chapter 9- cardiac pump

Question 1

what is syncytium

Answer 1

mass resulting forma fusion of cell

- atrial and ventricular syncytium

Question 2

what is the fibrous insulator

Answer 2

by fibrouds tissue, exists btwn atrium and ventricle

Question 3

what do cardic cells have

Answer 3

• actin and myosin

- intercalated disk

Question 4

what are intercalated disk

Answer 4

low resistance disk btwn the cells

1/400 the resistance of cell membrane

Question 5

what is the resting membrane potential of cardiac muscles

Answer 5

-85 to 95 millivolts

Question 6

what is the volts of the action potential

Answer 6

105 millivolts total ( from -85 to +20 mV)

Question 7

how long does the plateau last

Answer 7

.2 to -.3 sec in ventricular muscle ( but is much longer than skeletal m.)

Question 8

how do you power the heart

Answer 8

action potentials

Question 9

what is phase 0 of the ventricular ap

Answer 9

fast na channel open

Question 10

what is phase 1 of the ventricular ap

Answer 10

transient outward K channels open

Question 11

what is phase 2 of the ventricular ap

Answer 11

ca channels open more this ca is used for muslces contractions

Question 12

what is phase 3 of the ventricular ap

Answer 12

k channels open more

Question 13

what is phase 4 of the ventricular ap

Answer 13

resting membrane potential

Question 14

where is ca released from

Answer 14

saroplasmic reticulum

extracellular fluid

Question 15

what does the the released of the extracellular fluid ca do

Answer 15

1 works with the contractions

2 stimulated the sarcoplasmic reticulum to make mroe Ca++

Question 16

how does the Ca come form the extracellular fluid

Answer 16

through t tubules

Question 17

what is tid

Answer 17

slide 7

Question 18

what is diad

Answer 18

slide 7

Question 19

how does skeletal m. increase force development in the m.

Answer 19

recruit more motor units via motor neurons

Question 20

how does cardia m. increase the force of contraction

Answer 20

increase intracellular calcium unmask more binding sites

Question 21

how long is the conduction of the ap along both atrial and ventriclar m.

Answer 21

is about .3 to .5 m/sec

Question 22

how long is the conduction of the ap in the purkinje fibers is

Answer 22

about 4 m/sec

Question 23

what is the absolute refractory

Answer 23

this is during this time cardiac m. cannont be re excited

Question 24

how long is the absolute refractory in the ventricles

Answer 24

.25-30 sec

Question 25

how long is the absolute refractory in the atria

Answer 25

.15 sec

Question 26

what is the relative refracotry

Answer 26

.05 sec are more difficult to excite

Question 27

what is the absolute refracotry period

Answer 27

cell is completely unexcitable to a new stimulus

Question 28

what si effective refractory period

Answer 28

absolute refracotry period + short segment of phase 3 during which a stimulus may cause the cell to depolarize minimally but will not result in a propagated action potential

Question 29

what is relative refaractory period

Answer 29

a greater than normal stimulus will depolarized the cell and cause and action potential

Question 30

what is the supranormal period

Answer 30

hyper excitable period during which a weaker than normal stimulus will depolarize the ells and cause an ap

Question 31

what can supranormal period cause

Answer 31

can cause arrhythmias when exposed to an inappropriate timed stimulus

Question 32

what is the cardiac cycle

Answer 32

beginning of one heart beat to the beginning of the next heart beat

Question 33

what is the timing o the cardiac cycle related too

Answer 33

THE HR

Question 34

what is systole

Answer 34

ventricular m. stimulated by action potential and contracting

Question 35

what is diastole

Answer 35

ventricular m. reestablishing NA/ K/ CA gradient and is relaxing

Question 36

what is p wave

Answer 36

atrial wave

Question 37

what is QRS

Answer 37

ventricular wave

Question 38

What is T

Answer 38

ventricular repolarization