (2:1)
**contraction of heart muscle**
period of contraction of the ventricles of the heart that occurs between the first and second heart sounds. Systole causes the ejection of blood into the aorta and pulmonary trunk. Lasting usually 0.3 to 0.4 second, ventricular systole is introduced by a very brief period of contraction, followed by the ejection phase, during which 80 to 100 cubic centimetres of blood leave each ventricle. During systole, arterial blood pressurereaches its peak
**relaxation of heart muscle, blood returns through R atrial and R ventricle**
in the cardiac cycle, period of relaxation of the heart muscle, accompanied by the filling of the chambers with blood. Diastole is followed in the cardiac cycle by a period of contraction, or systole, of the heart muscle. Initially both atria and ventricles are in diastole, and there is a period of rapid filling of the ventricles followed by a brief atrial systole. At the same time, there is a corresponding decrease in arterial blood pressure to its minimum (diastolic blood pressure)
Phases of the cardiac cycle:
1.) Ventricular filling- mid to late diastole (blood pressure low, blood enters atria and flow in ventricles)
AV valves are open then atrial systole occurs
2.) Ventricular systole- atria relax, rising ventricular pressure causes AV valve to close. Ventricular ejection phase opens semilunar valve
3.) Isovolumetric relaxation- early diastole. Ventricles relax, back flow of blood in aorta and pulmonary trunk close semilunar valve
What is inside of the pericardial cavity?
Describe the layers of the heart:
What are the first arteries to branch off the aorta?
Major stages of Cardiac Cycle
The first stage, "early diastole," is when the semilunar valves close, AV valves open. Heart is relaxed.
The second stage, "atrial systole," is when the atrium contracts, and blood flows from atrium to the ventricle
The third stage, "isovolumic contraction" is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume.
The fourth stage, "ventricular ejection," is when the ventricles are contracting and emptying, and the semilunar valves are open.
During the fifth stage, "isovolumic relaxation time", pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
After leaving the coronary sinus, where does the blood go?
What is the chordae tendinae?
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Describe the structure of the valves of the heart:
Blood passes through a valve before leaving each chamber of the heart. The valves prevent the backward flow of blood. Valves are actually flaps (leaflets) that act as one-way inlets for blood coming into a ventricle and one-way outlets for blood leaving a ventricle. Normal valves have three flaps (leaflets), except the mitral valve, which only has two flaps.
What makes the heart valves open and close?
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Where does most of the calcium come from when the calcium concentration rises during a cardiac action potential?
Why does cardiac muscle have a long refractory period?
Can the heart be tatananized?
Stenosis of the mitral valve may cause an increase in pressure in the?
What is the refractory period of cardiac muscle?
What does digitalis do?
The PR interval is the time in seconds from the beginning of the P wave to the beginning of the QRS complex. It corresponds to the time lag from the onset of atrial depolarization to the onset of ventricular depolarization. This time lag allows atrial systole to occur, filling the ventricles before ventricular systole
**heart enters diastole at end of PR interval**
The heart lies in the mediastinum? T/F
If the stroke volume were 70ml/beat how much blood might be pumped in one day in a normal person? Cardiac Output =
What is angina pectoris?
What is the dicrotic notch?
When do isovolumetric contractions occur?
What happens to the heart when the vagus nerve is cut?
What is angina?
What is congestive heart failure?