Chapter 20 Part 2 Flashcards
there is a plate of fibrous ct between what
atria and ventricles
the plate of fibrous ct between the atria and ventricles forms a fibrous rings around the
AV and SL valves
functions of the heart skeleton
- support for AV and SL valves by reinforcing valve openings
- acts as electrical insulation between atria and ventricles
- rigid site to which cardiac muscles attach
the conducting system in the heart is a relay system for
action potentials
specializes cardiac muscle cells=
autorhythmic
cardiac pacemaker cells
SA node
cardiac pacemaker cells are able to depolarize spontaneously and
pace the heart
cardiac pacemaker cells initate aps that spread throuhgout the heart and trigger
rhythmic contractions
conducting system allows synchronous heart activity otherwise
there would be slower impulses
what is located in right aterial wall, inferior to SVC
sinoartial node
pacemaker is how many impulses per minute
75
what determines HR
sinus rhythm
wave of depolarization spreads via
gap junctions in atria and via internodal pathway to av node
what is located in inferior interatrial septum superior to tricuspid valve
av node
atrioventricular node
the av node impulse is delayed by
0.1 seconds
what is located in superior interventricular septum
av bundle
what is the only electrical connection between the atria and ventricles
av bundle
the cardiac skeleton in av bundle=
nonconducting and insulates the rest of av junction
what is extended beneath the endocardium of the itnerventricular septum to apex of r and l ventricles
left and right bundle branches
what is inferior terminal branches of the bundles
purkinje fibers
what has fewer myofibrils, structural modifications: intercalated disc and gap junctions well developed and plentiful, allows aps to travel along purkinje fibers much faster than other cardiac muscle
purkinje fibers
ectopic focus is defined as
abnormal pacemaker= any part of the heart other than the SA node generates heartbeat
ectopic focus may be due to
abnormal sa node, hypreexcitable state= premature
ectopic focus can be due to inflammation or ischemia which causes
cardiac tissue injury
if av node becomes the pacemaker what is the bpm
40-60
if av node becomes the pacemaker it is referred to as
junctional rhythm
ectopic focus can also be due to
conduction pathway blockage; not go through the AV node= hr 30 bpm
record of electrical activity of the heart
electrocardiogram
where are the electrodes placed in electrocardiogram
body surface on the chest wall, upper arms and legs and attached to recording device
when is electrocardiogram used to diagnose
abnormality in cardiac cycle
are ekg invasive
no
ekg dx
arrythmias, abnormal conduction pathways, hypertrophy/atrophy of heart and location of cardiac tissue damage
p wave=
atrial depolarizaton-> atrial contraction
qrs wave=
ventricular depolarization-> ventricular contraction
t wave+ ventricular repolarization->
precedes ventricular relaxation
2 pumps work together:
atrial pump and ventricle pump
atrial pump or primer pump does what
fills ventricles with blood
ventricle pump or power pump does what
sends blood to body and lungs
2 phases of cardiac cycle
systole and diastole
systole means
contract
diastole means
relax
in ventricular filling
relaxed chambers
low heart pressure as blood through atria, av valves and passively into ventricles
atria contract then relax when atria contract= active ventricular filling
ventricular systole
ventricles contract, pressure closes av
isovolumetric contraction=
briefly all valves closed
ventricular ejection=
ventricle pressure increases, SL valves forced open and blood out
isovolumetric relaxation
ventricles relax, pressure drops, aortic and pulmonary trunk blood backflows
brief closing of SL valves= isovolumetric relaxation
heart sounds are
produced by pumping heart
u hear heart sounds with
sthethoscope
heart sounds are produced as
valves closes
S1: 1st heart sound=LUB (closing of av valves)
beginning of ventricular systole
S2: 2nd heart sound= DUB (closing of SL valves)
beginning of ventricular diastole
S3: 3rd = ventricular gallop in early diastole
normal on kids and athletes (tuberlence)
vs >35= CHF
S4: 4th= atrial gallop in late diastole
always abnormal: HTN or aortic stenosis
murmurs indicate
cardiac abnormalities
incompetent/ insufficient valve=
leaking backward s valve flaps not close properly regurgitation-> tuberlence
stenosis=
narrow/stiff= turbulent rushing sound prior to valve opens
both increase the amount of work done by cardiac muscle->
heart failure
murmurs can also be caused by
MI, congential abnormalities
