A&P for Cardiac Flashcards
describe the pericardium
fibrous outer sac, serous parietal layer that minimizes friction during contraction, and visceral layer aka epicardium
what are the three layers of the heart
epi, myo, and endocardium
where is the tricuspid valve
between RA and RV
where is the pulmonary valve
between RV and Pulm Artery
where is the mitral valve
between the LA and LV
Without neural influence, the impulse from the SA node beats at _______ bpm (inherent rhythmicity)
100
what is the purpose of the AV node
delay A-V impulse until atria have had time to eject their contents into the ventricles
what is the inherent rhythmicity of the AVN
40-60 bpm
what is the p wave
atrial contraction
what is the QRS wave
ventricular contraction
what is the T wave
ventricular relaxation
how does the vagus nerve exert its influence over the heart?
parasympathetically - decreases HR
how do the upper thoracic nerves and rami of the sympathetic trunk exert their influence over the heart?
sympathetically - inc HR
the sympathetic receptors of the heart are primarily _________, and stimulation by ________ increases overall activity of the heart
beta-adrenergic; norepinephrine
the sympathetic receptors of the peripheral vasculature are primarily __________, and when activated they can cause systemic _________
alpha-adrenergic; vasoconstriction
describe the pressure-resistance relationship of the R side of the heart
low pressure system with little resistance from the pulm arteries
describe the pressure-resistance relationship of the L side of the heart
high pressure system with high resistance from systemic circulation
what is the primary determinant of oxygen delivery
cardiac output!
CO = SV x HR
what are the three factors that influence stroke volume
preload (starling effect), afterload, and myocardial contractility
how does preload influence stroke volume
increased preload = increased SV
how does afterload influence stroke volume
increased afterload = decreased SV
what is the frank-starling effect
increase in ventricular volume increases systolic force but excessive stretching in fluid overload impairs actin/myosin interaction thus impairing contractility
blood pressure is a product of __________ and ____________
CO and TPR
what is pulse pressure and what can it tell you about heart disease
pulse pressure is the difference between SBP and DBP and increased pulse pressure is a risk factor for heart disease
where in the body do we regulate BP?
vasomotor center in the medulla which mediates sympathetic and vagal inputs
what is the short term regulator of BP
arterial baroreceptors - if BP increase, CO and TPR decrease
what is the long term regulator of BP
renin-angiotensin-aldosterone system - kidneys compensate for BP decrease by activating angiotensin 2 which leads to vasoconstriction
water retention in the kidneys is another long term regulatory mechanism in response to low blood volume, but how does it work?
low blood volume stimulates posterior pituitary ADH which leads to vasopressin upregulation
