Cardiovascular Flashcards
How does first degree AV block show up on EKG, and what causes it?
- prolonged PR intervals
- delayed conduction between atria and ventricles
- hyperkalemia, myopathy
What do supernumerary P-waves on 2nd degree block EKG show?
intermittent conduction between atria and ventric;es
How does a 3rd degree block look on ekg?
- supernumerary P-waves
- no consistent relationship between P-wave and QRS complex (atria and ventricles contracting independently)
Describe isovolumic phases of the cardiac cycle.
- all 4 valves closed
- pressure changes
- volume remains constant
What does a Wigger’s diagram show?
pressure over time
What influences cardiac output?
- body position
- pregnancy
- age
- sleep, activity
- fitness
- meals
What does chronotropic mean?
influencing heart rate
What does ionotropic mean?
influencing force of contraction
What does dromotropic mean?
influencing conduction through AV node
What does lusitropic mean?
influencing relaxation (after contraction)
What is Starling’s Law of the Heart?
- Force of ventricular contraction increases as the ventricular myocardium is stretched (greater EDV leads to more forceful contraction)
- as preload increases, so does force of contraction
preload
resistance (or work that must be performed) to pump the ventricular blood out of the heart
afterload
the resistance of the discharge of blood imposed by the backpressure of the blood in the arteries and veins
Venous compliance
- change in volume that accompanies a change in pressure
- veins are 20 more compliant than arteries
- because of this, 2/3 of circulating blood resides in veins
Elevated central venous pressure occurs in what types of patients?
- right heart failure
- restrictive cardiomyopathy
- pericardial disease
- tricuspid valve stenosis
- SVC syndrome
Musculovenous pump
one-way check valves in veins of limbs
What effect would epinephrine binding to beta-2 receptors have on flow?
- would cause vasodilation
- increasing flow
How does local regulation act to maintain homeostasis is flow increases?
-will vasoconstrict
metabolic (active) hyperemia
blood vessels dilate to bring more blood to metabolically active tissue
reactive hyperemia
compensatory increase in flow following removal of a restriction that was blocking blood flow to a tissue
if local flow decreases, what mechanisms will act to cause vasodilation?
- myogenic autoregulation
- active hyperemia
- reactive hyperemia
How do baroreceptors elevate BP?
baroreceptor decreased firing leads to
- sympathetic activation, parasympathetic decrease
- constriction of arteries and veins
- elevated cardiac output (elevating BP)
How do baroreceptors decrease BP?
Firing rate of baroreceptors goes up, leading to
- parasympathetic activation, sympathetic decrease
- decrease in HR and CO
- decreasing MAP
