Conduction system of the heart Flashcards Preview

Perfusion Program Fall 2014 > Conduction system of the heart > Flashcards

Flashcards in Conduction system of the heart Deck (47)
Loading flashcards...
1

Name the conduction system in order starting at the top?

1.) Sinus Node
2.) AV Node
3.) AV bundle
4.) Left & Right bundle branch
5.) Purkinje Fibers

2

Cardiac Muscle

Elongated, branching cells containing 1-2 centrally located nucl

3

Cardiac Muscle contains ?

- actin and myosin
myofilaments

4

Intercalated disks

Specialized Cell - Cell contacts

5

Desmosomes

hold cells together

6

allow action potentials to move from one cell to the next

Gap junctions

7

Electrically, cardiac muscle of the atria and of the ventricles behave as ?

Single Unit

8

Cardiac Mitochondria comprise

30% of volume of the cell

9

Skeletal Mitochondria comprise

2 % volume of the cell

10

Cardiac action potential

conducted from cell to cell

11

Skeletal action potential

conducted along the length of a single fiber

12

Rate of Action Potential Propagation
in CARDIAC muscle?

Slow because of gap junctions and small diameter of fibers.

13

Rate of Action Potential Propagation
in SKELETAL muscle?

Faster due to larger diameter fibers.

14

CICR

Calcium-induced calcium release

15

What stimulates release of Ca2+ from sarcoplasmic reticulum
?

Movement of extracellular Ca2+ through plasma membrane and
T tubules into sarcoplasm

16

Action potential in T-tubule

also stimulates Ca++ release from sarco-plasmic reticulum

17

Rising phase of action potential is due to ?

opening of fast Na+ channels

18

Plateau phase of action potential is due to ?

- Closure of sodium
channels
- Opening of calcium
channels
- Slight increase in K+
permeability
- Prevents summation
and thus tetanus of
cardiac muscle

19

Repolarization phase of action potential is due to ?

- Calcium channels
closed
- Increased K+
permeability (K+ out)

20

SA node sends conduction to what 2 structures?

AV node
Left Atrium

21

mV =

millivolts

22

SA node

The Pacemaker
- Specialized cardiac
muscle cells.
- generate
spontaneous action
potentials
-

23

AV node

- Action potentials conducted more slowly here than in any other part of system.
- Ensures ventricles receive signal to contract after atria have contracted

24

passes through hole in cardiac skeleton to reach interventricular septum

AV bundle

25

extend beneath endocardium to apices of right and left ventricles

Right and left bundle branches

26

- Large diameter cardiac muscle cells with few myofibrils.
- Many gap junctions.
- Conduct action potential to ventricular muscle cells (myocardium)

Purkinje fibers

27

Depolarization of SA Node has ?

no stable resting membrane potential

28

Pacemaker potential

gradual depolarization from -60 mV, slow influx of Na+

29

At what threshold does Action potential
occur?

-40 mV

30

depolarizing phase to 0 mV is a result of what ?

fast Ca2+ channels open, (Ca2+ in)