Electrical activity of the heart Flashcards
What forms the physical connection between 2 cells?
desmosomes
What forms the electrical connection between 2 cells?
Gap junction
What name is given to the repeating alternate pattern of desmosomes and gap junctions in cardiac cells?
intercalated discs
What ion is responsible for the contraction of muscle?
Calcium
Does skeletal muscle or cardiac muscle demonstrate tetanus?
Skeletal muscle
What is meant by the functional syncytium in cardiac muscle?
It acts as a syncytium would ie one massive cell but really all the cells still have their own nucleus and are just helped to contract as one
Does cardiac muscle have a long or short action potential in comparison to skeletal muscle?
Long
Why can cardiac muscle not exhibit tetanic contraction?
Long refractory period
What can calcium entry regulate about the contraction?
strength
What do cells with unstable resting membrane potential act as?
Pacemakers
What is the initial depolarisation in non pacemaker cells due to?
Initial depolarisation due to sodium
What is the plateu in non pacemaker cells due to?
Increase in calcium through voltage gated channels and also a decrease in the leaky potassium channels
What is the repolarisation in non pacemaker cells due to?
Reversing the plateu eg reinstating the permeability of leaky potassium channels and a decrease in the permeability to calcium
What is the action potential in packemaker cells due to?
Increase in permeability to calcium
What is the pacemaker pre potential due to?
Not a simple story, basically anything that makes the cell more positive
For every degree Celsius change in body temperature how much does the heart rate increase by?
10 beats per minute
What drugs decrease the force of contraction?
calcium channel blockers
What drugs increase the force of contraction?
cardiac glycosides
How are hypo and hyper kalemia anomalous?
They both cause fibrillation and heart attack and are not opposites
What is the sino atrial node also known as?
The pacemaker
What is the main thing of importance about the annulus fibrosus?
It is non conducting
Why is the AV node also known as the delay box?
As the annulus fibrosus is not conducting all blood travels through via this and so slows down emptying of the atria before the ventricles contract
What is the function of the bundle of his and purkinje fibres?
Rapid conducting system and ensures the ventricles contract in unison
What does ECG stand for?
electrocardiogram
