Cardiovascular and Hematology Review Flashcards
Atrial Natriuretic Peptide (ANP) is secreted in response to?
Atrial pressure
B-type Natriuretic Peptide (BNP) is secreted in response to?
Overstretched ventricles
Individual cells in cardiac muscles are connected by what?
Intercalated discs
How do ions pass between myocytes in the heart?
Gap junctions
In the resting state there which ions are more concentrated on the outside? Inside?
Na+, Ca++
K+
Describe the four phases of muscle contraction of cardiac muscle.
Sodium influxes into cardiac myocytes causing deopolarization and then the channels close and K+ leaves via leaky channels causing some repolariztion, thencalcium enters through L-type Ca++ channels leading to the plateau phase, and then inactivation of Ca++ into cell leads to rest of repolarization as K+ continues to leave via leaky channels and than excess Na+ and Ca++ with restoration of membrane potential and K+ comes back into cell w/Na+/K+ ATPase
Absolute refractory period:
no action potential can be initiated regardless of the stimulus strength because sodium channels are closed in Phase 1 to mid Phase 3
Relative refractory period:
no action potential can be elicited, however a greater stimulus is needed - extends between the middle of Phase 3 to the start of Phase 4
Frank-Starling law:
Cardiac output is directly proportional to the venous return
Force of contraction is directly proportional to length of fiber
Greater amount of blood entering heart during diastole the greather the stretching on cardiac myocytes
The greater stretch results in greater F of contraction causing increase in cardiac output
What causes the first heart sound? (LUB)
Closure of tricuspid and mitral valves
What causes the second heart sound? (DUB)
Closure of the pulmonary and aortic valves
When is the third heart sound heard? (DUBup)
After second in patients with congestive heart failure
When is the fourth heart sound heard? (beLUB)
Before the 1st in hypertrophic ventricle
Systole (contraction) occurs between which heart sounds?
1 and 2
Diastole (relaxation) occurs between which heart sounds?
2 and 1
What is measured in an electrocardiogram?
Electrical activity in heart as the impulse generated in the SA node and propagated to the rest of the heart
How many times does the SA node go off in a minute?
80-100
What spreads the electrical impulse of the SA node through the heart?
Intra-atrial bundles
What is the rate of depolarization of the AV node per minute?
40-60X
When the SA node rhythm is superimposed upon AV node rhythm the heart rate is?
70 bpm
The impulse of the AV node is sent into what and then into what located in the muscular part of the interventricular septum?
Bundle of His
R/L bundle branches
Where is the conduction velocity slowest in the heart? Fastest?
Slow: AV node
Fast: Purkinje fibers
The rate of depolarization is slowest where in the heart? Fastest?
Purkinje fibers
SA node
P wave?
Atrial depolarization, precedes atrial contraction
PR interval:
P wave to Q wave
1st degree AV block causes?
Prolonged PR interval >200 ms
2nd degree AV block causes?
Progressive prolongation of PR interval w/dropped beats
3rd degree AV block causes?
No association btw P and QRS complex
QRS complex?
Ventricular depolariztion