Lecture 9 Flashcards
Are there more contractile or electrical cells in the heart
Contractile
Structure of electrical cells?
pale, strained apparence with low actin and myosin because they only weakly contract
What is the role of electrical cells?
To conduct an electrical signal quickly signalling the the contractile cell that it’s time to contract
What type of signal is sent by electrical cells
electrical - calcium signal
Why do electrical cells have less actin and myosin?
Only Weakly contract and allows more room for ions to flow through and communicate
Structure of contractile cells/
strained appearance with high actin and myosin.
Do APs propagate along the surface membrane of both cells?
Yes
What is the Sinoatrial Node (SA) node?
A collection of Cells.
Pacemaker that tells the heart when to beat.
Where depolarisation starts.
It is in communication with conduction cells
Where does electrical signal travel?
Down to contractile cells and between neighbouring electrical cells
What occurs in contractile cells?
Increased cytotoxic Calcium levels, cross bridge attachment and contraction
What structure connects most cells of the heart?
Intercalated discs (which contain gap junctions)
What are the pores on intercalated discs and what is their purpose?
Gap junctions - allow different types of molecules to move from one cell to the next.
Features of Gap junctions?
Small to limit the amount moving through.
ions move easily through gap junctions, increasing ca concentration
Where are gap junction located?
Between electrical and contractile cells, and between other contractile cells.
Function of gap junctions?
To increase speed of impulse throughout the heart
What is the Interatrial bundle?
Connects SA node to left atrium
What do internodal bundles do?
Send signal down to AV node
Role of AV node?
Collects electrical signal from SA node and puts a pause on it before sending it on, this allows the two atria to fully contract and start relacing.
What does the septal wall do?
Separates left and right ventricle
What does the AV bundle do?
Branches into two AV bundle branches which sends the signal down to the bottom of the heart
What are purkinje fibres?
Electrical cells that are embedded into ventricular walls
Where does contraction start?
At the bottom upwards through the purkinje fibres to pump blood in the most efficient way
order of Contraction?
Atria contract first… ventricles contract second.
Right and left pumps contract simultaneously.
What are ECG (Electrocariogram)?
ECG measure changes in electrical signal, by monitoring different areas of the body.
Looking at the output of ECG shows changes in the electrical signal eg, arriving and leaving depolarization
What is the P wave?
Represents atrial depolarization, initiated by the SA node
What is the QRS complex?
Represents when Ventricular depolarization begins and Atrial repolarization occurs
What is the T wave?
Represents when Ventricular repolarization occurs at apex
