Lecture 9 Heart Physiology Flashcards
Electrical cells of heart
1%
Pale striated appearance
Low actin and Myosin
Contractile cells of heart
99%
Striated appearance
High actin and Myosin
Action potentials spread (propagate) along the..
Surface membrane of electrical and contractile cells.
Where does depolarization start?
sinoatrial node (SAN). This signal spreads to neighbouring cells.
In a contractile cell:
increased cytosolic Ca2+ level, X-bridge attachment and contraction
What connects cardiac cells together?
Intercalated disks and gap junctions.
Intercalated discs connect
most cells of the heart.
Gap Junctions consists of
Pores with low resistance to ionic current.
Allows current flow between adjacent cells.
Connect electrical cells
Connect contraction cells
Connect electrical cells and contraction cells
why don/t Contractile cells communicate the signal quickly?
High actin and myosin
Functional syncytium
Individual cells work as a unit.
communicate using gap junctions
SA node (sinoatrial)
where signal begins to tell the heart to beat (contract)
sits above right atrium
where does the SA node signal go?
3 directions
right atrium
left atrium
AV node
Right atrium receives signal from SA node to..
contract
Left atrium receives signal from SA node to..
contract
Why and How does the SA node signal get to the left atrium?
Both atriums have to contract simultaneously
Goes across the interatrial bundle