anatomy and physiology review Flashcards
what are the two basic functions of the heart?
maintain good electrical function and good pump function (BP and CO)
what is BP? ___x ____
resistance x blood flow
what is CO?
HR x SV
what is SV?
preload, after load and contractility
out of preload, after load and contractility which does total circulating vol affect?
preload
out of preload, after load and contractility which does blood viscosity affect?
afterlaod
out of preload, after load and contractility which does body position affect?
preload
out of preload, after load and contractility which does acidosis affect?
contractility
where is the right coronary artery and what does it feed?
courses laterally around the right side of the heart int he right atrioventricular groove feeding the anterior right atrium and the anterior right ventricle and the sA node and all the way around to the crux (juncture of the atrioventricular and intraventricular grooves) supplying the AV node
once the right coronary artery descends towards the apex what is ti called and what does it feed
the posterior descending brand of the right coronary and feeds the inferior surface (wall) of both the right and left ventricles, the posterior 1/3 of the intraventricular septum and the posterior fascicle of the left bundle branch
what are the two main branches on the left coronary artery>
the left anterior descending (LAD) and the circumflex (Circ)
what does the LAD feed?
down anterior intraventricular groove feeding the anterior surface (wall) of left atrium and ventricle. and smaller branches (septal) feed the anterior right ventricular walls nd 2/3 anterior ventricular septum including the anterior fascicle of the eft b uncle branch and the r bundle branch
what does the circumflex feed?
circles laterally around the heart in the left atrioventricular groove feeding the left atrium and the lateral surface (wall) of the left ventricle
which layer of the heart contracts first? why is this off? why?
subendocardial (innermost layer). it is the last layer to receive blood bc coronary arteries penetrate the heart muscle from outside in
when do the coronary arteries perfuse the heart?
when the heart is relaxed (diastole)
at what point (PQRST) is the electrical stimulus slowed to allow for filling?
PR interval to allow or ventricular filling in diastole
how much of the atrial kick contributes to CO?
20-30%
does the electrical impulse go to the bundle of his or purkinje fibres first/
bundle of his
where is the SA node located? what does it consist of? what is its intrinsic rate? is it innervated by parasympathetic or sympathetic NS?
right atrium adjacent to the superior vena cava. highly specialized cells that initiate electrical impulses (automaticity) at 60-100bpm. both
where is the AV node located? function? intrinsic rate? does the AV node allow the electrical impulse to go faster or slower? why?
floor of the right atrium. can function as a secondary pacemaker if SA node fails. 40-60 bpm. slows it down to allow the atria to finish emptying its contents into the ventricles
what does the His-Purkinje system consist of? rate?
his bundle, bundle branches and the purkinje fibers. his bundle divides into two main divisions forming the r and l bundle branches and feed into the purkinje fires. can initiate an impulse if SA and AV node fail at 20-40 bpm
the fibres in the sympathetic system supply what? what are these fibres called?
atria and the ventricle. adrenergic fibres which indicates a relationship to adrenaline
what does the SNS stimulate? think location
the adrenal medulla to release epi and norepinephrine that act on the adrenergic receptors in the heart
what is the effect of flight or fight response?
inc HR, inc contraction, inc in conduction resp rate and dec activity in GI
what are drugs called that mimic SNS or block it? para SNS?
sympathomimetic and sympatholytic
parasympathomimetic and parasympatholytic
the paraSNS acts on the heart via the ___
vagus nerve