Electrical Activity of the Heart Flashcards
How do cells within the heart communicate with each other electrically ?
Via intercalated discs (desmosomes & gap junctions)
Unlike in skeletal muscle contractions what occurs in cardiac muscle with regards to Ca ?
Unlike in skeletal muscle Ca can be regulated in cardiac muscle. The amount of Ca coming in determines how strong the contraction is.
What is the resting membrane potential of cardiac muscle and what is this due to ?
-90mV due to leaky potassium channels
What are the two types of cell found within the heart ?
Pacemaker cells & non-pacemaker cells
What type of cell within the heart has an unstable resting membrane potential ?
Pacemaker cells
What maintains the resting membrane potential of non-pacemaker cells and what is the RMP ?
Leaky potassium channels and -90mV
What do Calcium channel blockers do to the heart ?
Decrease the force of contractions
What do cardiac glycosides do t the heart ?
Generate stronger contractions (more cross bridges are formed)
What are 3 mediators of electrical activity within the heart ?
Drugs
Temperature
Hyperkalaemia
What does Hyperkalaemia do to the heart ?
An increase in potassium in the plasma causes fibrillation & heart block
What is hypercalcaemia and what does it do to the electrical activity of the heart ?
Too much Calcium
Causes and increase in heart rate and increases the force of contractions
What is Hypocalcaemia and what does it do to the electrical activity of the heart ?
Low calcium levels (less cross bridges being formed)
Decreases heart rate and decreases force of contractions
What are the four main parts of the conduction system of the heart ?
Sinoatrial Node
Atrioventricular Node
Bundle of His
Purkinjie Fibres
What is the Annulus Fibrosis ?
It is tissue which separates the atria from the ventricles and it is non-conducting
