Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
72 Cards in this Set
- Front
- Back
|
Why does the EKG not show depolarization/repolarization of the nodes?
|
They are too physically small and size of the d/ring tissue determines the magnitude of the spike. (that is why the p wave is small)
|
|
|
What direction is the vector going during depolarization vs repolarization? Why?
|
same direction as depolarization, opposite direction as repolarization because the signs are switched.
|
|
|
Should you give prophylactic abx for mitral prolapse? Why or why not
|
no not anymore. most people live with mitral prolapse without complications for their life
|
|
|
Who gets mitral valve prolapse?
|
thin young girls and athletic people on boards, but equally on both
|
|
|
What would you hear on a mitrl valve prolapse?
|
A mid systolic click when the valve pops up followed by a late systolic murmur as the blood may regurgitate.
|
|
|
Why does mitral valve prolapse happen?
|
Either the tissue of the valve is weak or the tendons of the chordae tendonae snapped off.
|
|
|
How would you fix a mitral valve regurgitation?
|
You can implant a annuloplasty ring there in surgery and then reshape it using several methods afterwards to prevent regurgitation.
|
|
|
Why may a mitral valve have regurgitation without prolapse?
|
If you have cardiomegaly and the ring gets stretched out.
|
|
|
What are the most common types of valvular disease?
|
prolapse and regurgitation
|
|
|
On boards, how can you tell if it is a stenosis or regurgitation?
|
stenosis if during systole on A or P valve and regurgitation if during diastole on those.
|
|
|
What can give you left axis deviation or right axis deviation?
|
left or right hypertrophy or necrosis. Anything that changes the cells available to become electrically active.
|
|
|
How can you tell if you have sinus rhythm?
|
If there is a p wave before every QRS complex.
|
|
|
WHat does ACh on the SA node do?
|
Increases permeability to potassium?
|
|
|
What does NE on the SA Node do?
|
increases permeability to calcium and Na
|
|
|
What is sinus arrythmmia? Why may this happen?
|
When you get increased firing of the SA node with inspiration. This happens when there is a neuronal thing going on and there is crossfirign of respiratory neurons and autonomic neurons controlling the heart.
|
|
|
What is the normal PR interval?
|
120-200 ms
|
|
|
What does a Mobitz type I/Wenckeback heart block look like?
|
The PR interval gets gradually longer and longer until lose a QRST and then it resets to the beginning of the cycle again.
|
|
|
What causes Mobitz type I? Why do you think this?
|
A disease of the AV node because it is not being responsive to a conducted atrial signal. It's refractory period is longer than usual.
|
|
|
How does a Mobitz type II/Hay look different than a mobitz type I?
|
There is still a drop in QRS complex, but it is not proceeded by a gradually lengthening PR interval. You can have a 3:1 or 4:1 ratio of normal beats to dropped beats.
|
|
|
What causes a mobitz type II?
|
Some sort of disease below the AV node. The refractory period on cells pretty high up has increased, but the AV node is fine.
|
|
|
What is a first degree heart block?
|
One that blocks from the SA node to the AV node
|
|
|
What is a second degree heart block?
|
One that block s between the atria and the ventricles?
|
|
|
What is a complete heart block? What is it also called?
|
A third degree heart block. It is when the SA node signal doesn't get to the AV node at all.
|
|
|
What does a complete heart block look like on an EKG? Why?
|
More p waves than QRS and they don't seem to sync up. This is because the SA node is firing and contracting atria and the AV node is firing at it's low rate and contracting the ventricles.
|
|
|
What does a fib look like on an EKG? Why?
|
a bunch of small p waves together caused by reentry loops.
|
|
|
Why is a fib not so bad in younger people?
|
atrial contraction doesn't contribute that much to ventricular filling, about 10-15% so in younger people it doesn't cause much hemodynamic compromise.
|
|
|
What does ventricular fibrillation look like on an EKG?
|
completely irrgular with no clear P, QRS, or T and very low amplitude.
|
|
|
Why is the amplitude so low?
|
because there is depolarization in all directions so vectors will cancel each other out.
|
|
|
Why does shocking someone with ventricular fibrillation work?
|
It gets it so all cells are depolarized at once instead of them being all over the place. You hope that then the SA node can take over again.
|
|
|
Which part of the ventricle depolarizes first?
|
The left intraventricular septum.
|
|
|
So out of lead I, II, and III, which ones will go up in the beginning of ventricular depolarization and which ones will go down?
|
It's going from left to right so:
I and II will go down III will go up |
|
|
Whcih ventricle completely depolarizes first? What is the implication of this on the EKG?
|
The right because it is not as big. This means that the after septal depolarization, the vector will go from right to left.
|
|
|
What is the last part of the ventricle to depolarize? What direction is this vector in?
|
The upper part of the left ventricle wall. The vector will be pointing to the left and slightly upward.
|
|
|
Why is the T wave positive in lead I and II?
|
The ventricles repolarize from the outside in due to differences in cells on the outside and inside. So the vector is pointed to the left and down again.
Last cell to depolarize are the first to repolarize. |
|
|
What is the straight horizontal line on the EKG called?
|
The isoelectric line
|
|
|
What is included in the PR interval?
|
P wave to beginning of QRS
|
|
|
How long is the normal PR interval? What does this represent?
|
.12 - .2 seconds (3-5 boxes)
Atrial depolarization to passing the AV Node. |
|
|
What is included in the QRS?
|
from isoelectric line to isoelectric line
|
|
|
How long is the QRS complex? What does it represent?
|
.06 - .1 seconds (1.5 - 2.5 boxes)
Time for ventricular depolarization |
|
|
What waves make up the QRS complex?
|
Q wave (down)
R wave (large spike) S wave (down) |
|
|
What is the J point? What does it look like if the ST segment is not flat with the isoelectric point?
|
The J point is where the S wave ends and the ST segment begins. It can look like the point of kinking if the ST is not flat.
|
|
|
What does the Q wave correspond to?
|
The depolarization of the septum from left to right
|
|
|
What does the R wave correspond to?
|
The depolarization of most of the ventricle (largest mass and amplitude)
|
|
|
What does the S wave correspond to?
|
The final depolarization of the ventricle. (going to the top left of the ventricle, but facing mostly left horizontal)
|
|
|
What is the only lead out of einthovin's triangle that has the downward deflecting S wave?
|
Lead III because it is the only one with a right facing vectr component. The last depolarization goes only left.
|
|
|
In what order does cardiac tissue repolarize?
|
From the outside (esp on left) to the inside. The vector is down and to the left (reversed from direction of repolarization)
|
|
|
How long does the P wave usually last?
|
.08-.1 seconds (2-2.5 blocks)
|
|
|
What will stimulate endothelial cells to produce NO?
|
ACh on muscarinic receptors, Histamine on H1 receptors, Epi and NE on A2 receptors, and Thrombin
|
|
|
What enzyme creates NO and from what substrate?
|
Nitric Oxide Synthase (NOS) from L-arginine
|
|
|
What is the most important vasoconstrictor?
|
endothelin
|
|
|
How does angiotensin II act to vasoconstrict the smooth muscle?
|
It is either converted by the endothelial cell from angiotensin I and passed on to the smooth muscle layer or it diffuses right through.
|
|
|
What kinds of vessel abnormalities can result in turbulence or disturbed laminar flow?
|
Occlusions like atherosclerosis
Branch points Bends in the vessel |
|
|
Why doesn't transmural pressure just force all the water out when we stand?
|
legs are sturdy and exert a lot of pressure back.. We also have good lymph pumping out of the legs.
|
|
|
What does sheer stress on an endothelial cell do?
|
Activates mechanoreceptors that are achored to both the apical surface and the basement membrane to alter gene expression to constrict more by producing less NOS.
|
|
|
How does the normal endothelial cell exert anti inflammatory and antiatherosclerotic phenotype?
|
Production of NO and and lack of adhesion molecules.
|
|
|
Where do atherosclerotic plaques form first and why?
|
At brnach points because this is where changes in sheer stress occur first.
|
|
|
What signals from the muscle side tell the smooth muscle of arterioles to relax?
|
adenosine (breakdown of ATP), H+, CO2, and K+ (products of metabolism)
|
|
|
What are the two ways in which sodium raises blood pressure?
|
1. increases volume --> inc venous return --> inc stroke volume --> inc systolic
2. increases TPR |
|
|
What is the difference between atherosclerosis and arteriosclerosis?
|
arteriosclerosis is any hardening of the arteries whereas atherosclerosis is hardening and narrowing due to plaque buildup.
|
|
|
What does a plaque consist of?
|
A sometimes calcified necrotic lipid core with foam cell surrounded by a fibromuscular cap.
|
|
|
What are fatty streaks? How early do they begin to form?
|
initial lesion of deposition of LDL ingested by macrophages that stretch on. They are seen in most teenagers.
|
|
|
WHat results in the fibromuscular cap formation?
|
inflammation, healing, and more lipid deposition
|
|
|
How much do arteries have to narrow before you start experiencing symptoms?
|
70% stenosed
|
|
|
Describe the difference between a embolus and a thrombus?
|
Thrombus is when the plaque cracks and a clot forms. Embolus is when the plaque breaks off and lodges somehwere else.
|
|
|
What happens to the strength of the arterial wall after atherosclerosis? Why?
|
It weakens because the plaque blocks off blood supply so you are at risk for aneurysm.
|
|
|
Describe the types of arteriosclerosis.
|
Atherosclerosis - large and medium arteries
Arteriolosclerosis - small arteries |
|
|
What are the two types of arteriolosclerosis?
|
Hyaline and hyperplastic
|
|
|
What is hyaline arteriolosclerosis?
|
when there is thickening due to a protein deposition of hyaline membrane.
|
|
|
What causes hyaline arteriolosclerosis?
|
1. chronic benign HTN forcing protein in
2. diabetes glycosylating the basement membrane and making it leaky to allow protein in. |
|
|
Why do people with diabetes get renal failure?
|
Their hyaline arteriolosclerosis narrows the renal arteries, causing the glomeruli to die and scar.
|
|
|
Describe the cause and process of hyperplastic arteriosclerosis.
|
Smooth muscle cells start to proliferate and form many different layers. It looks like an onion skin and is caused by malignant hypertension in an attempt to contain the ridiculously high BP.
|
|
|
What is Monkelburg's Medial Calcific Sclerosis?
|
A nonclinical incidental finding of calcification of the artery walls that does not affect the caliber of the vessel lumen.
|
