cardiac muscle and conduction system

Question 1

are cardiomyocytes striated

in them, there is one central ___ surrounded by a light staining mass of _____

Answer 1

yes

nucleus, glycogen

Question 2

what join myocytes together

what interlock and increase the area of contact between cells on them

Answer 2

intercalated discs

interdigitating folds

Question 3

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

Answer 3

fascia adherens

transmembrane proteins

punctate

Question 4

in relation to electrical junctions: (gap junctions) ____ flow between cells, allows entire myocardium of either ____ atria or ventricles to act like a _____ unified cell

Answer 4

ions

two, single

Question 5

cardiac muscle depends almost exclusively on ____ ____ to make ATP

what two molecules are rich in myocytes

what fills 25% of the cell

Answer 5

aerobic respiration

myoglobin and glycogen

mitochondria

Question 6

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

Answer 6

60%
35%
5%

ketones, lactate

Question 7

the heart is fatigue resistant because it makes little use of _____ ____ or _____ debt mechanisms

Answer 7

anaerobic fermentation

oxygen debt

Question 8

what percent of the heart is made of nodes

what are they essentially

Answer 8

1%

modified myocytes

Question 9

what node is considered the pacemaker

Answer 9

SA node

Question 10

conduction system in words:

____ node fires
excitation spreads through _____ myocardium
____ node fires
______ conducting networks distributes excitation through ventricular myocardium (down and up)

Answer 10

SA
atrial
AV
purkinje

Question 12

what is the normal heartbeat triggered by SA node

Answer 12

sinus rhythm

Question 13

an adult at rests HR:
adult HR without vagal tone:
what nervous system deal with vagal tone

Answer 13

70-80 bpm
100 bpm
autonomic

Question 14

what is a region of spontaneous firing other than the SA node

Answer 14

ectopic focus

Question 15

what is the heart rate if there is an ectopic focus on the AV node

Answer 15

40-50 bpm

Question 16

what is the threshold for resting potential

Answer 16

-40 mV

Question 17

the SA node stimulates two ___ to contract almost simultaneously
how many ms does this take

where does the signal slow down through
how much does it delay the signal

Answer 17

atria
50

AV node
100 ms

Question 18

the signals travel very ____ through AV bundle and subendocardial conducting network

Answer 18

quickly

Question 19

what is another term for purkinje fibers

Answer 19

sunendocardial conducting network

Question 20

ventricular systole progresses ___ the apex

Answer 20

up

Question 21

what is a composite of all action potentials of nodal and myocardial cells detected

remember, it is a recording of ALL _____, not just nodes

Answer 21

ECG
myocardial

Question 22

deviations of ECG from normal can indicate:
myocardial ____
abnormalities in _______ pathways
heart ______
______ and _____ inbalances

Answer 22

infarction
conductions
enlargement
electrolyte, hormone

Question 23

what is endothelia in blood vessels

Answer 23

tunica interna

Question 24

where is the smooth muscle, collagen, and elastic tissue in blood vessels

Answer 24

tunica media

Question 25

where is the connective tissue in blood vessels

Answer 25

tunica externa

Question 26

what are at the boarder between interna and media

Answer 26

internal elastic lamina

Question 27

what are at the boarder between media and external

Answer 27

external elastic lamina

Question 28

the elastic lamina:

_____ during systole
what does this do

_____ during diastole
what does this do

Answer 28

expand
take pressure off smaller downstream vessels

recoil
maintains pressure during relaxation and keep blood flowing