cardiac questions help please

AnnieOaklyRN, BSN, RN, EMT-P · Mar 5, 2007

Your aorta has barro receptors which regulate heart rate depending on the pressure in them. THink about this one, its logical.

A u wave can represent an electrolyte imbalance if prominent (bigger than the pwave) or in a few poeple a smaller u wave represent the end of ventricular depolarization and is a normal finding. It comes shortly after the t wave before the p wave.

An increased heart rate may decrease arterial blood volume and decrease BP becasue the ventricals do not have as much time to fill, but this is dependent on how much of an increase in heart rate occurs. THis is also dependent on reason for the increased heart rate and if it is due to catacholamine release as both epi and nor epi effect the diameter of blood vessels in different ways depending on where they are located.

swtooth

emmycRN · Mar 5, 2007

I have an exam tomorrow in A&P II, and there are a couple of cardiac review questions that I had trouble with. If anyone has answers/websites I would really appreciate it - my book doesn't seem to discuss these particular things in the related chapter, but my prof has a bad habit of occasionally testing us on things covered in a chapter we haven't done yet.
1)How do decreases in carotid and aortic blood pressure affect the heart rate (speed up/slow down)? this is two questions
2)On an EKG, is there such a thing as a U wave? The question asks what P, QRS, T, and U represent. I know the first three - is U something we didn't cover, or a typo?
3)What effect does an increase in heart rate have on arterial blood volume and on blood pressure?
I'm not asking anyone to do my homework for me, and this is not something we turn in. We are encouraged to find the answers to these, as all this material is fair game for the exam. We can help each other, but I already posted this on my class discussion board and only got one tentative response so far, to one of the questions. The exam is tomorrow, so if anyone has already covered this stuff and can help, I would really really appreciate it! Thanks in advance!
-MMW

1) A decrease in BP usually causes the heart rate to increase. This is a compensatory response by the body.

2) I have heard of U waves but can't remember what causes them.

3) I don't think an increase in heart rate can effect blood volume but hypovolemia can result in an increased heart rate. Again, this is a compensatory response by the body to maintain tissue perfusion.

BBFRN, BSN, PhD · Mar 5, 2007

Attached is a picture of a U wave. Here is a link with info regarding causes and differentiation: http://library.med.utah.edu/kw/ecg/ecg_outline/Lesson12/index.html

An increase in heart rate can affect volume as swtooth said.

MB37 · Mar 5, 2007

Thanks guys! Our book really doesn't mention the U wave at all, and the EKGs it shows are flat between T and P. I did figure out the basoreceptor thing, What threw me off was carotid vs. aortic, because we aren't doing blood vessels/circulatory until the next exam, and haven't actually been taught what/where the carotid artery even is, let alone if there is anything special about blood pressure there. The I can see that because filling time is decreased with an increased heart rate, that would cause a drop in arterial blood volume. So, then if low BP leads to an increased heart rate, does an increased heart rate increase BP? I guess sympathetic stimulation is associated with both higher HR and BP, so maybe it depends on the cause as you said. Thanks for the help!

lisabeth · Mar 6, 2007

To be honest, all we studied was P,Q,R,S and T waves. :confused:

Princess Conswalla · Oct 27, 2009

I believe that the u wave has to do with potassium