Lecture 5 Flashcards
exam 1 contant
what is the purpose of the visceral serous pericardium?
this is the innermost layer of the pericardium it is really stretchy and helps the heart move around while limiting friction
where is the parietal layer of the serous pericardium?
this layer is “glued” to the fibrous layer (the outer) pericardium
What are the two ions that can move through gap junctions?
Na+ and Ca2+ (mainly Na+)
what structures attach to the cusps or leaflets of our AV valves? What is their function?
chordae tendineae attach to the cusps, which are attached to papillary muscles that are continuous with the ventricular muscles. These contract with the ventricle to keep the cusps of the valves from being blown out into the atria during ejection.
Which valve helps to increase coronary blood flow?
the aortic valve
How is coronary blood flow increased during ejection?
the cusps of the aortic valve form a bowl and and pressure in the aorta is really high which drives blood back into these “cups” which can aid filling of the coronary arteries
What acts as insulation to keep the electrical activity separate between the top half of the heart from the bottom half and how do the atria “talk” to the ventricles?
large cartilaginous rings separates the atrial muscles from the ventricular muscles (so that they cannot conduct electricity between one another). There is an opening for the Bundle of His in this ring structure which allows the atria to talk to the ventricles via nodal tissue
What are the three coronary arteries and which two originate from the left coronary?
- RCA (right)
- LAD (left)
- Circumflex (left)
How much blood per minute does the heart need to satisfy a normal metabolic requirement?
225 mL/min (70mL/min/100grams heart tissue)
what are the two components of the change in pressure that impact coronary blood flow (delta P)
- aortic pressure
- ventricular wall pressure
If aortic pressure is high, coronary blood flow_____.
increases
If aortic pressure is low, coronary perfusion_____.
decreases
In addition to pressures what else is important to coronary perfusion?
diastolic time
When ventricular pressure is higher than aortic pressure what are a few things that can happen
- aortic valve opens and blood is ejected
- delta P is negative –> retrograde perfusion of the coronaries (bad)
What does spinal anesthesia do to CO and filling pressure
decreases CO and reduces filling pressures (anesthesia causes a circulatory problem)
What causes a waves in the CVP waveform?
atrial contraction
What causes c waves in the CVP waveform?
a function of the AV valves bulging backwards
What causes the v wave in the CVP waveform?
increased atrial pressure as a result of filling while the AV valves are closed
what causes the x descent in the CVP waveform and where is it?
after AV valves bulge backwards and the atria are very empty which creates a very low pressure. After the c wave.
Where does the y descent in the CVP waveform occur and what causes it?
After the v wave. It is a function of decreased pressure as a result of the blood moving from the atria to the ventricle.
what is a normal range for SVR?
800-1600 dynes*sec/cm5
What is the formula for calculating SVR?
((MAP - CVP) / CO) x 80
What is a normal range for PVR (pulmonary vascular resistance)?
40-180 dynes*sec/cm5
What is the formula for PVR?
mean ((PAP - PAWP) / CO) x 80
What happens to PAP and CVP upon inspiration?
both of these decrease d/t more negative intrathoracic pressure
What happens to CO in the right heart initially with inspiration?
preload drops (due to the more negative pressure established in the thorax) and afterload is also reduced (reduced PAP) , so CO drops a little
What happens to CO in the left heart initially with inspiration?
preload drops (reduced PAP), but aortic pressure is still about 80 mmHg, which is pretty high (won’t really change because the aorta is not compliant) so CO decreases significantly
What is a normal intrapleural pressure?
-4 mmHg or -5 cmH2O
