cardiac muscle and conduction system Flashcards
are cardiomyocytes striated
in them, there is one central ___ surrounded by a light staining mass of _____
yes
nucleus, glycogen
what join myocytes together
what interlock and increase the area of contact between cells on them
intercalated discs
interdigitating folds
in relation to mechanical junctions on intercalated discs:
what are actin that are anchored to the plasma membrane
what are they linked via
what do desmosomes do
fascia adherens
transmembrane proteins
punctate
in relation to electrical junctions: (gap junctions) ____ flow between cells, allows entire myocardium of either ____ atria or ventricles to act like a _____ unified cell
ions
two, single
cardiac muscle depends almost exclusively on ____ ____ to make ATP
what two molecules are rich in myocytes
what fills 25% of the cell
aerobic respiration
myoglobin and glycogen
mitochondria
myocardia are adaptable to different organic fuels, what percentage correspond to the following:
fatty acids
glucose
amino acids
what two other things is it adaptable to
60%
35%
5%
ketones, lactate
the heart is fatigue resistant because it makes little use of _____ ____ or _____ debt mechanisms
anaerobic fermentation
oxygen debt
what percent of the heart is made of nodes
what are they essentially
1%
modified myocytes
what node is considered the pacemaker
SA node
conduction system in words:
____ node fires
excitation spreads through _____ myocardium
____ node fires
______ conducting networks distributes excitation through ventricular myocardium (down and up)
SA
atrial
AV
purkinje
what is the normal heartbeat triggered by SA node
sinus rhythm
an adult at rests HR:
adult HR without vagal tone:
what nervous system deal with vagal tone
70-80 bpm
100 bpm
autonomic
what is a region of spontaneous firing other than the SA node
ectopic focus
what is the heart rate if there is an ectopic focus on the AV node
40-50 bpm
